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： 对致密X射线源V1408 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、档案中的伦琴卫星(ROSAT)数据以及最近的Rossi 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上，但我们更倾向于将X射线谱解释为由于在大倾角下观测到的吸积盘。 支持这一假设的证据包括RXTE全天空监视器(ASM)观测到的长期（117天、235天、352天）周期性，我们认为这可能是由于扭曲的进动盘，以及ASCA数据中出现的1 keV特征，我们认为这可能是来自盘大气或风的L荧光特征的混合。 我们还提供了对RXTE数据的定时分析。 功率谱具有大约5%的均方根（rms）变化，并在0.03 Hz处表现出尖锐的截止，同时显示出弱的0.09 Hz准周期振荡（QPO）的证据。 前者如果与电子散射主导盘中的扩散有关，则意味着引力能量释放高度集中在盘的中平面。 紧凑天体是黑洞还是中子星的情况仍然存在歧义；然而，现在看来，X射线发射的扭曲吸积盘可能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 V1408 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. The power spectrum has a root mean square (rms) variability of approximately 5% and exhibits a sharp cutoff at 0.03 Hz as well as evidence of a weak 0.09 Hz quasi-periodic oscillation (QPO). The former, if associated with diffusion through an electron scattering dominated disk, implies that gravitational energy release is highly concentrated toward the disk midplane. 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.