On the Characterization of Ultraluminous X-ray Sources
- Paper number
IAC-06-A3.1.09
- Author
Ms. Diane Wong, University of California at Berkeley, United States
- Year
2006
- 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, ultraluminous X-ray sources, ULXs.
ULXs are non-nuclear point X-ray sources with X-ray luminosities intermediate between those of stellar mass black holes and supermassive black holes.
ULXs 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 ULX 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 ULXs 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 ULXs 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.)
This is a large-scale optical follow-up project of ULXs. 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-ULX connection.
- Abstract document