English

The X-ray Globular Cluster Population in NGC 1399

Astrophysics 2019-08-17 v1

Abstract

We report on the {\it 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 8×88' \times 8' {\it Chandra} image is resolved into point sources with luminosities 5×1037\ge 5 \times 10^{37} \ergsec. These sources are most likely Low Mass X-ray Binaries (LMXBs). In a region imaged by {\it HST} 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 ultra-soft 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.

Keywords

Cite

@article{arxiv.astro-ph/0107362,
  title  = {The X-ray Globular Cluster Population in NGC 1399},
  author = {Lorella Angelini and Michael Loewenstein and Richard F. Mushotzky},
  journal= {arXiv preprint arXiv:astro-ph/0107362},
  year   = {2019}
}

Comments

accepted in ApJ letter. 10 pages 5 figures