GMRT discovery of PSR J1544+4937, an eclipsing black-widow pulsar
  identified with a Fermi LAT source
  Using the Giant Metrewave Radio Telescope (GMRT) we performed deep
observations to search for radio pulsations in the directions of unidentified
Fermi Large Area Telescope (LAT) gamma-ray sources. We report the discovery of
an eclipsing black-widow millisecond pulsar, PSR J1544+4937, identified with
the un-cataloged gamma-ray source Fermi J1544.2+4941. This 2.16 ms pulsar is in
a 2.9 hours compact circular orbit with a very low-mass companion (Mc > 0.017
Msun). At 322 MHz this pulsar is found to be eclipsing for 13% of its orbit,
whereas at 607 MHz the pulsar is detected throughout the low-frequency eclipse
phase. Variations in the eclipse ingress phase are observed, indicating a
clumpy and variable eclipsing medium. Moreover, additional short-duration
absorption events are observed around the eclipse boundaries. Using the radio
timing ephemeris we were able to detect gamma-ray pulsations from this pulsar,
confirming it as the source powering the gamma-ray emission.
