TY - JOUR
T1 - The KMOS3DSurvey
T2 - Investigating the Origin of the Elevated Electron Densities in Star-forming Galaxies at 1 ≲ z ≲ 3
AU - Davies, Rebecca L.
AU - Schreiber, N. M.Förster
AU - Genzel, R.
AU - Shimizu, T. T.
AU - Davies, R. I.
AU - Schruba, A.
AU - Tacconi, L. J.
AU - Obler, H.
AU - Wisnioski, E.
AU - Wuyts, S.
AU - Fossati, M.
AU - Herrera-Camus, R.
AU - Lutz, D.
AU - Mendel, J. T.
AU - Naab, T.
AU - Price, S. H.
AU - Renzini, A.
AU - Wilman, D.
AU - Beifiori, A.
AU - Belli, S.
AU - Burkert, A.
AU - Chan, J.
AU - Contursi, A.
AU - Fabricius, M.
AU - Lee, M. M.
AU - Saglia, R. P.
AU - Sternberg, A.
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved..
PY - 2021/3/1
Y1 - 2021/3/1
N2 - We investigate what drives the redshift evolution of the typical electron density (n e ) in star-forming galaxies, using a sample of 140 galaxies drawn primarily from KMOS3D (0.6 < z < 2.6) and 471 galaxies from SAMI (z < 0.113). We select galaxies that do not show evidence of active galactic nucleus activity or outflows to constrain the average conditions within H ii regions. Measurements of the [S ii]λ6716/[S ii]λ6731 ratio in four redshift bins indicate that the local n e in the line-emitting material decreases from 187-132+140 cm-3 at z ∼ 2.2 to 32-9+4 cm-3 at z ∼ 0, consistent with previous results. We use the Hα luminosity to estimate the rms n e averaged over the volumes of star-forming disks at each redshift. The local and volume-averaged n e evolve at similar rates, hinting that the volume filling factor of the line-emitting gas may be approximately constant across 0 ≲ z ≲ 2.6. The KMOS3D and SAMI galaxies follow a roughly monotonic trend between n e and star formation rate, but the KMOS3D galaxies have systematically higher n e than the SAMI galaxies at a fixed offset from the star-forming main sequence, suggesting a link between the n e evolution and the evolving main sequence normalization. We quantitatively test potential drivers of the density evolution and find that n e (rms) nH2, suggesting that the elevated n e in high-z H ii regions could plausibly be the direct result of higher densities in the parent molecular clouds. There is also tentative evidence that n e could be influenced by the balance between stellar feedback, which drives the expansion of H ii regions, and the ambient pressure, which resists their expansion.
AB - We investigate what drives the redshift evolution of the typical electron density (n e ) in star-forming galaxies, using a sample of 140 galaxies drawn primarily from KMOS3D (0.6 < z < 2.6) and 471 galaxies from SAMI (z < 0.113). We select galaxies that do not show evidence of active galactic nucleus activity or outflows to constrain the average conditions within H ii regions. Measurements of the [S ii]λ6716/[S ii]λ6731 ratio in four redshift bins indicate that the local n e in the line-emitting material decreases from 187-132+140 cm-3 at z ∼ 2.2 to 32-9+4 cm-3 at z ∼ 0, consistent with previous results. We use the Hα luminosity to estimate the rms n e averaged over the volumes of star-forming disks at each redshift. The local and volume-averaged n e evolve at similar rates, hinting that the volume filling factor of the line-emitting gas may be approximately constant across 0 ≲ z ≲ 2.6. The KMOS3D and SAMI galaxies follow a roughly monotonic trend between n e and star formation rate, but the KMOS3D galaxies have systematically higher n e than the SAMI galaxies at a fixed offset from the star-forming main sequence, suggesting a link between the n e evolution and the evolving main sequence normalization. We quantitatively test potential drivers of the density evolution and find that n e (rms) nH2, suggesting that the elevated n e in high-z H ii regions could plausibly be the direct result of higher densities in the parent molecular clouds. There is also tentative evidence that n e could be influenced by the balance between stellar feedback, which drives the expansion of H ii regions, and the ambient pressure, which resists their expansion.
UR - http://www.scopus.com/inward/record.url?scp=85103184736&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/abd551
DO - 10.3847/1538-4357/abd551
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.systematicreview???
AN - SCOPUS:85103184736
SN - 0004-637X
VL - 909
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 78
ER -