We have studied X-ray spectral state transitions that can be seen in the long- term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) on board Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X- ray binaries monitored by the ASM and the BAT. In total we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu & Yan (2009), and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from the data before 2008. This further strengthen the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53.
We investigated the decades' long-term X-ray variations in bright low-mass X-ray binaries containing a neutron star (NS-LMXB). The light curves of MAXI/GSC and RXTE/ASM covers $\sim$ 26 yr, and high-quality X-ray light curves are obtained from 33 NS-LMXBs. Among them, together with Ginga/ASM, two sources (GX 3$+$1 and GX 9$+$1) showed an apparent sinusoidal variation with the period of $\sim 5$ yr and $\sim 10$ yr in the 34 yr light curve. Their X-ray luminosities were $(1-4)\times10^{37}$ erg s$^{-1}$ in the middle of the luminosity distribution of the NS-LMXB. Other seven sources (Ser X-1, 4…
Swift/BAT and RXTE/ASM observations have monitored the X-ray binary system Her X-1 for approximately 14.5 years each, and both were monitoring Her X-1 for a period of ~5.5 years. Here we study the 35-day cycle using these observations. Using a cross-correlation method we find the times of peaks of the 35-day cycles for ~150 cycles observed by Swift/BAT and ~150 cycles observed by RXTE/ASM. These cycles include ~60 observed with both instruments. The noise level of the RXTE/ASM measurements is larger than that of Swift/BAT, resulting in larger uncertainty in peak times. The distribution of 35-d…
We studied the long term flux distribution of Cygnus X-1 using RXTE-ASM lightcurves in two energy bands B (3-5 keV) & C (5-12.1 keV) as well as MAXI lightcurves in energy bands B (4-10 keV) & C (10-20 keV). The flux histograms were fitted using a two component model. For MAXI data, each of the components is better fitted by a log-normal distribution, rather than a Gaussian one. Their best fit centroids and fraction of time the source spends being in that component are consistent with those of the Hard and Soft spectral states Thus, the long term flux distribution of the states of Cygnus X-1 ha…
We study several Galactic black hole candidates using long-time RXTE/ASM X-ray data to search for telltale signatures of differences in viscous timescales in the two components used in the Two-Component Advective Flow (TCAF) paradigm. In high-mass X-ray binaries (HMXBs) mainly winds are accreted. This nearly inviscid and dominant sub-Keplerian flow falls almost freely towards the black hole. A standard Keplerian disc can form out of this sub-Keplerian matter in presence of a significant viscosity and could be small in size. However, in low-mass X-ray binaries (LMXBs), highly viscous and larger…
Probing the Mysteries of the X-Ray Binary 4U 1210-64 with ASM, PCA, MAXI, BAT and Suzaku
4U 1210-64被认为是由Be机制提供能量的大质量X射线双星。朱雀号、国际空间站全天空X射线图像监测器（MAXI）和罗西X射线定时探测器正比计数器阵列（PCA）和全天空监测器（ASM）的X射线观测提供了关于这一知之甚少的来源的详细时间和光谱信息。ASM和MAXI的长期观测显示出明显的高态和低态，并存在6.7101 +/- 0.0005天的调制，解释为轨道周期。折叠的光变曲线揭示了一个急剧的下降，解释为日食。为了确定质量供体的性质，计算了几种恒星光谱类型的预测日食半角作为倾角的函数。食半角与光谱型为B5 V的质量供体不一致，但光谱型为B 0 V或B 0 -5 III的恒星是可能的。最佳拟合光谱模型由指数γ = 1.85（+0.04，-0.05）的幂律和5.5 +/- 0.2 keV的高能截止组成，该截止由完全覆盖源以及部分覆盖吸收的吸收体修改。在Suzaku光谱中观察到S XVI K α、Fe K α、Fe XXV K α和Fe XXVI K α的发射线。在食外，Fe K α线通量与未吸收的连续通量有很强的相关性，表明Fe I发射是致密天体附近冷致密物质荧光的结果。在日食期间没有检测到Fe I的特征，进一步支持了靠近致密天体的起源。
We present the spectral and timing evolution of the persistent black hole X-ray binary GRS 1758-258 based on almost 12 years of observations using the Rossi X-ray Timing Explorer Proportional Counter Array. While the source was predominantly found in the hard state during this time, it entered the thermally dominated soft state seven times. In the soft state GRS 1758-258 shows a strong decline in flux above 3 keV rather than the pivoting flux around 10 keV more commonly shown by black hole transients. In its 3-20 keV hardness intensity diagram, GRS 1758-258 shows a hysteresis of hard and soft …
Stellar companion of a black hole orbiting in an eccentric orbit will experience modulating tidal force with a periodicity same as that of the orbital period. This, in turn, would modulate accretion rates, and the seed photon flux which are inverse Comptonized to produce harder X-rays. By analyzing complete all sky monitor (ASM) data (1.5-12 keV) of RXTE and all sky survey data (15-50 keV) of Swift/BAT we discover this periodicity in several objects. We also estimate eccentricities from the RMS power of the peak around quasi-orbital periods (QOP). Our method provides an independent way to obta…
We present analysis of RXTE--PCA observations of GX 1+4 between March 3, 2001 and January 31, 2003 together with the CGRO--BATSE X-ray flux and frequency derivative time series between 1991 and 1999. From the timing analysis of RXTE-PCA observations, we are able to phase connect pulse arrival times of the source within two different time intervals and obtain corresponding timing solutions. Using these pulse arrival times, we contribute to long term pulse frequency history of the source. We look for episodic correlations and anti-correlations between torque and X-ray luminosity using CGRO--BATS…
The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of…
