Searching a Thousand Radio Pulsars for Gamma-Ray Emission


Smith, D. A. ; Bruel, P. ; Cognard, I.; Cameron, A. D.; Camilo, F. ; Dai, S.; Guillemot, L. ; Johnson, T. J.; Johnston, S. ; Keith, M. J.; Kerr, M. ; Kramer, M. ; Lyne, A. G. ; Manchester, R. N. ; Shannon, R. ; Sobey, C. ; Stappers, B. W. ; Weltevrede, P.


Identifying as many gamma-ray pulsars as possible in the Fermi Large Area Telescope (LAT) data helps test pulsar emission models by comparing predicted and observed properties for a large, varied sample with as little selection bias as possible. It also improves extrapolations from the observed population to estimate the contribution of unresolved pulsars to the diffuse gamma-ray emission. We use a recently developed method to determine the probability that a given gamma-ray photon comes from a known position in the sky, convolving the photon's energy with the LAT's energy-dependent point-spread function, without the need for an accurate spatial and spectral model of the gamma-ray sky around the pulsar. The method is simple and fast and, importantly, provides probabilities, or weights, for gamma-rays from pulsars too faint for phase-integrated detection. We applied the method to over a thousand pulsars for which we obtained rotation ephemerides from radio observations, and discovered gamma-ray pulsations from 16 pulsars, 12 young and 4 recycled. PSR J2208+4056 has spindown power (E) over dot = 8 x 10(32) erg s(-1), about three times lower than the previous observed gamma-ray emission "deathline." PSRs J2208+4056 and J1816-0755 have radio interpulses, constraining their geometry and perhaps enhancing their gamma-ray luminosity. We discuss whether the deathline is an artifact of selection bias due to the pulsar distance.

Publication year


Publication type

Journal article


The Astrophysical Journal, Vol. 871, no. 1 (Jan 2019), article no. 78




American Astronomical Society


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