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arXiv · 1803.07571

A Potential Cyclotron Resonant Scattering Feature in the ULX Pulsar NGC 300 ULX1 seen by NuSTAR and XMM-Newton

D. J. Walton·M. Bachetti·F. Fuerst·D. Barret·M. Brightman·A. C. Fabian·B. W. Grefenstette·F. A. Harrison·M. Heida·J. Kennea·P. Kosec·R. M. Lau·K. K. Madsen·M. J. Middleton·C. Pinto·J. F. Steiner·N. Webb
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Abstract

Based on phase-resolved broadband spectroscopy using $XMM$-$Newton$ and $NuSTAR$, we report on a potential cyclotron resonant scattering feature at $E \sim 13$ keV in the pulsed spectrum of the recently discoverd ULX pulsar NGC 300 ULX1. If this interpretation is correct, the implied magnetic field of the central neutron star is $B \sim 10^{12}$ G (assuming scattering off electrons), similar to that estimated from the observed spin-up of the star, and also similar to known Galactic X-ray pulsars. We discuss the implications of this result for the connection between NGC 300 ULX1 and the other known ULX pulsars, particularly in light of the recent discovery of a likely proton Cyclotron line in another ULX, M51 ULX-8.

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D. J. Walton, M. Bachetti, F. Fuerst, D. Barret, M. Brightman, A. C. Fabian, B. W. Grefenstette, F. A. Harrison, M. Heida, J. Kennea, P. Kosec, R. M. Lau, K. K. Madsen, M. J. Middleton, C. Pinto, J. F. Steiner, N. Webb. 2018-03-20. A Potential Cyclotron Resonant Scattering Feature in the ULX Pulsar NGC 300 ULX1 seen by NuSTAR and XMM-Newton. https://doi.org/10.3847/2041-8213/aabadc

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