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Title: X-ray observations of XSS J12270-4859 in a new low state: A transformation to a disk-free rotation-powered pulsar binary

We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270-4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations with a decline in flux at superior conjunction. The X-ray emission remains predominantly non-thermal but with an order of magnitude lower mean luminosity and significantly harder spectrum relative to the previous high flux state. This phenomenology is identical to the behavior of the radio millisecond pulsar (MSP) binary PSR J1023+0038 in the absence of an accretion disk, where the X-ray emission is produced in an intra-binary shock driven by the pulsar wind. This further demonstrates that XSS J12270-4859 no longer has an accretion disk and has transformed to a full-fledged eclipsing 'redback' system that hosts an active rotation-powered MSP. There is no evidence for diffuse X-ray emission associated with the binary that may arise due to outflows or a wind nebula. An extended source situated 1.'5 from XSS J12270-4859 is unlikely to be associated, and is probably a previously uncataloged galaxy cluster.
Authors:
 [1] ;  [2] ; ; ; ;  [3] ;  [4]
  1. Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)
  2. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands)
  3. ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)
  4. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom)
Publication Date:
OSTI Identifier:
22356498
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; AMPLITUDES; BINARY STARS; BRIGHTNESS; ECLIPSE; EMISSION; GALAXY CLUSTERS; LUMINOSITY; MASS; NEBULAE; NEUTRONS; PULSARS; SPECTRA; STARS; STELLAR WINDS; TRANSFORMATIONS; X RADIATION