DR. VIKRAM RANA

The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (6 - 80 keV) telescope to orbit. NuSTAR will offer a factor 50 – 100 sensitivity improvement compared to previous collimated or coded mask imagers that have operated in this energy band. In addition, NuSTAR provides sub-arcminute imaging with good spectral resolution over a 12-arcminute field of view. In this talk, the speaker will provide an overview of NuSTAR and its science goals. He will focus particularly on advances that can be made in understanding the nature of Ultraluminous X-ray sources (ULXs) by NuSTAR in partnership with XMM-Newton and Chandra. The bright X-ray emission from ULXs greatly exceeds the Eddington luminosity for a spherically accreting stellar-mass compact object, and understanding why this is so is one of the biggest mysteries in high energy astrophysics. Broadband X-ray spectroscopy from 1 – 60 keV holds a key for constraining the accretion physics in ULXs, and addressing the possibility that they harbor intermediate mass black holes.