The nebular properties of star-forming galaxies at intermediate redshift from the Large Early Galaxy Astrophysics Census. (arXiv:2201.02207v2 [astro-ph.GA] UPDATED)

The nebular properties of star-forming galaxies at intermediate redshift from the Large Early Galaxy Astrophysics Census. (arXiv:2201.02207v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Helton_J/0/1/0/all/0/1">Jakob M. Helton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Strom_A/0/1/0/all/0/1">Allison L. Strom</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Greene_J/0/1/0/all/0/1">Jenny E. Greene</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bezanson_R/0/1/0/all/0/1">Rachel Bezanson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beaton_R/0/1/0/all/0/1">Rachael Beaton</a>

We present a detailed study of the partial rest-optical
($lambda_{mathrm{obs}} approx 3600-5600,$r{A}) spectra of $N = 328$
star-forming galaxies at $0.6 < z < 1.0$ from the Large Early Galaxy
Astrophysics Census (LEGA-C). We compare this sample with low-redshift ($z sim
0$) galaxies from the Sloan Digital Sky Survey (SDSS), intermediate-redshift
($z sim 1.6$) galaxies from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS
Survey, and high-redshift ($z sim 2$) galaxies from the Keck Baryonic
Structure Survey (KBSS). At a lookback time of $6-8 mathrm{Gyr}$, galaxies
with stellar masses $mathrm{log}(mathrm{M_{ast}/M_{odot}}) > 10.25$ appear
remarkably similar to $z sim 0$ galaxies in terms of their nebular excitation,
as measured using $mathrm{[O,III]}lambda5008 / mathrm{H}beta$. There is
some evidence that $0.6 < z < 1.0$ galaxies with lower $mathrm{M_{ast}}$ have
higher $mathrm{[O,III]}lambda5008 / mathrm{H}beta$ than $z sim 0$
galaxies and are more similar to less evolved $z sim 1.6$ and $z sim 2$
galaxies, which are offset from the $z sim 0$ locus at all
$mathrm{M_{ast}}$. We explore the impact selection effects, contributions
from active galactic nuclei, and variations in physical conditions (ionization
parameter and gas-phase oxygen abundance) have on the apparent distribution of
$mathrm{[O,III]}lambda5008 / mathrm{H}beta$ and find somewhat higher
ionization and lower enrichment in $0.6 < z < 1.0$ galaxies with lower
$mathrm{M_{ast}}$ relative to $z sim 0$ galaxies. We use new near-infrared
spectroscopic observations of $N = 53$ LEGA-C galaxies to investigate other
probes of enrichment and excitation. Our analysis demonstrates the importance
of obtaining complete rest-optical spectra of galaxies in order to disentangle
these effects.

We present a detailed study of the partial rest-optical
($lambda_{mathrm{obs}} approx 3600-5600,$r{A}) spectra of $N = 328$
star-forming galaxies at $0.6 < z < 1.0$ from the Large Early Galaxy
Astrophysics Census (LEGA-C). We compare this sample with low-redshift ($z sim
0$) galaxies from the Sloan Digital Sky Survey (SDSS), intermediate-redshift
($z sim 1.6$) galaxies from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS
Survey, and high-redshift ($z sim 2$) galaxies from the Keck Baryonic
Structure Survey (KBSS). At a lookback time of $6-8 mathrm{Gyr}$, galaxies
with stellar masses $mathrm{log}(mathrm{M_{ast}/M_{odot}}) > 10.25$ appear
remarkably similar to $z sim 0$ galaxies in terms of their nebular excitation,
as measured using $mathrm{[O,III]}lambda5008 / mathrm{H}beta$. There is
some evidence that $0.6 < z < 1.0$ galaxies with lower $mathrm{M_{ast}}$ have
higher $mathrm{[O,III]}lambda5008 / mathrm{H}beta$ than $z sim 0$
galaxies and are more similar to less evolved $z sim 1.6$ and $z sim 2$
galaxies, which are offset from the $z sim 0$ locus at all
$mathrm{M_{ast}}$. We explore the impact selection effects, contributions
from active galactic nuclei, and variations in physical conditions (ionization
parameter and gas-phase oxygen abundance) have on the apparent distribution of
$mathrm{[O,III]}lambda5008 / mathrm{H}beta$ and find somewhat higher
ionization and lower enrichment in $0.6 < z < 1.0$ galaxies with lower
$mathrm{M_{ast}}$ relative to $z sim 0$ galaxies. We use new near-infrared
spectroscopic observations of $N = 53$ LEGA-C galaxies to investigate other
probes of enrichment and excitation. Our analysis demonstrates the importance
of obtaining complete rest-optical spectra of galaxies in order to disentangle
these effects.

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