The X-ray globular cluster population in NGC 1399

被引:107
作者
Angelini, L
Loewenstein, M
Mushotzky, RF
机构
[1] NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA
[2] Univ Maryland, Dept Astron, College Pk, MD 20742 USA
关键词
galaxies : elliptical and lenticular; cD; galaxies : individual (NGC 1399) globular clusters : general; X-rays : binaries; X-rays : galaxies;
D O I
10.1086/323026
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report on the Chandra observations of the elliptical galaxy NGC 1399, concentrating on the X-ray sources identified with globular clusters (GCs). A large fraction of the 2-10 keV X-ray emission in the 8' x 8' Chandra image is resolved into point sources with luminosities greater than or equal to5 x 10(37) ergs s(-1). These sources are most likely low-mass X-ray binaries (LMXBs). In a region imaged by the Hubble Space Telescope, about 70% of the X-ray sources are located within GCs. This association suggests that in giant elliptical galaxies luminous X-ray binaries preferentially form in GCs. Many of the GC sources have super-Eddington luminosities (for an accreting neutron star), and their average luminosity is higher than the non-GC sources. The X-ray spectral properties of both GC and non-GC sources are similar to those of LMXBs in our Galaxy. Two of the brightest sources, one of which is in a GC, have an ultrasoft spectrum, similar to that seen in the high state of black hole candidates. The "apparent" super-Eddington luminosity in many cases may be due to multiple LMXB systems within individual GCs but with some of the most extremely luminous systems containing massive black holes.
引用
收藏
页码:L35 / L38
页数:4
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