Wolf, C. (2008) 'Tracing the mass-dependent star formation history of late-type galaxies using X-ray emission : results from the Chandra Deep Fields.', Astrophysical journal., 681 (2). pp. 1163-1182. Further information on publisher's website:
Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT We report on the X-ray evolution over the last %9 Gyr of cosmic history (i.e., since z ¼ 1:4) of late-type galaxy populations in the Chandra Deep FieldYNorth and Extended Chandra Deep FieldYSouth (CDF-N and E-CDF-S, respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies, which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei (AGNs). Over this redshift range, we find significant increases (factors of %5Y10) in the X-rayYtoYoptical mean luminosity ratio (L X /L B ) and the X-rayYtoYstellar mass mean ratio (L X /M ? ) for galaxy populations selected by L B and M ? , respectively. When analyzing galaxy samples selected via SFR, we find that the mean X-rayYtoYSFR ratio (L X /SFR) is consistent with being constant over the entire redshift range for galaxies with SFR = 1Y100 M yr À1 , thus demonstrating that X-ray emission can be used as a robust indicator of star formation activity out to z % 1:4. We find that the star formation activity (as traced by X-ray luminosity) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range z = 0.2Y1, which is consistent with previous studies of how star formation activity depends on stellar mass. Finally, we extend our X-ray analyses to Lyman break galaxies at z $ 3 and estimate that L X /L B at z $ 3 is similar to its value at z ¼ 1:4.