An Environmental Study of the Ultraluminous X-ray Source Population in Early-type Galaxies
Abstract
Ultraluminous X-ray sources (ULXs) are some of the brightest phenomena found outside of a galaxy's nucleus, and their explanation typically invokes accretion of material onto a black hole. Here, we perform the largest population study to date of ULXs in early-type galaxies. We search for ULXs within the AMUSE survey, which includes homogeneous X-ray coverage of 100 elliptical galaxies in the Virgo cluster and a similar number of elliptical galaxies in the field (spanning stellar masses of 10^8-10^12 Solar masses), allowing us to perform a focused study on whether a galaxy's large scale environment can affect its ULX content. We find that the number and specific frequency of ULXs, as well as their average X-ray spectral properties, are similar in both cluster and field environments. However, contrary to late-type galaxies, we do not see any trend between specific ULX frequency and host galaxy stellar mass, and we show that dwarf ellipticals host fewer ULXs than later-type dwarf galaxies at a statistically meaningful level. Our results are consistent with ULXs in early-type galaxies probing the luminous tail of the low-mass X-ray binary population, which we will discuss in terms of the properties of a galaxy's (older) stellar population across the galaxy mass scale.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22342202P