The Brightest Serendipitous X-ray Sources in ChaMPlane

TL;DR

This study analyzes the brightest low-luminosity X-ray sources in the Galactic Plane using multiwavelength data, identifying new sources and validating a novel spectral analysis technique for faint X-ray sources.

Contribution

It presents a population analysis of bright X-ray sources in ChaMPlane, including the discovery of new sources and validation of quantile analysis for spectral characterization.

Findings

Identification of a new quiescent low-mass X-ray binary or cataclysmic variable

Detection of ten stellar sources, including a flare star

Quantile analysis aligns well with spectral fitting results

Abstract

The Chandra Multiwavelength Plane (ChaMPlane) Survey is a comprehensive effort to constrain the population of accretion-powered and coronal low-luminosity X-ray sources (L_X < 10^33 erg s^-1) in the Galaxy. ChaMPlane incorporates X-ray, optical, and infrared observations of fields in the Galactic Plane imaged with Chandra in the past six years. We present the results of a population study of the brightest X-ray sources in ChaMPlane. We use X-ray spectral fitting, X-ray lightcurve analysis, and optical photometry of candidate counterparts to determine the properties of 21 sources. Our sample includes a previously unreported quiescent low-mass X-ray binary or cataclysmic variable (R = 20.9) and ten stellar sources (12.5 < R < 15), including one flare star (R = 17.3). We find that quantile analysis, a new technique developed for constraining the X-ray spectral properties of low-count sources, is largely consistent with spectral fitting.