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Title: The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources

Abstract

We have monitored the Cassiopeia dwarf galaxy (IC 10) in a series of 10 Chandra ACIS-S observations to capture its variable and transient X-ray source population, which is expected to be dominated by High Mass X-ray Binaries (HMXBs). We present a sample of 21 X-ray sources that are variable between observations at the 3 σ level, from a catalog of 110 unique point sources. We find four transients (flux variability ratio greater than 10) and a further eight objects with ratios >5. The observations span the years 2003–2010 and reach a limiting luminosity of >10{sup 35} erg s{sup −1}, providing sensitivity to X-ray binaries in IC 10 as well as flare stars in the foreground Milky Way. The nature of the variable sources is investigated from light curves, X-ray spectra, energy quantiles, and optical counterparts. The purpose of this study is to discover the composition of the X-ray binary population in a young starburst environment. IC 10 provides a sharp contrast in stellar population age (<10 My) when compared to the Magellanic Clouds (40–200 My) where most of the known HMXBs reside. We find 10 strong HMXB candidates, 2 probable background Active Galactic Nuclei, 4 foreground flare-stars or active binaries,more » and 5 not yet classifiable sources. Complete classification of the sample requires optical spectroscopy for radial velocity analysis and deeper X-ray observations to obtain higher S/N spectra and search for pulsations. A catalog and supporting data set are provided.« less

Authors:
;  [1]; ;  [2];  [3];  [4]
  1. Department of Physics and Applied Physics, University of Massachusetts Lowell, MA, 01854 (United States)
  2. University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States)
  4. Department of Mathematical Sciences, University of Massachusetts Lowell, MA, 01854 (United States)
Publication Date:
OSTI Identifier:
22663841
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BINARY STARS; CATALOGS; CLASSIFICATION; COMPARATIVE EVALUATIONS; GALAXY NUCLEI; LUMINOSITY; MAGELLANIC CLOUDS; MASS; MILKY WAY; PULSATIONS; RADIAL VELOCITY; SENSITIVITY; SPECTROSCOPY; STARS; VISIBLE RADIATION; X RADIATION; X-RAY SOURCES; X-RAY SPECTRA

Citation Formats

Laycock, Silas, Cappallo, Rigel, Williams, Benjamin F., Binder, Breanna, Prestwich, Andrea, and Christodoulou, Dimitris M. The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/1/50.
Laycock, Silas, Cappallo, Rigel, Williams, Benjamin F., Binder, Breanna, Prestwich, Andrea, & Christodoulou, Dimitris M. The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources. United States. doi:10.3847/1538-4357/836/1/50.
Laycock, Silas, Cappallo, Rigel, Williams, Benjamin F., Binder, Breanna, Prestwich, Andrea, and Christodoulou, Dimitris M. Fri . "The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources". United States. doi:10.3847/1538-4357/836/1/50.
@article{osti_22663841,
title = {The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources},
author = {Laycock, Silas and Cappallo, Rigel and Williams, Benjamin F. and Binder, Breanna and Prestwich, Andrea and Christodoulou, Dimitris M.},
abstractNote = {We have monitored the Cassiopeia dwarf galaxy (IC 10) in a series of 10 Chandra ACIS-S observations to capture its variable and transient X-ray source population, which is expected to be dominated by High Mass X-ray Binaries (HMXBs). We present a sample of 21 X-ray sources that are variable between observations at the 3 σ level, from a catalog of 110 unique point sources. We find four transients (flux variability ratio greater than 10) and a further eight objects with ratios >5. The observations span the years 2003–2010 and reach a limiting luminosity of >10{sup 35} erg s{sup −1}, providing sensitivity to X-ray binaries in IC 10 as well as flare stars in the foreground Milky Way. The nature of the variable sources is investigated from light curves, X-ray spectra, energy quantiles, and optical counterparts. The purpose of this study is to discover the composition of the X-ray binary population in a young starburst environment. IC 10 provides a sharp contrast in stellar population age (<10 My) when compared to the Magellanic Clouds (40–200 My) where most of the known HMXBs reside. We find 10 strong HMXB candidates, 2 probable background Active Galactic Nuclei, 4 foreground flare-stars or active binaries, and 5 not yet classifiable sources. Complete classification of the sample requires optical spectroscopy for radial velocity analysis and deeper X-ray observations to obtain higher S/N spectra and search for pulsations. A catalog and supporting data set are provided.},
doi = {10.3847/1538-4357/836/1/50},
journal = {Astrophysical Journal},
number = 1,
volume = 836,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2017},
month = {Fri Feb 10 00:00:00 EST 2017}
}