hide
Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
The 559 Hz black-widow pulsar PSR J1555-2908, originally discovered in radio,
is also a bright gamma-ray pulsar. Timing its pulsations using 12 yr of
Fermi-LAT gamma-ray data reveals long-term variations in its spin frequency
that are much larger than is observed from other millisecond pulsars. While
this variability in the pulsar rotation rate could be intrinsic "timing noise",
here we consider an alternative explanation: the variations arise from the
presence of a very-low-mass third object in a wide multi-year orbit around the
neutron star and its low-mass companion. With current data, this
hierarchical-triple-system model describes the pulsar's rotation slightly more
accurately than the best-fitting timing-noise model. Future observations will
show if this alternative explanation is correct.
