Young Crab-like Pulsars and Luminous X-Ray Sources in Starbursts and Optically Dull Galaxies
Abstract
Recent Chandra observations of nearby galaxies have revealed a number of ultraluminous X-ray sources (ULXs) with super-Eddington luminosities, away from the central regions of nonactive galaxies. The nature of these sources is still debated. We argue that a fraction of them could be young, Crab-like pulsars, the X-ray luminosity of which is powered by rotation. We use the pulsar birth parameters estimated from radio pulsar data to compute the steady state pulsar X-ray luminosity distribution as a function of the star formation rate (SFR) in the galaxy. We find that ~10% of optically dull galaxies are expected to have a source with LX>~1039 ergs s-1, while starburst galaxies should each have several of these sources. We estimate that the X-ray luminosity of a few percent of galaxies is dominated by a single bright pulsar with LX>~1039 ergs s-1, roughly independently of its SFR. We discuss observational diagnostics that can help distinguish the young pulsar population in ULXs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2004
- DOI:
- 10.1086/423950
- arXiv:
- arXiv:astro-ph/0407180
- Bibcode:
- 2004ApJ...615..222P
- Keywords:
-
- Galaxies: Starburst;
- Stars: Neutron;
- X-Rays: Galaxies;
- X-Rays: Stars;
- Astrophysics
- E-Print:
- 17 pages, 4 figures, accepted to ApJ