Walton, D. J.D. J.WaltonBACHETTI, MatteoMatteoBACHETTIFürst, F.F.FürstBarret, D.D.BarretBrightman, M.M.BrightmanFabian, A. C.A. C.FabianGrefenstette, B. W.B. W.GrefenstetteHarrison, F. A.F. A.HarrisonHeida, M.M.HeidaKennea, J.J.KenneaKosec, P.P.KosecLau, R. M.R. M.LauMadsen, K. K.K. K.MadsenMiddleton, M. J.M. J.MiddletonPINTO, CIROCIROPINTOSteiner, J. F.J. F.SteinerWebb, N.N.Webb2020-11-202020-11-2020182041-8205http://hdl.handle.net/20.500.12386/28484Based on phase-resolved broadband spectroscopy using XMM-Newton and NuSTAR, we report on a potential cyclotron resonant scattering feature (CRSF) at E ∼ 13 keV in the pulsed spectrum of the recently discovered ultraluminous X-ray source (ULX) pulsar NGC 300 ULX1. If this interpretation is correct, the implied magnetic field of the central neutron star is B ∼ 1012 G (assuming scattering by 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.STAMPAenArticle10.3847/2041-8213/aabadc2-s2.0-85045836992000429589100001https://iopscience.iop.org/article/10.3847/2041-8213/aabadc2018ApJ...857L...3WFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos