In search of the faintest X-ray transients: Results from the first epoch of the Swift Bulge Survey
Abstract
Very Faint X-ray Transients (VFXTs) show peak X-ray luminosities in the range 10E(34-36) erg/s. The luminosities of these sources imply an extremely low time-averaged accretion rate, which remains difficult to explain in the context of binary evolution models. Of order 20 VFXTs are known, but few have multi-wavelength studies to constrain the donor star, and the total size of the population is not well known. In 2017-2018 we initiated the first phase of the Swift Bulge Survey (SBS), a wide, shallow Swift/XRT imaging survey of 16 square degrees of the Galactic Bulge, with the intention of both uncovering new and studying known VFXTs. Here I will detail the optical/NIR follow-up of sources detected in the SBS, including evidence of a symbiotic X-ray binary that exhibits X-ray bursts, and a cataclysmic variable with an unusually long orbital period of >8 days. The follow-up of sources studied in the SBS has allowed us to place constraints on their counterparts and investigate the nature of accretion in these systems.
- Publication:
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AAS/High Energy Astrophysics Division
- Pub Date:
- March 2019
- Bibcode:
- 2019HEAD...1711260S