First characterization of a new high-mass X-ray binary in LMC eRASSU J050810.4-660653 with SRG/ART-XC, NuSTAR, and Swift

Galaxie

Losing a minute every two years: SRG X-ray view of the rapidly accelerating X-ray pulsar SXP 1323

High Energy Astrophysic

SRG/ART-XC, Swift, NICER, and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903-531

High Energy Astrophysic

Unveiling Soft Gamma-Ray Repeaters with INTEGRAL

Thanks to INTEGRAL's long exposures of the Galactic Plane, the two brightest Soft Gamma-Ray Repeaters, SGR 1806-20 and SGR 1900+14, have been monitored and studied in detail for the first time at hard-X/soft gamma rays. This has produced a wealth of new scientific results, which we will review here. Since SGR 1806-20 was particularly active during the last two years, more than 300 short bursts have been observed with INTEGRAL. and their characteristics have been studied with unprecedented sensitivity in the 15-200 keV range. A hardness-intensity anticorrelation within the bursts has been discovered and the overall Number-Intensity distribution of the bursts has been determined. In addition, a particularly active state, during which ~100 bursts were emitted in ~10 minutes, has been observed on October 5 2004, indicating that the source activity was rapidly increasing. This eventually led to the Giant Flare of December 27th 2004, for which a possible soft gamma-ray (>80 keV) early afterglow has been detected. The deep observations allowed us to discover the persistent emission in hard X-rays (20-150 keV) from 1806-20 and 1900+14, the latter being in a quiescent state, and to directly compare the spectral characteristics of all Magnetars (two SGRs and three Anomalous X-ray Pulsars) detected with INTEGRAL.Comment: 8 pages, 7 figures, Presented at the conference "Isolated Neutron Stars: from the Surface to the Interior", London, UK, 24-28 April 200

Recent Progress on Anomalous X-ray Pulsars

I review recent observational progress on Anomalous X-ray Pulsars, with an emphasis on timing, variability, and spectra. Highlighted results include the recent timing and flux stabilization of the notoriously unstable AXP 1E 1048.1-5937, the remarkable glitches seen in two AXPs, the newly recognized variety of AXP variability types, including outbursts, bursts, flares, and pulse profile changes, as well as recent discoveries regarding AXP spectra, including their surprising hard X-ray and far-infrared emission, as well as the pulsed radio emission seen in one source. Much has been learned about these enigmatic objects over the past few years, with the pace of discoveries remaining steady. However additional work on both observational and theoretical fronts is needed before we have a comprehensive understanding of AXPs and their place in the zoo of manifestations of young neutron stars.Comment: 10 pages, 6 figures; to appear in proceedings of the conference "Isolated Neutron Stars: From the Interior to the Surface" eds. S. Zane, R. Turolla, D. Page; Astrophysics & Space Science in pres

Changes in the nature of the spectral continuum and stability of the cyclotron line in the X-ray pulsar GRO J2058+42

High Energy Astrophysic

Changes in the nature of the spectral continuum and stability of the cyclotron line in the X-ray pulsar GRO J2058+42

The results of the broadband spectral and timing study of the transient X-ray pulsar GRO J2058+42 in a wide energy range at a low luminosity $L_{x} \simeq 2.5\times 10^{36}$ erg s$^{-1}$ are reported. The data revealed that the pulse profile and pulse fraction of the source are significantly changed in comparison with previous NuSTAR observations, when the source was ten times brighter. The cyclotron absorption line at $\sim10$ keV in the narrow phase interval is consistent with the high state observations. Spectral analysis showed that at high luminosities $L_{x}\simeq (2.7-3.2)\times 10^{37}$ erg s$^{-1}$ the spectrum has a shape typical of accreting pulsars, while when the luminosity drops by about an order of magnitude, to $2.5\times 10^{36}$ erg s$^{-1}$ a two-component model is necessary to its describing. This behavior fits into a model in which the low-energy part of the spectrum is formed in a hot spot, and the high-energy part is formed as a result of resonant Compton scattering by incident matter in an accretion channel above the surface of a neutron star.Comment: 16 pages, 6 figures, 3 table

First characterization of a new high-mass X-ray binary in LMC eRASSU J050810.4-660653 with SRG/ART-XC, NuSTAR, and Swift

Galaxie

Observations of Her X-1 in low states during SRG/eROSITA all-sky survey

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) instrument onboard the Russian-German 'Spectrum-Roentgen-Gamma' (SRG) mission observed the Her X-1/HZ Her binary system in multiple scans over the source during the first and second SRG all-sky surveys. Both observations occurred during a low state of the X-ray source when the outer parts of the accretion disk blocked the neutron star from view. The orbital modulation of the X-ray flux was detected during the low states. We argue that the detected X-ray radiation results from scattering of the emission of the central source by three distinct regions: (a) an optically thin hot corona with temperature ~(2-4) × 10K above the irradiated hemisphere of the optical star; (b) an optically thin hot halo above the accretion disk; and (c) the optically thick cold atmosphere of the optical star. The latter region effectively scatters photons with energies above 5-6 keV