| Popis: |
Using a compilation of 20 papers published since 2007, we investigate the evolution of the star-forming galaxy (SFG) Main Sequence (MS) out to z ~ 6 (age ~ 0.9 Gyr). These data encompass star formation rate (SFR) indicators from 1.4 GHz – UV, many MS galaxy selection methods, and both direct-detection and stacked data. After converting all observations to a common Kroupa initial mass function (IMF), we find a remarkable consensus among MS observations across all SFR indicators, which further improves once biases from selection methods are accounted for. We fit robust functional forms for the MS as a function of time using the observed mass ranges in each sample to account for evolving MS mass distributions and observational limits, and find that in all cases the MS slope is not constant in time. Using these fits, we are able to deconvolve the observed scatter about the MS within the observed redshift bins. After accounting for scatter between different SFR indicators, we find the width of the distribution may be as small as ~ .2 dex and remains constant over time, consistent with the scatter we observe between publications. We use empirical evolutionary tracks in order to constrain galaxy star formation histories, and show that scatter in the MS can easily be generated via differential evolutionary tracks. |
