Discovery of a high state AM CVn binary in the Galactic Bulge Survey
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2016
- DOI:
- 10.1093/mnrasl/slw141
- arXiv:
- arXiv:1607.04262
- Bibcode:
- 2016MNRAS.462L.106W
- Keywords:
-
- accretion;
- accretion discs;
- binaries: close;
- stars: evolution;
- white dwarfs;
- X-rays: binaries;
- CXOGBS J175107.6-294037;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in MNRAS Letters