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Magnetic field strength of a neutron-star-powered ultraluminous X-ray source

Brightman, Murray and Harrison, Fiona A. and Fürst, Felix and Middleton, M. J. and Walton, D. J. and Stern, D. and Fabian, Andrew C. and Heida, M. and Barret, D. and Bachetti, M. (2018) Magnetic field strength of a neutron-star-powered ultraluminous X-ray source. Nature Astronomy, 2 (4). pp. 312-316. ISSN 2397-3366. doi:10.1038/s41550-018-0391-6.

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Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar remnant, or an intermediate mass (~100–10^5M_⊙) black hole. Recently detected coherent pulsations coming from three bright ULXs demonstrate that some of these sources are powered by accretion onto a neutron star, implying accretion rates significantly in excess of the Eddington limit, a high degree of geometric beaming, or both. The physical challenges associated with the high implied accretion rates can be mitigated if the neutron star surface field is very high (10^(14) G), since this suppresses the electron scattering cross-section, reducing the radiation pressure that chokes off accretion for high luminosities. Surface magnetic field strengths can be determined through cyclotron resonance scattering features produced by the transition of charged particles between quantized Landau levels. Here, we present the detection at a significance of 3.8σ of an absorption line at 4.5 keV in the Chandra spectrum of a ULX in M51. This feature is likely to be a cyclotron resonance scattering feature produced by the strong magnetic field of a neutron star. Assuming scattering off electrons, the magnetic field strength is implied to be ~10^(11) G, while protons would imply a magnetic field of B ~ 10^(15) G.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Brightman, Murray0000-0002-8147-2602
Harrison, Fiona A.0000-0003-2992-8024
Fürst, Felix0000-0003-0388-0560
Middleton, M. J.0000-0002-8183-2970
Walton, D. J.0000-0001-5819-3552
Stern, D.0000-0003-2686-9241
Fabian, Andrew C.0000-0002-9378-4072
Heida, M.0000-0002-1082-7496
Barret, D.0000-0002-0393-9190
Bachetti, M.0000-0002-4576-9337
Additional Information:© 2018 Macmillan Publishers. Received: 05 December 2017. Accepted: 16 January 2018. Published online: 26 February 2018. M.J.M. and D.J.W. appreciate support from Ernest Rutherford Science and Technology Facilities Council fellowships. The work of D.S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Author Contributions: M. Brightman reduced and analysed the Chandra and XMM-Newton data. F.F. performed timing analysis of the Chandra and XMM-Newton data. M.H. analysed the ULX multiwavelength counterpart. M. Brightman, F.A.H., F.F., M.J.M., D.J.W., A.C.F., D.B. and M. Bachetti interpreted the results. M. Brightman, F.A.H., D.J.W. and D.S. prepared the manuscript. The authors declare no competing interests.
Group:Space Radiation Laboratory, NuSTAR, Astronomy Department
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20180110-105628140
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Official Citation:Magnetic field strength of a neutron-star-powered ultraluminous X-ray source M. Brightman, F. A. Harrison, F. Fürst, M. J. Middleton, D. J. Walton, D. Stern, A. C. Fabian, M. Heida, D. Barret & M. Bachetti Nature Astronomy 2, pages312–316 (2018) doi:10.1038/s41550-018-0391-6
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84230
Deposited By: George Porter
Deposited On:26 Feb 2018 18:16
Last Modified:15 Nov 2021 20:18

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