A BeppoSAX Observation of KS 1731-260 in its Quiescent State: Constraints on the NS Magnetic Field

Abstract

We report here the results of a 90 ks BeppoSAX observation of the low mass X-ray binary and atoll source KS 1731-260 during a quiescent phase. From this observation we derive a source X-ray luminosity of \sim 10^{33} ergs/s (for a source distance of 7 kpc). If the neutron star is spinning at a period of a few milliseconds, as inferred from the nearly-coherent oscillations observed during type-I X-ray bursts, the quiescent X-ray luminosity constrains the neutron star magnetic field strength to less than \sim 10^9 G. If the quiescent emission originates from the release of thermal energy accumulated through deep crust heating in the previous accretion phase, then the measured quiescent luminosity requires a neutron star mass of more than 1.7 M_\odot or a very long outbust recurrence time (\sim 10^3 yr). The former possibility would be in agreement with the expectation of the recycling scenario, namely that the neutron star has accreted a significant amount of mass, enough to spin it up to millisecond periods.

arXiv comment14 pages, including 1 figure. Submitted to ApJ

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Cited by in corpus (13)

• Cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29
• Cooling of Accretion-Heated Neutron Stars
• Analysing the atolls: X-ray spectral transitions of accreting neutron stars
• The magnetic field strengths of accreting millisecond pulsars
• Spin down during quiescence of the fastest known accretion-powered pulsar
• Chandra observations of the accretion-driven millisecond X-ray pulsars XTE J0929-314 and XTE J1751-305 in quiescence
• Constraints on the Neutron Star Magnetic Field of the two X-ray Transients SAX J1808.4-3658 and Aql X-1
• A Search for Pulsars in Quiescent Soft X-Ray Transients. I
• Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808
• Observations of the 599 Hz Accreting X-ray Pulsar IGR J00291+5934 during the 2004 Outburst and in Quiescence
• GRO J1744-28: an intermediate B-field pulsar in a low mass X-ray binary
• On the Origin of the Radio/X-Ray Luminosity Correlation in Black Hole Candidates
• New results on neutron star low mass transients in the quiescence