NGC 300 ULX1 is a newly identified ultra-luminous X-ray pulsar. The system is associated with the supernova impostor SN 2010da that was later classified as a possible supergiant Be X-ray binary. In this work we report on the spin period evolution of the neutron star based on all the currently available X-ray observations of the system. We argue that the X-ray luminosity of the system has remained almost constant since 2010, at a level above ten times the Eddington limit. Moreover, we find evidence that the spin period of the neutron star evolved from ~126 s down to ~18 s within a period of about 4 years. We explain this unprecedented spin evolution in terms of the standard accretion torque theory. An intriguing consequence for NGC 300 ULX1 is that a neutron star spin reversal should have occurred a few years after the SN 2010da event.
@article{arxiv.1811.11907,
title = {NGC 300 ULX1: A test case for accretion torque theory},
author = {Georgios Vasilopoulos and Frank Haberl and Stefania Carpano and Chandreyee Maitra},
journal= {arXiv preprint arXiv:1811.11907},
year = {2018}
}
Comments
10 pages with appendix, 9 figures, accepted to A&A Letters