The shape and scatter of the galaxy main sequence for massive galaxies at cosmic noon

Sydney Sherman, Shardha Jogee, Jonathan Florez, Steven L. Finkelstein, Robin Ciardullo, Isak Wold, Matthew L. Stevans, Lalitwadee Kawinwanichakij, Casey Papovich, Caryl Gronwall

Research output: Contribution to journalArticlepeer-review

Abstract

We present the main sequence for all galaxies and star-forming galaxies for a sample of 28 469 massive (M∗ ≥ 1011 M⊙) galaxies at cosmic noon (1.5 < z < 3.0), uniformly selected from a 17.5 deg2 area (0.33 Gpc3 comoving volume at these redshifts). Our large sample allows for a novel approach to investigating the galaxy main sequence that has not been accessible to previous studies. We measure the main sequence in small mass bins in the SFR-M∗ plane without assuming a functional form for the main sequence. With a large sample of galaxies in each mass bin, we isolate star-forming galaxies by locating the transition between the star-forming and green valley populations in the SFR-M∗ plane. This approach eliminates the need for arbitrarily defined fixed cutoffs when isolating the star-forming galaxy population, which often biases measurements of the scatter around the star-forming galaxy main sequence. We find that the main sequence for all galaxies becomes increasingly flat towards present day at the high-mass end, while the star-forming galaxy main sequence does not. We attribute this difference to the increasing fraction of the collective green valley and quiescent galaxy population from z = 3.0 to z = 1.5. Additionally, we measure the total scatter around the star-forming galaxy main sequence and find that it is ~0.5-1.0 dex with little evolution as a function of mass or redshift. We discuss the implications that these results have for pinpointing the physical processes driving massive galaxy evolution.

Original languageEnglish (US)
Pages (from-to)947-962
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume505
Issue number1
DOIs
StatePublished - Jul 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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