On the Characterization of Intermediate-Luminosity X-ray Objects
- Paper number
IAC-05-A3.P.02
- Author
Ms. Diane Wong, University of California at Berkeley, United States
- Year
2005
- Abstract
The Chandra X-ray Observatory was launched in July 1999. Operating in the 0.1- 10 keV energy range, it has on board several instruments: AXAF CCD Imaging Spectrometer (ACIS), High Resolution Camera (HRC), High Energy Transmission Grating Spectrometer (HETGS) and Low Energy Transmission Grating Spectrometer (LETGS). ACIS has been instrumental in finding a new class of objects, intermediate- luminosity X-ray objects, IXOs.
IXOs – also called ultraluminous X-ray sources, ULXs – are non-nuclear point X-ray sources with X-ray luminosities intermediate between those of stellar mass black holes and supermassive black holes.
IXOs have generated much interest in the past ∼four years: As mentioned above, on the observational front, the advent of Chandra (better pointing and high spatial resolution (< 1 arcsec)) has allowed isolation of the IXO phenomenon. Also, theorists have proposed viable mechanisms of creating the new class of intermediate-mass black holes (100-1000 solar masses) that must be necessary if accretion onto these IXOs is to obey the Eddington limit.
The multi-wavelength approach to identifying intermediate-mass black holes has been under-utilized until now: I present the latest results in my ongoing multi-wavelength search for intermediate-mass black holes. Using Keck spectroscopy and analysis of the X-ray data, I have identified dozens of the IXOs from the Colbert & Ptak (2002) catalog. I have done astrometry to verify their optical counterparts. In addition, I have calculated their X-ray to optical flux ratios to compare with the ratios of known objects (such as the supermassive black holes in luminous active galactic nuclei.)
To my knowledge, this is the largest-scale optical follow-up of IXOs. Thus, I am able to discuss their statistical properties. Some are background active galactic nuclei in the fields of elliptical galaxies and I discuss this in terms of the spiral galaxy-IXO connection.
- Abstract document