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Orbital Decay in 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 (2022) Orbital Decay in M82 X-2. Astrophysical Journal, 937 (2). Art. No. 125. ISSN 0004-637X. doi:10.3847/1538-4357/ac8d67.

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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 (Ṗ_(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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Bachetti, Matteo0000-0002-4576-9337
Heida, Marianne0000-0002-1082-7496
Maccarone, Thomas0000-0003-0976-4755
Huppenkothen, Daniela0000-0002-1169-7486
Israel, Gian Luca0000-0001-5480-6438
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
Pilia, Maura0000-0001-7397-8091
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 Victoria Grinberg, 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, which allowed a prompt analysis of the data. We would also wish to thank the anonymous referee, and the three referees of a previous submission, who provided very insightful feedback that led to a substantial improvement of the quality of the analysis. M.B. was funded in part by PRIN TEC INAF 2019 "SpecTemPolar!—Timing analysis in the era of high-throughput photon detectors". M.H. is supported by an ESO fellowship. G.L.I. and M.B. acknowledge funding from the Italian MIUR PRIN grant No. 2017LJ39LM. A.D.J. was funded in part by the Chandra grant No. 803-0000-716015-404H00-6100-2723-4210-40716015HH83121. J.P. was supported by the grant No. 14.W03.31.0021 of the Ministry of Science and Higher Education of the Russian Federation and the Academy of Finland grant No. 333112. D.J.W. acknowledges support from STFC in the form of an Ernest Rutherford Fellowship. H.P.E. 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, and scinum, and can easily be verified using the solutions in Tables 1 and 2. The implementation of the Pletsch & Clark (2015) method can be found in the github repository Figures were produced using the Matplotlib library and the Veusz software. The data used for this work come from the NuSTAR and XMM-Newton missions and are usually held private for one year, and made public on the High Energy Astrophysics Science archive (HEASARC) and the XMM-Newton Science Archive (XSA) afterwards. NuSTAR is a Small Explorer mission led by Caltech and managed by the 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. XMM-Newton is an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.
Group:Astronomy Department, Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Istituto Nazionale di Astrofisica (INAF)PRIN-TEC 2019
European Southern Observatory (ESO)UNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)2017LJ39LM
NASA803-0000-716015-404H00-6100-2723-4210-40716015HH 83121
Ministry of Science and Higher Education of the Russian Federation14.W03.31.0021
Academy of Finland333112
Science and Technology Facilities Council (STFC)UNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20221017-15547800.31
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117469
Deposited By: Research Services Depository
Deposited On:21 Oct 2022 20:39
Last Modified:25 Oct 2022 19:51

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