Open AccessNGC 5474 X-1: the neutron star ULX in an old stellar cluster
Author(s) -
К. Атапин,
А. Винокуров,
Yu. Solovyeva,
S. Fabrika
Publication year - 2022
Publication title -
astronomy at the epoch of multimessenger studies. proceedings of the vak-2021 conference, aug 23–28, 2021
Language(s) - English
Resource type - Conference proceedings
DOI - 10.51194/vak2021.2022.1.1.097
Subject(s) - physics , neutron star , astrophysics , cyclotron , star cluster , star (game theory) , cluster (spacecraft) , compact star , line (geometry) , cyclotron resonance , astronomy , magnetic field , stars , geometry , mathematics , quantum mechanics , computer science , programming language
We report the discovery of a cyclotron resonant scattering feature (CRSF) in the ultraluminous X-ray source (ULX)NGC5474 X-1 that makes it the third ULX with a CRSF. Cyclotron lines arise in strong magnetic elds, which requiresthe object to be a neutron star. The line energy of 7.5 keV corresponds to the magnetic eld strength ∼ 10 12 G. The sourceshows a hard X-ray spectrum with Γ ∼ 1 and strong X-ray variability which is also typical for neutron star ULXs. In theoptical range, the object is interesting by the fact that it is projected onto an old stellar cluster (or located inside) with anage of about 1 Gyr.