Pulsations detected from accreting high-mass X-ray binaries at low luminosities

Robert E. Rutledge, Lars Bildsten, Edward F. Brown, Deepto Chakrabarty, George G. Pavlov, Vyacheslav E. Zavlin

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24 Scopus citations


We report the detection of pulsations from two accreting transient high-mass X-ray binaries (HMXBs) at low X-ray luminosities (≈1-4 × 1034 ergs s-1). While one (4U 1145-619) has been detected pulsing previously at a lower luminosity, the second (1A 1118-615) has not, making it the third such transient HMXB from which pulsations are detected at low luminosity. The pulsars exhibit broadband rms variability (22.3% ± 0.1% and 9.2% ± 0.1%, respectively). While the present observations do not permit measurement of a spin frequency derivative, spin-down is implied in comparison with previous Compton Gamma Ray Observatory/BATSE observations. If spin-down occurred at the presently observed X-ray luminosity of 4U 1145-619, the required mass accretion rate is insufficient to produce the observed X-ray luminosity from a shock at the magnetosphere, and only a fraction of the mass accretion makes its way to the neutron star surface, with most of the mass leaving the system, carrying away angular momentum to affect spin-down.

Original languageEnglish (US)
Pages (from-to)514-519
Number of pages6
JournalAstrophysical Journal
Issue number1 I
StatePublished - Mar 20 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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