20 research outputs found
Burst phase distribution of SGR J1935+2154 based on Insight-HXMT
On April 27, 2020, the soft gamma ray repeater SGR J1935+2154 entered its
intense outburst episode again. Insight-HXMT carried out about one month
observation of the source. A total number of 75 bursts were detected during
this activity episode by Insight-HXMT, and persistent emission data were also
accumulated. We report on the spin period search result and the phase
distribution of burst start times and burst photon arrival times of the
Insight-HXMT high energy detectors and Fermi Gamma-ray Burst Monitor (GBM). We
find that the distribution of burst start times is uniform within its spin
phase for both Insight-HXMT and Fermi-GBM observations, whereas the phase
distribution of burst photons is related to the type of a burst's energy
spectrum. The bursts with the same spectrum have different distribution
characteristics in the initial and decay episodes for the activity of magnetar
SGR J1935+2154.Comment: 12 pages, 9 figure
Insight-HXMT on-orbit thermal control status and thermal deformation impact analysis
Purpose: The Hard X-ray Modulation Telescope is China's first X-ray astronomy
satellite launched on June 15th, 2017, dubbed Insight-HXMT. Active and passive
thermal control measures are employed to keep devices at suitable temperatures.
In this paper, we analyzed the on-orbit thermal monitoring data of the first 5
years and investigated the effect of thermal deformation on the point spread
function (PSF) of the telescopes.
Methods: We examined the data of the on-orbit temperatures measured using 157
thermistors placed on the collimators, detectors and their support structures
and compared the results with the thermal control requirements. The thermal
deformation was evaluated by the relative orientation of the two star sensors
installed on the main support structure. its effect was estimated with
evolution of the PSF obtained with calibration scanning observations of the
Crab nebula.
Conclusion: The on-orbit temperatures met the thermal control requirements
thus far, and the effect of thermal deformation on the PSF was negligible after
the on-orbit pointing calibration.Comment: 25 pages, 35 figures, submitte
Insight-HXMT observations of Swift J0243.6+6124 during its 2017-2018 outburst
The recently discovered neutron star transient Swift J0243.6+6124 has been
monitored by {\it the Hard X-ray Modulation Telescope} ({\it Insight-\rm HXMT).
Based on the obtained data, we investigate the broadband spectrum of the source
throughout the outburst. We estimate the broadband flux of the source and
search for possible cyclotron line in the broadband spectrum. No evidence of
line-like features is, however, found up to . In the absence of
any cyclotron line in its energy spectrum, we estimate the magnetic field of
the source based on the observed spin evolution of the neutron star by applying
two accretion torque models. In both cases, we get consistent results with
, and peak luminosity of which makes the source the first Galactic ultraluminous
X-ray source hosting a neutron star.Comment: publishe