ZFOURGE: Using Composite Spectral Energy Distributions to Characterize Galaxy Populations at 1 < z < 4 Academic Article uri icon

abstract

  • Abstract We investigate the properties of galaxies as they shut off star formation over the 4 billion years surrounding peak cosmic star formation. To do this, we categorize 7000 galaxies from 1<z<4 into 90 groups based on the shape of their spectral energy distributions (SEDs) and build composite SEDs with R50 resolution. These composite SEDs show a variety of spectral shapes and also show trends in parameters such as color, mass, star formation rate, and emission-line equivalent width. Using emission-line equivalent widths and strength of the 4000 break, , we categorize the composite SEDs into five classes: extreme emission line, star-forming, transitioning, post-starburst, and quiescent galaxies. The transitioning population of galaxies shows modest H emission (EWREST40 ) compared to more typical star-forming composite SEDs at log10(M/M )10.5 (EWREST80 ). Together with their smaller sizes (3 kpc vs. 4 kpc) and higher Srsic indices (2.7 vs. 1.5), this indicates that morphological changes initiate before the cessation of star formation. The transitional group shows a strong increase of over 1 dex in number density from z3 to z1, similar to the growth in the quiescent population, while post-starburst galaxies become rarer at z1.5. We calculate average quenching timescales of 1.6 Gyr at z1.5 and 0.9 Gyr at z2.5 and conclude that a fast-quenching mechanism producing post-starbursts dominated the quenching of galaxies at early times, while a slower process has become more common since z2.

published proceedings

  • ASTROPHYSICAL JOURNAL

altmetric score

  • 8.08

author list (cited authors)

  • Forrest, B., Tran, K., Broussard, A., Cohn, J. H., Kennicutt, R., Papovich, C., ... Straatman, C.

citation count

  • 31

complete list of authors

  • Forrest, Ben||Tran, Kim-Vy H||Broussard, Adam||Cohn, Jonathan H||Kennicutt, Robert C Jr||Papovich, Casey||Allen, Rebecca||Cowley, Michael||Glazebrook, Karl||Kacprzak, Glenn G||Kawinwanichakij, Lalitwadee||Nanayakkara, Themiya||Salmon, Brett||Spitler, Lee R||Straatman, Caroline MS

publication date

  • August 2018