Atomic Gas Dominates the Baryonic Mass of Star-forming Galaxies at $z approx 1.3$. (arXiv:2207.08834v3 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Chowdhury_A/0/1/0/all/0/1">Aditya Chowdhury</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kanekar_N/0/1/0/all/0/1">Nissim Kanekar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chengalur_J/0/1/0/all/0/1">Jayaram N. Chengalur</a>

We present a comparison between the average atomic gas mass, $langle
M_{Atom}rangle$ (including HI and He), the average molecular gas mass,
$langle M_{Mol}rangle$, and the average stellar mass, $langle M_*rangle$,
of a sample of star-forming galaxies at $zapprox0.75-1.45$, to probe the
baryonic composition of galaxies in and during the epoch of peak star-formation
activity in the universe. The $langle M_{Atom}rangle$ values of star-forming
galaxies in two stellar-mass matched samples at $z=0.74-1.25$ and
$z=1.25-1.45$, were derived by stacking their HI 21cm signals in the
GMRT-CAT$z1$ survey. We find that the baryonic composition of star-forming
galaxies at $zgtrsim 1$ is dramatically different from that at $zapprox0$.
For star-forming galaxies with $langle M_*rangleapprox10^{10} M_odot$, the
contribution of stars to the total baryonic mass, $M_{Baryon}$, is
$approx61%$ at $zapprox0$, but only $approx16%$ at $zapprox1.3$, while
molecular gas constitutes $approx6%$ of the baryonic mass at $zapprox0$, and
$approx14%$ at $zapprox1.3$. Remarkably, we find that atomic gas makes up
$approx70%$ of $M_{Baryon}$ in star-forming galaxies at $zapprox1.3$. We
find that the ratio $langle M_{Atom}rangle/langle M_*rangle$ is higher both
at $zapprox1.0$ and at $zapprox1.3$ than in the local Universe, with $langle
M_{Atom}rangle/langle M_*rangleapprox1.4$ at $zapprox1.0$, and
$approx4.4$ at $zapprox1.3$, compared to its value of $approx0.5$ today.
Further, we find that the ratio $langle M_{Atom}rangle/langle
M_{Mol}rangle$ in star-forming galaxies with $langle M_*rangle
approx10^{10} M_odot$ is $approx2.3$ at $zapprox1.0$ and $approx5.0$ at
$zapprox1.3$. Overall, we find that atomic gas is the dominant component of
the baryonic mass of star-forming galaxies at $zapprox1.3$, during the epoch
of peak star-formation activity in the universe.

We present a comparison between the average atomic gas mass, $langle
M_{Atom}rangle$ (including HI and He), the average molecular gas mass,
$langle M_{Mol}rangle$, and the average stellar mass, $langle M_*rangle$,
of a sample of star-forming galaxies at $zapprox0.75-1.45$, to probe the
baryonic composition of galaxies in and during the epoch of peak star-formation
activity in the universe. The $langle M_{Atom}rangle$ values of star-forming
galaxies in two stellar-mass matched samples at $z=0.74-1.25$ and
$z=1.25-1.45$, were derived by stacking their HI 21cm signals in the
GMRT-CAT$z1$ survey. We find that the baryonic composition of star-forming
galaxies at $zgtrsim 1$ is dramatically different from that at $zapprox0$.
For star-forming galaxies with $langle M_*rangleapprox10^{10} M_odot$, the
contribution of stars to the total baryonic mass, $M_{Baryon}$, is
$approx61%$ at $zapprox0$, but only $approx16%$ at $zapprox1.3$, while
molecular gas constitutes $approx6%$ of the baryonic mass at $zapprox0$, and
$approx14%$ at $zapprox1.3$. Remarkably, we find that atomic gas makes up
$approx70%$ of $M_{Baryon}$ in star-forming galaxies at $zapprox1.3$. We
find that the ratio $langle M_{Atom}rangle/langle M_*rangle$ is higher both
at $zapprox1.0$ and at $zapprox1.3$ than in the local Universe, with $langle
M_{Atom}rangle/langle M_*rangleapprox1.4$ at $zapprox1.0$, and
$approx4.4$ at $zapprox1.3$, compared to its value of $approx0.5$ today.
Further, we find that the ratio $langle M_{Atom}rangle/langle
M_{Mol}rangle$ in star-forming galaxies with $langle M_*rangle
approx10^{10} M_odot$ is $approx2.3$ at $zapprox1.0$ and $approx5.0$ at
$zapprox1.3$. Overall, we find that atomic gas is the dominant component of
the baryonic mass of star-forming galaxies at $zapprox1.3$, during the epoch
of peak star-formation activity in the universe.

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