Galaxy population constraints on cosmology and star formation in the early Universe

• We present the first post-cosmic-microwave-background early-Universe observational constraints on $\textbackslashsigma_8$, $\textbackslashOmega_\textbackslashrm m$, mean galaxy star-forming efficiency and galaxy UV magnitude scatter at redshifts $z = 4-10$. We perform a simultaneous 11-parameter cosmology and star-formation physics fit using the new code GalaxyMC, with redshift $z\textgreater4$ galaxy UV luminosity and correlation function data. Consistent with previous studies, we find evidence for redshift-independent star formation physics, regulated by halo assembly. For a flat $\textbackslashLambda$CDM universe with a low-redshift Hubble constant and a Type Ia supernovae $\textbackslashOmega_\textbackslashrm m$ prior, we constrain $\textbackslashsigma_8 = 0.81 \textbackslashpm 0.03$, and a mean star-forming efficiency peaking at $\textbackslashlog_10 \textbackslashrm SFE = -[(0.09 \textbackslashpm 0.20) + (0.58 \textbackslashpm 0.29) \textbackslashtimes \textbackslashlog_10 (1+z)]$ for halo mass $\textbackslashlog_10 M_\textbackslashrm p / h⌃-1 M_\textbackslashodot = 11.48 \textbackslashpm 0.09$. The suppression of star formation due to feedback is given by a double power law in halo mass with indices $\textbackslashalpha = 0.56 \textbackslashpm 0.08, \textbackslashbeta = -1.03 \textbackslashpm 0.07$. The scatter in galaxy UV magnitude for fixed halo mass is $\textbackslashsigma_M = 0.56 \textbackslashpm 0.08$. Without a prior on $\textbackslashOmega_\textbackslashrm m$ we obtain $\textbackslashsigma_8 = 0.78 \textbackslashpm 0.06$, $\textbackslashOmega_\textbackslashrm m = 0.33 \textbackslashpm 0.07$ and at most $1\textbackslashsigma$ differences in all other parameter values. Our best-fit galaxy luminosity functions yield a reionization optical depth $\textbackslashtau \textbackslashapprox 0.048$, consistent with the Planck 2018 value.

Subject headings

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Keyword

Astrophysics - Cosmology and Nongalactic Astrophysics

Astrophysics - Astrophysics of Galaxies

Publication and Content Type

ref (subject category)

art (subject category)