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Title: Around 200 new X-ray binary IDs from 13 YR of Chandra observations of the M31 center

We have created 0.3-10 keV, 13 yr, unabsorbed luminosity lightcurves for 528 X-ray sources in the central 20' of M31. We have 174 Chandra observations spaced at ∼1 month intervals due to our transient monitoring program, deeper observations of the M31 nucleus, and some public data from other surveys. We created 0.5-4.5 keV structure functions (SFs) for each source for comparison with the ensemble SF of active galactic nuclei (AGN). We find 220 X-ray sources with luminosities ≳10{sup 35} erg s{sup –1} that have SFs with significantly more variability than the ensemble AGN SF, and which are likely X-ray binaries (XBs). A further 30 X-ray sources were identified as XBs using other methods. We therefore have 250 probable XBs in total, including ∼200 new identifications. This result represents great progress over the ∼50 XBs and ∼40 XB candidates previously identified out of the ∼2000 X-ray sources within the D {sub 25} region of M31; it also demonstrates the power of SF analysis for identifying XBs in external galaxies. We also identify a new transient black hole candidate, associated with the M31 globular cluster B128.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  2. School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)
  3. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  4. Johns Hopkins University, Baltimore, MD (United States)
Publication Date:
OSTI Identifier:
22348298
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; 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; BLACK HOLES; COMPARATIVE EVALUATIONS; COSMIC X-RAY SOURCES; DATA ANALYSIS; GALAXIES; GALAXY NUCLEI; KEV RANGE; LUMINOSITY; MONITORING; NUCLEI; SPACE; STARS; STRUCTURE FUNCTIONS; SULFUR IONS; TRANSIENTS; X RADIATION