Kavli Affiliate: Roberto Maiolino
| First 5 Authors: A. Lola Danhaive, Sandro Tacchella, Hannah Übler, Anna de Graaff, Eiichi Egami
| Summary:
Recent studies of gas kinematics at high redshift have reported disky systems
which appear to challenge models of galaxy formation, but it is unclear whether
they are representative of the underlying galaxy population. We present the
first statistical sample of spatially resolved ionised gas kinematics at high
redshift, comprised of $272$ H$alpha$ emitters in GOODS-S and GOODS-N at
redshifts $zapprox3.9-6.5$, observed with JWST/NIRCam slitless spectroscopy
and imaging from JADES, FRESCO and CONGRESS. The sample probes two orders of
magnitude in stellar mass ($log (M_{star}[mathrm{M}_{odot}])approx8-10$)
and star formation rate ($text{SFR}approx0.3-100thinspace M_{odot}/$yr),
and is representative down to $log(M_{star}[mathrm{M}_{odot}])approx 9$.
Using a novel inference tool, $texttt{geko}$, we model the grism data to
measure morphological and kinematic properties of the ionised gas, as probed by
H$alpha$. Our results are consistent with a decrease of the rotational support
$v/sigma_0$ and increase of the velocity dispersion $sigma_0$ with redshift,
with $sigma_0approx100$ km/s and $v/sigma_0approx1-2$ at $zapprox3.9-6.5$.
We study the relations between $sigma_0$, and $v/sigma_0$, and different star
formation tracers and find a large scatter and diversity, with the strongest
correlations between $sigma_0$ and SFR and SFR surface density. The fraction
of rotationally supported systems ($v/sigma_0>1$) slightly increases with
cosmic time, from $(36pm6)%$ to $(41pm6)%$ from $zsim 5.5$ to $zsim 4.5$,
for galaxies with masses $9<log(M_{star}[mathrm{M}_{odot}])<10$. Overall,
disks do not dominate the turbulent high-redshift galaxy population in the mass
range probed by this work. When placed in the context of studies up to cosmic
noon, our results are consistent with a significant increase of disk-like
systems with cosmic time.
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