<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Carpano, S.</style></author><author><style face="normal" font="default" size="100%">Haberl, F.</style></author><author><style face="normal" font="default" size="100%">Maitra, C.</style></author><author><style face="normal" font="default" size="100%">Vasilopoulos, G.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Discovery of pulsations from NGC 300 ULX1 and its fast period evolution</style></title><short-title><style face="normal" font="default" size="100%">Monthly Notices of the Royal Astronomical Society</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Astrophysics - High Energy Astrophysical Phenomena</style></keyword><keyword><style  face="normal" font="default" size="100%">pulsars: individual: NGC 300 ULX1- galaxies: individual: NGC 300</style></keyword><keyword><style  face="normal" font="default" size="100%">stars: neutron</style></keyword><keyword><style  face="normal" font="default" size="100%">X-rays: binaries</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2018</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2018/05/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2018MNRAS.476L..45C</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">OUP</style></publisher><volume><style face="normal" font="default" size="100%">476</style></volume><pages><style face="normal" font="default" size="100%">L45 - L49</style></pages><isbn><style face="normal" font="default" size="100%">0035-8711</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The supernova impostor SN 2010da located in the nearby galaxy NGC 300, later identified as a likely supergiant B[e] high-mass X-ray binary, was simultaneously observed by NuSTAR and XMM-Newton between 2016 December 16 and 20, over a total time span of ∼310 ks. We report the discovery of a strong periodic modulation in the X-ray flux with a pulse period of 31.6 s and a very rapid spin-up, and confirm therefore that the compact object is a neutron star. We find that the spin period is changing from 31.71 s to 31.54 s over that period, with a spin-up rate of -5.56 × 10&lt;SUP&gt;-7&lt;/SUP&gt; s s&lt;SUP&gt;-1&lt;/SUP&gt;, likely the largest ever observed from an accreting neutron star. The spectrum is described by a power-law and a disc blackbody model, leading to a 0.3-30 keV unabsorbed luminosity of 4.7 × 10&lt;SUP&gt;39&lt;/SUP&gt; erg s&lt;SUP&gt;-1&lt;/SUP&gt;. Applying our best-fitting model successfully to the spectra of an XMM-Newton observation from 2010, suggests that the lower fluxes of NGC 300 ULX1 reported from observations around that time are caused by a large amount of absorption, while the intrinsic luminosity was similar as seen in 2016. A more constant luminosity level is also consistent with the long-term pulse period evolution approaching an equilibrium value asymptotically. We conclude that the source is another candidate for the new class of ultraluminous X-ray pulsars.</style></abstract></record></records></xml>