AAS 197, January 2001
Session 118. Binary Systems with Black Holes and Neutron Stars
Oral, Thursday, January 11, 2001, 10:30am-12:00noon, Towm and Country

## [118.01] The Microquasar GRS 1758-258 as Seen by Chandra

W.A. Heindl (UCSD/CASS), D.M. Smith (UCB/SSL)

GRS~1758-258 and its sister source 1E~1740.7-2942 were the first objects dubbed micro-quasars''. Their X-ray spectra are typical of Galactic black hole candidates, and they are apparently associated with time variable cores of double-lobed radio sources, reminiscent of extra-galactic radio sources. This morphology, seen on a parsec scale within the Milky Way, earned them their nickname. Unlike the Galactic \emph{superluminal} radio sources GRS~1915+105 and GRO~J1655-40 more typically thought of as micro-quasars, the GRS~1758-258 and 1E~1740.7-2942 radio lobes are quite stable. This raises the possibility that the X-ray/radio source association is by chance. We have made two \emph{Chandra}/HRC-I observations of GRS~1758-258 for the purposes of: (1) confirming the identification of the X-ray source with the time variable radio source, and (2) searching for arcsecond scale X-ray jets which are presumably the source of relativistic particles powering the radio lobes. First results from these observations are reported.