标题： X射线对仙后座A中子星和年轻中心致密天体的冷却、成分和磁场的限制 显示英文标题

标题： X-ray bounds on cooling, composition, and magnetic field of the Cassiopeia A neutron star and young central compact objects

摘要： 我们对四个年龄小于2500年的最年轻的中心致密天体（CCOs）的多组钱德拉和XMM-Newton光谱进行了分析，这些光谱相隔9-19年：CXOU J232327.9+584842（仙后座A），CXOU J160103.1-513353（G330.2+1.0），1WGA J1713.4-3949（G347.3-0.5），以及XMMU J172054.5-372652（G350.1-0.3）。 通过用热模型拟合这些光谱，我们试图限制每个CCO的长期冷却率、成分和磁场。 对于仙后座A中的CCO，19年间的14次测量表明，温度以每十年2.2±0.2或2.8±0.3百分比（1sigma误差）的速度下降，分别对应于恒定或变化的X射线吸收。 我们得到CXOU J160103.1-513353的冷却率上限为17%，XMMU J172054.5-372652的冷却率上限为6%。 对于最老的CCO，1WGA J1713.4-3949，在十年期间其温度似乎增加了4±2%。 假设每个CCO的首选距离和一个占总恒星表面较大比例的发射区域，非磁性碳大气光谱可以很好地拟合所有四个CCO的光谱。 如果距离更大且发射区域稍小，则使用氢大气可以得到同样良好的光谱拟合，对于CXOU J160103.1-513353，B ≤ 7x10^10 G或B ≥ 10^12 G；对于XMMU J172054.5-372652，B ≤ 10^10 G或B ≥ 10^12 G；而对于1WGA J1713.4-3949，则使用非磁性氢大气。 在CCO演化的统一图景中，我们的结果表明，大多数CCO，因此年轻中子星的相当大一部分，其表面磁场在其生命早期较低，但在几千年内逐渐增强。 显示英文摘要

摘要： We present analysis of multiple Chandra and XMM-Newton spectra, separated by 9-19 years, of four of the youngest central compact objects (CCOs) with ages < 2500 yr: CXOU J232327.9+584842 (Cassiopeia A), CXOU J160103.1-513353 (G330.2+1.0), 1WGA J1713.4-3949 (G347.3-0.5), and XMMU J172054.5-372652 (G350.1-0.3). By fitting these spectra with thermal models, we attempt to constrain each CCO's long-term cooling rate, composition, and magnetic field. For the CCO in Cassiopeia A, 14 measurements over 19 years indicate a decreasing temperature at a ten-year rate of 2.2+/-0.2 or 2.8+/-0.3 percent (1sigma error) for a constant or changing X-ray absorption, respectively. We obtain cooling rate upper limits of 17 percent for CXOU J160103.1-513353 and 6 percent for XMMU J172054.5-372652. For the oldest CCO, 1WGA J1713.4-3949, its temperature seems to have increased by 4+/-2 percent over a ten year period. Assuming each CCO's preferred distance and an emission area that is a large fraction of the total stellar surface, a non-magnetic carbon atmosphere spectrum is a good fit to spectra of all four CCOs. If distances are larger and emission areas are somewhat smaller, then equally good spectral fits are obtained using a hydrogen atmosphere with B <= 7x10^10 G or B >= 10^12 G for CXOU J160103.1-513353, B <= 10^10 G or B >= 10^12 G for XMMU J172054.5-372652, and non-magnetic hydrogen atmosphere for 1WGA J1713.4-3949. In a unified picture of CCO evolution, our results suggest most CCOs, and hence a sizable fraction of young neutron stars, have a surface magnetic field that is low early in their life but builds up over several thousand years.