Revealing jet radio emission from intermediate-mass black holes
Abstract
Relativistic jets were first discovered in the nuclei of galaxies. The later finding of collimated jets arising from the compact counterpart of X-ray binaries suggested that jets should be present not only in supermassive and stellar-mass black holes (BHs), but also in intermediate-mass BHs (IMBHs). According to evolutionary models of BH growth, IMBHs are the initial seed of supermassive BHs, which subsequently grow either through hierarchical BH merging or gas accretion. IMBHs with masses up to 1000 Msun could be formed from very young and massive stars via super-Eddington accretion or from the core collapse of young and massive stars, while < 1E6 Msun BHs could result from the direct collapse of pre-galactic gas discs. These processes should have left a population of IMBHs in the haloes of galaxies, where the presence of wandering BHs is also expected after tidal stripping of merging satellite galaxies. The most probable IMBH candidates are the most extreme ultraluminous X-ray sources (ULXs), whose X-ray luminosities in excess of 5E40 erg/s can difficulty be explained by stellar evolution models or super-Eddington accretion. However, observational evidence of IMBHs is scarce and no steady jet emission has ever been detected in an IMBH. I will present the results of a program aimed at studying radio emission in ULXs and clarifying the nature of these sources. The radio observations reveal compact radio emission from two ULXs, which become potential IMBH candidates, as well as the first detection of possible steady jet emission from an IMBH. With a total size of ~600 pc, this source could be the largest non-nuclear extragalactic jet ever discovered.
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E2083M