标题： 对新磁星Swift J1555.2-5402在X射线爆发期间一个月的监测 显示英文标题

标题： A month of monitoring the new magnetar Swift J1555.2-5402 during an X-ray outburst

摘要： 软伽马射线重复暴Swift J1555.2-5402是通过Swift BAT于2021年6月3日检测到的一个持续12毫秒的短爆发发现的。第一次爆发检测后1.6小时，NICER开始对该X射线源进行为期一个月的日常监测。在监测期间，吸收的2-10 keV通量几乎保持在约4e-11 erg/s/cm2，仅显示出轻微的逐渐下降。检测到一个3.86秒的周期性，并测量该周期的时间导数为3.05(7)e-11 s/s。软X射线脉冲呈现出单一的正弦波形状，其均方根脉冲分数随着能量从1.5 keV时的15%增加到7 keV时的39%。在偶极磁场近似下推导出的赤道表面磁场、特征年龄和自转损耗光度分别为3.5e+14 G、2.0 kyr和2.1e+34 erg/s。一个吸收黑体，温度为1.1 keV，可以近似软X射线谱。假设源距离为10 kpc，在2-10 keV波段的峰值X射线光度约为8.5e+35 erg/s。在观测期间，我们分别用Swift/BAT和NICER检测到5次和37次短爆发。基于这些观测特性，特别是推断出的强磁场，这个新源被归类为磁星。我们还协调了NuSTAR、DSN和VERA的硬X射线和射电观测。在3-sigma显著性水平上检测到一个延伸至至少40 keV的硬X射线幂律成分。由幂律成分主导的10-60 keV通量约为9e-12 erg/s/cm2，光子指数约为1.2。脉冲分数在10 keV以上有尖锐的截止，在硬尾部成分带中降至约10%。在DSN或VERA观测期间未检测到射电脉动。我们在S波段和X波段分别对通量密度设置了7个{\sigma }的上限，分别为0.043mJy和0.026 mJy。 显示英文摘要

摘要： The soft gamma-ray repeater Swift J1555.2-5402 was discovered by means of a 12-ms duration short burst detected with Swift BAT on 2021 June 3. Then 1.6 hours after the first burst detection, NICER started daily monitoring of this X-ray source for a month. The absorbed 2-10 keV flux stays nearly constant at around 4e-11 erg/s/cm2 during the monitoring timespan, showing only a slight gradual decline. A 3.86-s periodicity is detected, and the time derivative of this period is measured to be 3.05(7)e-11 s/s. The soft X-ray pulse shows a single sinusoidal shape with a root-mean-square pulsed fraction that increases as a function of energy from 15% at 1.5 keV to 39% at 7 keV. The equatorial surface magnetic field, characteristic age, and spin-down luminosity are derived under the dipole field approximation to be 3.5e+14 G, 2.0 kyr, and 2.1e+34 erg/s, respectively. An absorbed blackbody with a temperature of 1.1 keV approximates the soft X-ray spectrum. Assuming a source distance of 10 kpc, the peak X-ray luminosity is ~8.5e+35 erg/s in the 2--10 keV band. During the period of observations, we detect 5 and 37 short bursts with Swift/BAT and NICER, respectively. Based on these observational properties, especially the inferred strong magnetic field, this new source is classified as a magnetar. We also coordinated hard X-ray and radio observations with NuSTAR, DSN, and VERA. A hard X-ray power-law component that extends up to at least 40 keV is detected at 3-sigma significance. The 10-60 keV flux, which is dominated by the power-law component, is ~9e-12 erg/s/cm2 with a photon index of ~1.2. The pulsed fraction has a sharp cutoff above 10 keV, down to ~10% in the hard-tail component band. No radio pulsations are detected during the DSN nor VERA observations. We place 7{\sigma} upper limits of 0.043mJy and 0.026 mJy on the flux density at S-band and X-band, respectively.