GOODS-ALMA 2.0: Starbursts in the main sequence reveal compact star
  formation regulating galaxy evolution prequenching
  Compact star formation appears to be generally common in dusty star-forming
galaxies (SFGs). However, its role in the framework set by the scaling
relations in galaxy evolution remains to be understood. In this work we follow
up on the galaxy sample from the GOODS-ALMA 2.0 survey, an ALMA blind survey at
1.1mm covering a continuous area of 72.42arcmin$^2$ using two array
configurations. We derived physical properties, such as star formation rates,
gas fractions, depletion timescales, and dust temperatures for the galaxy
sample built from the survey. There exists a subset of galaxies that exhibit
starburst-like short depletion timescales, but they are located within the
scatter of the so-called main sequence of SFGs. These are dubbed starbursts in
the main sequence and display the most compact star formation and they are
characterized by the shortest depletion timescales, lowest gas fractions, and
highest dust temperatures of the galaxy sample, compared to typical SFGs at the
same stellar mass and redshift. They are also very massive, accounting for
$\sim 60\%$ of the most massive galaxies in the sample ($\log
(M_{\rm{*}}/M_{\odot}) > 11.0$). We find trends between the areas of the
ongoing star formation regions and the derived physical properties for the
sample, unveiling the role of compact star formation as a physical driver of
these properties. Starbursts in the main sequence appear to be the extreme
cases of these trends. We discuss possible scenarios of galaxy evolution to
explain the results drawn from our galaxy sample. Our findings suggest that the
star formation rate is sustained in SFGs by gas and star formation compression,
keeping them within the main sequence even when their gas fractions are low and
they are presumably on the way to quiescence.
