A Synoptic X-Ray Study of M31 with the Chandra High Resolution Camera
A Synoptic X-Ray Study of M31 with the Chandra High Resolution Camera
复制标题
使用 Chandra 高分辨率相机对 M31 进行概要 X 射线研究
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
S. Murray
中科院分区：
文献类型：
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作者：
B. Williams;Michael R. Garcia;A. Kong;F. Primini;A. King;R. Di Stefano;S. Murray
我们已经获得了17个纪元的钱德拉高分辨率相机(HRC)快照图像，每个图像覆盖了M31磁盘的大部分。这些数据涵盖了大约2.5年的总基线，包含了17k的平均有效暴露。我们已经测量了这些数据中探测到的166个天体的平均通量和长期光曲线。至少有25%的来源表现出显著的变异性。盘源的累积光度函数(CLF)符合幂定律，其斜率与在典型椭圆星系中观测到的斜率相当。凸起的CLF是一个违反的幂定律，类似于以前的调查所做的测量。我们注意到西南盘中具有LX>；1037ERGS S-1的几个震源。我们将我们的所有来源与已公布的光学和无线电目录以及新的光学数据相互关联，为55个来源寻找对应的候选来源。此外，17个源可能是X射线瞬变。我们分析了后续哈勃太空望远镜(HST)WFPC2的两个X射线瞬变数据，找到了对应的F336W(U波段当量)。在这两种情况下，对应关系都是可变的。在一种情况下，光学对应物是瞬变的，F336W=22.3±0.1毫克。该天体的X射线和光学性质与轨道周期为23天的~10M☉黑洞X射线新星一致。在另一种情况下，光学对应值在F336W=20.82±0.06到21.11±0.02毫克之间变化。地面观测和HST观测表明，该天体是明亮的(V=18.8±0.1)，略有伸展。最后，M31球体中亮X射线瞬变的频率表明，在低质量X射线双星(NS/BH)中，中子星与黑洞初级恒星的比率为~1。
We have obtained 17 epochs of Chandra High Resolution Camera (HRC) snapshot images, each covering most of the M31 disk. The data cover a total baseline of ~2.5 yr and contain a mean effective exposure of 17 ks. We have measured the mean fluxes and long-term light curves for 166 objects detected in these data. At least 25% of the sources show significant variability. The cumulative luminosity function (CLF) of the disk sources is well fitted by a power law with a slope comparable to those observed in typical elliptical galaxies. The CLF of the bulge is a broken power law similar to measurements made by previous surveys. We note several sources in the southwestern disk with LX > 1037 ergs s-1. We cross-correlate all of our sources with published optical and radio catalogs, as well as new optical data, finding counterpart candidates for 55 sources. In addition, 17 sources are likely X-ray transients. We analyze follow-up Hubble Space Telescope (HST) WFPC2 data of two X-ray transients, finding F336W (U-band equivalent) counterparts. In both cases, the counterparts are variable. In one case, the optical counterpart is transient with F336W = 22.3 ± 0.1 mag. The X-ray and optical properties of this object are consistent with a ~10 M☉ black hole X-ray nova with an orbital period of 23 days. In the other case, the optical counterpart varies between F336W = 20.82 ± 0.06 and 21.11 ± 0.02 mag. Ground-based and HST observations show that this object is bright (V = 18.8 ± 0.1) and slightly extended. Finally, the frequency of bright X-ray transients in the M31 bulge suggests that the ratio of neutron star to black hole primaries in low-mass X-ray binaries (NS/BH) is ~1.