A new dipping source in the M31 galaxy

We have discovered a 107min periodic modulation in the light curve of source XMMU J004308.6+411247 from the XMM-Newton observation carried out on 2002 January 6. The source count rate was consistent with zero at the dip minimum. The same modulation is also detected in archival XMM-Newton observations carried out on 2000 June 25, 2001 June 29 and in Chandra observation carried out on 2001 October 5. The dips show no energy dependence. The average X-ray flux of XMMU J004308.6+411247 was nearly constant across different observations (~ 10³⁷ergs^-1 for an assumed M31 distance of 780kpc in the 0.3-10keV band); the spectrum was well fit by an absorbed power law with a photon index ~0.8 or an absorbed Comptonization model. Observed flux and spectral parameters of the XMMU J004308.6+411247 are consistent with a dipping low mass X-ray binary (LMXRB) located in M31.