The ultra-compact binary 4U1850-087 observed with INTEGRAL: hard X-ray emission from an X-ray burster

Abstract

The X-ray burster 4U1850-087, located in the Galactic globular cluster NGC6712, is an ultracompact binary (orbital period~21 min),likely harbouring a degenerate companion.The source has been observed at soft gamma-rays several times with the INTEGRAL satellite,during the monitoring of the Galactic plane, with an unprecedented exposure time.We analysed all available INTEGRAL observations, with the main aim of studying the long-term behaviour of this Galactic bulge X-ray burster.The spectral results are based on the systematic analysis of all INTEGRAL observations covering the source position performed between March 2003 and November 2005.The source X-ray emission is hard and is observed, for the first time, up to 100keV.A broad-band spectrum obtained combining the INTEGRAL spectrum together with a quasi-simultaneous XMM-Newton observation performed in September 2003 is well modeled with a disk-blackbody emission (with kTin=0.8keV) together with a power-law (photon index=2.1).The 2-100keV luminosity is 1.5E36 erg/s (assuming a distance of 6.8kpc).

Accepted for publication in Astronomy & Astrophysics

References in corpus (10)

• ISGRI: the INTEGRAL Soft Gamma-Ray Imager
• On the interpretation of the multicolour disc model for black hole candidates
• Hard X-ray Emission From Low Mass X-ray Binaries
• Ultracompact X-Ray Binaries with Neon-Rich Degenerate Donors
• The broad band X-ray/hard X-ray spectra of accreting neutron stars
• Average hard X-ray emission from NS LMXBs: Observational evidence of different spectral states in NS LMXBs
• BeppoSAX study of the broad-band properties of luminous globular cluster X-ray sources
• X-ray Spectroscopy of Candidate Ultracompact X-ray Binaries
• VLT Observations of the Peculiar Globular Cluster NGC6712, III: The Evolved Stellar Population
• Low-energy absorption towards the ultra-compact binary 4U1850-087 located in the globular cluster NGC6712

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• The INTEGRAL long monitoring of persistent Ultra Compact X-ray Bursters
• SAXJ1712.6-3739: a persistent hard X-ray source as monitored with INTEGRAL
• Discovery of a long thermonuclear X-ray burst from the ultra-compact binary 4U 1850$-$087
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• The MAVERIC Survey: Dynamical Origin of Radio Sources in Galactic Globular Clusters
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