标题： 关于神秘的X射线源V1408 Aql (=4U 1957+11) 显示英文标题

标题： On the enigmatic X-ray Source V1408 Aql (=4U 1957+11)

摘要： 对紧凑X射线源V1498 Aql (=4U 1957+11) 的特征性软X射线谱的模型从光学厚康普顿化到多色吸积盘模型不等。 我们通过档案中的高级宇宙学和天体物理卫星(ASCA)数据、档案中的X射线卫星(ROSAT)数据以及最近的罗西X射线时变探测器(RXTE)数据，对V1408 Aql的X射线谱进行了批判性检查。 尽管我们能够将各种X射线光谱模型拟合到这些数据中，但我们更倾向于将X射线谱解释为在大倾角下观测到的吸积盘。 这一假设的证据包括RXTE全天空监测器(ASM)观察到的长期(117天、235天、352天)周期性，我们认为这是由于扭曲的进动盘引起的，以及ASCA数据中的一个1 keV特征，我们认为这是来自盘大气或风的L荧光特征的混合。 我们还展示了RXTE数据的时间分析，并发现f=0.001-16 Hz之间的均方根(rms)变化上限为4%。 该致密天体是黑洞还是中子星的情况仍然存在歧义；然而，现在似乎更有可能的是，一个发射X射线的扭曲吸积盘是该系统的重要组成部分。 显示英文摘要

摘要： Models for the characteristically soft X-ray spectrum of the compact X-ray source V1498 Aql (=4U 1957+11) have ranged from optically thick Comptonization to multicolor accretion disk models. We critically examine the X-ray spectrum of V1408 Aql via archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data, archival Roentgensatellit (ROSAT) data, and recent Rossi X-Ray Timing Explorer (RXTE) data. Although we are able to fit a variety of X-ray spectral models to these data, we favor an interpretation of the X-ray spectrum as being due to an accretion disk viewed at large inclination angles. Evidence for this hypothesis includes long term (117 day, 235 day, 352 day) periodicities seen by the RXTE All Sky Monitor (ASM), which we interpret as being due to a warped precessing disk, and a 1 keV feature in the ASCA data, which we interpret as being the blend of L fluorescence features from a disk atmosphere or wind. We also present timing analysis of the RXTE data and find upper limits of 4% for the root mean square (rms) variability between f=0.001-16 Hz. The situation of whether the compact object is a black hole or neutron star is still ambiguous; however, it now seems more likely that an X-ray emitting, warped accretion disk is an important component of this system.