* Astronomy

Title: GMRT discovery of PSR J1544+4937, an eclipsing black-widow pulsar identified with a Fermi LAT source
Authors: B. Bhattacharyya, J. Roy, P. S. Ray, Y. Gupta, D. Bhattacharya, R. W. Romani, S. M. Ransom, E. C. Ferrara, M. T. Wolff, F. Camilo, I. Cognard, A. K. Harding, P. R. den Hartog, S. Johnston, M. Keith, M. Kerr, P. F. Michelson, P. M. Saz Parkinson, D. L. Wood, K. S. Wood

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-catalogued 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 solar masses). 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.

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