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Title: A HIGH BRAKING INDEX FOR A PULSAR

We present a phase-coherent timing solution for PSR J1640–4631, a young 206 ms pulsar using X-ray timing observations taken with NuSTAR. Over this timing campaign, we have measured the braking index of PSR J1640–4631 to be n = 3.15 ± 0.03. Using a series of simulations, we argue that this unusually high braking index is not due to timing noise, but is intrinsic to the pulsar's spin-down. We cannot, however, rule out contamination due to an unseen glitch recovery, although the recovery timescale would have to be longer than most yet observed. If this braking index is eventually proven to be stable, it demonstrates that pulsar braking indices greater than three are allowed in nature; hence, other physical mechanisms such as mass or magnetic quadrupoles are important in pulsar spin-down. We also present a 3σ upper limit on the pulsed flux at 1.4 GHz of 0.018 mJy.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Department of Physics and McGill Space Institute, McGill University, 3600 University Street, Montréal, QC H3A 2T8 (Canada)
  2. Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027-6601 (United States)
  3. Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile)
  4. Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, Pasadena, CA 91125 (United States)
  5. SKA Organization, Jodrell Bank Observatory, Cheshire SK11 9DL (United Kingdom)
  6. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550-9234 (United States)
  7. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  8. Space Science Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States)
Publication Date:
OSTI Identifier:
22518601
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 819; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GHZ RANGE; INDEXES; MASS; NEUTRONS; NOISE; PULSARS; QUADRUPOLES; SPIN; STARS; X RADIATION