Ann-Sofie Bak Nielsen – University of Copenhagen

16 February 2018

Ann-Sofie Bak Nielsen will give a lecture  March 6th at 14:00 in the lounge

A possible super-Eddington source

The zoo of pulsars spans multiple regimes of wavelength and configurations. Of those, X-ray pulsars are a class with many variations across the different systems. One of the more peculiar X-ray binaries is 2A 1822-371. This is a slow accreting X-ray pulsar which shows several peculiar properties. The pulsar is observed to spin-up continuously on a timescale of 7000 years, shorter than expected for these type of systems. The orbital period is expanding on an extremely short timescale that challenges current theories of binary evolution. Furthermore, the presence of a thick accretion disc corona poses a problem, since we observe X-ray pulsations which should have been smeared out by the Compton scattering of the accretion disk. A proposed solution to all of the above problems is that the system could be a super-Eddington source with a donor which is out of thermal equilibrium.