Searching a Thousand Radio Pulsars for Gamma-Ray Emission

Author(s)

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.

Abstract

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

2019

Publication type

Journal article

Source

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

ISSN

1538-4357

Publisher

American Astronomical Society

Copyright

Copyright © 2019 The American Astronomical Society. All rights reserved.

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