NEW XMM-NEWTON ANALYSIS OF THREE BRIGHT X-RAY SOURCES IN M31 GLOBULAR CLUSTERS, INCLUDING A NEW BLACK HOLE CANDIDATE

被引：18

作者：

Barnard, R. ^{[1
]}

Stiele, H. ^{[2
]}

Hatzidimitriou, D. ^{[3
]}

Kong, A. K. H. ^{[4
,5
]}

Williams, B. F. ^{[6
]}

Pietsch, W. ^{[2
]}

Kolb, U. C. ^{[1
]}

Haberl, F. ^{[2
]}

Sala, G. ^{[2
]}

机构：

[1] Open Univ, Milton Keynes MK7 6AA, Bucks, England

[2] Max Planck Inst Extraterr Phys, D-37075 Garching, Germany

[3] Univ Crete, Khania, Greece

[4] Natl Tsing Hua Univ, Inst Astron, Hsinchu, Taiwan

[5] Natl Tsing Hua Univ, Dept Phys, Hsinchu, Taiwan

[6] Univ Washington, Dept Astron, Seattle, WA 98195 USA

来源：

ASTROPHYSICAL JOURNAL | 2008年 / 689卷 / 02期

基金：

美国国家航空航天局; 英国科学技术设施理事会;

关键词：

galaxies: individual (M31); methods: data analysis; X-rays: binaries;

D O I：

10.1086/592594

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a detailed analysis of three globular cluster X-ray sources in the XMM-Newton extended survey of M31. The X-ray counterpart to the M31 globular cluster Bo 45 (XBo 45) was observed with XMM-Newton on 2006 December 26. Its combined pn+MOS 0.3-10 keV light curve was seen to vary by similar to 10%, and its 0.3-7.0 keV emission spectrum was well described by an absorbed power law with photon index 1: 44 +/- 0: 12. Its variability and emission is characteristic of low-mass X-ray binaries (LMXBs) in the low-hard state, whether the accretor is a neutron star or black hole. Such behavior is typically observed at luminosities less than or similar to 10% Eddington. However, XBo 45 exhibited this behavior at an unabsorbed, 0.3-10 keV luminosity of 2.5 +/- 0.2 x 10(38) erg s(-1), or similar to 140% Eddington for a 1.4 M-circle dot neutron star accreting hydrogen. Hence, we identify XBo 45 as a new candidate black hole LMXB. XBo 45 appears to have been consistently bright for similar to 30 years, consistent with theoretical prediction for a globular cluster black hole binary formed via tidal capture. Bo 375 was observed in the 2007 January 2 XMM-Newton observation, and has a two-component spectrum that is typical for a bright neutron star LMXB. Bo 135 was observed in the same field as Bo 45, and could contain either a black hole or a neutron star.

引用

页码：1215 / 1221

页数：7

共 58 条

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