Discovery of Optical Bursts from MS1603.6+2600 = UW CrB

Abstract

We report the discovery of several optical burst-like events from the low-mass X-ray binary MS1603.6+2600 (UW CrB). The events last for a few tens of seconds, exhibit a very fast rise and slow decay, and involve optical brightening of a factor of 2-3. The flares appear distinct from the lower level flickering and instead strongly resemble reprocessed type-I X-ray bursts as seen in a number of other neutron star low-mass X-ray binaries. In conjunction with the previously reported candidate X-ray burst, these confirm that the compact object in UW CrB is a neutron star. We examine the optical burst brightness and recurrence times and discuss how the nature of the system can be constrained. We conclude that the source is most likely an accretion disk corona source at an intermediate distance, rather than a nearby quiescent system or very distant dipper.

arXiv commentAccepted for publication in ApJ Letters, 4 pages

References in corpus (8)

• A CCD Time-Series Photometer
• Fast Photometry of Quiescent Soft X-ray Transients with the Gemini-South Acquisition Camera
• X-ray/Optical Bursts from GS 1826-24
• X-Ray Flares and Oscillations from the Black Hole Candidate X-Ray Transient XTE J1650-500 at Low Luminosity
• Chandra follow-up of bursters with low persistent emission
• Evidence for a 2 hr Optical Modulation in GS1826-24
• ASCA Observation of MS 1603.6+2600 (=UW Coronae Borealis): a Dipping Low-Mass X-ray Binary in the Outer Halo?
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Cited by in corpus (5)

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• Identification of 5 Interacting Binaries in the Galactic Bulge Survey
• XMM-Newton observations of UW CrB -- detection of X-ray bursts and evidence for accretion disc evolution
• The Optical Orbital Light Curve of the Low-mass X-ray Binary V1408 Aquilae (= 4U 1957+115)
• Light Curve Morphology Study of UW CrB -- Evidence for a 5 d Superorbital Period