Do Ultraluminous X-Ray Sources Exist in Dwarf Galaxies?

Abstract

A thorough search for Ultraluminous X-ray source candidates within the Local Volume is made. The search spatially matches potential ULXs detected in X-ray images or cataloged in the literature with galaxies tabulated in the Catalog of Neighboring Galaxies compiled by Karachentsev et al. (2004). The specific ULX frequency (occurrence rate per unit galaxy mass) is found to be a decreasing function of host galaxy mass for host masses above $\sim 10^{8.5}$ solar mass. There is too little mass in galaxies below this point to determine if this trend continues to lower galaxy mass. No ULXs have yet been detected in lower-mass galaxies. Systematic differences between dwarf and giant galaxies that may explain an abundance of ULXs in dwarf galaxies and what they may imply about the nature of ULXs are discussed.

Accepted to ApJ

References in corpus (5)

• The Baryon Content of Extremely Low Mass Dwarf Galaxies
• The Different Physical Mechanisms that Drive the Star-Formation Histories of Giant and Dwarf Galaxies
• Probing the formation of intermediate- to high-mass stars in protoclusters II. Comparison between millimeter interferometric observations of NGC 2264-C and SPH simulations of a collapsing clump
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Cited by in corpus (1)

• Low metallicity and ultra-luminous X-ray sources in the Cartwheel galaxy