2017/05/02 by Rhythm Shimakawa, Shimakawa, Rhythm, Yusei Koyama +9
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.1705.01127
openalex publication_date 2017/05/02 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28
Because the timescale of Hα emission (several tens of Myr) following star formation is significantly shorter than that of UV radiation (a few hundred Myr), the Hα/UV flux ratio provides insight on the star formation histories (SFHs) of galaxies on timescales shorter than ∼100 Myr. We present Hα/UV ratios for galaxies at z= 0.02--0.1 on the familiar star-forming main sequence based on the AKARI-GALEX-SDSS archive dataset. The data provide us with robust measurements of dust-corrected SFRs in both Hα and UV for 1,050 galaxies. The results show a correlation between the Hα/UV ratio and the deviation from the main sequence in the sense that galaxies above/below the main sequence tend to have higher/lower Hα/UV ratios. This trend increases the dispersion of the main sequence by 0.04 dex (a small fraction of the total scatter of 0.36 dex), suggesting that diversity of recent SFHs of galaxies has a direct impact on the observed main sequence scatter. We caution that the results suffer from incompleteness and a selection bias which may lead us to miss many sources with high Hα/UV ratios, this could further increase the scatter from SFHs in the star-forming main sequence.