NICER observations of the Crab pulsar glitch of 2017 November. (arXiv:1911.10028v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Vivekanand_M/0/1/0/all/0/1">M. Vivekanand</a>
Context: The Crab pulsar underwent its largest timing glitch on 2017 Nov 8.
The event was discovered at radio wavelengths, and was followed at soft X-ray
energies by observatories, such as XPNAV and NICER. aims: This work aims to
compare the glitch behavior at the two wavelengths mentioned above. Preliminary
work in this regard has been done by the X-ray satellite XPNAV. NICER with its
far superior sensitivity is expected to reveal much more detailed behavior.
methods: NICER has accumulated more than $301$ kilo seconds of data on the Crab
pulsar, equivalent to more than $3.3$ billion soft X-ray photons. These data
were first processed using the standard NICER analysis pipeline. Then the
arrival times of the X-ray photons were referred to the solar system’s
barycenter. Then specific analysis was done to study the specific behavior
outlined in the following sections, while taking dead time into account.
results: The variation of the rotation frequency of the Crab pulsar and its
time derivative during the glitch is almost exactly similar at the radio and
X-ray energies. The following properties of the Crab pulsar remain essentially
constant before and after the glitch: the total X-ray flux; the flux, widths,
and peaks of the two components of its integrated profile; and the soft X-ray
spectrum. There is no evidence for giant pulses at X-ray energies. However, the
timing noise of the Crab pulsar shows quasi sinusoidal variation before the
glitch, with increasing amplitude, which is absent after the glitch.
conclusions: Even the strongest glitch in the Crab pulsar appears not to affect
all but one of the properties mentioned above, at either frequency. The fact
that the timing noise appears to change due to the glitch is an important clue
to unravel as this is still an unexplained phenomenon.
Context: The Crab pulsar underwent its largest timing glitch on 2017 Nov 8.
The event was discovered at radio wavelengths, and was followed at soft X-ray
energies by observatories, such as XPNAV and NICER. aims: This work aims to
compare the glitch behavior at the two wavelengths mentioned above. Preliminary
work in this regard has been done by the X-ray satellite XPNAV. NICER with its
far superior sensitivity is expected to reveal much more detailed behavior.
methods: NICER has accumulated more than $301$ kilo seconds of data on the Crab
pulsar, equivalent to more than $3.3$ billion soft X-ray photons. These data
were first processed using the standard NICER analysis pipeline. Then the
arrival times of the X-ray photons were referred to the solar system’s
barycenter. Then specific analysis was done to study the specific behavior
outlined in the following sections, while taking dead time into account.
results: The variation of the rotation frequency of the Crab pulsar and its
time derivative during the glitch is almost exactly similar at the radio and
X-ray energies. The following properties of the Crab pulsar remain essentially
constant before and after the glitch: the total X-ray flux; the flux, widths,
and peaks of the two components of its integrated profile; and the soft X-ray
spectrum. There is no evidence for giant pulses at X-ray energies. However, the
timing noise of the Crab pulsar shows quasi sinusoidal variation before the
glitch, with increasing amplitude, which is absent after the glitch.
conclusions: Even the strongest glitch in the Crab pulsar appears not to affect
all but one of the properties mentioned above, at either frequency. The fact
that the timing noise appears to change due to the glitch is an important clue
to unravel as this is still an unexplained phenomenon.
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