标题： SRGA J144459.2$-$604207 在 2024 年爆发期间利用 NICER、Einstein Probe、IXPE、NuSTAR、Insight-HXMT 和 INTEGRAL 进行的时间和光谱研究 显示英文标题

标题： Timing and spectral studies of SRGA J144459.2$-$604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT and INTEGRAL during its 2024 outburst

摘要： SRGA J144459.2$-$604207 是一个新确认的吸积毫秒X射线脉冲星和I型X射线爆发源。 我们展示了SRGA J144459.2$-$604207 在其2024年爆发期间的宽能段X射线定时和光谱行为。 数据来自NICER、爱因斯坦探针、IXPE、慧眼HXMT、NuSTAR和 INTEGRAL观测。 在爆发的“ON”阶段，从MJD$\sim 60355-60385$开始，已在1.5$-$90 keV能量范围内检测到X射线脉动。 我们假设轨道为圆形，改进了轨道和自转历元，并发现脉冲星在MJD$\sim$60361--60377期间处于自转加速状态，显示出显著的自转加速率$\dot{\nu}$为$(3.15\pm 0.36)\times10^{-13}~{\rm Hz~s^{-1}}$。 在MJD$\sim 60377$附近，检测到了自转演化中的摆动，并伴随着脉冲辐射的显著增强。 我们研究了Insight-HXMT、IXPE和NuSTAR观测到的X射线爆发期间的脉冲轮廓形态。 在爆发期间，在2$-$60 keV范围内检测到了脉动，其形状大致与持续辐射中观测到的相符。 然而，我们发现“爆发”脉冲轮廓相对于爆发前和爆发后的轮廓存在显著的相位偏移。 这些偏移量随着能量的增加而系统地减小，与爆发前后的剖面相比，IXPE、Insight-HXMT ME 和 HE 在 2-8、5-30 和 20-60 keV 内的偏移量分别为 $\Delta \phi\approx0.15$、0.11 和 0.02，NuSTAR 在 3-10、20-35 和 35-60 keV 内的偏移量分别为 $\Delta \phi\approx0.21$、0.10 和 0.07。 我们对两个时期进行了NICER、NuSTAR和Insight-HXMT的准同时联合光谱分析。 两次观测的结果一致，并且可以通过吸收的热康普顿化模型nthcomp加上相对论反射relxillCp很好地描述。 显示英文摘要

摘要： SRGA J144459.2$-$604207 is a newly confirmed accreting millisecond X-ray pulsar and type I X-ray burster. We present the broadband X-ray timing and spectral behaviors of SRGA J144459.2$-$604207 during its 2024 outburst. The data were collected from NICER, Einstein Probe, IXPE, Insight-HXMT, NuSTAR and INTEGRAL observations. X-ray pulsations have been detected for the 1.5$-$90 keV energy range throughout the `ON' phase of the outburst from MJD $\sim 60355-60385$. We refined the orbital and spin ephemerides assuming a circular orbit, and found that the pulsar was in a spin-up state during MJD $\sim$ 60361--60377 showing a significant spin-up rate $\dot{\nu}$ of $(3.15\pm 0.36)\times10^{-13}~{\rm Hz~s^{-1}}$. Around MJD $\sim 60377$ a swing was detected in the spin evolution accompanied by significantly enhanced pulsed emission. We studied the pulse profile morphology during the X-ray bursts as observed by Insight-HXMT, IXPE and NuSTAR. During the bursts, pulsations were detected across the 2$-$60 keV with shapes broadly consistent with those observed for the persistent emission. We found, however, that the `burst' pulse profiles exhibit significant phase offsets relative to the pre- and post-burst profiles. These offsets systematically decrease with increasing energy, $\Delta \phi\approx0.15$, 0.11 and 0.02 for IXPE, Insight-HXMT ME and HE in 2$-$8, 5$-$30 and 20$-$60 keV, respectively, and $\Delta \phi\approx0.21$, 0.10 and 0.07 for NuSTAR in 3$-$10, 20$-$35 and 35$-$60 keV, respectively, compared to the pre- and post-burst profiles. We performed a joint spectral analysis of quasi-simultaneous NICER, NuSTAR, and Insight-HXMT data for two epochs. The resulting spectra from both observations were consistent and well-described by an absorbed thermal Comptonization model, nthcomp, plus relativistic reflection, relxillCp.