Keck Spectroscopy of IXOs
Diane Wong
University of California, Berkeley
dianew@astro.berkeley.edu
Additional authors: Diane Sonya Wong, Alex Filippenko, Ryan Chornock
Intermediate-luminosity X-ray objects (IXOs) are non-nuclear point X-ray sources with X-ray luminosities L_x = 10^39-10^41 erg/s. Much interest in them has been generated of late due to the advent of Chandra, and on the theoretical front, viable mechanisms of creating the new class of intermediate-mass black holes (IMBH, 10-1000 solar masses) that must be necessary if accretion onto these IXOs is to obey the Eddington limit. Radio observations have been used successfully on the IXO NGC 5204 X-1, to rule out some of the known candidates for explaining the IXO phenomenon (Wong et al. 2004). However, the multiwavelength approach to deciphering IXOs has been under-utilized until now. We present our latest results in a long-term multi-wavelength IXO project. Using Keck optical spectroscopy, we have identified several of the IXOs from the Colbert & Ptak (2002) catalog to be background QSOs in elliptical galaxies and discuss this in terms of the spiral galaxy-IXO connection.
