95 research outputs found
Metal enrichment and evolution in four z > 6.5 quasar sightlines observed with JWST/NIRSpec
We present JWST/NIRSpec R2700 spectra of four high-redshift quasars:
VDES J0020-3653 (z = 6.860), DELS J0411-0907(z = 6.825), UHS J0439+1634 (z =
6.519) and ULAS J1342+0928 (z = 7.535). The exquisite data quality,
signal-to-noise ratio of 50-200, and large spectral coverage allows us to identify between 13 and 17
intervening and proximate metal absorption line systems in each quasar
spectrum, with a total number of 61 absorption-line systems detected at
including the highest redshift intervening OI 1302 and
MgII systems at and . We investigate the evolution of the
metal enrichment in the epoch of reionization at and find: i) A continued
increase of the low-ionization OI, CII, and SiII incidence, ii) Decreasing
high-ionization CIV and SiIV incidence with a transition from predominantly
high- to low-ionization at , and iii) a constant MgII incidence
across all redshifts. The observations support a change in the ionization state
of the intergalactic medium in the EoR rather than a change in metallicity. The
abundance ratio of [Si/O] in five absorption systems show enrichment
signatures produced by low-mass Pop III pair instability supernovae, and
possibly Pop III hypernovae. In the Gunn-Peterson troughs we detect
transmission spikes where Ly photons can escape. From 22 absorption
systems at , only a single low-ionization system out of 13 lies within
2000 km s from a spike, while four high-ionization systems out of nine
lie within 2000 km s from a spike. This confirms that galaxies
responsible for the heavy elements that are transported into the circumgalactic
medium lie in predominantly in high-density, neutral environments, while lower
density environments are ionized without being polluted by metals at
6-7. [abridged]Comment: 50 pages including 30 pages of appendices. Submitted to A&
The MOSDEF Survey: Kinematic and Structural Evolution of Star-Forming Galaxies at
We present ionized gas kinematics for 681 galaxies at from
the MOSFIRE Deep Evolution Field survey, measured using models which account
for random galaxy-slit misalignments together with structural parameters
derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes
are used to derive dynamical masses. Baryonic masses are estimated from stellar
masses and inferred gas masses from dust-corrected star formation rates (SFRs)
and the Kennicutt-Schmidt relation. We measure resolved rotation for 105
galaxies. For the remaining 576 galaxies we use models based on HST imaging
structural parameters together with integrated velocity dispersions and
baryonic masses to statistically constrain the median ratio of intrinsic
ordered to disordered motion, . We find that
increases with increasing stellar mass and decreasing specific SFR (sSFR).
These trends may reflect marginal disk stability, where systems with higher gas
fractions have thicker disks. For galaxies with detected rotation we assess
trends between their kinematics and mass, sSFR, and baryon surface density
(). Intrinsic dispersion correlates most with
and velocity correlates most with mass. By comparing
dynamical and baryonic masses, we find that galaxies at are
baryon dominated within their effective radii (), with Mdyn/Mbaryon
increasing over time. The inferred baryon fractions within ,
, decrease over time, even at fixed mass, size, or surface
density. At fixed redshift, does not appear to vary with
stellar mass but increases with decreasing and increasing
. For galaxies at , the median inferred baryon
fractions generally exceed 100%. We discuss possible explanations and future
avenues to resolve this tension.Comment: Accepted to ApJ. Added Figure 9, corrected sample size (main results
unchanged). 28 pages, 13 figure
Physics of ULIRGs with MUSE and ALMA: The PUMA project: III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion, and its dependence on starburstiness
CONTEXT:
A classical scenario suggests that ultra-luminous infrared galaxies (ULIRGs) transform colliding spiral galaxies into a spheroid-dominated early-type galaxy. Recent high-resolution simulations have instead shown that, under some circumstances, rotation disks can be preserved during the merging process or rapidly regrown after coalescence. Our goal is to analyse in detail the ionised gas kinematics in a sample of ULIRGs to infer the incidence of gas rotational dynamics in late-stage interacting galaxies and merger remnants.
AIMS:
We analysed integral field spectrograph MUSE data of a sample of 20 nearby (z < 0.165) ULIRGs (with 29 individual nuclei) as part of the Physics of ULIRGs with MUSE and ALMA (PUMA) project. We used multi-Gaussian fitting techniques to identify gaseous disk motions and the 3D-Barolo tool to model them.
METHODS:
We found that 27% (8 out of 29) individual nuclei are associated with kiloparsec-scale disk-like gas motions. The rest of the sample displays a plethora of gas kinematics, dominated by winds and merger-induced flows, which makes the detection of rotation signatures difficult. On the other hand, the incidence of stellar disk-like motions is ∼2 times larger than gaseous disks, as the former are probably less affected by winds and streams. The eight galaxies with a gaseous disk present relatively high intrinsic gas velocity dispersion (σ0 ∈ [30 − 85] km s−1), rotationally supported motions (with gas rotation velocity over velocity dispersion vrot/σ0 ∼ 1 − 8), and dynamical masses in the range (2 − 7)×1010 M⊙. By combining our results with those of local and high-z disk galaxies (up to z ∼ 2) from the literature, we found a significant correlation between σ0 and the offset from the main sequence (δMS), after correcting for their evolutionary trends.
RESULTS:
Our results confirm the presence of kiloparsec-scale rotating disks in interacting galaxies and merger remnants in the PUMA sample, with an incidence going from 27% (gas) to ≲50% (stars). Their gas σ0 is up to a factor of ∼4 higher than in local normal main sequence galaxies, similar to high-z starbursts as presented in the literature; this suggests that interactions and mergers enhance the star formation rate while simultaneously increasing the velocity dispersion in the interstellar medium
The PUMA project. III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion and its dependence on starburstiness
A classical scenario suggests that ULIRGs transform colliding spiral galaxies
into a spheroid dominated early-type galaxy. Recent high-resolution simulations
have instead shown that, under some circumstances, rotation disks can be
preserved during the merging process or rapidly regrown after coalescence. Our
goal is to analyze in detail the ionised gas kinematics in a sample of ULIRGs
to infer the incidence of gas rotational dynamics in late-stage interacting
galaxies and merger remnants. We analysed MUSE data of a sample of 20 nearby
(z<0.165) ULIRGs, as part of the "Physics of ULIRGs with MUSE and ALMA" (PUMA)
project. We found that 27% individual nuclei are associated with kpc-scale
disk-like gas motions. The rest of the sample displays a plethora of gas
kinematics, dominated by winds and merger-induced flows, which make the
detection of rotation signatures difficult. On the other hand, the incidence of
stellar disk-like motions is ~2 times larger than gaseous disks, as the former
are probably less affected by winds and streams. The eight galaxies with a
gaseous disk present relatively high intrinsic gas velocity dispersion (sigma =
30-85 km/s), rotationally-supported motions (with gas rotation velocity over
velocity dispersion vrot/sigma > 1-8), and dynamical masses in the range
(2-7)x1e10 Msun. By combining our results with those of local and high-z disk
galaxies from the literature, we found a significant correlation between sigma
and the offset from the main sequence (MS), after correcting for their
evolutionary trends. Our results confirm the presence of kpc-scale rotating
disks in interacting galaxies and merger remnants, with an incidence going from
27% (gas) to ~50% (stars). The ULIRGs gas velocity dispersion is up to a factor
of ~4 higher than in local normal MS galaxies, similar to high-z starbursts as
presented in the literature
The Kinematics and Dark Matter Fractions of TNG50 Galaxies at z=2 from an Observational Perspective
We contrast the gas kinematics and dark matter contents of star-forming
galaxies (SFGs) from state-of-the-art cosmological simulations within the
CDM framework to observations. To this end, we create realistic mock
observations of massive SFGs (, SFR
yr) from the TNG50 simulation of the IllustrisTNG suite,
resembling near-infrared, adaptive-optics assisted integral-field observations
from the ground. Using observational line fitting and modeling techniques, we
analyse in detail the kinematics of seven TNG50 galaxies from five different
projections per galaxy, and compare them to observations of twelve massive SFGs
by Genzel et al. (2020). The simulated galaxies show clear signs of disc
rotation but mostly exhibit more asymmetric rotation curves, partly due to
large intrinsic radial and vertical velocity components. At identical
inclination angle, their one-dimensional velocity profiles can vary along
different lines of sight by up to km s. From dynamical
modelling we infer rotation speeds and velocity dispersions that are broadly
consistent with observational results. We find low central dark matter
fractions compatible with observations (), however for disc effective
radii that are mostly too small: at fixed the TNG50 dark matter
fractions are too high by a factor of . We speculate that the
differences in gas kinematics and dark matter content compared to the
observations may be due to physical processes that are not resolved in
sufficient detail with the numerical resolution available in current
cosmological simulations.Comment: 25 pages, 16 figures, accepted for publication in MNRA
From Nuclear to Circumgalactic:Zooming in on AGN-driven Outflows at z ∼ 2.2 with SINFONI
We use deep adaptive optics assisted integral field spectroscopy from SINFONI
on the VLT to study the spatially resolved properties of ionized gas outflows
driven by active galactic nuclei (AGN) in three galaxies at z~2.2 -- K20-ID5,
COS4-11337 and J0901+1814. These systems probe AGN feedback from nuclear to
circumgalactic scales, and provide unique insights into the different
mechanisms by which AGN-driven outflows interact with their host galaxies.
K20-ID5 and COS4-11337 are compact star forming galaxies with powerful
1500 km s AGN-driven outflows that dominate their nuclear
H emission. The outflows do not appear to have any impact on the
instantaneous star formation activity of the host galaxies, but they carry a
significant amount of kinetic energy which could heat the halo gas and
potentially lead to a reduction in the rate of cold gas accretion onto the
galaxies. The outflow from COS4-11337 is propagating directly towards its
companion galaxy COS4-11363, at a projected separation of 5.4 kpc. COS4-11363
shows signs of shock excitation and recent truncation of star formation
activity, which could plausibly have been induced by the outflow from
COS4-11337. J0901+1814 is gravitationally lensed, giving us a unique view of a
compact (R = 470 70 pc), relatively low velocity (650 km s)
AGN-driven outflow. J0901+1814 has a similar AGN luminosity to COS4-11337,
suggesting that the difference in outflow properties is not related to the
current AGN luminosity, and may instead reflect a difference in the
evolutionary stage of the outflow and/or the coupling efficiency between the
AGN ionizing radiation field and the gas in the nuclear regions.Comment: Accepted for publication in ApJ. Main text 23 pages, 15 figures and 4
tables, plus Appendix (3 pages, 3 figures, 1 table
GA-NIFS: co-evolution within a highly star-forming galaxy group at z=3.7 witnessed by JWST/NIRSpec IFS
We present NIRSpec IFS observations of a galaxy group around the massive
GS_4891 galaxy at z=3.7 in GOODS-South that includes two other two systems,
GS_4891_n to the north and GS_28356 to the east. These observations, obtained
as part of the GTO GA-NIFS program, allow for the first time to study the
spatially resolved properties of the interstellar medium (ISM) and ionized gas
kinematics of a galaxy at this redshift. Leveraging the wide wavelength range
spanned with the high-dispersion grating (with resolving power R=2700)
observations, covering from [OII]3726,29 to
[SII]6716,31, we explore the spatial distribution of
star-formation rate, nebular attenuation and gas metallicity, together with the
mechanisms responsible for the excitation of the ionized gas. GS_4891 presents
a clear gradient of gas metallicity (as traced by 12 + log(O/H)) by more than
0.2dex from the south-east (where a star-forming clump is identified) to the
north-west. The gas metallicity in the less-massive northern system, GS_4891_n,
is also higher by 0.2 dex than at the center of GS_4891, suggesting that
inflows of lower-metallicity gas might be favoured in higher-mass systems. The
kinematic analysis shows that GS_4891 presents velocity gradients in the
ionized gas consistent with rotation. The region between GS_4891 and GS_4891_n
does not present high gas turbulence which, together with the difference in gas
metallicities, suggests that these two systems might be in a pre-merger stage.
Finally, GS_4891 hosts an ionized outflow that extends out to r_out=1.2 kpc
from the nucleus and reaches maximum velocities v_out of approximately 400
km/s. Despite entraining an outflowing mass rate of M_out2Msun/yr, the
low associated mass-loading factor, =0.05, implies that the outflow does
not have a significant impact on the star-formation activity of the galaxy.Comment: Submitted to Astronomy & Astrophysics on September 25th, 202
The ultra-dense, interacting environment of a dual AGN at z 3.3 revealed by JWST/NIRSpec IFS
LBQS 0302-0019 is a blue quasar (QSO) at z ~ 3.3, hosting powerful outflows,
and residing in a complex environment consisting of an obscured AGN candidate,
and multiple companions, all within 30 kpc in projection. We use JWST NIRSpec
IFS observations to characterise the ionized gas in this complex system. We
develop a procedure to correct for the spurious oscillations (or 'wiggles') in
NIRSpec single-spaxel spectra, due to the spatial under-sampling of the point
spread function. We perform a quasar-host decomposition with the QDeblend3D
tools, and use multi-component kinematic decomposition of the optical emission
line profiles to infer the physical properties of the emitting gas. The
quasar-host decomposition allows us to identify i) a low-velocity component
possibly tracing a warm rotating disk, with a dynamical mass Mdyn Msun and a rotation-to-random motion ratio /; ii) a spatially unresolved ionised outflow, with a velocity of 1000
km/s and an outflow mass rate of Msun/yr. We also detect eight
interacting companion objects close to LBQS 0302-0019. Optical line ratios
confirm the presence of a second, obscured AGN at kpc of the primary
QSO; the dual AGN dominates the ionization state of the gas in the entire
NIRSpec field-of-view. This work has unveiled with unprecedented detail the
complex environment of this dual AGN, which includes nine interacting
companions (five of which were previously unknown), all within 30 kpc of the
QSO. Our results support a scenario where mergers can trigger dual AGN, and can
be important drivers for rapid early SMBH growth.Comment: 23 pages, 23 figures; accepted for publication by A&
Rotation Curves in z ∼ 1–2 Star-forming Disks: Evidence for Cored Dark Matter Distributions
We report high quality, Halpha or CO rotation curves (RCs) to several Re for
41 large, massive, star-forming disk galaxies (SFGs), across the peak of cosmic
galaxy evolution (z~0.67-2.45), taken with the ESO-VLT, the LBT and IRAM-NOEMA.
Most RC41 SFGs have reflection symmetric RCs plausibly described by equilibrium
dynamics. We fit the major axis position-velocity cuts with beam-convolved,
forward modeling with a bulge, a turbulent rotating disk, and a dark matter
(DM) halo. We include priors for stellar and molecular gas masses, optical
light effective radii and inclinations, and DM masses from abundance matching
scaling relations. Two-thirds or more of the z>1.2 SFGs are baryon dominated
within a few Re of typically 5.5 kpc, and have DM fractions less than maximal
disks (=0.12). At lower redshift (z<1.2) that fraction is less than
one-third. DM fractions correlate inversely with the baryonic angular momentum
parameter, baryonic surface density and bulge mass. Inferred low DM fractions
cannot apply to the entire disk & halo but more plausibly reflect a flattened,
or cored, inner DM density distribution. The typical central 'DM deficit' in
these cores relative to NFW distributions is ~30% of the bulge mass. The
observations are consistent with rapid radial transport of baryons in the first
generation massive gas rich halos forming globally gravitationally unstable
disks, and leading to efficient build-up of massive bulges and central black
holes. A combination of heating due to dynamical friction and AGN feedback may
drive DM out of the initial cusps.Comment: 15 figures, 4 tables, accepted for publication in Ap
Rotation Curves in z ∼ 1–2 Star-forming Disks: Comparison of Dark Matter Fractions and Disk Properties for Different Fitting Methods
We present a follow-up analysis examining the dynamics and structures of 41
massive, large star-forming galaxies at z~0.67-2.45 using both ionized and
molecular gas kinematics. We fit the galaxy dynamics with models consisting of
a bulge, a thick, turbulent disk, and a NFW dark matter halo, using code that
fully forward models the kinematics, including all observational and
instrumental effects. We explore the parameter space using Markov Chain Monte
Carlo (MCMC) sampling, including priors based on stellar and gas masses and
disk sizes. We fit the full sample using extracted 1D kinematic profiles. For a
subset of 14 well-resolved galaxies, we also fit the 2D kinematics. The MCMC
approach robustly confirms the results from least-squares fitting presented in
Paper I (Genzel et al. 2020): the sample galaxies tend to be baryon-rich on
galactic scales (within one effective radius). The 1D and 2D MCMC results are
also in good agreement for the subset, demonstrating that much of the galaxy
dynamical information is captured along the major axis. The 2D kinematics are
more affected by the presence of non-circular motions, which we illustrate by
constructing a toy model with constant inflow for one galaxy that exhibits
residual signatures consistent with radial motions. This analysis, together
with results from Paper I and other studies, strengthens the finding that
massive, star-forming galaxies at z~1-2 are baryon-dominated on galactic
scales, with lower dark matter fractions towards higher baryonic surface
densities. Finally, we present details of the kinematic fitting code used in
this analysis.Comment: Accepted for publication in ApJ (23 pages, 8 figures, 5 tables
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