A deep XMM-Newton survey of M 31
A deep XMM-Newton survey of M 31
复制标题
M 31 的深度 XMM-牛顿调查
DOI：
10.1051/0004-6361/201015270
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发表时间：
2007
影响因子：
4.8
通讯作者：
B. F. Williams
中科院分区：
文献类型：
--
作者：
H. Stiele;W. Pietsch;F. Haberl;Robin Barnard;V. Burwitz;M. Freyberg;Jochen Greiner;D. Hatzidimitriou;Margarita Hernanz;U. Kolb;A. Kong;P. Plucinsky;P. Reig;M. Sasaki;G. Sala;L. S. Greening;L. Stella;B. F. Williams
目标。最大的本星系群M 31首次被完整成像，在0.2–4.5 keV波段获得了~10 35 erg s -1 的光度下限。我们的 XMM-Newton EPIC 调查结合了 2000 年 6 月至 2004 年 7 月沿主轴的档案观测，以及 2006 年 6 月至 2008 年 2 月期间覆盖 D 25 椭圆其余部分的观测。论文的主要目标是研究M 31的X射线源群。
方法。创建了 1897 个源的 X 射线目录，其中 914 个源是首次检测到的。源分类和识别基于 X 射线硬度比、源的空间范围以及与 X 射线、光学、红外和无线电波长目录的互相关性。我们还分析了 X 射线源的长期变化，这种变化使我们能够区分 X 射线双星和活动星系核 (AGN)。此外，可以验证先前研究中不使用长期变异性作为分类标准的超新星遗迹分类。将之前的钱德拉和 ROSAT 观测纳入长期变异性研究中，使我们能够检测到额外的瞬态源或至少高度可变的源，这些源是很好的候选 X 射线双星。
结果。 30 个候选超软源 (SSS) 中的 14 个代表光学新星的超软发射。 25 个超新星遗迹 (SNR) 和 31 个 SNR 候选者中的许多都位于 M 31 的 10 kpc 尘埃环和其他恒星形成区域内。SNR 和恒星形成区域之间的这种联系意味着大多数遗迹起源于 II 型超新星。 M 31 中最亮的 X 射线源属于 X 射线双星 (XRB) 类。根据其时间变异性鉴定出 10 个低质量 XRB (LMXB) 和 26 个 LMXB 候选物。此外，由于与球状星团和球状星团候选者的相关性，还确定了 36 个 LMXB 和 17 个 LMXB 候选者。从光学和 X 射线颜色图，选择了可能的高质量 XRB (HMXB) 候选物。其中两个候选物具有与包含中子星初级的 HMXB 预期相同的 X 射线光谱。
结论。虽然我们的调查极大地提高了我们对 M 31 中 X 射线源群的了解，但目前 65% 的源仍然只能归类为“硬”源；也就是说，无法确定这些源是 X 射线双星还是 M 31 中的蟹状超新星遗迹，还是背景中的 X 射线源。对 X 射线和其他波长进行更深入的观察将有助于对这些源进行分类。
Aims. The largest Local Group spiral galaxy, M 31, has been completely imaged for the first time, obtaining a luminosity lower limit ~10 35 erg s -1 in the 0.2–4.5 keV band. Our XMM-Newton EPIC survey combines archival observations along the major axis, from June 2000 to July 2004, with observations taken between June 2006 and February 2008 that cover the remainder of the D 25 ellipse. The main goal of the paper is to study the X-ray source population of M 31.
Methods. An X-ray catalogue of 1897 sources was created, with 914 detected for the first time. Source classification and identification were based on X-ray hardness ratios, spatial extent of the sources, and cross correlation with catalogues in the X-ray, optical, infrared, and radio wavelengths. We also analysed the long-term variability of the X-ray sources and this variability allows us to distinguish between X-ray binaries and active galactic nuclei (AGN). Furthermore, supernova remnant classifications of previous studies that did not use long-term variability as a classification criterion could be validated. Including previous Chandra and ROSAT observations in the long-term variability study allowed us to detect additional transient or at least highly variable sources, which are good candidate X-ray binaries.
Results. Fourteen of the 30 supersoft source (SSS) candidates represent supersoft emission of optical novae. Many of the 25 supernova remnants (SNRs) and 31 SNR candidates lie within the 10 kpc dust ring and other star-forming regions in M 31. This connection between SNRs and star-forming regions implies that most of the remnants originate in type II supernovae. The brightest sources in X-rays in M 31 belong to the class of X-ray binaries (XRBs). Ten low-mass XRBs (LMXBs) and 26 LMXB candidates were identified based on their temporal variability. In addition, 36 LMXBs and 17 LMXB candidates were identified owing to correlations with globular clusters and globular cluster candidates. From optical and X-ray colour-colour diagrams, possible high-mass XRB (HMXB) candidates were selected. Two of these candidates have an X-ray spectrum as is expected for an HMXB containing a neutron star primary.
Conclusions. While our survey has greatly improved our understanding of the X-ray source populations in M 31, at this point 65% of the sources can still only be classified as “hard” sources; i.e. it is not possible to decide whether these sources are X-ray binaries or Crab-like supernova remnants in M 31 or X-ray sources in the background. Deeper observations in X-ray and at other wavelengths would help classify these sources.