A New Census of the 0.2 < z < 3.0 Universe, Part I: The Stellar Mass Function. (arXiv:1910.04168v1 [astro-ph.GA])

A New Census of the 0.2 < z < 3.0 Universe, Part I: The Stellar Mass Function. (arXiv:1910.04168v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Leja_J/0/1/0/all/0/1">Joel Leja</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Speagle_J/0/1/0/all/0/1">Joshua S. Speagle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnson_B/0/1/0/all/0/1">Benjamin D. Johnson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Conroy_C/0/1/0/all/0/1">Charlie Conroy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dokkum_P/0/1/0/all/0/1">Pieter van Dokkum</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Franx_M/0/1/0/all/0/1">Marijn Franx</a>

There has been a long-standing factor-of-two tension between the observed
star formation rate density and the observed stellar mass buildup after
$zsim2$. Recently we have proposed that sophisticated panchromatic SED models
can resolve this tension, as these methods infer systematically higher masses
and lower star formation rates than standard approaches. In a series of papers
we now extend this analysis and present a complete, self-consistent census of
galaxy formation over $0.2 < z < 3$ inferred with the texttt{Prospector} galaxy SED-fitting code. In this work, Paper I, we present the evolution of the galaxy stellar mass function using new mass measurements of $sim$10$^5$ galaxies in the 3D-HST and COSMOS-2015 surveys. We employ a new methodology to infer the mass function from the observed stellar masses: instead of fitting independent mass functions in a series of fixed redshift intervals, we construct a continuity model that directly fits for the redshift evolution of the mass function. This approach ensures a smooth picture of galaxy assembly and makes use of the full, non-Gaussian uncertainty contours in our stellar mass inferences. The resulting mass function has higher number densities at a fixed stellar mass than almost any other measurement in the literature, largely owing to the older stellar ages inferred by texttt{Prospector}. The stellar mass density is $sim$50% higher than previous measurements, with the offset peaking at $zsim1$. The next two papers in this series will present the new measurements of star-forming main sequence and the cosmic star formation rate density, respectively.

There has been a long-standing factor-of-two tension between the observed
star formation rate density and the observed stellar mass buildup after
$zsim2$. Recently we have proposed that sophisticated panchromatic SED models
can resolve this tension, as these methods infer systematically higher masses
and lower star formation rates than standard approaches. In a series of papers
we now extend this analysis and present a complete, self-consistent census of
galaxy formation over $0.2 < z < 3$ inferred with the texttt{Prospector}
galaxy SED-fitting code. In this work, Paper I, we present the evolution of the
galaxy stellar mass function using new mass measurements of $sim$10$^5$
galaxies in the 3D-HST and COSMOS-2015 surveys. We employ a new methodology to
infer the mass function from the observed stellar masses: instead of fitting
independent mass functions in a series of fixed redshift intervals, we
construct a continuity model that directly fits for the redshift evolution of
the mass function. This approach ensures a smooth picture of galaxy assembly
and makes use of the full, non-Gaussian uncertainty contours in our stellar
mass inferences. The resulting mass function has higher number densities at a
fixed stellar mass than almost any other measurement in the literature, largely
owing to the older stellar ages inferred by texttt{Prospector}. The stellar
mass density is $sim$50% higher than previous measurements, with the offset
peaking at $zsim1$. The next two papers in this series will present the new
measurements of star-forming main sequence and the cosmic star formation rate
density, respectively.

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