Abstract
We report the discovery of 1.97 ms period gamma-ray pulsations from the
75 minute orbital-period binary pulsar now named PSR J1653-0158. The
associated Fermi Large Area Telescope gamma-ray source 4FGL J1653.6-0158
has long been expected to harbor a binary millisecond pulsar. Despite
the pulsar-like gamma-ray spectrum and candidate optical/X-ray
associations—whose periodic brightness modulations suggested an
orbit—no radio pulsations had been found in many searches. The
pulsar was discovered by directly searching the gamma-ray data using the
GPU-accelerated Einstein@Home distributed volunteer computing system.
The multidimensional parameter space was bounded by positional and
orbital constraints obtained from the optical counterpart. More
sensitive analyses of archival and new radio data using knowledge of the
pulsar timing solution yield very stringent upper limits on radio
emission. Any radio emission is thus either exceptionally weak, or
eclipsed for a large fraction of the time. The pulsar has one of the
three lowest inferred surface magnetic-field strengths of any known
pulsar with Bsurf ≍ 4 × 107 G. The
resulting mass function, combined with models of the companion star's
optical light curve and spectra, suggests a pulsar mass ≳2
M⊙. The companion is lightweight with mass ∼0.01
M⊙, and the orbital period is the shortest known for any
rotation-powered binary pulsar. This discovery demonstrates the Fermi
Large Area Telescope's potential to discover extreme pulsars that would
otherwise remain undetected.
Original language | English (US) |
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Article number | L46 |
Journal | The Astrophysical Journal Letters |
Volume | 902 |
Issue number | 2 |
DOIs | |
State | Published - Oct 20 2020 |
Keywords
- Gamma-ray sources
- Millisecond pulsars
- Neutron stars
- Binary pulsars
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ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science