Intermediate long X-ray bursts from the ultra-compact binary source SLX 1737-282

Abstract

Aims: The low persistent X-ray burster source SLX 1737-282 is classified as an ultra-compact binary candidate. We compare the data on SLX 1737-282 with the other similar objects and attempt to derive constraints on the physical processes responsible for the formation of intermediate long bursts. Methods: Up to now only three intermediate long bursts, all with duration between ~15-30 minutes, have been recorded for SLX 1737-282. The properties of two intermediate long X-ray bursts observed by INTEGRAL from SLX 1737-282 are investigated. The broadband spectrum of the persistent emission in the 3-100 keV energy band is studied with the INTEGRAL data. Results: The persistent emission is measured to be < 1% Eddington luminosity. From the photospheric radius expansion observed during the bursts we derive the source distance at 7.3 kpc. The observed intermediate long burst properties from SLX 1737-282 are consistent with helium ignition at the column depth of 7-8 x 10E-9 g cm-2 and a burst energy release of 1E41 erg. The apparent recurrence time of ~80 days between the intermediate long bursts from SLX 1737-282 suggests a regime of unstable burning of a thick, pure helium layer slowly accreted from a helium donor star.

9 pages, 9 figures, 2 tables, accepted for publication in A&A

References in corpus (9)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)
• Six new candidate ultracompact X-ray binaries
• Sedimentation and Type I X-ray Bursts at Low Accretion Rates
• First superburst from a classical low-mass X-ray binary transient
• Discovery of X-ray burst triplets in EXO 0748-676
• The X-ray spectrum of the bursting atoll source 4U~1728-34 observed with INTEGRAL
• Simultaneous INTEGRAL and RXTE observations of the accreting millisecond pulsar HETE J1900.1-2455
• IGR J17254-3257, a new bursting neutron star

Cited by in corpus (3)

• The Swift capture of a long X-ray burst from XTE J1701-407
• The new intermediate long bursting source XTE J1701-407
• The INTEGRAL long monitoring of persistent Ultra Compact X-ray Bursters