First characterization of a new High Mass X-ray Binary in LMC eRASSU J050810.4$-$660653 with SRG/ART-XC, NuSTAR and Swift

Abstract

We report results of the first detailed spectral and temporal studies of the recently discovered Be/X-ray binary eRASSU J050810.4$-$660653 in LMC based on the data from the SRG/ART-XC, NuSTAR and Swift/XRT instruments obtained in December 2021 - May 2022 in a wide energy range of 0.5-79 keV. Pulsations with the period of $40.5781\pm 0.0004$ s were found in the source light curve with the pulsed fraction monotonically increasing with the energy. An estimate of the orbital period of $\sim 38$ days was obtained based on the long-term monitoring of the system. The source spectrum can be well approximated with a power-law model modified by an exponential cutoff at high energies. The pulse phase-resolved spectroscopy shows a strong variation of spectral parameters depending on the phase of a neutron star rotation. We have not found any features connected with the cyclotron absorption line both in the phase-averaged and phase-resolved spectra of eRASSU J050810.4$-$660653. However, the neutron star magnetic field was estimated around several $10^{13}$ G using different indirect methods. Discovered variations of the hardness ratio over the pulse phase is discussed in terms of physical and geometrical properties of the emitting region.

Accepted for publication in MNRAS. 8 pages, 6 figures, 2 tables

References in corpus (14)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars
• The critical accretion luminosity for magnetized neutron stars
• The ART-XC telescope on board the SRG observatory
• On the dependence of the X-ray continuum variations with luminosity in accreting X-ray pulsars
• Giant outburst of EXO 2030+375: pulse-phase resolved analysis of INTEGRAL data
• XMMU J050722.1-684758: Discovery of a new Be X-ray binary pulsar likely associated with the supernova remnant MCSNR J0507-6847
• Discovery of the 5 keV cyclotron line followed by three harmonics in SwiftJ1626.6-5156
• Three new high-mass X-ray binaries in the Large Magellanic Cloud
• Diverse Long-Term Variability of Five Candidate High-Mass X-ray Binaries from Swift Burst Alert Telescope Observations
• SRGA J124404.1-632232/SRGU J124403.8-632231: a new X-ray pulsar discovered in the all-sky survey by SRG
• SRG/ART-XC discovery of SRGA J204318.2+443815: towards the complete population of faint X-ray pulsars

Cited by in corpus (2)

• RX J0440.9+4431: another supercritical X-ray pulsar
• SRG/eROSITA-triggered XMM-Newton observations of three Be/X-ray binaries in the LMC: Discovery of X-ray pulsations