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The extreme mass transfer and high magnetic field of the first ultraluminous pulsar M82 X-2

Bachetti, Matteo and Heida, Marianne and Maccarone, Thomas and Huppenkothen, Daniela and Israel, Gian Luca and Barret, Didier and Brightman, Murray and Brumback, McKinley and Earnshaw, Hannah P. and Forster, Karl and Fürst, Felix and Grefenstette, Brian W. and Harrison, Fiona A. and Jaodand, Amruta D. and Madsen, Kristin K. and Middleton, Matthew and Pike, Sean N. and Pilia, Maura and Poutanen, Juri and Stern, Daniel and Tomsick, John A. and Walton, Dominic J. and Webb, Natalie and Wilms, Jörn (2021) The extreme mass transfer and high magnetic field of the first ultraluminous pulsar M82 X-2. . (Unpublished)

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M82 X-2 is the first pulsating ultraluminous X-ray source (PULX) 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 an apparent luminosity boosted by geometrical beaming. Only an independent measurement of the mass transfer can help discriminate between these two scenarios. In this Paper, we follow the orbit of the neutron star for seven years, measure the decay of the orbit, and demonstrate that this orbital decay is driven by extreme mass transfer of more than 150 times the mass transfer limit set by the Eddington luminosity. This measurement shows that 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.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Bachetti, Matteo0000-0002-4576-9337
Heida, Marianne0000-0002-1082-7496
Maccarone, Thomas0000-0003-0976-4755
Huppenkothen, Daniela0000-0002-1169-7486
Barret, Didier0000-0002-0393-9190
Brightman, Murray0000-0002-8147-2602
Brumback, McKinley0000-0002-4024-6967
Earnshaw, Hannah P.0000-0001-5857-5622
Forster, Karl0000-0001-5800-5531
Fürst, Felix0000-0003-0388-0560
Grefenstette, Brian W.0000-0002-1984-2932
Harrison, Fiona A.0000-0003-2992-8024
Jaodand, Amruta D.0000-0002-3850-6651
Madsen, Kristin K.0000-0003-1252-4891
Middleton, Matthew0000-0002-8183-2970
Pike, Sean N.0000-0002-8403-0041
Poutanen, Juri0000-0002-0983-0049
Stern, Daniel0000-0003-2686-9241
Tomsick, John A.0000-0001-5506-9855
Walton, Dominic J.0000-0001-5819-3552
Wilms, Jörn0000-0003-2065-5410
Additional Information:The authors wish to thank Włodek Kluźniak and Alessandro Ridolfi for useful discussions, and the staff at the NuSTAR Science Operations Center at Caltech for the help in scheduling the observations and the frequent clock correction file updates, that allowed a prompt analysis of the data. MB was funded in part by PRIN TEC INAF 2019 “SpecTemPolar! – Timing analysis in the era of high-throughput photon detectors”. MH is supported by an ESO fellowship. GLI acknowledges funding from the Italian MIUR PRIN grant 2017LJ39LM. ADJ was funded in part by the Chandra grant 803-0000-716015-404H00-6100-2723-4210-40716015HH83121. JP was supported by the grant 14.W03.31.0021 of the Ministry of Science and Higher Education of the Russian Federation and the Academy of Finland grant 333112. DJW acknowledges support from STFC in the form of an Ernest Rutherford Fellowship. HPE acknowledges support under NASA Contract No. NNG08FD60C. All the analysis of this Paper was done using open-source software: Astropy, Stingray, HENDRICS, PINT, emcee, corner, scinum, and can easily be verified using the solution in Table 1. Figures were produced using the Matplotlib library and the Veusz software. The data used for this work come from the NuSTAR mission and are usually held private for one year, and made public on the High Energy Astrophysics Science archive (HEASARC) afterwise. NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia.
Group:Space Radiation Laboratory, NuSTAR, Astronomy Department
Funding AgencyGrant Number
Istituto Nazionale di Astrofisica (INAF)PRIN 2019
European Southern Observatory (ESO)UNSPECIFIED
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)2017LJ39LM
Ministry of Science and Higher Education of the Russian Federation14.W03.31.0021
Academy of Finland333112
Science and Technology Facilities Council (STFC)UNSPECIFIED
Record Number:CaltechAUTHORS:20220113-234521215
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112893
Deposited By: George Porter
Deposited On:14 Jan 2022 17:02
Last Modified:02 Jun 2023 01:20

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