Variable Low-Mass X-ray Binaries in Early-Type Galaxies

TL;DR

This study analyzes the variability of low-mass X-ray binaries in early-type galaxies using Chandra observations, finding that their luminosity functions are stable over years with few transients detected.

Contribution

It provides the first comprehensive analysis of LMXB variability in early-type galaxies over multiple timescales using Chandra data.

Findings

Luminosity functions remain stable over several years.

Few sources exhibit strong variability or transience.

The number of transient LMXBs in early-type galaxies is relatively small.

Abstract

As the Chandra X-ray Observatory mission matures, increasing numbers of nearby galaxies are being observed multiple times, sampling the variability of extragalactic X-ray binaries on timescales extending from seconds to years. We present results on luminous low-mass X-ray binaries from several early-type galaxies. We show that instantaneous LMXB luminosity functions of early-type galaxies do not significantly change between observations; a relatively low fraction of sources are strongly variable on <~ 5 yr timescales. We discuss the implications that a relatively small number of transient LMXBs are being discovered in early-type galaxies.