Ultraluminous X-ray Sources in Extremely Metal Deficient Galaxies
Abstract
Theoretical considerations suggest that Ultra-Luminous X-ray sources (ULXs) preferentially form in star-forming, metal-poor galaxies. The correlation between the number of ULXs (N_ULX}) and the Star Formation Rate (SFR) of a galaxy is indeed very robust; instead, the evidence about metallicity is weaker. Here we look at a sample of 22 newly observed extremely metal-deficient galaxies (with metallicity ≤ 1/20 of the solar value), and find that both the ratios N_ULX/SFR and L_X/SFR (where L_X is the total X-ray luminosity of sources in the sample) are higher than what is found in samples of galaxies of higher metallicity.
- Publication:
-
Massive Young Star Clusters Near and Far: From the Milky Way to Reionization
- Pub Date:
- September 2014
- Bibcode:
- 2014mysc.conf..181R