A possible new dipping X-ray source in the field of M31

Abstract

We report the discovery of the new dipping X-ray source, XMMU J004308.6+411247, in M31, during a systematic search for periodicities in XMM-Newton archival observations. During the 2002 January 6 observation, the dips recur with a 107 min period and the source count rate is consistent with zero at the dip minimum. Dips with the same modulation and period are also observed during the XMM-Newton observations carried out on 2000 June 25, 2001 June 29 and the Chandra observation of 2001 October 5. The dips of XMMU J004308.6+411247 show no evidence of energy dependence. The average X-ray flux of XMMU J004308.6+411247 is nearly constant across different observations (~1.e37 erg/s for an assumed M31 distance of 780 kpc in the 0.3-10 keV band); the spectrum is well fit by an absorbed power law with a photon index ~0.8 or an absorbed Comptonization model. The photo-electric absorption is consistent with the Galactic value in the source direction. If XMMU J004308.6+411247 is located in M31 its properties are consistent with those of dipping low mass X-ray binaries in the Galaxy. Present observations do not allow to distinguish between dips and eclipses. The possibility that XMMU J004308.6+411247 is a foreground X-ray source cannot be ruled out at present; in this case the source might be a magnetic cataclysmic variable.

Accepted for publication in A&A, 16 pages, 8 postscript figures

References in corpus (6)

• The energy balance in polars revisited
• A Chandra High-Resolution Camera Observation of X-Ray Point Sources in M31
• A Chandra observation of the neutron star X-ray transient and eclipsing binary MXB 1659-29 in quiescence
• Bursts, eclipses, dips and a refined position for the luminous low-mass X-ray binary in the globular cluster Terzan 6
• The discovery of 2.78 hour periodic modulation of the X-ray flux from globular cluster source Bo 158 in M31
• Variability of the Accretion Stream in the Eclipsing Polar EP Dra

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• X-ray source variability study of the M 31 central field using Chandra HRC-I
• On the artificial nature of aperiodic variability in XMM-Newton observations of M31 X-ray sources and the ultraluminous X-ray source NGC 4559 ULX-7
• X-Ray Eclipse Time Delays in 4U2129+47
• Discovery of periodic dips in the brightest hard X-ray source of M31 with EXTraS