2011/03/31 by Zhao-Yu Zuo, Xiang-Dong Li · 7 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #COSMIC cancer database #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Luminosity #Population #Star formation #Stellar evolution #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/733/1/5
published in The Astrophysical Journal 733(1), 5 (IOP Publishing) · 8 figures, 1 table, accepted for publication in the Astrophysical Journal, now available at http://stacks.iop.org/0004-637X/733/5
openalex publication_date 2011/04/27 · arxiv created 2011/04/29 · arxiv updated 2015/05/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
X-ray studies of normal late-type galaxies have shown that non-nuclear X-ray emission is typically dominated by X-ray binaries and provides a useful measure of star formation activity. We have modeled the X-ray evolution of late-type galaxies over the ∼14 Gyr of cosmic history, with an evolutionary population synthesis code developed by Hurley et al. Our calculations reveal a decrease in the X-ray luminosity-to-mass ratio L X / M with time, in agreement with observations. We show that this decrease is a natural consequence of stellar and binary evolution and the mass accumulating process in galaxies. The X-ray-to-optical luminosity ratio L X / L B is found to be fairly constant (around ∼10 30 erg s −1 L −1 B,☉ ) and insensitive to the star formation history in the galaxies. The nearly constant value of L X / L B is in conflict with the observed increase in L X / L B from z = 0 to 1.4. The discrepancy may be caused by intense obscured star formation activity that leads to a nonlinear relationship between X-ray and B -band emission.