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Published December 1, 2021 | Version Submitted
Discussion Paper Open

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

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Abstract

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.

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.

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Additional details

Identifiers

Eprint ID
112893
Resolver ID
CaltechAUTHORS:20220113-234521215

Related works

Describes
http://arxiv.org/abs/2112.00339 (URL)

Funding

Istituto Nazionale di Astrofisica (INAF)
PRIN 2019
European Southern Observatory (ESO)
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)
2017LJ39LM
Chandra
803-0000-716015-404H00-6100-2723-4210-40716015HH83121
Ministry of Science and Higher Education of the Russian Federation
14.W03.31.0021
Academy of Finland
333112
Science and Technology Facilities Council (STFC)
NASA
NNG08FD60C
NASA/JPL/Caltech

Dates

Created
2022-01-14
Created from EPrint's datestamp field
Updated
2023-06-02
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Caltech Custom Metadata

Caltech groups
Space Radiation Laboratory, NuSTAR, Astronomy Department