Orbital Decay in M82 X-2

Bachetti M, Heida M, Maccarone T, Huppenkothen D, Israel GL, Barret D, Brightman M, Brumback M, Earnshaw HP, Forster K, Furst F, Grefenstette BW, Harrison FA, Jaodand AD, Madsen KK, Middleton M, Pike SN, Pilia M, Poutanen J, Stern D, Tomsick JA, Walton DJ, Webb N, Wilms J (2022)

Publication Type: Journal article

Publication year: 2022


Book Volume: 937

Article Number: 125

Journal Issue: 2

DOI: 10.3847/1538-4357/ac8d67


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 ̇ orb / P orb ≈ − 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.

Authors with CRIS profile

Involved external institutions

How to cite


Bachetti, M., Heida, M., Maccarone, T., Huppenkothen, D., Israel, G.L., Barret, D.,... Wilms, J. (2022). Orbital Decay in M82 X-2. Astrophysical Journal, 937(2). https://doi.org/10.3847/1538-4357/ac8d67


Bachetti, Matteo, et al. "Orbital Decay in M82 X-2." Astrophysical Journal 937.2 (2022).

BibTeX: Download