The MAVERIC survey: Chandra/ACIS catalog of faint X-ray sources in 38 galactic globular clusters

Arash Bahramian, Jay Strader, James C.A. Miller-Jones, Laura Chomiuk, Craig O. Heinke, Thomas J. Maccarone, David Pooley, Laura Shishkovsky, Vlad Tudor, Yue Zhao, Kwan Lok Li, Gregory R. Sivakoff, Evangelia Tremou, Johannes Buchner

Research output: Contribution to journalReview articlepeer-review

27 Citations (Scopus)


Globular clusters host a variety of lower-luminosity (LX < 1035 erg s−1) X-ray sources, including accreting neutron stars (NSs) and black holes (BHs), millisecond pulsars (MSPs), cataclysmic variables, and chromospherically active binaries. In this paper, we provide a comprehensive catalog of more than 1100 X-ray sources in 38 Galactic globular clusters (GCs) observed by the Chandra X-ray Observatory's Chandra/ACIS detector. The targets are selected to complement the MAVERIC survey's deep radio continuum maps of Galactic GCs. We perform photometry and spectral analysis for each source, determine a best-fit model, and assess the possibility of it being a foreground or background source based on its spectral properties and location in the cluster. We also provide basic assessments of variability. We discuss the distribution of X-ray binaries in GCs and their X-ray luminosity function, and we carefully analyze systems with LX > 1033 erg s−1. Among these moderately bright systems, we discover a new source in NGC 6539 that may be a candidate accreting stellar-mass BH or a transitional MSP. We show that quiescent NS low-mass X-ray binaries in GCs may spend ∼2% of their lifetimes as transitional MSPs in their active (LX > 1033 erg s−1) state. Finally, we identify a substantial underabundance of bright (LX > 1033 erg s−1) intermediate polars in GCs compared to the Galactic field, in contrast with the literature of the past two decades.

Original languageEnglish
Article number57
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 2020 Sept 20

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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