Refereed journal article or data article (A1)
Orbital Decay in M82 X-2
List of Authors: Bachetti Matteo, Heida Marianne, Maccarone Thomas, Huppenkothen Daniela, Israel Gian Luca, Barret Didier, Brightman Murray, Brumback McKinley, Earnshaw Hannah P, Forster Karl, Fürst Felix, Grefenstette Brian W, Harrison Fiona A, Jaodand Amruta D, Madsen Kristin K, Middleton Mathew, Pike Sean N, Pilia Maura, Poutanen Juri, Stern Daniel, Tomsick John A, Walton Dominic J, Webb Natalie, Wilms Jörn
Publisher: IOP Publishing Ltd
Publication year: 2022
Journal: Astrophysical Journal
Journal name in source: ASTROPHYSICAL JOURNAL
Journal acronym: ASTROPHYS J
Article number: 125
Volume number: 937
Issue number: 2
Number of pages: 12
ISSN: 0004-637X
eISSN: 1538-4357
DOI: http://dx.doi.org/10.3847/1538-4357/ac8d67
URL: https://iopscience.iop.org/article/10.3847/1538-4357/ac8d67
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/176809419
M82 X-2 is the first pulsating ultraluminous X-ray source discovered. The luminosity of these extreme pulsars, if isotropic, implies an extreme mass transfer rate. An alternative is to assume a much lower mass transfer rate, but with an apparent luminosity boosted by geometrical beaming. Only an independent measurement of the mass transfer rate can help discriminate between these two scenarios. In this paper, we follow the orbit of the neutron star for 7 yr, measure the decay of the orbit ((P) over dot(orb)/(P) over dot(orb) approximate to -8.10(-6) yr(-1)), and argue that this orbital decay is driven by extreme mass transfer of more than 150 times the mass transfer limit set by the Eddington luminosity. If this is true, the mass available to the accretor is more than enough to justify its luminosity, with no need for beaming. This also strongly favors models where the accretor is a highly magnetized neutron star.
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