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[15.03] Using Chandra to Resolve the X-ray Emission in the Sa Galaxy NGC1291

J. A. Irwin (University of Michigan), C. L. Sarazin (University of Virginia), J. N. Bregman (University of Michigan)

Previous X-ray observations of Sa bulges revealed several similarities with a sub-group of elliptical and S0 galaxies that were very X-ray faint for their optical luminosities, including their X-ray-to-optical ratio (L_X/L_B) and X-ray colors. In addition, the X-ray emission seemed to fill the hole in the HI disk around the galaxy, indicating a possible anti-correlation between the hot and cold phases of the gas. Here, we present deep Chandra ACIS-S observations of the bulge-dominated Sa galaxy NGC1291. Much like the Chandra observation of the X-ray faint elliptical galaxy NGC4697, our Chandra observation of NGC1291 reveals that a majority of the X-ray emission is resolved into discrete point sources down to a limiting luminosity of about 2 X 10³⁷ ergs s^-1, most likely low-mass X-ray binaries, although some of the emission is truly diffuse. We discuss the implications of the paucity of interstellar gas in this system, as well as the luminosity distribution function of the X-ray binaries.

J.A.I. was supported by Chandra Fellowship Grant PF9-10009