A search for new Galactic microquasars

Abstract

A complete sample of bright ROSAT sources with hard XRB-like spectra in the Galactic Plane (|b| < 15 deg.) has been tentatively identified with radio sources in the GB6/PMN/NVSS surveys, and subsequently observed with the Australia Telescope Compact Array and the Very Large Array. Most of them are unresolved at the sub-arcsec scale and have flat or inverted spectra. Precise radio coordinates have made unambiguous optical identifications possible, which, after the removal of galaxies, yielded a final list of 40 microquasar candidates. They are successfully going through the moderate dispersion spectroscopy by the 4-m telescope of the Anglo-Australian Observatory. Our goal is to obtain evidence for a characteristic accreting behaviour and establish binarity, thence permitting actual microquasar classification. VLBI observations of the brightest candidates are also underway. We expect some of these objects could be QSOs, or radio galaxies, or cataclysmic variables. However, this would be a valuable by-product of the proposed program. Photometry of these objects dedicated to find possible eclipses and, also, characteristic accreting disc driven flares.