星系的天体物理学

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[1] arXiv:2508.02776 [中文pdf, pdf, html, 其他]

标题： SDP.81引力透镜系统中质量结构的ALMA长基线观测研究 显示英文标题

标题： Investigation of mass substructure in gravitational lens system SDP.81 with ALMA long-baseline observations

H. R. Stacey, D. M. Powell, S. Vegetti, J. P. McKean, D. Wen

评论： 提交至A&A；14页

主题： 星系的天体物理学 (astro-ph.GA)

低质量暗物质晕的普遍性和特性是理解暗物质本质的关键测试，并可能通过强引力透镜弧的引力偏折来约束。 先前的研究在对引力透镜、尘埃星形成星系SDP.81的观测中发现了低质量暗物质晕存在的证据，使用的是阿塔卡马大型毫米波/亚毫米波阵列（ALMA）。 在本工作中，我们分析这些观测以评估这些报告结果的可靠性。 虽然我们的分析表明数据支持在椭圆幂律密度轮廓之外的透镜质量分布的额外角结构，但我们没有发现之前报告的两个次晕检测的证据。 然而，我们通过现实的模拟数据验证了，如果真实数据中存在一个之前报告的$\approx 10^{9}\,{\rm M_{\odot}}$次晕，我们可能会找到支持它的证据，其对数贝叶斯因子为29。 在测试了各种系统误差后，我们发现这次晕推断很可能是虚假的，原因是平滑模型不足，特别是多极矩拟合不佳。 虽然我们没有发现任何单个次晕的证据，但我们发现多极矩（$m=3,4$）和单个大质量次晕的透镜特征具有相似性，这与其他最近的工作一致。 我们建议未来的透镜弧中低质量晕的搜索应包括以多极形式表示的透镜角结构，直到四阶，并需要一个良好的拟合平滑模型作为前提条件。 总体而言，我们的发现证明了这种质量的ALMA数据适合同时约束低质量晕的丰度和透镜角结构。 显示英文摘要

The prevalence and properties of low-mass dark matter haloes serve as a crucial test for understanding the nature of dark matter, and may be constrained through the gravitational deflection of strongly lensed arcs. Previous studies found evidence for the presence of low-mass dark matter haloes in observations of the gravitationally lensed, dusty star-forming galaxy SDP.81, using the Atacama Large Millimetre/sub-millimetre Array (ALMA). In this work, we analyse these observations to assess the robustness of these reported results. While our analysis indicates that the data support additional angular structure in the lensing mass distribution beyond an elliptical power-law density profile, we do not find evidence for two previously reported sub-halo detections. However, we verify with realistic mock data that we could have found evidence in favour of a previously reported $\approx 10^{9}\,{\rm M_{\odot}}$ sub-halo with a log Bayes factor of 29, should it exist in the real data. After testing various systematics, we find that this previous sub-halo inference was most likely spurious and resulted from an inadequate smooth model, specifically, poorly fitting multipoles. While we do not find evidence in favour of any individual sub-halo, we find evidence for similarity in the lensing signatures of multipoles ($m=3,4$) and single massive sub-haloes, consistent with other recent work. We suggest that future searches for low-mass haloes in lensed arcs include lens angular structure in the form of multipoles up to 4th order and require a good-fitting smooth model as a prerequisite. Overall, our findings demonstrate the suitability of ALMA data of this quality to simultaneously constrain the abundance of low-mass haloes and lens angular structure.

[2] arXiv:2508.02792 [中文pdf, pdf, html, 其他]

标题： 发光中红外选定的宇宙午夜SDSS Stripe82 II中的隐匿类星体：光谱多样性与宽H$α$ Emissions 显示英文标题

标题： Luminous Mid-IR Selected Obscured Quasars at Cosmic Noon in SDSS Stripe82 II: Spectroscopic Diversity and Broad H$α$ Emissions

Ben Wang, Yuzo Ishikawa, Joseph F. Hennawi, Zheng Cai, Gordon T. Richards, Nadia L. Zakamska, Daming Yang, Jan-Torge Schindler

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

我们对23个明亮的中红外选择的II型类星体进行了多波长光谱调查，红移范围为z = 0.88至3.49。这些目标基于SDSS Stripe 82区域内的亮WISE W4检测（通量>5 mJy）和极暗或红色的光学对应物（例如，r > 23或r - W4 > 8.4）进行选择，旨在识别被严重遮蔽的类星体。深近红外（Gemini/GNIRS）和光学（Keck/LRIS和KCWI）光谱确认了24个候选体中有23个在该红移范围内为II型类星体，包括12个z > 2的天体。光谱显示有强烈的静止框架紫外和光学发射线（Ly-alpha，C IV，[O III]，H-alpha），具有广泛的线宽，表明光谱多样性显著。大约三分之一的样本（23个中的8个）尽管属于II型分类，但仍显示出宽H-alpha发射（FWHM > 2000 km/s），其余天体仅有窄线（FWHM < 2000 km/s），这是经典遮蔽类星体的特征。值得注意的是，这些宽线II型类星体与JWST发现的“小红点”（LRD）活动星系核具有相似的光谱能量分布，表明我们的样本可能是JWST揭示的被严重遮蔽的宽线活动星系核的低红移类似物。我们还发现，对于其高全波段光度而言，[O III] 5007埃发射相对较弱，偏离了低红移II型QSO中看到的趋势。我们使用本样本构建了一个新的II型QSO综合光谱。总体而言，我们的结果表明，中红外选择能有效地揭示被遮蔽类星体的多样化群体，而光谱后续观测对于揭示它们的真实性质至关重要。这项研究为宇宙鼎盛时期被严重遮蔽的超大质量黑洞增长提供了新见解，并填补了现在由JWST揭示的被遮蔽活动星系核群体之间的空白。 显示英文摘要

We present a multiwavelength spectroscopic survey of 23 luminous mid-infrared-selected Type-2 quasars at redshifts z = 0.88 to 3.49. The targets were selected in the SDSS Stripe 82 field based on their bright WISE W4 detections (flux > 5 mJy) and extremely faint or red optical counterparts (e.g., r > 23 or r - W4 > 8.4), designed to identify heavily obscured quasars. Deep near-infrared (Gemini/GNIRS) and optical (Keck/LRIS and KCWI) spectroscopy confirm 23 out of 24 candidates as Type-2 quasars in this redshift range, including 12 objects at z > 2. The spectra exhibit strong rest-frame UV and optical emission lines (Ly-alpha, C IV, [O III], H-alpha) with a wide range of line widths, indicating significant spectral diversity. Approximately one-third of the sample (8 of 23) shows broad H-alpha emission (FWHM > 2000 km/s) despite their Type-2 classification, while the rest have only narrow lines (FWHM < 2000 km/s) characteristic of classical obscured quasars. Notably, these broad-line Type-2 quasars share similar spectral energy distributions with the JWST-discovered "little red dot" (LRD) AGNs, suggesting that our sample could be lower-redshift analogues of the heavily obscured broad-line AGNs uncovered by JWST. We also find that the [O III] 5007 angstrom emission is relatively weak for their high bolometric luminosities, deviating from trends seen in lower-redshift Type-2 QSOs. A new composite spectrum for Type-2 QSOs is built using our sample. Overall, our results demonstrate that mid-IR selection efficiently uncovers a diverse population of obscured quasars and that spectroscopic follow-up is crucial for revealing their true nature. This study provides new insights into heavily obscured SMBH growth at cosmic noon and bridges the gap to the obscured AGN populations now being revealed by JWST.

[3] arXiv:2508.02837 [中文pdf, pdf, html, 其他]

标题： 星系团质量吸积的回忆：探测模拟星系团中星系间光的边缘 显示英文标题

标题： Memoirs of mass accretion: probing the edges of intracluster light in simulated galaxy clusters

Tara Dacunha, Phil Mansfield, Risa Wechsler

评论： 提交至天体物理学杂志，24页，13图

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

在大质量星系团中广泛存在的弥漫星光，称为星系间光（ICL），有可能被解读为质量吸积的回忆录：有信息量、个体化且不完美。 在这里，我们将 Symphony 套件中的暗物质仅模拟与 Nimbus 的“恒星标记”模型相结合，以评估从理想化的 ICL 外缘测量中能获取多少关于单个星系团质量组装的信息。 我们表明，星系团恒星分布的边缘——主要（Rsp*1）和次级（Rsp*2）恒星“溅落”半径——对连续的质量吸积历史和离散的合并事件都很敏感，使它们成为探测星系团过去的强大探针。 我们发现 Rsp*1 与星系团质量在约一个动力学时间前的值高度相关，而 Rsp*2 在一定程度上更弱地追踪了近期的质量吸积历史。 结合这些特征，可以进一步区分在过去一个动力学时间内是否经历过重大合并的星系团。 我们使用它们来预测现实的星系团质量吸积历史，通过 MultiCAM 框架。 这些外部 ICL 特征比恒星质量间隙和晕浓度对质量吸积和合并历史更敏感，并且其表现与常用的基于 X 射线的松弛度示踪器 x_off 相当。 虽然我们的分析是理想化的，但相关的 ICL 特征在下一代深空成像中可能被检测到。 这项工作突显了 ICL 测量的潜力，并为更详细的预测其能力奠定了基础。 显示英文摘要

The diffuse starlight extending throughout massive galaxy clusters, known as intracluster light (ICL), has the potential to be read as a memoir of mass accretion: informative, individual, and yet imperfect. Here, we combine dark matter-only zoom-in simulations from the Symphony suite with the Nimbus "star-tagging" model of the stellar halo to assess how much information about the mass assembly of an individual galaxy cluster can be gleaned from idealized measurements of ICL outskirts. We show that the edges of a cluster's stellar profile -- the primary (Rsp*1) and secondary (Rsp*2) stellar "splashback" radii -- are sensitive to both continuous mass accretion histories and discrete merger events, making them potentially powerful probes of a cluster's past. We find that Rsp*1 strongly correlates with the cluster's mass ~1 dynamical time ago, while Rsp*2 traces more recent mass accretion history to a slightly lesser degree. In combination, these features can further distinguish between clusters that have and have not undergone a major merger within the past dynamical time. We use both to predict realistic cluster mass accretion histories with the MultiCAM framework. These outer ICL features are significantly more sensitive to mass accretion and merger histories than the stellar mass gap and halo concentration, and perform comparably to the commonly used X-ray-based tracer of relaxedness, x_off. While our analysis is idealized, the relevant ICL features are potentially detectable in next-generation deep imaging of nearby clusters. This work highlights the promise of ICL measurements and lays the groundwork for more detailed forecasts of their power.

[4] arXiv:2508.02842 [中文pdf, pdf, html, 其他]

标题： 低质量恒星形成区域中的（亚）毫米水脉泽调查 显示英文标题

标题： Survey of (sub)mm water masers in low-mass star-forming regions

P. K. Humire, C. Goddi, G. N. Ortiz-León, A. Hernández-Gómez, J-C Loison

评论： 已被A&A接收。论文包含10页，3幅图和5张表，包括附录

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

水激微波在恒星形成区域（SFRs）中很常见，22.235 GHz的跃迁在高质量和低质量原恒星中都被广泛检测到。相反，(亚)毫米波水激微波跃迁研究较少，尤其是在低质量SFRs中。我们搜索了一个已知表现出22 GHz发射的低质量SFRs样本中的毫米波水激微波。我们针对183.3、321.2和325.2 GHz的跃迁分别进行观测。我们还通过与之前报道的I类甲醇激微波（MM）比较，检查它们作为演化阶段探测器的潜力。我们使用了APEX 12米望远镜。为了评估每个源的演化阶段，我们使用档案数据对其光谱能量分布（SEDs）进行了建模，并将得出的尘埃温度作为年龄的代理。然后我们比较了样本中水激微波和甲醇激微波的出现情况。我们在18个源中的5个中检测到了183.3 GHz的水激微波。IRAS 16293-2422显示了所有三个跃迁，而Serpens FIRS 1也显示了321.2 GHz的线。尽管观测条件良好，但检测率随着频率的增加而下降，这反映了内在线弱和变化性。值得注意的是，最亮的(亚)毫米波激微波的通量密度可以与22 GHz的线相媲美。速度轮廓的比较显示，不同的跃迁通常追踪不同的气体成分。水激微波通常出现在比MM更早或相当的演化阶段，这表明没有普遍的基于激微波的年龄序列。我们的结果证明了在低质量SFRs中检测亚毫米波水激微波的可行性，尽管它们的出现较为稀少。一些厘米波和毫米波成分之间的速度重叠表明部分空间重合，但许多特征只在一个频率范围内出现，表明不同的跃迁通常追踪具有不同物理条件的不同气体区域。 显示英文摘要

Water masers are common in star-forming regions (SFRs), with the 22.235 GHz transition widely detected in both high- and low-mass protostars. In contrast, (sub)millimeter water maser transitions remain poorly studied, especially in low-mass SFRs. We search for millimeter water masers in a sample of low-mass SFRs previously known to exhibit 22 GHz emission. We target the transitions at 183.3, 321.2, and 325.2 GHz, respectively. We also examine their potential as probes of evolutionary stage by comparing them with previously reported Class I methanol masers (MM). We used the APEX 12m telescope. To assess the evolutionary stage of each source, we modeled their spectral energy distributions (SEDs) using archival data and used the derived dust temperatures as proxies of ages. We then compared the occurrence of water and methanol masers across the sample. We detected 183.3 GHz water masers in 5 out of 18 sources. IRAS 16293-2422 shows all three transitions, while Serpens FIRS 1 also displays the 321.2 GHz line. Despite excellent observing conditions, detection rates drop with increasing frequency, reflecting both intrinsic line weakness and variability. Notably, the brightest (sub)millimeter masers can reach flux densities comparable to the 22 GHz line. Comparisons of velocity profiles show that different transitions often trace distinct gas components. Water masers generally appear at earlier or comparable evolutionary stages than MM, suggesting no universal maser-based age sequence. Our results demonstrate the detectability of submillimeter water in low-mass SFRs, although their occurrence is sparse. Velocity overlap between some centimeter and millimeter components suggests partial spatial coincidence, but many features appear uniquely in one frequency regime, indicating that different transitions often trace distinct gas regions with varying physical conditions.

[5] arXiv:2508.02940 [中文pdf, pdf, html, 其他]

标题： 高红移金属增丰和丰度模式的多样性：通过z~5处的强Lyman-alpha吸收体对富含气体星系的麦哲伦调查 显示英文标题

标题： The Diversity of Metal-Enrichment and Abundance Patterns at High Redshift: A Magellan Survey of Gas-rich Galaxies Traced by Damped Lyman-alpha Absorbers at z~5

Jianghao Huyan, Varsha P. Kulkarni, Suraj Poudel, Nicolas Tejos, Celine Peroux, Sebastian Lopez

评论： 已接受发表于《天体物理学杂志》

主题： 星系的天体物理学 (astro-ph.GA)

一种强大的技术是通过在氢浓缩储层中的金属富集来追踪第一颗恒星的特征，例如早期宇宙中的高红移Lyman-alpha吸收体（DLAs）。我们进行了一项调查，旨在沿着高红移类星体视线发现DLAs，以测量z>4处的元素丰度。在这里，我们报告了10个红移约为4.2-5.0的DLAs的初步结果。我们确定了C、O、Si、S和Fe的丰度，从而确定了金属丰度和尘埃耗竭程度。我们发现z>4.5的DLA金属丰度表现出广泛的多样性，跨度约为3个数量级。在3.7<z<5.3范围内的DLA金属丰度相比低红移时具有更大的离散性。将我们的样本与文献结合，我们发现金属丰度随红移的变化相对平滑，直到z~5.3，且在4.5<z<5.3范围内有轻微上升的迹象（约2倍标准差）。相对丰度显示，无论是贫金属还是富金属的DLA都显示出C的增强。此外，在一些DLA中可以明显看出alpha元素的增强，包括一个红移为4.7的超太阳金属丰度的DLA。将[C/O]和[Si/O]与模型预测进行比较，我们的调查中有4个DLA似乎与非零的第三星族恒星贡献一致（其中3个的第三星族恒星贡献大于等于30%）。将我们的样本和文献结合起来，我们发现尘埃耗竭强度和尘埃与金属比与总（气相+固相）金属丰度呈正相关，证实了即使在大爆炸后约10亿年，金属丰富且富含尘埃的DLA仍然存在。 显示英文摘要

A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Lyman-alpha absorbers (DLAs) in the early universe. We conducted a survey aimed at discovering DLAs along sight lines to high-z quasars in order to measure element abundances at z>4. Here we report our first results from this survey for 10 DLAs with redshifts of ~4.2-5.0. We determine abundances of C, O, Si, S, and Fe, and thereby the metallicities and dust depletions. We find that DLA metallicities at z>4.5 show a wide diversity spanning ~3 orders of magnitude. The metallicities of DLAs at 3.7<z<5.3 show a larger dispersion compared to that at lower redshifts. Combining our sample with the literature, we find a relatively smooth evolution of metallicity with redshift out to z~5.3, with a tentative (~2 sigma) indication of a slight rise in metallicity at 4.5<z<5.3. The relative abundances exhibit C enhancement for both metal-poor and metal-enriched DLAs. In addition, alpha-element enhancement is evident in some DLAs, including a DLA at z=4.7 with a super-solar metallicity. Comparing [C/O] and [Si/O] with model predictions, 4 DLAs in our survey seem consistent with a non-zero Pop III contribution (3 with >=30% Pop-III contribution). Combining our sample and the literature, we find the dust depletion strength and dust-to-metal ratios to correlate positively with the total (gas+solid phase) metallicity, confirming the presence of metal-rich, dusty DLAs even at ~1 billion years after the Big Bang.

[6] arXiv:2508.03015 [中文pdf, pdf, html, 其他]

标题： M87核中的CO吸收线的重新审视 显示英文标题

标题： Re-examination of the CO absorption line in the M87 nucleus

Norita Kawanaka, Hiroshi Nagai, Yutaka Fujita

评论： 9页，4图，已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA)

我们分析了M87核区域的档案ALMA数据，并从CO(2--1)吸收线评估了分子气体含量。 我们在两个仅相隔两个月的时期之间发现了吸收线深度的神秘变化。 我们重新检查了用于分析的数据集，发现同一数据集中的波段校准源也显示出类似的吸收线结构。 此外，我们观察到系统噪声温度谱有所上升。 我们得出结论，之前研究中识别出的吸收线结构，被归因于CO(2--1)，并非来自M87，而是由大气污染引起的，而且我们仍然只有M87核周围分子气体的上限。 显示英文摘要

We analyzed the archival ALMA data of the nuclear region of M87 and evaluate the molecular gas content from the CO(2--1) absorption line. We found an enigmatic variability in the absorption line depth between two epochs separated by only two months. We reexamined the dataset used in the analysis and found that the bandpass calibration source within the same dataset also revealed a similar absorption line structure. Furthermore, we observed a rise in the system noise temperature spectrum. We concluded that the absorption line structure identified in a previous study, and attributed to CO(2--1), does not originate from M87 but instead results from telluric contamination, and that we still have only the upper limit on the molecular gas around the nucleus of M87.

[7] arXiv:2508.03022 [中文pdf, pdf, html, 其他]

标题： 本地宇宙中星际游荡恒星：它们的距离和光度分布的理论预测 显示英文标题

标题： Intergalactic Wandering Stars in the Local Universe: Theoretical Predictions for Their Distance and Luminosity Distribution

Jia-Hui Wang, Maosheng Xiang, Ji-Feng Liu

评论： 已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

星际游荡恒星（IWSs）在10 Mpc范围内仍然是天文学中一个研究不足的领域。 这些恒星如果存在的话，应该被视为游荡天体，因为它们不受任何星系引力势的束缚。 我们开始进行专门的研究，以揭示这种游荡恒星种群。 作为该系列的第一篇论文，本文中我们对通过银河系中心大质量黑洞（GCMBH）的Hills机制形成的IWSs的距离分布和光度函数进行建模。 我们实施了一个数值模拟，生成IWSs时考虑了GCMBH的抛射历史和恒星演化过程，并给出了200kpc - 10Mpc距离范围内的光度函数。 我们的结果表明，在过去的140亿年中，GCMBH通过Hills机制已经产生了几十万个IWSs。 这些IWSs在SDSS$r-$波段的视星等峰值为30至35星等，难以探测。 然而，其中一些在明亮端的恒星可以通过即将开展的大范围深空巡天项目进行探测，例如中国空间站望远镜（CSST）和Vera Rubin天文台（LSST）。 这类游荡恒星种群的发现将为精确理解附近星系际空间的物质构成以及本地宇宙中星系的动力学历史打开一扇门。 显示英文摘要

Intergalactic wandering stars (IWSs) within 10 Mpc remain a poorly explored area of astronomy. Such stars, if they exist, are supposed to be wandering objects as they are not bounded by the gravitational potential of any galaxy. We set out to conduct dedicated studies for unraveling such a wandering stellar population. As the first paper of the series, in the present work we model the distance distribution and luminosity function of IWSs formed via the Hills mechanism of the Galactic central massive black hole (GCMBH). We implement a numerical simulation to generate IWSs taking the ejection history of the GCMBH and the stellar evolution process into consideration, and present their luminosity function in the distance range of 200kpc - 10Mpc. Our results suggest that a few hundred thousand IWSs have been generated by the GCMBH via the Hills mechanism in the past 14 billion years. These IWSs have an apparent magnitude peaking at 30 to 35 mag in SDSS $r-$band, which are hard to detect. However, a few thousand of them at the bright end are detectable by upcoming wide-field deep surveys, such as China Space Station Telescope (CSST) and Vera Rubin Observatory (LSST). The forthcoming discovery of such a wandering stellar population will open a door for precise understanding of the matter constitution of the nearby intergalactic space and the dynamical history of galaxies in the local universe.

[8] arXiv:2508.03229 [中文pdf, pdf, html, 其他]

标题： ALMA-QUARKS调查：III. 团块到核心的碎片化和高质星无核心的搜索 显示英文标题

标题： The ALMA-QUARKS Survey: III. Clump-to-core fragmentation and search for high-mass starless cores

Dongting Yang, Hong-Li Liu, Tie Liu, Xunchuan Liu, Fengwei Xu, Sheng-Li Qin, Anandmayee Tej, Guido Garay, Lei Zhu, Xiaofeng Mai, Wenyu Jiao, Siju Zhang, Sami Dib, Amelia M. Stutz, Aina Palau, Patricio Sanhueza, Annie Zavagno, A.Y. Yang, Xindi Tang, Mengyao Tang, Yichen Zhang, Pablo Garcia, Tianwei Zhang, Anindya Saha, Shanghuo Li, Paul F. Goldsmith, Leonardo Bronfman, Chang Won Lee, Kotomi Taniguchi, Swagat Ranjan Das, Prasanta Gorai, Ariful Hoque, Li Chen, Zhiping Kou, Jianjun Zhou, Yankun Zhang, L. Viktor Toth, Tapas Baug, Xianjin Shen, Chuanshou Li, Jiahang Zou, Ankan Das, Hafiz Nazeer, L. K. Dewangan, Jihye Hwang, James O. Chibueze

评论： 30页，16图，已被ApJS接收

主题： 星系的天体物理学 (astro-ph.GA)

通过ALMA解析的气体动力学和结构（QUARKS）调查研究大质量恒星形成的潜在机制，观测了139个红外明亮（IR-bright）的大质量原星团，在1.3毫米波长下使用ALMA。这项研究调查了团块到核心的碎片化，并利用结合的ALMA 12米（C-2）和阿塔卡马紧凑阵列（ACA）7米数据，在IR-bright团块中寻找高质量无恒星核心的候选者，提供了$\sim$1角秒（$\sim\rm0.02~pc$在3.7千秒差距）的分辨率和$\sim\rm0.6\,mJy\,beam^{-1}$续谱灵敏度（$\sim 0.3~M_{\odot}$在30 K）。我们使用getsf从1.3毫米连续谱发射中识别出1562个致密核心。 观测到的线性核心分离（$\lambda_{\rm obs}$）明显小于热 Jeans 长度（$\lambda_{\rm J}$），其中 $\lambda_{\rm obs}/\lambda_{\rm J}$ 比值在 $\sim0.2$ 处达到峰值。 这表明在此研究的红外明亮原星团云块中已经发生了热 Jeans 分裂。 观测到的 $\lambda_{\rm obs}/\lambda_{\rm J}\ll 1$ 低比值可能是核心分离演化或分层分裂的结果。 根据恒星形成的相关特征（例如，外流和电离气体），我们将核心分为三类：127个无恒星核心，971个温暖核心和464个演化核心。 两个无恒星核心的质量超过16$\,M_{\odot}$，代表高质量子候选体。 这类候选体的稀缺性表明，在这些红外明亮原星团云块中的高质子星形成中，竞争吸积模型可能比湍流核心吸积模型更适用。 显示英文摘要

The Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures (QUARKS) survey observed 139 infrared-bright (IR-bright) massive protoclusters at 1.3 mm wavelength with ALMA. This study investigates clump-to-core fragmentation and searches for candidate high-mass starless cores within IR-bright clumps using combined ALMA 12-m (C-2) and Atacama Compact Array (ACA) 7-m data, providing $\sim$ 1 arcsec ($\sim\rm0.02~pc$ at 3.7 kpc) resolution and $\sim\rm0.6\,mJy\,beam^{-1}$ continuum sensitivity ($\sim 0.3~M_{\odot}$ at 30 K). We identified 1562 compact cores from 1.3 mm continuum emission using getsf. Observed linear core separations ($\lambda_{\rm obs}$) are significantly less than the thermal Jeans length ($\lambda_{\rm J}$), with the $\lambda_{\rm obs}/\lambda_{\rm J}$ ratios peaking at $\sim0.2$. This indicates that thermal Jeans fragmentation has taken place within the IR-bright protocluster clumps studied here. The observed low ratio of $\lambda_{\rm obs}/\lambda_{\rm J}\ll 1$ could be the result of evolving core separation or hierarchical fragmentation. Based on associated signatures of star formation (e.g., outflows and ionized gas), we classified cores into three categories: 127 starless, 971 warm, and 464 evolved cores. Two starless cores have mass exceeding 16$\,M_{\odot}$, and represent high-mass candidates. The scarcity of such candidates suggests that competitive accretion-type models could be more applicable than turbulent core accretion-type models in high-mass star formation within these IR-bright protocluster clumps.

[9] arXiv:2508.03286 [中文pdf, pdf, html, 其他]

标题： 矮椭球星系Fornax在银河系势场中的质量损失和动力摩擦 显示英文标题

标题： Mass loss and dynamical friction on the Fornax dSph galaxy in the Milky Way potential

Pierfrancesco Di Cintio, Giuliano Iorio, Carlo Nipoti, Francesco Calura

评论： 4页，2图。将发表在第398届IAU研讨会“MODEST-致密星体和密集群中的双星”论文集上

主题： 星系的天体物理学 (astro-ph.GA)

我们研究了质量损失与动力摩擦（DF）在银河系（MW）势场中对富隆克斯矮椭球星系轨道衰减的相互作用。 通过结合简化单粒子方法和由$N-$体模拟外推的质量损失率，我们发现时间依赖的质量损失部分抵消了 DF 的影响，并通常导致近日点距离的衰减不那么明显，从而证实了在没有 DF 的平滑 MW 势场中的$N-$体模拟可以作为矮卫星星系动力学的良好模型。 显示英文摘要

We study the interplay between mass-loss and dynamical friction (DF) on the orbital decay of the Fornax dwarf spheroidal galaxy in the potential of the Milky Way (MW). Using a simplified single particle approach combined with a mass-loss rate extrapolated by $N-$body simulations we find that the the effect of a time-dependent mass partially compensates DF, and typically produces a much less evident decay of the pergalactic distance, thus confirming that $N-$body simulations in smooth MW potentials without DF can be taken as a good model of the dynamics of dwarf satellite galaxies.

[10] arXiv:2508.03322 [中文pdf, pdf, html, 其他]

标题： 球状星团中通过双星-单星散射的恒星种群空间混合 显示英文标题

标题： Spatial mixing of stellar populations in globular clusters via binary-single star scattering

Václav Pavlík, Melvyn B. Davies, Ellen I. Leitinger, Holger Baumgardt, Alexey Bobrick, Ivan Cabrera-Ziri, Michael Hilker, Andrew J. Winter

评论： 11页，10图，已投稿至A&A，欢迎提出意见

主题： 星系的天体物理学 (astro-ph.GA)

大多数银河系球状星团（GCs）已被报告含有至少两代恒星（我们用P1表示原始一代，P2表示化学富集一代）。最近的观测研究发现，动力学古老的GCs由于弛豫过程导致P1和P2在空间上混合。然而，在动力学年轻的GCs中，P2预计在出生时更集中于中心，P1和P2的空间分布有时在不同系统之间差异很大。这表明某些特定GCs可能有更复杂的动力学过程塑造了这些分布。我们的目标是研究动力学年轻GCs中P1和P2恒星的空间集中度之间的差异。我们的重点是评估大质量双星（例如黑洞）是否能通过核心中的双星-单星相互作用导致P2恒星的扩展，以及它们是否能混合甚至径向反转P1和P2的分布。我们使用一组理论和经验论点来评估双星-单星散射的有效性。然后，我们构建一组包含大质量原始双星的直接N体模型，以进一步验证我们的估计并获得更多关于GCs动力学过程的见解。我们发现，双星-单星散射可以在几个弛豫时间内将中心的P2恒星向外推动。虽然我们没有在任何测试的初始条件下产生P1和P2的径向反转，但这种机制系统地产生了P1和P2在投影下看起来完全混合的星团。这种混合在1）密度更高的GCs中、2）包含更多双星的GCs中以及3）双星组分与星团成员的质量比更高时得到增强。双星-单星相互作用似乎能够解释一些动力学年轻的GCs（例如NGC4590或NGC5904）的可观测特性，其中P1和P2完全径向混合。 显示英文摘要

The majority of Galactic globular star clusters (GCs) have been reported to contain at least two populations of stars (we use P1 for the primordial and P2 for the chemically-enriched population). Recent observational studies found that dynamically-old GCs have P1 and P2 spatially mixed due to relaxation processes. However, in dynamically-young GCs, where P2 is expected to be more centrally concentrated from birth, the spatial distributions of P1 and P2 are sometimes very different from system to system. This suggests that more complex dynamical processes specific to certain GCs might have shaped those distributions. We aim to investigate the discrepancies between the spatial concentration of P1 and P2 stars in dynamically-young GCs. Our focus is to evaluate whether massive binary stars (e.g. BHs) can cause the expansion of the P2 stars through binary-single interactions in the core, and whether they can mix or even radially invert the P1 and P2 distributions. We use a set of theoretical and empirical arguments to evaluate the effectiveness of binary-single star scattering. We then construct a set of direct N-body models with massive primordial binaries to verify our estimates further and gain more insights into the dynamical processes in GCs. We find that binary-single star scatterings can push the central P2 stars outwards within a few relaxation times. While we do not produce radial inversion of P1 and P2 for any initial conditions we tested, this mechanism systematically produces clusters where P1 and P2 look fully mixed even in projection. The mixing is enhanced 1) in denser GCs, 2) in GCs containing more binary stars, and 3) when the mass ratio between the binary components and the cluster members is higher. Binary-single star interactions seem able to explain the observable properties of some dynamically-young GCs (e.g. NGC4590 or NGC5904) where P1 and P2 are fully radially mixed.

[11] arXiv:2508.03536 [中文pdf, pdf, html, 其他]

标题： X射线晕与早期类型星系中的AGN反馈和星系际介质吸积：模型与观测 显示英文标题

标题： X-ray Halos of Early-Type Galaxies with AGN Feedback and Accretion from a Circumgalactic Medium: models and observations

Silvia Pellegrini (1), Luca Ciotti (1), Zhaoming Gan (2), Dong-Woo Kim (3), Jeremiah P. Ostriker (4) ((1) Dept. of Physics and Astronomy, Bologna University, Italy, (2) New Mexico Consortium, Los Alamos, NM, USA, (3) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA, (4) Dept. of Astronomy, Columbia University, NY, USA)

评论： 17页，7图；已接受发表于天体物理杂志

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO) ; 高能天体物理现象 (astro-ph.HE)

早期类型星系热气体晕的X射线特性知识在过去几年中有了显著进展，这是由于对大而均匀调查的样本的研究。 我们将这些结果与在现实早期类型星系中产生的探索性气体演化模型的X射线特性进行比较，这些模型是使用我们的高分辨率二维流体动力学代码MACER生成的，该代码包括AGN反馈和从星系际介质的吸积。 模型的X射线发射和吸收是沿着视线方向积分的，以获得表面亮度Sigma_X和温度Tx的地图。 考虑的X射线诊断包括整个星系的光度和平均温度（Lx和<Tx>）以及在5个光学有效半径内的（Lx5和<Tx5>），以及圆化后的轮廓Sigma_X(R)和Tx(R)。 Lx、Lx5、<Tx>和<Tx5>的值与观测结果非常吻合。 Sigma_X(R)和Tx(R)也与代表性星系NGC5129以及具有最常见Tx(R)形状的ETGs有定性的相似之处；Sigma_X(R)在多个光学有效半径Re范围内与观测轮廓相匹配，Tx(R)再现了在R=(1-3)Re处达到峰值的特征凸起。 在峰值位置内部，Tx(R)向中心下降，但所研究的模型整体上更热约30%；讨论了这种差异的可能解释。 有趣的是，只有在从星系际介质显著吸积的情况下，才能重现R~Re以外观测到的Sigma_X(R)和Tx(R)，这突显了星系际介质的重要性。 显示英文摘要

The knowledge of the X-ray properties of the hot gas halos of early-type galaxies has significantly advanced in the past years, for large and homogeneously investigated samples. We compare these results with the X-ray properties of an exploratory set of gas evolution models in realistic early-type galaxies, produced with our high-resolution 2D hydrodynamical code MACER that includes AGN feedback and accretion from a circumgalactic medium. The model X-ray emission and absorption are integrated along the line of sight, to obtain maps of the surface brightness Sigma_X and temperature Tx. The X-ray diagnostics considered are the luminosity and average temperature for the whole galaxy (Lx and <Tx>) and within 5 optical effective radii (Lx5 and <Tx5>), and the circularized profiles Sigma_X(R) and Tx(R). The values for Lx, Lx5, <Tx>, and <Tx5> compare very well with those observed. The Sigma_X(R) and Tx(R) also present qualitative similarities with those of the representative galaxy NGC5129, and of ETGs with the most commonly observed shape for Tx(R): Sigma_X(R) matches the observed profile over many optical effective radii Re, and Tx(R) reproduces the characteristic bump that peaks at R=(1 - 3)Re. Inside the peak position, Tx(R) declines towards the center, but the explored models are systematically hotter by ~30%; possible explanations for this discrepancy are discussed. Interestingly, Sigma_X(R) and Tx(R) as large as observed outside of R~Re are reproduced only with significant accretion from a circumgalactic medium, highlighting its importance.

[12] arXiv:2508.03569 [中文pdf, pdf, html, 其他]

标题： 重佐法则再审视：星系重子-暗物质耦合的统计研究 显示英文标题

标题： Renzo's rule revisited: A statistical study of galaxies' baryon - dark matter coupling

Enoch Ko (1, 2 and 3), Tariq Yasin (1), Harry Desmond (4), Richard Stiskalek (1), Matt J. Jarvis (1 and 5) ((1) Astrophysics, University of Oxford, (2) DAMTP, University of Cambridge, (3) Department of Physics, University of Warwick, (4) Institute of Cosmology and Gravitation, University of Portsmouth, (5) Department of Physics and Astronomy, University of the Western Cape)

评论： 20页，15图；将提交给MNRAS

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

我们对一种非正式的天体物理现象——Renzo定律（或Sancisi定律）进行了系统的统计分析，该定律指出：“对于星系光度轮廓中的任何特征，旋转曲线中都有相应的特征，反之亦然。” 这通常被提出作为标准LCDM模型的挑战，同时支持如MOND等替代理论。 确实，我们在矮旋涡星系NGC 1560中识别出清晰的特征——这是Renzo定律的一个典型例子，并发现相关统计结果支持Renzo定律，略微倾向于MOND而非LCDM晕模型。 然而，对SPARC数据库中星系的更广泛分析显示，旋转曲线中存在过多缺乏明显重子对应物的特征，相关统计结果平均偏离MOND和LCDM晕模型预测的$3\sigma$，这挑战了Renzo定律的有效性。 因此，总体而言，我们在当前的星系数据中没有找到明确支持Renzo定律的证据。 我们还进行了模拟测试，结果显示，对Renzo定律的确定性测试主要受限于当前星系数据中缺乏清晰解析的重子特征。 显示英文摘要

We present a systematic statistical analysis of an informal astrophysical phenomenon known as Renzo's rule (or Sancisi's law), which states that "for any feature in a galaxy's luminosity profile, there is a corresponding feature in the rotation curve, and vice versa." This is often posed as a challenge for the standard LCDM model while supporting alternative theories such as MOND. Indeed, we identify clear features in the dwarf spiral NGC 1560 -- a prime example for Renzo's rule -- and find correlation statistics which support Renzo's rule with a slight preference for MOND over LCDM halo fits. However, a broader analysis on galaxies in the SPARC database reveals an excess of features in rotation curves that lack clear baryonic counterparts, with correlation statistics deviating up to $3\sigma$ on average from that predicted by both MOND and LCDM haloes, challenging the validity of Renzo's rule. Thus we do not find clear evidence for Renzo's rule in present galaxy data overall. We additionally perform mock tests, which show that a definitive test of Renzo's rule is primarily limited by the lack of clearly resolved baryonic features in current galaxy data.

[13] arXiv:2508.03626 [中文pdf, pdf, html, 其他]

标题： JWST NIRCam 对 RXJ 2129.7+0005 球状星团群的观测 显示英文标题

标题： JWST NIRCam Observations of the Globular Cluster Population of RXJ 2129.7+0005

Kaitlyn E. Keatley, William E. Harris

评论： 11页，15图

主题： 星系的天体物理学 (astro-ph.GA)

我们基于JWST NIRCam在三个滤镜F115W、F150W和F200W下的成像，对星系团RXJ 2129.7+0005（z = 0.234）中的球状星团（GC）群体进行了分析。 我们利用这些材料详细展示了GC的颜色-星等分布及其围绕中心巨椭圆星系的空间分布。 我们识别出3,160个比F150W=29.5更亮的GC候选体，并通过人工星测试评估了测光完整性。 我们确定GC遵循径向幂律分布，指数为$1.58 \pm 0.04$，较红的GC表现出稍高的中心集中度。 它们的空间分布也高度椭圆，紧密跟随BCG晕光的形状。 显示英文摘要

We present an analysis of the globular cluster (GC) population in the galaxy cluster RXJ 2129.7+0005 (z = 0.234) based on JWST NIRCam imaging in three filters: F115W, F150W, and F200W. We use this material to provide a detailed look at the color-magnitude distribution of the GCs and their spatial distribution around the central giant galaxy. We identified 3,160 GC candidates brighter than F150W=29.5, and assessed photometric completeness through artificial star tests. We determined that the GCs follow a radial power-law distribution with an index of $1.58 \pm 0.04$, with the redder GCs exhibiting a slightly greater central concentration. Their spatial distribution is also highly elliptical, closely following the shape of the BCG halo light.

[14] arXiv:2508.03656 [中文pdf, pdf, html, 其他]

标题： 未知X射线源在7 Ms钱德拉深场-南 catalog 中的性质 显示英文标题

标题： The Nature of an Unidentified X-ray Source in the 7 Ms Chandra Deep Field-South Catalog

Quinn P. Sullivan, Zhibo Yu, William N. Brandt, Bin Luo, Fan Zou

主题： 星系的天体物理学 (astro-ph.GA)

在7 Ms钱德拉深场-南天区目录中，只有一个源XID 912在X射线中被高度显著检测到，但在紫外线、光学、红外线或射电波段没有正式报告的对应源。 我们识别了其潜在的JWST和VLT VIMOS对应源，并测量了相应的孔径测光以构建其光谱能量分布（SED）。 我们使用CIGALE拟合了该SED。 结果表明，该源最可能是一个非核的超亮X射线源，而不是背景活动星系核。 显示英文摘要

In the 7 Ms Chandra Deep Field-South catalog, only one source, XID 912, was highly significantly detected in X-rays but had no formally reported counterparts in the UV, optical, infrared, or radio bands. We identified its potential JWST and VLT VIMOS counterparts and measured the corresponding aperture photometry to construct its spectral energy distribution (SED). We fitted this SED using CIGALE. The results indicate that the source is most likely an off-nuclear ultraluminous X-ray source, rather than a background active galactic nucleus.

[15] arXiv:2508.03684 [中文pdf, pdf, html, 其他]

标题： 球状星团在NGC 4874中的SED拟合：质量与金属丰度 显示英文标题

标题： SED Fitting of Globular Clusters in NGC 4874: Masses and Metallicities

Kate Hartman, William E. Harris, Jinoo Kim

评论： 14页，11图。已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA)

在大多数邻近星系中，它们的球状星团（GCs）的整体光度仅在两个滤镜中获得，只产生一个颜色指数。 然而，室女座星系团中最明亮的中心星系NGC 4874现在有哈勃空间望远镜（HST）在十个滤镜中的光度数据，使我们有机会在遥远星系的GCs上测试SED拟合程序。 我们用E-MILES的SED库拟合了29个最亮的GCs，并计算了每个星团的最佳拟合金属丰度和质量。 使用从GC光谱平坦部分的最红亮度得出的拟合质量和光度，我们还计算了样本GCs的推导质量-光度比；这些比值在(M/L)$\simeq 2 - 4$范围内，略大于银河系GCs的平均值，但仍在传统范围内。 显示英文摘要

In most nearby galaxies, photometry of the integrated light of their globular clusters (GCs) has been obtained in only two filters, yielding just a single color index. However, NGC 4874, the brightest central galaxy in the Coma cluster, now has Hubble Space Telescope (HST) photometry available in ten filters, giving us a special opportunity to test SED fitting procedures on GCs in distant galaxies. We fitted 29 of the brightest GCs with a library of SEDs from E-MILES and calculated the best-fit metallicity and mass of each cluster. Using the fitted masses and luminosities derived from the reddest magnitudes, in the flat portion of the GC spectrum, we also calculated inferred mass-to-light ratios for our sample GCs; these were in the range (M/L) $\simeq 2 - 4$, slightly larger than the average values for Milky Way GCs but within the conventional range.

交叉提交 (展示 15 之 15 条目 )

[16] arXiv:2508.02777 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 星际天体3I/ATLAS的光谱特性来自SOAR观测 显示英文标题

标题： Spectral Characteristics of Interstellar Object 3I/ATLAS from SOAR Observations

Thomas H. Puzia, Rohan Rahatgaonkar, Juan Pablo Carvajal, Prasanta K. Nayak, Baltasar Luco

评论： 6页，2图，已修改并重新提交至ApJL

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

星际物体（ISOs）为了解太阳系外行星系统的构建块和条件提供了独特的见解。 新发现的物体， 3I/ATLAS（C/2025 N1），是在1I/'Oumuamua和 2I/Borisov之后第三个已知的ISO。 我们展示了使用智利4.1米SOAR望远镜上的Goodman高通量光谱仪在7月3日夜间观测到的3I的初始光谱特征。 3I的反射率光谱，覆盖3700-7000 \AA 显示出与极端海王星外天体相当的红色连续谱，具有弱紫外-光学转折，表明存在复杂的碳质和辐射有机物。 在观测时，当3I处于4.4天文单位的日心距离时，我们没有检测到来自典型彗星物种（CN，C$_3$，C$_2$，CO$^+$，[O{\sc i}]）的明显气体发射。 这与我们的热演化模型预期一致，该模型表明，一旦3I/ATLAS接近更小的日心距离，升华驱动的活动应该开始。 然而，早期彗发出现但缺乏升华示踪物的矛盾情况需要其他释放尘埃的机制，这些机制可能在大日心距离下作用于古老的ISO。 显示英文摘要

Interstellar objects (ISOs) provide unique insights into the building blocks and conditions of extrasolar planetary systems. The newly discovered object, 3I/ATLAS (C/2025 N1), represents the third known ISO after 1I/'Oumuamua and 2I/Borisov. We present initial spectroscopic characterizations of 3I using observations from the Goodman High Throughput Spectrograph on the 4.1 m SOAR Telescope in Chile during the night of July 3rd. The reflectance spectrum of 3I, covering 3700-7000\,\AA\, reveals a red continuum, comparable to extreme trans-Neptunian objects, with a weak UV-optical turnover indicative of complex carbonaceous and irradiated organics. At the time of observation, when 3I was at a heliocentric distance of 4.4 AU, we detected no discernible gas emission from canonical cometary species (CN, C$_3$, C$_2$, CO$^+$, [O{\sc i}]). This is in agreement with expectations from our thermal-evolution model, which indicates sublimation-driven activity should commence once 3I/ATLAS approaches smaller heliocentric distances. Nonetheless, the paradoxical situation of early onset coma without evidence of sublimation tracers calls for other dust-liberating mechanisms that ancient ISOs may be subjected to at large heliocentric distances.

[17] arXiv:2508.02779 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 欧几里得：使用自组织图进行光度红移校准 显示英文标题

标题： EUCLID: Photometric redshift calibration with self-organising maps

W. Roster, A. H. Wright, H. Hildebrandt, R. Reischke, O. Ilbert, W. d'Assignies D., M. Manera, M. Bolzonella, D. C. Masters, S. Paltani, W. G. Hartley, Y. Kang, H. Hoekstra, B. Altieri, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, R. Bender, A. Biviano, E. Branchini, M. Brescia, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, R. Casas, S. Casas, F. J. Castander, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, S. de la Torre, G. De Lucia, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, S. Farrens, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, W. Gillard, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, W. Holmes, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, B. Kubik, H. Kurki-Suonio, A. M. C. Le Brun, D. Le Mignant, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, D. Maino, E. Maiorano, O. Mansutti, O. Marggraf, M. Martinelli

评论： 20页，16图

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

The Euclid survey aims to trace the evolution of cosmic structures up to redshift $z$ $\sim$ 3 and beyond. Its success depends critically on obtaining highly accurate mean redshifts for ensembles of galaxies $n(z)$ in all tomographic bins, essential for deriving robust cosmological constraints. However, photometric redshifts (photo-$z$s) suffer from systematic biases arising from various sources of uncertainty. To address these challenges, we utilised self-organising maps (SOMs) with mock samples resembling the Euclid Wide Survey (EWS), to validate Euclid's uncertainty requirement of $|\Delta\langle z \rangle| = \langle z_{\text{est}} \rangle - \langle z \rangle \leq 0.002 (1+z)$ per tomographic bin, assuming DR3-level data. We observe that defining the redshift tomography using the mean spectroscopic redshift (spec-$z$) per SOM cell, results in none of the ten tomographic redshift bins satisfying the requirement. 与之相反，对类似EWS样本的光度$z$进行红移分层观测得到了更优的结果，其中十个区间中的八个[$0 < z\leq 2.5$]满足欧几里得任务的要求。 为了增强研究的真实性，我们逐步将校准样本进行变形，以模拟C3R2调查。 在此背景下，最多有六个区间满足要求，强烈建议采用由单个星系的光度$z$定义的红移分层方法，而不是通常使用的SOM单元的平均光谱$z$。 为了检查对欧几里得测量的$\Omega_{\text{m}}$、$\sigma_{8}$和$\Delta w_{0}$预期偏差的影响，我们仅基于红移不确定性进行了宇宙剪切的费舍尔预测。 在这里，我们发现即使在考虑红移偏差影响较大的不确定性评估下，理想化情景中大多数绝对偏差仍低于0.1$\sigma$，而在更现实的情况下，大多数绝对偏差仍低于0.3$\sigma$。 显示英文摘要

The Euclid survey aims to trace the evolution of cosmic structures up to redshift $z$ $\sim$ 3 and beyond. Its success depends critically on obtaining highly accurate mean redshifts for ensembles of galaxies $n(z)$ in all tomographic bins, essential for deriving robust cosmological constraints. However, photometric redshifts (photo-$z$s) suffer from systematic biases arising from various sources of uncertainty. To address these challenges, we utilised self-organising maps (SOMs) with mock samples resembling the Euclid Wide Survey (EWS), to validate Euclid's uncertainty requirement of $|\Delta\langle z \rangle| = \langle z_{\text{est}} \rangle - \langle z \rangle \leq 0.002 (1+z)$ per tomographic bin, assuming DR3-level data. We observe that defining the redshift tomography using the mean spectroscopic redshift (spec-$z$) per SOM cell, results in none of the ten tomographic redshift bins satisfying the requirement. In contrast, the redshift tomography on the photo-$z$s of the EWS-like sample yields superior results, with eight out of ten bins [$0 < z\leq 2.5$] meeting the Euclid requirement. To enhance the realism of our study, we morph our calibration sample to mimic the C3R2 survey in incremental steps. In this context, a maximum of six out of ten bins meet the requirement, strongly advocating the adoption of a redshift tomography defined by the photo-$z$s of individual galaxies rather than the commonly used mean spec-$z$ of SOM cells. To examine the impact on the expected biases for $\Omega_{\text{m}}$, $\sigma_{8}$, and $\Delta w_{0}$ measured by Euclid, we perform a Fisher forecast for cosmic shear only, based on our redshift uncertainties. Here, we find that even under an evaluation of the uncertainty where the impact of the redshift bias is substantial, most absolute biases remain below 0.1$\sigma$ in the idealised scenario and below 0.3$\sigma$ in the more realistic case.

[18] arXiv:2508.02780 (交叉列表自 astro-ph.IM) [中文pdf, pdf, html, 其他]

标题： NASIM：从遗留的VISTA数据中揭示低表面亮度宇宙 显示英文标题

标题： NASIM: Revealing the low surface brightness Universe from legacy VISTA data

Elham Saremi, Ignacio Trujillo, Mohammad Akhlaghi, Zohreh Ghaffari, Johan H. Knapen, Manda Banerji, Helmut Dannerbauer, Sébastien Comerón

评论： 14页，12图，1表，4个附录，已被天文学与天体物理学杂志接受。可下载的源代码（在arXiv上）包含Maneage中的完整再现信息：https://maneage.org 。它也带有Git历史记录：https://gitlab.com/nasim-projects/pipeline （存档于SoftwareHeritage），以及在Zenodo：https://zenodo.org/records/16152699

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA)

近红外成像是观测天文学中一种强大的技术，但主要来自地球大气的明亮背景使得检测微弱特征尤其具有挑战性。为了恢复此类数据中的低表面亮度（LSB）结构，我们介绍了NASIM（近红外自动低表面亮度处理工具），这是一个完全自动化且可重复的数据处理管道，专门针对VISTA/VIRCAM观测优化。NASIM基于GNU天文工具（Gnuastro），以有效去除大尺度仪器伪影，同时保留微弱的弥散辐射。作为关键科学应用，我们专注于欧几里得南深场（KEDFS）的深度Ks波段观测，这是最深的VISTA/VIRCAM数据集之一，也是与当前和未来设施（包括欧几里得、JWST、LSST、罗曼、斯皮策和ALMA）协同观测的优先领域。随着VIRCAM不再运行，KEDFS现在成为一项独特的遗留数据集。我们发布了KEDFS调查中的选定图块，并强调了科学案例，包括星系外围、低表面亮度星系和星系团内光，这些案例展示了NASIM恢复弥散结构的能力。与传统VISTA数据处理管道的直接比较显示了NASIM在不牺牲紧凑源检测的情况下保留弥散辐射的优势。本文中所有定量结果均可通过Maneage（提交4d32667）完全重现。 显示英文摘要

Near-infrared imaging is a powerful technique in observational astronomy, but the bright background, primarily from the Earth\'s atmosphere, makes the detection of faint features particularly challenging. To recover low surface brightness (LSB) structures in such data, we present NASIM (Near-infrared Automated low Surface brightness reduction In Maneage), a fully automated and reproducible data reduction pipeline optimised for VISTA/VIRCAM observations. NASIM builds on GNU Astronomy Utilities (Gnuastro) to effectively remove large-scale instrumental artefacts while preserving faint, diffuse emission. As a key science application, we focus on deep Ks-band observations of the Euclid Deep Field South (KEDFS), one of the deepest VISTA/VIRCAM datasets and a high-priority field for synergy with current and future facilities, including Euclid, JWST, LSST, Roman, Spitzer, and ALMA. With VIRCAM no longer operational, KEDFS now stands as a unique legacy dataset. We release selected tiles from the KEDFS survey and highlight science cases, including galaxy outskirts, LSB galaxies, and intracluster light, that demonstrate NASIM\'s ability to recover diffuse structures. A direct comparison with conventional VISTA data reduction pipelines demonstrates the advantages of NASIM in preserving diffuse emission without compromising compact source detection. All quantitative results presented in this paper are fully reproducible with Maneage (commit 4d32667).

[19] arXiv:2508.02790 (交叉列表自 astro-ph.SR) [中文pdf, pdf, html, 其他]

标题： 蓝水平分支星的二进制分数 显示英文标题

标题： The binary fraction of Blue Horizontal-Branch (BHB) Stars

Yanjun Guo, Kun Chen, Zhenwei Li, Jie Ju, Chao Liu, Xiangxiang Xue, Matti Dorsch, Zhanwen Han, XueFei Chen

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 星系的天体物理学 (astro-ph.GA)

蓝水平分支（BHB）恒星是古老的低质量、金属贫乏恒星，它们是银河晕结构、运动学和演化的关键示踪物。了解它们的双星特性可以提供关于其形成渠道以及双星相互作用在水平分支恒星演化中作用的关键见解。我们旨在研究BHB恒星的固有双星分数$f_{\rm b}^{\rm in}$及其与金属丰度、运动学和有效温度的依赖关系。我们从LAMOST收集了\GG{299}个BHB恒星，这些恒星有多次径向速度（RV）测量，并根据它们的运动学和金属丰度将其样本分为晕类和盘类BHB恒星，同时根据它们的\G{effective temperature}分为更蓝和更红的BHB恒星。然后，我们根据径向速度变化研究每组的观测双星分数，并应用一组蒙特卡洛模拟，假设$f(P) \propto P^\pi$和$f(q) \propto q^\kappa$的分布，以校正观测偏差并推导出固有双星分数。在校正观测偏差后，固有双星分数增加到n > 2时的31%和n > 3时的32%。观察到晕类和盘类BHB恒星之间存在明显差异，晕类BHB恒星的固有双星分数较低（n > 2时为28%，n > 3时为29%），而盘类BHB恒星的固有双星分数较高（分别为46%和51%），这表明不同的形成途径。此外，我们发现更蓝的BHB恒星的双星分数显著高于更红的BHB恒星（n > 2时为42%，n > 3时为45%），而更红的BHB恒星则为24%和23%，这表明双星性可能与有效温度有关，尽管需要更多的样本来确认这一点。 显示英文摘要

Blue horizontal-branch (BHB) stars are old, low-mass, metal-poor stars that serve as important tracers of the Galactic halo structure, kinematics, and evolution.Understanding their binary properties provides key insights into their formation channels and the role of binary interactions in the evolution of horizontal branch stars. We intend to investigate the intrinsic binary fraction $f_{\rm b}^{\rm in}$ of BHB stars and its dependencies on metallicity, kinematics, and effective temperature. We collect \GG{299} BHB stars from LAMOST with multiple radial velocity (RV) measurements and classify the sample into halo-like and disk-like BHBs based on their kinematics and metallicity, as well as into bluer and redder BHBs based on their \G{effective temperature}. We then investigate the observed binary fraction for each group based on the radial velocity variations and apply a set of Monte Carlo simulations, assuming distributions of $f(P) \propto P^\pi$ and $f(q) \propto q^\kappa$, to correct the observed binary fraction for observational biases and derive the intrinsic binary fraction. After correcting for observational biases, the intrinsic binary fraction increases to 31% for n > 2 and 32% for n > 3. A clear contrast is observed between halo-like and disk-like BHB stars, with halo-like BHBs exhibiting a lower intrinsic binary fraction (28% for n > 2 and 29% for n> 3) compared to disk-like BHBs (46% and 51%, respectively), indicating different formation pathways. Additionally, we find that bluer BHB stars exhibit a significantly higher binary fraction (42% for n > 2 and 45% for n> 3) than redder BHB stars (24% and 23%, respectively), which suggests a possible link between binarity and the effective temperature, although more samples are required to confirm this.

[20] arXiv:2508.02876 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： X射线变异性及矮星暴星系IC 10中大质量X射线双星的光度函数 显示英文标题

标题： The X-ray Variability and Luminosity Function of High Mass X-ray Binaries in the Dwarf Starburst Galaxy IC 10

Breanna A. Binder, Rosalie Lazarus, Mina Thoresen, Silas Laycock, Sayantan Bhattacharya

评论： 12页，7图；已被《天体物理学杂志》接受

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

我们对钱德拉观测获得的235 ks的$\sim$数据进行了分析，这些观测是在过去$\sim$年的邻近矮星暴星系IC 10中进行的，目的是研究其X射线双星（XRB）群体的X射线变异性以及X射线光度函数（XLF）。我们在2MASS$K_S$等光度半径内识别出23个可能的XRB，并发现它们的动态范围和持续时间分布与以超巨星（sg）供能系统为主的年轻、高质XRB群体一致，这与之前的研究结果一致。一般来说，我们发现更亮的高质量X射线双星（HMXBs）（那些具有$L_X\gtrsim$几个$\times10^{36}$erg s$^{-1}$的）比较暗的天体具有更高的持续时间（即，是更持久的X射线源），并且在IC 10较低金属丰度环境中的sgHMXBs的动态范围高于在银河系中类似系统的观测结果。在基于盖亚视差过滤掉前景恒星后，我们首次构建了IC 10的XLF。 我们随后使用XLF来模拟星系的恒星形成历史，发现需要一个非常近期（3-8 Myr）的恒星形成爆发，其速率为$\sim$0.5 $M_{\odot}$年$^{-1}$，才能充分解释观测到的HMXB XLF的亮端 ($L_X\sim10^{37}$ erg s$^{-1}$)。 显示英文摘要

We present an analysis of $\sim$235 ks of Chandra observations obtained over $\sim$19 years of the nearby dwarf starburst galaxy IC 10 in order to study the X-ray variability and X-ray luminosity function (XLF) of its X-ray binary (XRB) population. We identify 23 likely XRBs within the 2MASS $K_S$ isophotal radius and find the distributions of their dynamic ranges and duty cycles are consistent with a young, high-mass XRB population dominated by supergiant (sg)-fed systems, consistent with previous work. In general, we find that brighter HMXBs (those with $L_X\gtrsim$several$\times10^{36}$ erg s$^{-1}$) have higher duty cycles (i.e., are more persistent X-ray sources) than fainter objects, and the dynamic ranges of the sgHMXBs in the lower metallicity environment of IC 10 are higher than what is observed for comparable systems in the Milky Way. After filtering out foreground stars on the basis of Gaia parallaxes we construct, for the first time, the XLF of IC 10. We then use the XLF to model the star formation history of the galaxy, finding that a very recent (3-8 Myr) burst of star formation with rate of $\sim$0.5 $M_{\odot}$ yr$^{-1}$ is needed to adequately explain the observed bright-end ($L_X\sim10^{37}$ erg s$^{-1}$) of the HMXB XLF.

[21] arXiv:2508.02934 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 哈勃空间望远镜对星际闯入者3I/ATLAS的观测 显示英文标题

标题： Hubble Space Telescope Observations of the Interstellar Interloper 3I/ATLAS

David Jewitt, Man-To Hui, Max Mutchler, Yoonyoung Kim, Jessica Agarwal

评论： 13页，4图，2表

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA)

我们提供了对第三颗已知的星际闯入者3I/ATLAS的高角分辨率观测结果，来自哈勃空间望远镜。 该天体在近日点前3.8天文单位处明显活跃，显示出从核的面向太阳的热侧释放出尘埃，并有一条微弱的、受辐射压力吹动的尾部远离太阳。 我们应用一个简单模型来估算尘埃的质量损失率，为dM/dt = 6 a kg/s，其中a是以微米为单位的平均粒子大小。 对于1 < a < 100，我们推断dM/dt = 6到60 kg/s。 对内彗发表面亮度分布的拟合将核的有效半径限制为r < 2.8公里，假设其几何反照率为0.04。 相反，如果其彗发由二氧化碳升华提供，则核的半径不能小于0.16公里，如果导致质量损失的分子挥发性较低，则核必须更大。 显示英文摘要

We present high angular resolution observations of the third known interstellar interloper, 3I/ATLAS, from the Hubble Space Telescope. The object is clearly active at 3.8 au pre-perihelion, showing dust emitted from the hot Sun-facing side of the nucleus and a weak, radiation pressure swept tail away from the Sun. We apply a simple model to estimate the mass loss rate in dust as dM/dt = 6 a kg/s, where a is the mean particle size in microns. With 1 < a < 100, we infer dM/dt = 6 to 60 kg/s. A fit to the surface brightness distribution of the inner coma limits the effective radius of the nucleus to be r < 2.8 km, assuming red geometric albedo 0.04. Conversely, the nucleus cannot be smaller than 0.16 km in radius if its coma is supplied by sublimation of carbon monoxide, and must be larger if a less volatile molecule drives the mass loss.

[22] arXiv:2508.03044 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 使用毫秒波长在 parsec 尺度上的甚长基线干涉测量法研究 CTA 102 的喷流宽度分布 显示英文标题

标题： Investigating the Jet Width Profile of CTA 102 with Very Long Baseline Interferometry at Parsec Scales

ZhanHao Ng, Juan Carlos Algaba, Zamri Zainal Abidin

评论： 9页，7图，已接受发表于MNRAS

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

活动星系核喷流长期以来被认为表现出锥形喷流形状，但最近发现一些喷流呈现出从抛物线到锥形结构的过渡。随着更多源的研究，这种准直轮廓似乎代表了一种常见的范式。先前的研究表明，Bondi半径可能作为过渡位置的指示器，尽管在一些源中观察到了差异。为了进一步探讨这一点，我们选择了CTA 102，因为现有文献中关于喷流几何断裂的存在存在混合证据。我们研究了CTA 102的喷流宽度轮廓，以研究喷流中可能的过渡变化，从而改善对Bondi半径与喷流过渡之间关系的理解。我们使用了CTA 102在2、5和8 GHz（单次观测）以及15、22和43 GHz（叠加）的多频VLBA图像。喷流宽度轮廓被建模为一个单一幂律$W_{jet}\propto r^{\epsilon}$，得出幂律指数为$\epsilon=0.69\pm0.02$，表明准抛物线几何形状，没有明显的向锥形区的过渡。在Bondi半径周围缺乏可辨别的结构断裂意味着仅与该半径相关的物理条件不足以解释喷流准直行为。另一方面，我们在喷流宽度轮廓中观察到振荡特征，表明有额外的物理过程影响，超出重力约束之外。这些发现有助于更细致地理解活动星系核中的喷流准直，并突显了喷流-环境相互作用的复杂性。 显示英文摘要

Active Galactic Nucleus jets have long be thought to exhibit a conical jet shape, but recently, several jets were found to have a transition from parabolic to conical structure. As more sources are investigated, this collimation profile appears to represent a common paradigm. Previous works suggest that the Bondi radius may serve as an indicator of the transition location, although discrepancies have been observed in some sources. To explore this further, we selected CTA 102 for which existing literature presents mixed evidence regarding the presence of a jet geometry break. We investigated the jet width profile of CTA 102 to study the possible transition changes in the jet, thereby improving the understanding of connection between Bondi radius and jet transition. We used multi-frequency VLBA images of CTA 102 at 2, 5, and 8 (single epoch), and 15, 22 and 43 GHz (stacked). The jet width profile was modeled with a single power law $W_{jet}\propto r^{\epsilon}$ yielding a power-law index of $\epsilon=0.69\pm0.02$, indicative of a quasi-parabolic geometry with no clear transition to a conical regime. The absence of discernible structural break around the Bondi radius implies that the physical conditions associated with the radius alone are insufficient to explain the jet collimation behaviour. On the other hand, we observe oscillatory features in the jet width profile, suggesting the influence of additional physical processes beyond gravitational confinement. These findings contribute to a more nuanced understanding of jet collimation in AGN and highlight the complexity of jet-environment interactions.

[23] arXiv:2508.03089 (交叉列表自 astro-ph.SR) [中文pdf, pdf, html, 其他]

标题： 红团簇巨星中的锂富集：过去双星相互作用或合并事件的线索 显示英文标题

标题： Li-enrichment in red clump giants: Clues for past binary interaction or merger events

Raghubar Singh, Bacham E. Reddy, Anohita Mallick, Gang Zhao

评论： 8页，4图，已被ApJL接收

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 星系的天体物理学 (astro-ph.GA)

为了理解核心氦燃烧或红团（RC）巨星中高锂丰度的潜在机制，我们分析了一个包含5227个RC巨星的样本，其质量为M $\leq$ 2~M$_{\odot}$，使用了光谱和星震数据。 我们发现120个RC巨星（$\sim$2~$\%$）具有A(Li) = 0.7~dex的下限，比接近RGB顶端的前驱星高出40倍。 在120个RC巨星中，我们通过开普勒光曲线分析中的恒星斑点测量了16个RC巨星的实际旋转速度。 我们发现大多数高速旋转的RC巨星也是非常富锂的RC巨星，且旋转似乎随着锂丰度的减少而迅速下降，这表明高速旋转和高锂丰度都是瞬态现象，并与单一来源有关。 此外，我们发现极端低质量RC巨星中富锂RC巨星的出现率显著较高，分别为15~$\%$和RC巨星中异常[C/N]比值的12~$\%$。 RC巨星的极端低质量、快速旋转和异常[C/N]值归因于它们过去的双星相互作用/合并历史。 这些结果提出了一个问题：双星相互作用/合并是否是RC巨星中锂增强的必要条件，与氦闪同时发生。 显示英文摘要

To understand the underlying mechanisms for high lithium abundances among core He-burning or red clump (RC) giants, we analyzed a sample of 5227 RC giants of mass M $\leq$ 2~M$_{\odot}$ using spectra and asteroseismic data. We found 120 RC giants ($\sim$2~$\%$) with a lower limit of A(Li) = 0.7~dex, a factor of 40 more than their predecessors close to the RGB tip. Of the 120 RC giants, we could measure actual rotations for 16 RC giants using stellar spots from the Kepler light curve analysis. We found that most of the high rotation RC giants are also very high Li-rich RC giants, and the rotation seems to decline rapidly with Li abundance depletion, suggesting that both the high rotation and high Li abundance are transient phenomena and associated with a single source. Further, we found a significantly high occurrence of 15~$\%$ and 12~$\%$ of Li-rich RC giants among extremely low-mass RC giants and RC giants with anomalous [C/N] ratios, respectively. The extremely low mass, fast rotation and anomalous [C/N] values of RC giants are attributed to their past binary interaction/merger history. The results pose a question of whether the binary interaction/merger is a prerequisite along with the He-flash for Li-enhancement among RC giants.

[24] arXiv:2508.03161 (交叉列表自 astro-ph.SR) [中文pdf, pdf, html, 其他]

标题： 原恒星喷流在最早阶段（POETS）。VIII。 中间质量恒星形成区域G105.42+9.88（别名LkHα 234）中的喷流 显示英文标题

标题： Protostellar Outflows at the EarliesT Stages (POETS). VIII. The jets in the intermediate-mass star-forming region G105.42+9.88 (alias LkHα 234)

Luca Moscadelli, Fabrizio Massi, Olga Bayandina

评论： 12页，6图，已被接受发表于《天文学与天体物理学》（A&A）

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 星系的天体物理学 (astro-ph.GA)

我们的目标是研究年轻恒星体（YSO）团G105.42+9.88（别名LkH$\alpha$234）内部的原恒星喷流。这是Protostellar Outflows at the EarliesT Stages（POETS）调查中亮度最低的目标之一，该调查最近进行，旨在研究10-100 au尺度上的年轻喷流发射。多历次水脉泽甚长基线干涉测量（VLBI）观测与灵敏的Jansky Very Large Array（JVLA）连续谱和Large Binocular Telescope（LBT）H$_2$2.12$\mu$m观测相结合，使我们能够研究由相距约0.22"的中等质量双星系统VLA 3A和3B产生的原恒星喷流，以及位于VLA 3西北约1"处的中等质量YSO VLA 2。朝向VLA 2，2001年和2011年的Very Long Baseline Array（VLBA）观测一致表明，水脉泽正在追踪一条喷流。3D流动速度的分析证明，该喷流是由磁流体动力学（MHD）盘风（DW）中的磁力离心作用启动的。我们推断水脉泽追踪的流线的启动半径范围为10-50 au。全局VLBI 2023年水脉泽观测表明，喷流传播可能受到位于VLA 2东北方向的一个非常致密的云块阻碍，并且这与大尺度的LBT H$_2$发射一致，仅追踪了VLA 2喷流的西南叶。相反，附近的YSO VLA 3A和3B发出的平行喷流可以通过H$_2$发射在几10"的尺度上可靠地追踪到西南和东北方向。特别是，在VLA 3东北方向，这两条喷流的方向穿过一系列间隔的H$_2$结，这是周期性喷流的明显特征。由水脉泽在约10 au尺度上观察到的VLA 3B的可变喷射，可能是较大尺度上观测到的周期性喷流的起源。 显示英文摘要

Our aim is to investigate the protostellar jets inside the young stellar object (YSO) cluster G105.42+9.88 (alias LkH$\alpha$ 234). This is one of the least luminous targets of the Protostellar Outflows at the EarliesT Stages (POETS) survey, which has been recently carried out to study young outflow emission on scales of 10-100 au. The combination of multi-epoch water maser very long baseline interferometry (VLBI) observations with sensitive Jansky Very Large Array (JVLA) continuum and Large Binocular Telescope (LBT) H$_2$ 2.12 $\mu$m observations, allows us to study the protostellar outflows from the intermediate-mass binary system VLA 3A and 3B, separated by ~0.22", and from VLA 2, an intermediate-mass YSO placed ~1" to northwest of VLA 3. Toward VLA 2, the 2001 and 2011 Very Long Baseline Array (VLBA) observations consistently show that the water masers are tracing a jet. The analysis of the 3D flow velocities proves that the jet is magneto-centrifugally launched in a magnetohydrodynamic (MHD) disk wind (DW). We infer launch radii in the range 10-50 au for the streamlines traced by the water masers. The global VLBI 2023 water maser observations indicate that the jet propagation can be hindered by a very dense clump placed northeast of VLA 2 and that is consistent with the large-scale LBT H$_2$ emission, tracing only the southwest lobe of the VLA 2 jet. Instead, the parallel jets emitted by the nearby YSOs VLA 3A and 3B can be reliably tracked with the H$_2$ emission at scales of a few 10" to both the southwest and the northeast. In particular, northeast of VLA 3 the direction of these two jets crosses a linear chain of spaced H$_2$ knots, which is a clear signature of an episodic jet. The variable ejection from VLA 3B, witnessed by the water masers at scales of ~10 au, could be the origin of the episodic jet observed at larger scales.

[25] arXiv:2508.03264 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 人类与机器——1:3。 经典和基于机器学习的Lyman-$α$森林摘要统计量的联合分析 显示英文标题

标题： Human vs. machine -- 1:3. Joint analysis of classical and ML-based summary statistics of the Lyman-$α$ forest

S. Chang, P. Nayak, M. Walther, D. Gruen

评论： 8页，9图（包括附录）。提交给《天文学与天体物理学》

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

为了压缩和更易解释Lyman-$\alpha$ forest (Ly$\alpha$F) 数据集，通常使用汇总统计量，例如功率谱。然而，这种汇总不可避免地会丢失一些信息，从而削弱对感兴趣参数的约束能力。最近，基于机器学习（ML）的汇总方法被提出作为人类定义的统计量的替代方法。这引发了一个问题：基于ML的汇总是否能包含传统统计量所捕捉的全部信息，反之亦然？在本研究中，我们将三种人类定义的技术和一种基于ML的方法应用于从流体力学模拟中生成的模拟Ly$\alpha$F数据，并假设幂律温度-密度关系，推断出两个宇宙间介质的热参数。我们引入了一种度量标准，用于衡量在结合两种汇总时优劣指标的改进程度。因此，我们证明了基于ML的汇总方法不仅包含了人类定义统计量的几乎全部信息，而且通过温度-密度关系参数的后验体积比率，其约束力更强，优于1:3。 显示英文摘要

In order to compress and more easily interpret Lyman-$\alpha$ forest (Ly$\alpha$F) datasets, summary statistics, e.g. the power spectrum, are commonly used. However, such summaries unavoidably lose some information, weakening the constraining power on parameters of interest. Recently, machine learning (ML)-based summary approaches have been proposed as an alternative to human-defined statistical measures. This raises a question: can ML-based summaries contain the full information captured by traditional statistics, and vice versa? In this study, we apply three human-defined techniques and one ML-based approach to summarize mock Ly$\alpha$F data from hydrodynamical simulations and infer two thermal parameters of the intergalactic medium, assuming a power-law temperature-density relation. We introduce a metric for measuring the improvement in the figure of merit when combining two summaries. Consequently, we demonstrate that the ML-based summary approach not only contains almost all of the information from the human-defined statistics, but also that it provides significantly stronger constraints by a ratio of better than 1:3 in terms of the posterior volume on the temperature-density relation parameters.

[26] arXiv:2508.03291 (交叉列表自 astro-ph.IM) [中文pdf, pdf, html, 其他]

标题： 基于深度学习的星系图像转换模型的研究 显示英文标题

标题： Investigation on deep learning-based galaxy image translation models

Hengxin Ruan, Qiufan Lin, Shupei Chen, Yang Wang, Wei Zhang

评论： 已被A&A接收；18+6页；12+6图

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA) ; 计算机视觉与模式识别 (cs.CV)

银河图像翻译是银河物理和宇宙学中的一个重要应用。 基于深度学习的生成模型已被用于图像生成、数据质量增强、信息提取，并被推广到其他任务，如去混叠和异常检测。 然而，大多数关于图像翻译的研究主要集中在银河图像的像素级和形态学级统计特征上。 对于复杂高阶银河物理信息的保留讨论较少，这在依赖高保真图像翻译的研究中更为具有挑战性但至关重要。 因此，我们研究了生成模型在保留高阶物理信息（以光谱红移表示）的同时，保留像素级和形态学级信息的效果。 我们使用SDSS和CFHTLS的银河图像测试了四种代表性模型，即一个Swin变换器、一个SRGAN、一个胶囊网络和一个扩散模型。 我们发现，这些模型在保留红移信息方面表现出不同程度的能力不足，即使银河的全局结构和形态学级统计特征可以大致再现。 特别是，发现银河的跨波段峰值通量包含有意义的红移信息，但在图像翻译过程中它们受到明显的不确定性影响，这可能主要是由于多对多映射的性质。 尽管如此，不完美的翻译图像仍可能包含大量信息，因此对于高图像保真度不是强需求的下游应用具有前景。 我们的工作可以促进进一步研究复杂物理信息如何在银河图像上表现，并为科学用途的图像翻译模型的发展提供启示。 显示英文摘要

Galaxy image translation is an important application in galaxy physics and cosmology. With deep learning-based generative models, image translation has been performed for image generation, data quality enhancement, information extraction, and generalized for other tasks such as deblending and anomaly detection. However, most endeavors on image translation primarily focus on the pixel-level and morphology-level statistics of galaxy images. There is a lack of discussion on the preservation of complex high-order galaxy physical information, which would be more challenging but crucial for studies that rely on high-fidelity image translation. Therefore, we investigated the effectiveness of generative models in preserving high-order physical information (represented by spectroscopic redshift) along with pixel-level and morphology-level information. We tested four representative models, i.e. a Swin Transformer, an SRGAN, a capsule network, and a diffusion model, using the SDSS and CFHTLS galaxy images. We found that these models show different levels of incapabilities in retaining redshift information, even if the global structures of galaxies and morphology-level statistics can be roughly reproduced. In particular, the cross-band peak fluxes of galaxies were found to contain meaningful redshift information, whereas they are subject to noticeable uncertainties in the translation of images, which may substantially be due to the nature of many-to-many mapping. Nonetheless, imperfect translated images may still contain a considerable amount of information and thus hold promise for downstream applications for which high image fidelity is not strongly required. Our work can facilitate further research on how complex physical information is manifested on galaxy images, and it provides implications on the development of image translation models for scientific use.

[27] arXiv:2508.03395 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 超新星1987A的致密天体和最内层抛射物 显示英文标题

标题： The compact object and innermost ejecta of SN 1987A

J. Larsson, C. Fransson, P. J. Kavanagh, B. Sargent, M. J. Barlow, M. Matsuura, C. Gall, R. D. Gehrz, N. Habel, A. S. Hirschauer, O. C. Jones, R. P. Kirshner, M. Meixner, S. Rosu, T. Temim

评论： 已接受发表于ApJ

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

詹姆斯·韦布空间望远镜对SN 1987A的首次观测提供了明确的证据，表明一个致密天体正在电离最内层的抛射物。 在这里，我们分析了第二次JWST NIRSpec和MIRI/MRS观测的数据，以更准确地描述该区域的特性，新的NIRSpec数据提供了更高的光谱分辨率，有助于此分析。 我们确认了中心区域之前识别出的窄线的存在；[Ar VI] 4.5292 $\mu$m，[Ar II] 6.9853 $\mu$m，[S IV] 10.5105 $\mu$m，以及 [S III] 18.7130 $\mu$m，并且在 [Ca V] 4.1585 $\mu$m，[Cl II] 14.3678 $\mu$m 和可能的 [Fe II] 1.6440 $\mu$m 中识别出类似的组分。这些线条向蓝端偏移了 $\sim$ -250 km/s，而发射区域在空间上未分辨，并位于中心的东南方向。 偏移和蓝移可能意味着中子星的踢速度为$510 \pm 55$km/s。 我们还在中心附近识别出 [Ca IV] 3.2068$\mu$m，但它向北偏移，并具有红移$\sim 700$km/s。 我们发现，由典型粒径为$\sim 0.3\ \mu$m 的尘埃散射可以解释 [Ca IV] 的特性以及短波长处其他窄线的缺失，而尘埃吸收在$\lambda \gtrsim 8\ \mu$m 处很重要。脉冲星风星云和冷却中子星的电离模型都与观测结果相符，除了 [Fe II] 特征。 这两种模型主要在短波长处存在差异，随着膨胀抛射物中尘埃光学厚度的减少，预计未来会出现新的线条。 显示英文摘要

The first JWST observations of SN 1987A provided clear evidence that a compact object is ionizing the innermost ejecta. Here we analyze a second epoch of JWST NIRSpec and MIRI/MRS observations to better characterize the properties of this region, aided by a higher spectral resolving power for the new NIRSpec data. We confirm the presence of the previously identified narrow lines from the central region; [Ar VI] 4.5292 $\mu$m, [Ar II] 6.9853 $\mu$m, [S IV] 10.5105 $\mu$m, and [S III] 18.7130 $\mu$m, and also identify similar components in [Ca V] 4.1585 $\mu$m, [Cl II] 14.3678 $\mu$m, and possibly [Fe II] 1.6440 $\mu$m. These lines are blueshifted by $\sim$ -250 km/s, while the emission region is spatially unresolved and located southeast of the center. The offset and blueshift could imply a kick velocity of $510 \pm 55$ km/s for the neutron star. We also identify [Ca IV] 3.2068 $\mu$m near the center, but it is displaced to the north and has a redshift of $\sim 700$ km/s. We find that scattering by dust in the ejecta with a typical grain size $\sim 0.3\ \mu$m can explain the [Ca IV] properties and the absence of other narrow lines at shorter wavelengths, while dust absorption is important at $\lambda \gtrsim 8\ \mu$m. Photoionization models for a pulsar wind nebula and a cooling neutron star are both compatible with the observations, with the exception of the [Fe II] feature. The two models primarily differ at short wavelengths, where new lines are expected to emerge over time as the optical depth of dust in the expanding ejecta decreases.

[28] arXiv:2508.03451 (交叉列表自 astro-ph.SR) [中文pdf, pdf, 其他]

标题： JWST对环状星云（NGC 6720）的观测——II。 多环芳烃发射 显示英文标题

标题： JWST observations of the Ring Nebula (NGC 6720) -- II. PAH emission

Nicholas Clark, Els Peeters, Nick L. J. Cox, Jan Cami, Michael J. Barlow, Patrick J. Kavanagh, Griet Van de Steene, Mikako Matsuura, Albert Zijlstra, Isabel Aleman, Jeronimo Bernard-Salas, Harriet L. Dinerstein, Kay Justtanont, Kyle F. Kaplan, Arturo Manchado, Raghvendra Sahai, Peter van Hoof, Kevin Volk, Roger Wesson

评论： 发表于MNRAS

期刊参考： MNRAS 540, 1984-1997 (2025)

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 星系的天体物理学 (astro-ph.GA)

多环芳烃（PAHs）和含碳尘埃已在致密的恒星周围环境中被观测到，但它们在这些环境中的形成和演化途径仍然不明确。 我们的目标是表征致密行星状星云中的PAH发射，以阐明它们的形成和演化途径。 我们获得了詹姆斯·韦布空间望远镜近红外光谱仪（NIRSpec）和中红外仪器（MIRI）积分场单元光谱观测数据，针对环状星云（NGC 6720）中的两个单独结区，这是一个致密的行星状星云，并确定了PAH的光谱特征。 我们在两个结区都检测到了3.3和11.2微米的PAH发射带，但在6-9微米范围内未检测到PAH发射。 我们补充了斯皮策红外光谱仪（IRS）短低分辨率1（SL1）和SL2数据，其中包含11.2微米、弱的6.2微米和弱的7.7微米PAH发射带。 JWST数据确认了11.2微米带的异常轮廓，与典型的11.2微米PAH轮廓相比，该带非常宽且红移。 我们估计PAH群体主要是中性的。 3.3和11.2微米带的相对积分表面亮度表明存在由35±6个碳原子组成的较小尺寸的PAH。 我们发现PAH发射集中在结区之外的星际介质中，并证实了在中心恒星周围的狭窄“PAH环”中存在增强的PAH发射。 这种形态表明，PAH是在环状星云的渐近巨星分支阶段形成的，是在中心恒星的尘埃驱动风中形成的。 显示英文摘要

Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous dust have been observed in clumpy circumstellar environments, yet their formation and evolutionary pathways in such environments remain elusive. We aim to characterize the PAH emission in a clumpy planetary nebula to decipher their formation and evolution pathways. We obtained JWST Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI) integral field unit spectroscopic observations of two individual knots in the Ring Nebula (NGC 6720), a clumpy planetary nebula, and determine the PAH spectral characteristics. We detect the 3.3 and 11.2 um PAH emission bands in both knots but do not detect PAH emission in the 6-9 um range. We supplement our data with Spitzer Infrared Spectrograph (IRS) Short-Low 1 (SL1) and SL2 data, containing 11.2, weak 6.2, and weak 7.7 um PAH emission bands. The JWST data confirm the unusual profile of the 11.2 um band, which is very broad and redshifted with respect to typical 11.2 um PAH profiles. We estimate the PAH population to be largely neutral. The relative integrated surface brightness of the 3.3 and 11.2 um bands indicates the presence of small-sized PAHs, consisting of 35 +/- 6 carbon atoms. We find that the PAH emission is concentrated outside of the clumps, in the inter-clump medium, and confirm the existence of enhanced PAH emission in a narrow 'PAH ring' centred on the central star. This morphology suggests that PAHs formed during the Ring Nebula's asymptotic giant branch phase, in the central star's dust-driven wind.

[29] arXiv:2508.03462 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 高频峰值射电源来自AT20G目录及其射电光谱 显示英文标题

标题： High Frequency Peak Radio Sources from the AT20G Catalogue and Their Radio Spectra

Elena Majorova, Olga Zhelenkova

评论： 32页，9图，7表；将发表于天体物理公报

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

从AT20G目录中的射电源形成了一个高频峰值器（HFP）候选样本，这些射电源的光学厚发射区的光谱指数$\alpha_{below}$超过+0.5。 对包含269个射电源的样本中的源进行了光谱特性研究。 构建了这些源的光谱，并确定了低于$\alpha_{below}$和高于峰值$\alpha_{above}$的光谱指数、峰值频率$\nu_{obs}$、峰值频率处的通量密度$S_{peak}$以及射电谱中的峰值半宽。 光谱分析表明，该样本相当均匀，由具有$\nu_{obs}>5$GHz 的HFP组成。 大多数源（67%）在0.8 GHz以下没有数据。 187个源具有超反转光谱（$\alpha_{below}>$+0.7），这是AT20G目录中所有源的3.2%，也是我们样本中射电源的70%。 对样本中射电源的光学识别显示，70%的宿主是类星体。 样本包含射电光度在20 GHz范围内的致密天体，为$10^{23}$-$10^{30}$W/Hz，射电源发射区域的角大小为0.002-0.25 mas，投影线性大小从0.2到30 pc。 射电源的峰值频率与其角大小之间的依赖关系与之前对CSS和GPS源发现的结果一致。 显示英文摘要

A sample of high-frequency peaker (HFP) candidates was formed from the AT20G catalog radio sources with spectral indices of the optically thick emission region $\alpha_{below}$ exceeding +0.5. A study of the spectral properties of the sources in the sample, which included 269 radio sources, was performed. The spectra of the sources were constructed and the spectral indices below $\alpha_{below}$ and above the peak $\alpha_{above}$, the peak frequency $\nu_{obs}$, the flux density at the peak frequency $S_{peak}$, and the peak half-width in the radio spectrum were determined. Analysis of the spectra showed that the sample is fairly homogeneous and consists of HFPs with $\nu_{obs}>5$ GHz. Most sources (67%) do not have data at frequencies below 0.8 GHz. 187 sources have ultra-inverted spectra ($\alpha_{below}>$+0.7), which is 3.2% of all sources in the AT20G catalog and 70% of radio sources in our sample. Optical identification of radio sources in the sample showed that 70% of the hosts are quasars. The sample consists of compact objects with radio luminosity at 20 GHz in the range of $10^{23}$-$10^{30}$ W/Hz, angular sizes of emitting regions of radio sources are 0.002-0.25 mas, projected linear sizes are from 0.2 to 30 pc. The dependence of the peak frequencies of radio sources on their angular sizes is in good agreement with that previously discovered for CSS and GPS sources.

[30] arXiv:2508.03637 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 迁移陷阱在活动星系核盘中双黑洞形成中的作用 显示英文标题

标题： The role of migration traps in the formation of binary black holes in AGN disks

Maria Paola Vaccaro, Yannick Seif, Michela Mapelli

评论： 欢迎评论，13页，9图

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

双黑洞（BBHs）在活动星系核（AGN）的吸积盘中形成，是产生引力波的一个有前景的渠道。 BBHs通常被认为起源于迁移陷阱，即嵌入的恒星级黑洞（BHs）的I型迁移从向外转变为向内的径向位置。 在本工作中，我们通过显式模拟不同扭矩方案下AGN盘中BH对的径向迁移来检验这一假设，包括热效应和向II型迁移的转换。 我们量化了双黑洞形成的位置和时间，作为超大质量黑洞（SMBH）质量、盘粘度和迁移BH质量的函数。 我们发现，虽然大多数配对事件发生在迁移陷阱附近，但相当一部分发生在盘的其他地方，特别是在高粘度盘（$\alpha=0.1-0.4$）和质量超过阈值$10^{7.5}$太阳质量的SMBH中，其中差分迁移最有效。 包含热力矩有利于在盘的外侧进行配对，并促进快速配对。 我们还研究了分级BBH形成，表明更高代的配对更紧密地聚集在陷阱位置周围。 我们的结果提供了BBH配对位置和时标的真实方案，强调了假设固定BBH形成地点的局限性。 显示英文摘要

Binary black holes (BBHs) forming in the accretion disks of active galactic nuclei (AGNs) represent a promising channel for gravitational-wave production. BBHs are typically expected to originate at migration traps, i.e. radial locations where the Type I migration of embedded stellar-mass black holes (BHs) transitions from outwards to inwards. In this work, we test this assumption by explicitly simulating the radial migration of BH pairs in AGN disks under different torque prescriptions, including thermal effects and the switch to Type II migration. We quantify where and when binaries form as a function of supermassive BH (SMBH) mass, disk viscosity, and migrating BH mass. We find that while the majority of pair-up events occur near migration traps, a substantial fraction takes place elsewhere in the disk, particularly for high-viscosity disks ($\alpha=0.1-0.4$) and SMBHs with mass above a threshold of $10^{7.5}$ solar masses, where differential migration is most efficient. The inclusion of thermal torques favors pair-up in outer locations of the disk and facilitates rapid pair-up. We also investigate hierarchical BBH formation, showing that higher-generation pair-ups are more tightly clustered around trap locations. Our results provide realistic prescriptions for BBH pair-up locations and timescales, highlighting the limitations of assuming fixed BBH formation sites.

替换提交 (展示 8 之 8 条目 )

[31] arXiv:2312.03984 (替换) [中文pdf, pdf, html, 其他]

标题： 控制可压缩模态：体积粘度和湍流发电机 显示英文标题

标题： Taking control of compressible modes: bulk viscosity and the turbulent dynamo

James R. Beattie, Christoph Federrath, Neco Kriel, Justin Kin Jun Hew, Amitava Bhattacharjee

评论： 31页，21图，已被MNRAS接收

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE) ; 等离子体物理 (physics.plasm-ph)

许多多原子天体物理等离子体是可压缩的，并且处于化学和热力学非平衡状态，通过分子组成的内部自由度引入了体积粘度，直接影响可压缩模式的衰减，$\mathbf{v}_{\parallel}(\mathbf{k})$。 这对于星际介质中的小尺度湍流发电机过程尤其重要，这些过程已知对压缩效应非常敏感。 为了控制$\mathbf{v}_{\parallel}(\mathbf{k})$的粘性特性，我们进行了跨音速、粘性电阻发电机模拟，并加入了额外的体积粘度$\nu_{\rm bulk}$，推导出一个新的$\nu_{\rm bulk}$雷诺数$\rm{Re}_{\rm bulk}$以及粘性普朗特数$\rm{P}\nu \equiv \rm{Re}_{\rm bulk} / \rm{Re}_{\rm shear}$，其中$\rm{Re}_{\rm shear}$是剪切粘度雷诺数。 我们通过$\nabla\otimes\mathbf{v}$的正交张量分解，推导出一种将$E_{\rm mag}$增长率分解为不可压缩和可压缩项的框架，其中$\mathbf{v}$是流体速度。 我们发现$\mathbf{v}_{\parallel}(\mathbf{k})$起着双重作用，既促进又抑制$E_{\rm mag}$，并且即使在可压缩发电机中，场线拉伸也是增长的主要驱动因素。 在没有$\nu_{\rm bulk}$（$\rm{P}\nu \to \infty$）的情况下，$\mathbf{v}_{\parallel}(\mathbf{k})$在小尺度上堆积，形成谱瓶颈，这在$\rm{P}\nu \approx 1$时消失。 （摘要）。 我们强调进一步理解$\nu_{\rm bulk}$在可压缩天体物理等离子体中的重要性，我们认为其强度可能与冷星际介质中的剪切粘度相当，并指出没有体积粘度的可压缩直接数值模拟存在未解析的可压缩模式耗散尺度。 显示英文摘要

Many polyatomic astrophysical plasmas are compressible and out of chemical and thermal equilibrium, introducing a bulk viscosity into the plasma via the internal degrees of freedom of the molecular composition, directly impacting the decay of compressible modes, $\mathbf{v}_{\parallel}(\mathbf{k})$. This is especially important for small-scale, turbulent dynamo processes in the interstellar medium, which are known to be sensitive to the effects of compression. To control the viscous properties of $\mathbf{v}_{\parallel}(\mathbf{k})$, we perform trans-sonic, visco-resistive dynamo simulations with additional bulk viscosity $\nu_{\rm bulk}$, deriving a new $\nu_{\rm bulk}$ Reynolds number $\rm{Re}_{\rm bulk}$, and viscous Prandtl number $\rm{P}\nu \equiv \rm{Re}_{\rm bulk} / \rm{Re}_{\rm shear}$, where $\rm{Re}_{\rm shear}$ is the shear viscosity Reynolds number. We derive a framework for decomposing $E_{\rm mag}$ growth rates into incompressible and compressible terms via orthogonal tensor decompositions of $\nabla\otimes\mathbf{v}$, where $\mathbf{v}$ is the fluid velocity. We find that $\mathbf{v}_{\parallel}(\mathbf{k})$ play a dual role, growing and decaying $E_{\rm mag}$, and that field-line stretching is the main driver of growth, even in compressible dynamos. In the absence of $\nu_{\rm bulk}$ ($\rm{P}\nu \to \infty$), $\mathbf{v}_{\parallel}(\mathbf{k})$ pile up on small-scales, creating a spectral bottleneck, which disappears for $\rm{P}\nu \approx 1$. (abridged). We emphasize the importance of further understanding the role of $\nu_{\rm bulk}$ in compressible astrophysical plasmas, which we estimate could be as strong as the shear viscosity in the cold ISM, and highlight that compressible direct numerical simulations without bulk viscosity have unresolved compressible mode dissipation scales.

[32] arXiv:2505.14426 (替换) [中文pdf, pdf, html, 其他]

标题： 暗物质的统一径向分布 显示英文标题

标题： Unified Radial Distributions of Dark Matter

P. Steffen

评论： 预印本，10页，4图

主题： 星系的天体物理学 (astro-ph.GA) ; 高能物理 - 现象学 (hep-ph)

一种方法被提出，用于获得不同星系的暗物质属性的统一径向分布，而无需考虑其质量、类型或大小。 使用SPARC组[3]的153个不同星系的2693个恒星天体的公开可用测量数据来证明该方法的有效性。 获得的如速度、加速度、质量及质量密度等暗物质属性的统一径向分布，提供了对星系内一般暗物质行为的详细理解。 显示英文摘要

A method is presented for obtaining unified radial distributions of dark matter properties for different galaxies independent of their mass, type, or size. The publicly available measurements of 2693 stellar objects of 153 different galaxies of the SPARC-group [3] are used to demonstrate the effectivity of the method. The obtained unified radial distributions of dark matter properties like velocity, acceleration, mass and mass density give a detailed understanding of the general dark matter behavior within in the galaxies.

[33] arXiv:2506.13093 (替换) [中文pdf, pdf, html, 其他]

标题： NGC 4261双喷流的次帕克加速与准直 显示英文标题

标题： Sub-Parsec Acceleration and Collimation of NGC 4261's Twin Jets

Xi Yan, Lang Cui, Kazuhiro Hada, Sandor Frey, Ru-sen Lu, Liang Chen, Wancheng Xu, Elika P. Fariyanto, Luis C. Ho

评论： 即将发表于ApJ。然而，我们仍建议参考arXiv版本1（v1）以简要讨论磁驱动喷流模型背景下的亚秒差距尺度结构转变（见附录E）

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

我们报告了在近邻低光度活动星系核（LLAGN）NGC 4261的双喷流中，首次获得共空间亚秒差距加速和准直区域（ACZ）的可靠证据。 这一结果来自于多频率甚长基线阵列成像，结合了射电核心的频率依赖特性（核心位移和核心大小）以及通过喷流与对称喷流亮度比确定的喷流动力学特性。 通过应用多种分析方法并结合文献中的结果，我们在喷流和对称喷流中识别出抛物线到圆锥形的结构过渡，过渡发生在喷流的$(1.23\pm0.24)$pc 或$(8.1\pm1.6)\times10^3 R_{\rm s}$（施瓦茨希尔德半径）以及对称喷流的$(0.97\pm0.29)$pc 或$(6.4\pm1.9)\times10^3 R_{\rm s}$。 我们还推导了距离为$\sim (10^3-2\times10^4) R_{\rm s}$处的喷流速度场。 尽管存在局部的运动学变化，从$\sim 10^3$到$\sim8\times10^3 R_{\rm s}$，喷流整体加速到相对论速度，最大洛伦兹因子为$\Gamma_{\rm max} \approx 2.6$。 在此区域之外，喷流逐渐减速到亚相对论速度。 这些发现支持了NGC 4261中存在一个亚秒差距尺度（$\lesssim 1.5$pc）的ACZ，其中喷流通过磁能到动能的转换被加速，同时受到外部压力的约束。 与M 87的简要比较表明，NGC 4261中的ACZ可能代表M 87中ACZ的一个缩小版。 这些结果指向喷流ACZ特性可能存在多样性，强调了将此类研究扩展到更广泛的AGN群体的重要性，以阐明其中的物理机制。 显示英文摘要

We report the first robust evidence for a co-spatial sub-parsec acceleration and collimation zone (ACZ) in the twin jets of the nearby low-luminosity active galactic nucleus (LLAGN) NGC 4261. This result is derived from multifrequency Very Long Baseline Array imaging, combined with the frequency-dependent properties of the radio core (core shift and core size) and jet kinematics determined from the jet-to-counterjet brightness ratio. By applying multiple analysis methods and incorporating results from the literature, we identify a parabolic-to-conical structural transition in both the jet and counterjet, with the transition occurring at $(1.23\pm0.24)$ pc or $(8.1\pm1.6)\times10^3 R_{\rm s}$ (Schwarzschild radii) for the jet and $(0.97\pm0.29)$ pc or $(6.4\pm1.9)\times10^3 R_{\rm s}$ for the counterjet. We also derive the jet velocity field at distances of $\sim (10^3-2\times10^4) R_{\rm s}$. While local kinematic variations are present, the jet shows an overall acceleration to relativistic speeds from $\sim 10^3$ to $\sim8\times10^3 R_{\rm s}$, with a maximum Lorentz factor of $\Gamma_{\rm max} \approx 2.6$. Beyond this region, the jet gradually decelerates to sub-relativistic speeds. These findings support the existence of a sub-parsec-scale ($\lesssim 1.5$ pc) ACZ in NGC 4261, where the jet is accelerated via magnetic-to-kinetic energy conversion while being confined by external pressure. A brief comparison with M 87 suggests that the ACZ in NGC 4261 may represent a scaled-down analogue of that in M 87. These results point towards a potential diversity in jet ACZ properties, emphasizing the importance of extending such studies to a broader AGN population to elucidate the physical mechanisms at play.

[34] arXiv:2506.19570 (替换) [中文pdf, pdf, html, 其他]

标题： 在DESI中寻找从银河系中心弹出的恒星 显示英文标题

标题： Searching for stars ejected from the Galactic Centre in DESI

Sill Verberne, Sergey E. Koposov, Elena Maria Rossi, Zephyr Penoyre

评论： 7页，5图，已被A&A接收

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

星体与银河系中心（GC）的超大质量黑洞Sgr A*之间的动力学相互作用可能会将星体抛入银河晕中。 尽管最近通过Sgr A*的快速抛射已被识别为高速星体（数百至数千公里/秒），但也预计银河晕中包含较慢的星体，这些星体是在过去数十亿年内被抛射出去的。 在本研究中，我们使用DESI的第一数据发布来寻找这些较慢的GC抛射物，这些抛射物因其综合的高金属度（${\rm [Fe/H]}\gtrsim0$）和垂直角动量的小值（$L_Z$）而应从星体晕群体中突出，其分布应在零处达到峰值。 我们的搜索没有得到检测结果，但使我们能够对过去约5 Gyr内GC抛射星体的速率设定上限为$\sim2.8\times10^{-3}$yr$^{-1}$，这一结果与抛射模型无关。 这意味着我们的结果可以用于对不同的抛射模型施加限制，包括那些涉及Sgr A*在过去数十亿年内与其他大质量黑洞合并的模型。 显示英文摘要

Dynamical interactions between stars and the super massive black hole Sgr A* at the Galactic Centre (GC) may eject stars into the Galactic halo. While recent fast ejections by Sgr A* have been identified in the form of hypervelocity stars (hundreds to thousands km/s), it is also expected that the stellar halo contains slower stars, ejected over the last few billion years. In this study, we use the first data release of DESI to search for these slower GC ejecta, which are expected to stand out from the stellar halo population for their combined high metallicity (${\rm [Fe/H]}\gtrsim0$) and small values of their vertical angular momentum ($L_Z$), whose distribution should peak at zero. Our search does not yield a detection, but allows us to place an upper limit on the ejection rate of stars from the GC of $\sim2.8\times10^{-3}$ yr$^{-1}$ over the past ~5 Gyr, which is ejection model independent. This implies that our result can be used to put constraints on different ejection models, including that invoking mergers of Sgr A* with other massive black holes in the last last few billion years.

[35] arXiv:2507.14072 (替换) [中文pdf, pdf, html, 其他]

标题： 使用K均值和随机森林方法进行恒星、星系和类星体的半监督分类 显示英文标题

标题： Semi-supervised classification of stars, galaxies and quasars using K-means and random-forest approaches

Vahid Asadi, Hosein Haghi, Akram Hasani Zonoozi

评论： 9页，9图，2表，已接受发表于A&A

主题： 星系的天体物理学 (astro-ph.GA)

分类恒星、星系和类星体对于理解宇宙结构和演化至关重要；然而，现代调查产生的大量数据使得手动分类不切实际，而监督学习方法仍受限于标记光谱数据的稀缺性。 我们旨在通过利用半监督学习（SSL）克服完全监督方法的局限性，开发一种可扩展且标签高效的天文学分类方法。 我们提出了一种结合K均值聚类和随机森林分类的新SSL框架。 我们的方法将未标记的数据分为50个簇，将光谱确认的中心点标签传播给95%的簇成员，并在扩展的伪标记数据集上训练随机森林。 我们将这种方法应用于CPz目录，该目录包含多调查的光电和光谱数据，并与完全监督的随机森林进行性能比较。 我们的SSL方法分别对恒星、星系和类星体实现了98.8%、98.9%和92.0%的F1分数，与F1分数分别为99.1%、99.1%和93.1%的监督方法非常接近，同时优于传统的颜色切割技术。 该方法在高维特征空间中表现出稳健性，并且相比之前的工作具有更好的标签效率。 这项工作突显了SSL在标记数据有限时作为天文学分类的可扩展解决方案的潜力，尽管在低维设置中性能可能会下降。 显示英文摘要

Classifying stars, galaxies, and quasars is essential for understanding cosmic structure and evolution; however, the vast data from modern surveys make manual classification impractical, while supervised learning methods remain constrained by the scarcity of labeled spectroscopic data. We aim to develop a scalable, label-efficient method for astronomical classification by leveraging semi-supervised learning (SSL) to overcome the limitations of fully supervised approaches. We propose a novel SSL framework combining K-means clustering with random forest classification. Our method partitions unlabeled data into 50 clusters, propagates labels from spectroscopically confirmed centroids to 95% of cluster members, and trains a random forest on the expanded pseudo-labeled dataset. We applied this to the CPz catalog, containing multi-survey photometric and spectroscopic data, and compared performance with a fully supervised random forest. Our SSL approach achieves F1 scores of 98.8%, 98.9%, and 92.0% for stars, galaxies, and quasars, respectively, closely matching the supervised method with F1 scores of 99.1%, 99.1%, and 93.1%, while outperforming traditional color-cut techniques. The method demonstrates robustness in high-dimensional feature spaces and superior label efficiency compared to prior work. This work highlights SSL as a scalable solution for astronomical classification when labeled data is limited, though performance may be degraded in lower dimensional settings.

[36] arXiv:2503.22442 (替换) [中文pdf, pdf, html, 其他]

标题： 欧几里得快速数据发布（Q1）——深场中超冷矮星的光谱搜索、分类与分析 显示英文标题

标题： Euclid Quick Data Release (Q1) -- Spectroscopic search, classification and analysis of ultracool dwarfs in the Deep Fields

C. Dominguez-Tagle, M. Žerjal, N. Sedighi, P. Mas-Buitrago, E. L. Martín, J.-Y. Zhang, N. Vitas, V. J. S. Béjar, S. Tsilia, S. Muñoz Torres, N. Lodieu, D. Barrado, E. Solano, P. Cruz, R. Tata, N. Phan-Bao, A. Burgasser

评论： 18页，15图，已接受发表于ApJ

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA)

近红外光谱仪和光度计搭载在欧几里得空间任务上，已获得了数百万个天体的近红外（NIR）无狭缝光谱，包括数百个超冷矮星。 欧几里得观测同时获取图像和光谱。 这种观测模式标志着发现新天体的新时代，例如L型和T型矮星，可以通过H2O和CH4吸收带直接识别。 NISP光谱分辨率（R~450）足以通过已知的标准模板按光谱类型对天体进行分类。 Q1在一次访问欧几里得深场时提供了超过400万条NIR光谱。 这些区域释放的大量光谱使我们能够：a) 确认张等人（2024）编译的几乎一半光度候选体的超冷矮星性质；b) 通过Q1数据中的特定光谱指数搜索发现至少11个新的晚期L型和T型矮星；以及c) 通过Zerjal等人（待发表）进行的新光度选择，光谱确认了100多个候选体。 我们呈现了一个初步的欧几里得超冷矮星模板列表，该列表由所有这些搜索中最佳光谱的组合构建而成。 我们包括了来自Q1数据的已确认超冷矮星的首次光谱分析；光谱分类；有效温度的确定；H2O、CH4和NH3光谱指数；以及KI吸收双线的测量。 本文是研究欧几里得超冷矮星的第一步，并将在每次后续的数据发布中得到改进。 显示英文摘要

The Near-Infrared Spectrometer and Photometer onboard the Euclid space mission has obtained near-infrared (NIR) slitless spectra of millions of objects, including hundreds of ultracool dwarfs. Euclid observations retrieve images and spectra simultaneously. This observing mode marks a new era in the discovery of new objects, such as L- and T-type dwarfs, which can be found from direct identification through the H2O and CH4 absorption bands. NISP spectral resolution (R~450) is enough to classify the objects by the spectral type using known standard templates. Q1 provided more than 4 million NIR spectra in one visit to the Euclid Deep Fields. The large amount of spectra released in these fields allowed us to: a) confirm the ultracool dwarf nature of almost half of the photometric candidates compiled by Zhang et al. (2024); b) discover at least 11 new late L- and T-type dwarfs by a specific spectral index search in Q1 data; and c) spectroscopically confirm one hundred more candidates from a new photometric selection conducted by Zerjal et al. (in prep.). We present a preliminary list of Euclid ultracool dwarf templates built by the combination of the best spectra from all these searches. We include the first spectral analysis of confirmed ultracool dwarfs from Q1 data; spectral classifications; determination of effective temperatures; H2O, CH4 and NH3 spectral indices; and measurements of the KI absorption doublet. This paper is a first step in the study of Euclid ultracool dwarfs and will be improved with each subsequent data release.

[37] arXiv:2505.04694 (替换) [中文pdf, pdf, html, 其他]

标题： 聚类引力透镜质量反演（CLUMI+）：结合星系团周围的动力学和弱引力透镜 显示英文标题

标题： Cluster Lensing Mass Inversion (CLUMI+): Combining Dynamics and Weak Lensing around Galaxy Clusters

Keiichi Umetsu, Michele Pizzardo, Antonaldo Diaferio, Margaret J. Geller

评论： 已发表版本在《天体物理学杂志》上，有少量文本修改（例如，第3节的清晰度得到改善；第5.6节中对轮廓推断的准确性和稳健性的讨论有所扩展）。26页，16图

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

我们提出CLUMI+，这是一种自洽的多探针方法，通过结合引力透镜和动力学观测来重建星系团内部及周围的质量分布。 基于K. Umetsu（2013）的联合似然框架，CLUMI+将弱透镜剪切和放大数据与集群流入区域的投影逃逸速度测量相结合，从而在不依赖平衡假设的情况下对引力势获得更严格的约束。 质量分布使用一种灵活的、分段定义的收敛轮廓进行建模，该轮廓描述了透镜场内方位平均的表面质量密度，并在较大半径处过渡到投影幂律形式，此时相空间约束补充透镜效应。 通过中心孔径质量测量引入额外的强透镜约束，使得从星系团核心到外围的全尺度质量重建成为可能。 我们使用IllustrisTNG模拟中一个大质量星系团的合成弱透镜和相空间数据验证CLUMI+，展示了对投影质量和三维质量轮廓的无偏恢复，并在大半径处实现了10%--30%的精度提升。 作为案例研究，我们将CLUMI+应用于A2261，结合Subaru和哈勃空间望远镜的弱+强透镜数据以及Hectospec星系团调查的光谱测量。 该分析展示了多探针、无平衡假设建模在稳健星系团质量重建中的强大能力。 显示英文摘要

We present CLUMI+, a self-consistent, multiprobe methodology for reconstructing the mass distribution in and around galaxy clusters by combining gravitational lensing and dynamical observations. Building on the joint likelihood framework of K. Umetsu (2013), CLUMI+ integrates weak-lensing shear and magnification data with projected escape velocity measurements in the cluster infall region, yielding tighter constraints on the gravitational potential without relying on equilibrium assumptions. The mass distribution is modeled using a flexible, piecewise-defined convergence profile that characterizes the azimuthally averaged surface mass density within the lensing field, transitioning to a projected power-law form at larger radii where phase-space constraints complement lensing. Additional strong-lensing constraints are incorporated via central aperture-mass measurements, enabling full-scale mass reconstruction from the cluster core to the outskirts. We validate CLUMI+ using synthetic weak-lensing and phase-space data for a massive cluster from the IllustrisTNG simulations, demonstrating unbiased recovery of projected and three-dimensional mass profiles and achieving 10%--30% improvement in precision at large radii. As a case study, we apply CLUMI+ to A2261, combining Subaru and Hubble Space Telescope weak+strong lensing data with spectroscopic measurements from the Hectospec Cluster Survey. This analysis demonstrates the power of multiprobe, equilibrium-free modeling for robust cluster mass reconstruction.

[38] arXiv:2507.16929 (替换) [中文pdf, pdf, html, 其他]

标题： 偏振作为探测耀变体中中微子发射的探针 显示英文标题

标题： Polarisation as a probe of neutrino emission from blazars

G. F. Paraschos, E. Traianou, L. C. Debbrecht, I. Liodakis, E. Ros

评论： 9页，2图，1表，已接受发表于《天体物理杂志》

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

在TeV-PeV范围内的河外中微子的来源是研究非常活跃的问题，其中耀变体喷流被认为至少是部分检测结果的来源。 耀变体PKS 0735+178是一个显著的例子；在其2021年末的多波段爆发期间，四个观测站报告了一个中微子事件，其来源与该天体的方向一致。 尽管在这一狭窄的时间范围内没有观察到新的喷流成分被喷射出来，但我们的分析表明，来自核心区域的传播激波前缘很可能是多波段爆发的来源，这是基于PKS 0735+178在偏振光中的非常长基线干涉测量图像。 综合来看，我们的发现暗示了一个连贯的情景，其中激波可能有助于质子的加速，而目标光子可能来源于喷流周围的环境介质或质子同步辐射。 因此，通过质子-光子相互作用产生中微子的必要条件存在于这个喷流中。 显示英文摘要

The source of extragalactic neutrinos in the TeV-PeV range is a matter of very active research, with blazar jets having been postulated to be the origin of at least some of the detections. The blazar PKS 0735+178 is a prominent example; during its multi-band flare in late 2021 a neutrino event was reported by four observatories, with its origin consistent with the direction of that source. While no new jet component was observed to be ejected during that narrow time-frame, our analysis shows that a propagating shock front originating from the core region was the likely source of the multi-band flare, using very-long-baseline interferometry images of PKS 0735+178 in polarised light. Taken together, our findings are suggestive of a coherent scenario in which the shock may contribute to the acceleration of protons, with the target photons potentially originating either from the ambient medium surrounding the jet or from proton synchrotron radiation. The necessary conditions for neutrino emission via proton-photon interactions are, hence, present in this jet.