A CHANDRA PERSPECTIVE ON GALAXY-WIDE X-RAY BINARY EMISSION AND ITS CORRELATION WITH STAR FORMATION RATE AND STELLAR MASS: NEW RESULTS FROM LUMINOUS INFRARED GALAXIES

We present new Chandra observations that complete a sample of seventeen (17) luminous infrared galaxies (LIRGs) with D < 60 Mpc and low Galactic column densities of N-H less than or similar to 5 x 10(20) cm(-2). The LIRGs in our sample have total infrared (8-1000 mu m) luminosities in the range of L-IR approximate to (1-8) x 10(11) L-circle dot. The high-resolution imaging and X-ray spectral information from our Chandra observations allow us to measure separately X-ray contributions from active galactic nuclei and normal galaxy processes (e. g., X-ray binaries and hot gas). We utilized total infrared plus UV luminosities to estimate star formation rates (SFRs) and K-band luminosities and optical colors to estimate stellar masses (M-star) for the sample. Under the assumption that the galaxy-wide 2-10 keV luminosity (L-HX(gal)) traces the combined emission from high-mass X-ray binaries (HMXBs) and low-mass X-ray binaries, and that the power output from these components is linearly correlated with SFR and M-star, respectively, we constrain the relation L-HX(gal) = alpha M-star + beta SFR. To achieve this, we construct a Chandra-based data set composed of our new LIRG sample combined with additional samples of less actively star-forming normal galaxies and more powerful LIRGs and ultraluminous infrared galaxies (ULIRGs) from the literature. Using these data, we measure best-fit values of alpha = (9.05 +/- 0.37) x 10(28) erg s(-1) M-circle dot(-1) and beta = (1.62 +/- 0.22) x 10(39) erg s(-1) (M-circle dot yr(-1))(-1). This scaling provides a more physically meaningful estimate of L-HX(gal), with approximate to 0.1-0.2 dex less scatter, than a direct linear scaling with SFR. Our results suggest that HMXBs dominate the galaxy-wide X-ray emission for galaxies with SFR/M-star greater than or similar to 5.9 x 10(-11) yr(-1), a factor of approximate to 2.9 times lower than previous estimates. We find that several of the most powerful LIRGs and ULIRGs, with SFR/M-star greater than or similar to 10(-9) yr(-1), appear to be X-ray underluminous with respect to our best-fit relation. We argue that these galaxies are likely to contain X-ray binaries residing in compact star-forming regions that are buried under thick galactic columns large enough to attenuate emission in the 2-10 keV band (N-H greater than or similar to 10(23) cm(-2)).