CXOGBS~J173620.2--293338: A Candidate Symbiotic X-ray Binary Associated with a Bulge Carbon Star

Abstract

The Galactic Bulge Survey is a wide but shallow X-ray survey of regions above and below the Plane in the Galactic Bulge. It was performed using the Chandra X-ray Observatory's ACIS camera. The survey is primarily designed to find and classify low luminosity X-ray binaries. The combination of the X-ray depth of the survey and the accessibility of optical and infrared counterparts makes this survey ideally suited to identification of new symbiotic X-ray binaries in the Bulge. We consider the specific case of the X-ray source CXOGBS J173620.2-293338. It is coincident to within 1 arcsec with a very red star, showing a carbon star spectrum and irregular variability in the Optical Gravitational Lensing Experiment data. We classify the star as a late C-R type carbon star based on its spectral features, photometric properties, and variability characteristics, although a low-luminosity C-N type cannot be ruled out. The brightness of the star implies it is located in the Bulge, and its photometric properties overall are consistent with the Bulge carbon star population. Given the rarity of carbon stars in the Bulge, we estimate the probability of such a close chance alignment of any Galactic Bulge Survey source with a carbon star to be <1e-3 suggesting that this is likely to be a real match. If the X-ray source is indeed associated with the carbon star, then the X-ray luminosity is around 9e32 erg/s. Its characteristics are consistent with a low luminosity symbiotic X-ray binary, or possibly a low accretion rate white dwarf symbiotic.

Accepted for publication in the Astrophysical Journal

References in corpus (4)

• M-type giants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319
• Symbiotic stars and other Halpha emission line stars towards the Galactic Bulge
• White-dwarf red-giant mergers, early-type R stars, J stars and lithium
• ChaMPlane Discovery of Candidate Symbiotic Binaries in Baade's and Stanek's Windows

Cited by in corpus (22)

• A census of symbiotic stars in the 2MASS, WISE and Gaia surveys
• Evolution Through the Post-Starburst Phase: Using Post-Starburst Galaxies as Laboratories for Understanding the Processes that Drive Galaxy Evolution
• Wind-accreting Symbiotic X-ray Binaries
• Low-Mass X-ray Binaries
• A Deep X-ray Survey of the Globular Cluster Omega Centauri
• The MAVERIC Survey: Chandra/ACIS Catalog of Faint X-ray sources in 38 Galactic globular clusters
• The Swift Bulge Survey: Motivation, Strategy, and First X-ray Results
• The Galactic Bulge Survey: completion of the X-ray survey observations
• Identification of twenty-three accreting binaries in the Galactic Bulge Survey
• The Galactic LMXB Population and the Galactic Centre Region
• Discovery of carbon-rich Miras in the Galactic bulge
• The Relationship Between X-ray Luminosity and Duty Cycle for Dwarf Novae and their Specific Frequency in the Inner Galaxy
• SRGA J181414.6-225604: A new Galactic symbiotic X-ray binary outburst triggered by an intense mass loss episode of a heavily obscured Mira variable
• Revealing a new symbiotic X-ray binary with Gemini NIFS
• Variability of Optical Counterparts in the Chandra Galactic Bulge Survey
• The Chandra Galactic Bulge Survey: optical catalogue and point-source counterparts to X-ray sources
• Infrared identification of hard X-ray sources in the Galaxy
• Gemini Spectroscopy of Galactic Bulge Sources: A Population of Hidden Accreting Binaries Revealed?
• Spectroscopic classification of X-ray sources in the Galactic Bulge Survey
• A massive AGB donor in Scutum X-1: Identification of the first Mira variable in an X-ray binary
• CGCS 6306, another X-ray-emitting asymptotic giant branch star confirmed to be a symbiotic binary
• 3C 294 revisited: Deep Large Binocular Telescope AO NIR images and optical spectroscopy