Anomalous phase variations of the accretion-powered millisecond pulsar XTE J1807-294

Yi Chou, Yi Ying Chung, Chin Ping Hu, Ting Chang Yang

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


This study reports pulse variation analysis results for the forth discovered accretion-powered millisecond pulsar XTE Jl 807-294 during its 2003 outburst observed by Rossi Timing Explorer (RXTE). The fine orbital parameters with Porb =40.073601(8) min and ax; sin i = 4.823(5) It-ms were first obtained after applying trend removal for the daily phase drift. The binary barycenter corrected pulse phases show smooth variation plus clear negative phase shifts coincident with the flares seen on the light curve as well as enhancements of fractional pulse amplitude. The non-flare pulse phases are well described as a fourth order polynomial implying that the neutron star was spun-up during the ourburst. Significant soft phase lags up to ∼500/μs between 2 to 20 keV were detected for the non-flare pulse phases. The variations of pulse phases during the flares and their energy-dependent shifts indicate that the anomalous phase shifts are a result from the "hot spot" shifting on the surface of neutron star.

Original languageEnglish
Title of host publicationAstrophysics of Compact Objects - International Conference on Astrophysics of Compact Objects
Number of pages3
StatePublished - 2008
EventInternational Conference on Astrophysics of Compact Objects - Huangshan City, China
Duration: 1 Jul 20077 Jul 2007

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


ConferenceInternational Conference on Astrophysics of Compact Objects
CityHuangshan City


  • Accretion, accretion disks
  • Binaries: Close
  • Pulsars: Individual (XTE JL 807-294)
  • Stars: Neutron
  • X-rays: Binaries


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