The Ups &amp; Downs of Accreting X-Ray Pulsars: Decade-long observations with the Fermi Gamma-Ray Burst Monitor

Malacaria, C.; Jenke, P.; Roberts, O. J.; Wilson-Hodge, C. A.; Cleveland, W. H.; Mailyan, B.

doi:10.48550/arxiv.2004.00051

Cited by 5 publications

(6 citation statements)

References 215 publications

(291 reference statements)

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“…The Gamma-ray Burst Monitor (GBM, Meegan et al 2009) on-board the Fermi spacecraft is continuously monitoring the spin histories of X-ray pulsars (Finger et al 2009;Malacaria et al 2020). For the date (MJD 58035-58042) without HXMT observations, we compiled the GBM pulsed profile data.…”

Section: Observation Datamentioning

confidence: 99%

Super-Eddington accretion of the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Liu

Jenke

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a detailed timing study of the pulse profile of Swift J0243.6+6124 with HXMT and Fermi/GBM data during its 2017 giant outburst. The double-peak profile at luminosity above 5 × 1038erg s−1 is found to be 0.25 phase offset from that below 1.5 × 1038erg s−1, which strongly supports for a transition from a pencil beam to a fan beam, and thus for the formation of shock dominated accretion column. During the rising stage of the high double-peak regime, the faint peak got saturated in 10-100 keV band above a luminosity of Lt ∼ 1.3 × 1039erg s−1, which is coincident with sudden spectral changes of both the main and faint peaks. They imply a sudden change of emission pattern around Lt. The spin-up rate ($\dot{\nu }$) is linearly correlated with luminosity (L) below Lt, consistent with the prediction of a radiation pressure dominated (RPD) disk. The $\dot{\nu }-L$ relation flattens above Lt, indicating a less efficient transfer of angular momentum and a change of accretion disk geometry above Lt. It is likely due to irradiation of the disk by the central accretion column and indicates significant radiation feedback before the inner disk radius reaching the spherization radius.

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Section: Observation Datamentioning

confidence: 99%

Super-Eddington accretion of the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Liu

Jenke

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…In this analysis we have used the pulse frequency and 12-50 keV pulsed flux measurements with the Fermi-GBM (Finger et al 2009;Camero-Arranz et al 2009). The measurement technique is discussed thoroughly in Malacaria et al (2020).…”

Section: Fermi -Gbm Observationsmentioning

confidence: 99%

Broad-band X-ray characteristics of the transient pulsar GRO J2058+42

Kabiraj

Paul

2020

Monthly Notices of the Royal Astronomical Society

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The Be X-ray binary GRO J2058+42 recently went through a Type-II outburst during March-April 2019 lasting for about 50 days. This outburst was detected with the operating all sky X-ray monitors like the Fermi-GBM, Swift-BAT and MAXI-GSC. Two NuSTAR observations were also made, one during the rise and other during the decay of the outburst. It gave us the unique opportunity to analyze the broadband characteristics of the pulsar for the first time and accretion torque characteristics of the pulsar over a range of X-ray luminosity. The pulse profiles are strongly energy dependent, with at least four different pulse components at low energy (< 20 keV) which evolves to a single-peaked profile at high energy (> 30 keV). In each of the narrow energy bands, the pulse profiles are nearly identical in the two NuSTAR observations. The spectra from both the observations are fitted well to a power-law with a Fermi-Dirac type high energy cutoff. We ruled out presence of a cyclotron line in the pulse phase averaged X-ray spectrum in the NuSTAR band with an optical depth greater than 0.15. An iron emission line is detected in both the NuSTAR spectra with an equivalent width of about 125 eV. We looked at the dependence of the spin-up rate on the luminosity and estimated the magnetic field strength from that, which came out to be much higher compared to other known BeXRB pulsars. Lastly, we discussed the inadequacy of the torque-luminosity relation for determination of magnetic field strength of neutron stars.

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“…The Gamma-ray Burst Monitor (GBM, Note: texp refers to the effective exposure of the ME telescope. Meegan et al 2009) on the Fermi spacecraft is continuously monitoring the spin histories of X-ray pulsars 1 (Finger et al 2009;Malacaria et al 2020).…”

Section: Observation Datamentioning

confidence: 99%

Disk vs wind accretion in X-ray pulsar GX 301-2

Liu,

Ji,

Jenke

et al. 2021

Preprint

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GX 301-2 provides a rare opportunity to study both disk and wind accretion in a same target. We report Insight-HXMT observations of the spin-up event of GX 301-2 happened in 2019 and compare with those of wind-fed state. The pulse profiles of the initial rapid spin-up period are dominated by one main peak, while those of the later slow spin-up period are composed of two similar peaks, as those of wind-fed state. These behaviors are confirmed by Fermi/GBM data, which also show that during the rapid spin-up period, the main peak increases with luminosity up to 8 × 10 37 erg s −1 , but the faint peak keeps almost constant. The absorption column densities during the spin-up period are ∼ 1.5 × 10 23 cm −2 , much less than those of wind-fed state at similar luminosity (∼ 9 × 10 23 cm −2 ), supporting the scenario that most of material is condensed into a disk during the spin-up period. We discuss possible differences between disk and wind accretion that may explain the observed different trend of pulse profiles.

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The Ups & Downs of Accreting X-Ray Pulsars: Decade-long observations with the Fermi Gamma-Ray Burst Monitor

Cited by 5 publications

References 215 publications

Super-Eddington accretion of the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Super-Eddington accretion of the first Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124

Broad-band X-ray characteristics of the transient pulsar GRO J2058+42

Disk vs wind accretion in X-ray pulsar GX 301-2

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