15 research outputs found
KAOSS: turbulent, but disc-like kinematics in dust-obscured star-forming galaxies at z ∼ 1.3–2.6
We present spatially resolved kinematics of 27 ALMA-identified dust-obscured star-forming galaxies (DSFGs) at z ∼ 1.3–2.6, as traced by Hα emission using VLT/KMOS near-infrared integral field spectroscopy from the ‘KMOS-ALMA Observations of Submillimetre Sources’ (KAOSS) Large Programme. We derive Hα rotation curves and velocity dispersion profiles for the DSFGs, and find that among the 27 sources with bright, spatially extended Hα emission, 24 display evidence for disc-like kinematics. We measure a median inclination-corrected velocity at 2.2 Rd of vrot = 190 ± 40 km s−1 and intrinsic velocity dispersion of σ0 = 87 ± 6 km s−1 for these disc-like sources. The kinematics yield median circular velocities of vcirc = 230 ± 20 km s−1 and dynamical masses within 2Re (∼ 7 kpc radius) of Mdyn = (1.1 ± 0.2) × 1011 M⊙. Compared to less actively star-forming galaxies, KAOSS DSFGs are both faster rotating with higher intrinsic velocity dispersions, but have similar vrot/σ0 ratios, median v/σ0 = 2.5 ± 0.5. We suggest that the kinematics of the DSFGs are primarily rotation supported but with a non-negligible contribution from pressure support, which may be driven by star formation or mergers/interactions. We estimate the normalization of the stellar mass Tully–Fisher relation (sTFR) for the disc-like DSFGs and compare it with local studies, finding no evolution at fixed slope between z ∼ 2 and z ∼ 0. Finally, we show that the kinematic properties of the DSFG population are consistent with them evolving into massive early-type galaxies, the dominant z ∼ 0 population at these masses
KAOSS: turbulent, but disc-like kinematics in dust-obscured star-forming galaxies at 1.3-2.6
We present spatially resolved kinematics of 31 ALMA-identified dust-obscured
star-forming galaxies (DSFGs) at 1.3-2.6, as traced by H
emission using VLT/KMOS near-infrared integral field spectroscopy from our
on-going Large Programme ''KMOS-ALMA Observations of Submillimetre Sources''
(KAOSS). We derive H rotation curves and velocity dispersion profiles
for the DSFGs. Of the 31 sources with bright, spatially extended H
emission, 25 display rotation curves that are well fit by a Freeman disc model,
enabling us to measure a median inclination-corrected velocity at 2.2 of = 190 30 kms and a median intrinsic velocity
dispersion of = 87 6 kms for these
sources. By comparison with less actively star-forming galaxies, KAOSS DSFGs
are both faster rotating and more turbulent, but have similar ratios, median 2.4 0.5. We suggest that alone is insufficient to describe the kinematics of DSFGs, which
are not kinematically ''cold'' discs, and that the individual components
and indicate that they are in fact turbulent, but
rotationally supported systems in 50 per cent of cases. This turbulence
may be driven by star formation or mergers/interactions. We estimate the
normalisation of the stellar Tully-Fisher relation (sTFR) for the disc-like
DSFGs and compare it with local studies, finding no evolution at fixed slope
between 2 and 0. Finally, we use kinematic estimates of DSFG halo
masses to investigate the stellar-to-halo mass relation, finding our sources to
be consistent with shock heating and strong feedback which likely drives the
declining stellar content in the most massive halos.Comment: 20 pages, 12 figures, submitted to MNRAS, updated author lis
TEMPLATES: A Robust Outlier Rejection Method for JWST/NIRSpec Integral Field Spectroscopy
We describe a custom outlier rejection algorithm for JWST/NIRSpec integral
field spectroscopy. This method uses a layered sigma clipping approach that
adapts clipping thresholds based upon the spatial profile of the science
target. We find that this algorithm produces a robust outlier rejection while
simultaneously preserving the signal of the science target. Originally
developed as a response to unsatisfactory initial performance of the jwst
pipeline outlier detection step, this method works either as a standalone
solution, or as a supplement to the current pipeline software. Comparing
leftover (i.e., not flagged) artifacts with the current pipeline's outlier
detection step, we find that our method results in one fifth as many residual
artifacts as the jwst pipeline. However, we find a combination of both methods
removes nearly all artifacts -- an approach that takes advantage of both our
algorithm's robust outlier rejection and the pipeline's use of individual
dithers. This combined approach is what the TEMPLATES Early Release Science
team has converged upon for our NIRSpec observations. Finally, we publicly
release the code and Jupyter notebooks for the custom outlier rejection
algorithm.Comment: 10 pages, including 5 figures. Submitted to the Publications of the
Astronomical Society of the Pacific (PASP). Code associated with paper
released at https://github.com/aibhleog/baryon-swee
An ALMA/NOEMA survey of the molecular gas properties of high-redshift star-forming galaxies
We have used ALMA and NOEMA to study the molecular gas reservoirs in 61 ALMA-identified submillimetre galaxies (SMGs) in the COSMOS, UDS, and ECDFS fields. We detect 12CO (Jup= 2–5) emission lines in 50 sources, and [C I](3P1 − 3P0) emission in eight, at z= 1.2–4.8 and with a median redshift of 2.9 ± 0.2. By supplementing our data with literature sources, we construct a statistical CO spectral line energy distribution and find that the 12CO line luminosities in SMGs peak at Jup ∼ 6, consistent with similar studies. We also test the correlations of the CO, [C I], and dust as tracers of the gas mass, finding the three to correlate well, although the CO and dust mass as estimated from the 3-mm continuum are preferable. We estimate that SMGs lie mostly on or just above the star-forming main sequence, with a median gas depletion timescale, tdep = Mgas/SFR, of 210 ± 40 Myr for our sample. Additionally, tdep declines with redshift across z ∼ 1–5, while the molecular gas fraction, μgas = Mgas/M*, increases across the same redshift range. Finally, we demonstrate that the distribution of total baryonic mass and dynamical line width, Mbaryon–σ, for our SMGs is consistent with that followed by early-type galaxies in the Coma cluster, providing strong support to the suggestion that SMGs are progenitors of massive local spheroidal galaxies. On the basis of this, we suggest that the SMG populations above and below an 870-μm flux limit of S870 ∼ 5 mJy may correspond to the division between slow and fast rotators seen in local early-type galaxies
JWST's TEMPLATES for Star Formation: The First Resolved Gas-Phase Metallicity Maps of Dust-Obscured Star-Forming Galaxies at 4
We present the first spatially resolved maps of gas-phase metallicity for
dust-obscured star-forming galaxies (DSFGs) at 4, from the JWST
TEMPLATES Early Release Science program, derived from NIRSpec integral field
unit spectroscopy of the H and [NII] emission lines. Empirically
derived literature optical line calibrations are used to determine that the
sources are highly metal rich, with both appearing to display regions of
supersolar metallicity, particularly in SPT2147-50. While we cannot rule out
shocks or AGN in these regions, we suggest that the two systems have already
undergone significant enrichment as a result of their extremely high
star-formation rates. Utilising ALMA rest-frame 380m continuum and
[CI](P-P) line maps we compare metallicity and gas-to-dust
ratio variations in the two galaxies, finding the two to be anticorrelated on
highly resolved spatial scales, consistent with various literature studies of
0 galaxies. The data are indicative of the enormous potential of
JWST to probe the enrichment of the interstellar medium on kpc scales in
extremely dust-obscured systems at 4 and beyond.Comment: 12 pages, 5 figures, submitted to Ap
JWST's TEMPLATES for Star Formation: The First Resolved Gas-phase Metallicity Maps of Dust-obscured Star-forming Galaxies at z ∼ 4
We present the first spatially resolved maps of gas-phase metallicity for two dust-obscured star-forming galaxies at z ∼ 4, from the JWST TEMPLATES Early Release Science program, derived from NIRSpec integral field unit spectroscopy of the Hα and [N ii] emission lines. Empirical optical line calibrations are used to determine that the sources are globally enriched to near-solar levels. While one source shows elevated [N ii]/Hα ratios and broad Hα emission consistent with the presence of an active galactic nucleus in a ≳1 kpc region, we argue that both systems have already undergone significant metal enrichment as a result of their extremely high star formation rates. Utilizing Atacama Large Millimeter/submillimeter Array rest-frame 380 μm continuum and [Ci](3P2–3P1) line maps we compare the spatial variation of the metallicity and gas-to-dust ratio in the two galaxies, finding the two properties to be anticorrelated on highly resolved spatial scales, consistent with various literature studies of z ∼ 0 galaxies. The data are indicative of the enormous potential of JWST to probe the enrichment of the interstellar medium on ∼kpc scales in extremely dust-obscured systems at z ∼ 4 and beyond
VLA Legacy Survey of Molecular Gas in Massive Star-forming Galaxies at High Redshift
We present the initial results of an ongoing survey with the Karl G. Jansky Very Large Array targeting the CO(J = 1-0) transition in a sample of 30 submillimeter-selected, dusty star-forming galaxies (SFGs) at z = 2-5 with existing mid-J CO detections from the Atacama Large Millimeter/submillimeter Array and NOrthern Extended Millimeter Array, of which 17 have been fully observed. We detect CO(1-0) emission in 11 targets, along with three tentative (∼1.5σ-2σ) detections; three galaxies are undetected. Our results yield total molecular gas masses of 6-23 × 1010 (α CO/1) M ⊙, with gas mass fractions, f gas = M mol/(M *+M mol), of 0.1-0.8 and a median depletion time of (140 ± 70) Myr. We find median CO excitation ratios of r 31 = 0.75 ± 0.39 and r 41 = 0.63 ± 0.44, with significant scatter. We find no significant correlation between the excitation ratio and a number of key parameters such as redshift, CO(1-0) line width, or ΣSFR. We only find a tentative positive correlation between r 41 and the star-forming efficiency, but we are limited by our small sample size. Finally, we compare our results to predictions from the SHARK semi-analytical model, finding a good agreement between the molecular gas masses, depletion times, and gas fractions of our sources and their SHARK counterparts. Our results highlight the heterogeneous nature of the most massive SFGs at high redshift, and the importance of CO(1-0) observations to robustly constrain their total molecular gas content and interstellar medium properties.</p
KAOSS: turbulent, but disc-like kinematics in dust-obscured star-forming galaxies at z~1.3-2.6
We present spatially resolved kinematics of 27 ALMA-identified dust-obscured star-forming galaxies (DSFGs) at z ∼ 1.3–2.6, as traced by Hα emission using VLT/KMOS near-infrared integral field spectroscopy from the ‘KMOS-ALMA Observations of Submillimetre Sources’ (KAOSS) Large Programme. We derive Hα rotation curves and velocity dispersion profiles for the DSFGs, and find that among the 27 sources with bright, spatially extended Hα emission, 24 display evidence for disc-like kinematics. We measure a median inclination-corrected velocity at 2.2 Rd of vrot = 190 ± 40 km s−1 and intrinsic velocity dispersion of σ0 = 87 ± 6 km s−1 for these disc-like sources. The kinematics yield median circular velocities of vcirc = 230 ± 20 km s−1 and dynamical masses within 2Re (∼ 7 kpc radius) of Mdyn = (1.1 ± 0.2) × 1011 M⊙. Compared to less actively star-forming galaxies, KAOSS DSFGs are both faster rotating with higher intrinsic velocity dispersions, but have similar vrot/σ0 ratios, median v/σ0 = 2.5 ± 0.5. We suggest that the kinematics of the DSFGs are primarily rotation supported but with a non-negligible contribution from pressure support, which may be driven by star formation or mergers/interactions. We estimate the normalization of the stellar mass Tully–Fisher relation (sTFR) for the disc-like DSFGs and compare it with local studies, finding no evolution at fixed slope between z ∼ 2 and z ∼ 0. Finally, we show that the kinematic properties of the DSFG population are consistent with them evolving into massive early-type galaxies, the dominant z ∼ 0 population at these masses
KAOSS: turbulent, but disc-like kinematics in dust-obscured star-forming galaxies at <i>z</i> ∼ 1.3–2.6
We present spatially resolved kinematics of 27 ALMA-identified dust-obscured star-forming galaxies (DSFGs) at z ∼ 1.3–2.6, as traced by Hα emission using VLT/KMOS near-infrared integral field spectroscopy from the “KMOS-ALMA Observations of Submillimetre Sources” (KAOSS) Large Programme. We derive Hα rotation curves and velocity dispersion profiles for the DSFGs, and find that among the 27 sources with bright, spatially extended Hα emission, 24 display evidence for disc-like kinematics. We measure a median inclination-corrected velocity at 2.2 Rd of vrot = 190 ± 40 km s−1 and intrinsic velocity dispersion of σ0 = 87 ± 6 km s−1 for these disc-like sources. The kinematics yield median circular velocities of vcirc = 230 ± 20 km s−1 and dynamical masses within 2Re (∼ 7 kpc radius) of Mdyn = (1.1 ± 0.2) × 1011 M⊙. Compared to less actively star-forming galaxies, KAOSS DSFGs are both faster rotating with higher intrinsic velocity dispersions, but have similar vrot/σ0 ratios, median v/σ0 = 2.5 ± 0.5. We suggest that the kinematics of the DSFGs are primarily rotation supported but with a non-negligible contribution from pressure support, which may be driven by star formation or mergers/interactions. We estimate the normalisation of the stellar mass Tully-Fisher relation (sTFR) for the disc-like DSFGs and compare it with local studies, finding no evolution at fixed slope between z ∼ 2 and z ∼ 0. Finally, we show that the kinematic properties of the DSFG population are consistent with them evolving into massive early-type galaxies, the dominant z ∼ 0 population at these masses
KAOSS:turbulent, but disc-like kinematics in dust-obscured star-forming galaxies at z ∼ 1.3–2.6
We present spatially resolved kinematics of 27 ALMA-identified dust-obscured star-forming galaxies (DSFGs) at z ∼ 1.3–2.6, as traced by Hα emission using VLT/KMOS near-infrared integral field spectroscopy from the ‘KMOS-ALMA Observations of Submillimetre Sources’ (KAOSS) Large Programme. We derive Hα rotation curves and velocity dispersion profiles for the DSFGs, and find that among the 27 sources with bright, spatially extended Hα emission, 24 display evidence for disc-like kinematics. We measure a median inclination-corrected velocity at 2.2 Rd of vrot = 190 ± 40 km s−1 and intrinsic velocity dispersion of σ0 = 87 ± 6 km s−1 for these disc-like sources. The kinematics yield median circular velocities of vcirc = 230 ± 20 km s−1 and dynamical masses within 2Re (∼ 7 kpc radius) of Mdyn = (1.1 ± 0.2) × 1011 M∘. Compared to less actively star-forming galaxies, KAOSS DSFGs are both faster rotating with higher intrinsic velocity dispersions, but have similar vrot/σ0 ratios, median v/σ0 = 2.5 ± 0.5. We suggest that the kinematics of the DSFGs are primarily rotation supported but with a non-negligible contribution from pressure support, which may be driven by star formation or mergers/interactions. We estimate the normalization of the stellar mass Tully–Fisher relation (sTFR) for the disc-like DSFGs and compare it with local studies, finding no evolution at fixed slope between z ∼ 2 and z ∼ 0. Finally, we show that the kinematic properties of the DSFG population are consistent with them evolving into massive early-type galaxies, the dominant z ∼ 0 population at these masses.</p