X-ray emission from star-forming galaxies - III. Calibration of the Lx-SFR relation up to redshift z$\simeq$1.3. (arXiv:1207.2157v1 [astro-ph.HE])

X-ray emission from star-forming galaxies - III. Calibration of the Lx-SFR relation up to redshift z$\simeq$1.3. (arXiv:1207.2157v1 [astro-ph.HE]):
We investigate the relation between total X-ray emission from star-forming
galaxies and their star formation activity. Using nearby late-type galaxies and
ULIRGs from Paper I and star-forming galaxies from Chandra Deep Fields, we
construct a sample of 54 galaxies spanning the redshift range z\approx0-1.3 and
the SFR range ~0.1-10^{3} Msun/yr. In agreement with previous results, we find
that the Lx-SFR relation is consistent with a linear law both at z=0 and for
the z=0.1-1.3 CDF galaxies, within the statistical accuracy of ~0.1 in the
slope of the Lx-SFR relation. For the total sample, we find a linear scaling
relation Lx/SFR\approx(3.5\pm0.4)\times10^{39}(erg/s)/(Msun/yr), with a scatter
of \approx0.4 dex. About ~3/4 of the 0.5-8 keV luminosity generated per unit
SFR is provided by HMXBs. We find no statistically significant trends in the
Lx/SFR ratio with the redshift or star formation rate and constrain the
amplitude of its variations by \lesssim0.1-0.2 dex. These properties make X-ray
observations a powerful tool to measure the star formation rate in normal
star-forming galaxies that dominate the source counts at faint fluxes.