CANDELS Meets GSWLC: Evolution of the Relationship Between Morphology
  and Star Formation Since z = 2
  Galaxy morphology and its evolution over the cosmic epoch hold important
clues for understanding the regulation of star formation (SF). However,
studying the relationship between morphology and SF has been hindered by the
availability of consistent data at different redshifts. Our sample, combining
CANDELS (0.8 < z < 2.5) and the GALEX-SDSS-WISE Legacy Catalog (GSWLC; z ~ 0),
has physical parameters derived using consistent SED fitting with flexible dust
attenuation laws. We adopt visual classifications from Kartaltepe et al. 2015
and expand them to z ~ 0 using SDSS images matching the physical resolution of
CANDELS rest-frame optical images and deep FUV GALEX images matching the
physical resolution of the CANDELS rest-frame FUV images. Our main finding is
that disks with SF clumps at z ~ 0 make a similar fraction (~15%) of
star-forming galaxies as at z ~ 2. The clumpy disk contribution to the SF
budget peaks at z ~ 1, rather than z ~ 2, suggesting that the principal epoch
of disk assembly continues to lower redshifts. Star-forming spheroids ("blue
nuggets"), though less centrally concentrated than quenched spheroids,
contribute significantly (~15%) to the SF budget at z ~ 1-2, suggesting that
compaction precedes quenching. Among green valley and quiescent galaxies, the
pure spheroid fraction drops since z ~ 1, whereas spheroids with disks
(S0-like) become dominant. Mergers at or nearing coalescence are enhanced in
SFR relative to the main sequence at all redshifts by a factor of ~2, but
contribute $\lesssim$5% to the SF budget, with their contribution remaining
small above the main sequence.
