Abstract
We report on the discovery of a hydrogen-deficient compact binary (CXOGBS J175107.6- 294037) belonging to the AM CVn class in the Galactic Bulge Survey. Deep archival X-ray observations constrain the X-ray positional uncertainty of the source to 0.57 arcsec, and allow us to uniquely identify the optical and UV counterpart. Optical spectroscopic observations reveal the presence of broad, shallow He I absorption lines while no sign of hydrogen is present, consistent with a high state system. We present the optical light curve from Optical Gravitational Lensing Experiment monitoring, spanning 15 yr. It shows no evidence for outbursts; variability is present at the 0.2 mag level on time-scales ranging from hours to weeks. A modulation on a time-scale of years is also observed. A Lomb-Scargle analysis of the optical light curves shows two significant periodicities at 22.90 and 23.22 min. Although the physical interpretation is uncertain, such time-scales are in line with expectations for the orbital and superhump periods. We estimate the distance to the source to be between 0.5 and 1.1 kpc. Spectroscopic follow-up observations are required to establish the orbital period, and to determine whether this source can serve as a verification binary for the eLISA gravitational wave mission.
Original language | English |
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Pages (from-to) | L106-L110 |
Journal | Monthly Notices of the Royal Astronomical Society: Letters |
Volume | 462 |
Issue number | 1 |
DOIs | |
State | Published - Oct 11 2016 |
Keywords
- Accretion, accretion discs
- Binaries: close
- CXOGBS J175107.6-294037
- Stars: evolution
- White dwarfs
- X-rays: binaries