Discovery of a high state AM CVn binary in the Galactic Bulge Survey

Understand

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 lightcurve from Optical Gravitational Lensing Experiment monitoring, spanning 15 years.