Super-Eddington driven winds in ultraluminous X-ray sources
Abstract
The detection of fully-grown supermassive black holes powering active galactic nuclei at high redshift, when the Universe was young, challenges the theories of black holes growth, requiring long periods of high accretion, most likely above the Eddington limit. This is a focus of the next generation large missions, such as ATHENA, but cannot be done with the current instrumentation due to the large distances. Therefore, we need to study objects accreting at high Eddington rates in the nearby Universe. Most ultraluminous X-ray sources (ULXs, luminosities above 10^{39}erg/s) show X-ray spectra that are consistent with stellar mass black holes or neutron stars accreting at or above Eddington and provide the best workbench to study super-Eddington accretion and fast growth rates. The detection of pulsations in a few ULXs confirms that some of them must be powered by neutron stars and support their compact nature and extreme accretion rates. It is not clear though how strong are their magnetic fields and what are their effects on the accretion discs. For instance, do magnetic fields inhibit radiation-pressure driven winds? In this talk I will discuss our recent discoveries of relativistic outflows in archetypal ULXs and the most recent results obtained with high-resolution X-ray spectroscopy of ultra-luminous X-ray pulsars.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2683P