Abstract
We present a high-resolution kinematic study of the massive main-sequence star-forming galaxy (SFG) SDSS J090122.37+181432.3 (J0901) at
z
= 2.259, using ∼0.″36 Atacama Large ...Millimeter/submillimeter Array CO(3–2) and ∼0.″1–0.″5 SINFONI/VLT H
α
observations. J0901 is a rare, strongly lensed but otherwise normal massive (
log
(
M
⋆
/
M
⊙
)
∼
11
) main-sequence SFG, offering a unique opportunity to study a typical massive SFG under the microscope of lensing. Through forward dynamical modeling incorporating lensing deflection, we fit the CO and H
α
kinematics in the image plane out to about one disk effective radius (
R
e
∼ 4 kpc) at an ∼600 pc delensed physical resolution along the kinematic major axis. Our results show high intrinsic dispersions of the cold molecular and warm ionized gas (
σ
0,mol.
∼ 40 km s
−1
and
σ
0,ion.
∼ 66 km s
−1
) that remain constant out to
R
e
; a moderately low dark matter fraction (
f
DM
∼ 0.3–0.4) within
R
e
; and a centrally peaked Toomre
Q
parameter—agreeing well with the previously established
σ
0
versus
z
,
f
DM
versus Σ
baryon
, and
Q
's radial trends using large-sample non-lensed main-sequence SFGs. Our data further reveal a high stellar mass concentration within ∼1–2 kpc with little molecular gas, and a clumpy molecular gas ring-like structure at
R
∼ 2–4 kpc, in line with the inside-out quenching scenario. Our further analysis indicates that J0901 had assembled half of its stellar mass only ∼400 Myr before its observed cosmic time, and the cold gas ring and dense central stellar component are consistent with signposts of a recent wet compaction event of a highly turbulent disk found in recent simulations.
The spin of the supermassive black hole that resides at the Galactic Center can, in principle, be measured by accurate measurements of the orbits of stars that are much closer to Sgr A* than S2, the ...orbit of which recently provided the measurement of the gravitational redshift and the Schwarzschild precession. The GRAVITY near-infrared interferometric instrument combining the four 8m telescopes of the VLT provides a spatial resolution of 2–4 mas, breaking the confusion barrier for adaptive-optics-assisted imaging with a single 8–10m telescope. We used GRAVITY to observe Sgr A* over a period of six months in 2019 and employed interferometric reconstruction methods developed in radio astronomy to search for faint objects near Sgr A*. This revealed a slowly moving star of magnitude 18.9 in the
K
-band within 30 mas of Sgr A*. The position and proper motion of the star are consistent with the previously known star S62, which is at a substantially greater physical distance, but in projection passes close to Sgr A*. Observations in August and September 2019 detected S29 easily, with
K
-magnitude of 16.6, at approximately 130 mas from Sgr A*. The planned upgrades of GRAVITY, and further improvements in the calibration, offer greater chances of finding stars fainter than
K
-magnitude of 19.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
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 (AGNs) 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−1 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 that 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 toward 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−1) 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.
We present the results of our near-infrared spectroscopic observations of a rich cluster candidate around a radio galaxy at z = 1.52 (4C65.22) with Subaru/MOIRCS and Large binocular telescope/LUCI. ...We observed 71 galaxies mostly on the star-forming main sequence selected by our previous broadband (photo-z) and narrowband H imaging observation in this cluster environment. We successfully confirmed the redshifts of 39 galaxies, and concluded that this is a gravitationally bound, real cluster at z = 1.517. Our spectroscopic data also suggest a hint of large-scale filaments or sheet-like three-dimensional structures crossing at the highest-density cluster core. By stacking the spectra to derive their average interstellar medium gas-phase metallicity based on the N ii/H emission line flux ratio, we find that the mass-metallicity relation (MZR) in the 4C65.22 cluster environment is consistent with that of H -selected field galaxies at similar redshifts. Our results suggest that the environmental impacts on the MZR is small at high redshifts, but a larger sample of high-z clusters and their member galaxies is still required to fully address the effect of environment as well as its cluster-cluster variation.
By using the GRAVITY instrument with the near-infrared (NIR) Very Large Telescope Interferometer (VLTI), the structure of the broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can ...be spatially resolved, allowing the central black hole (BH) mass to be determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) with resolved broad-line emission. Dynamical modelling of interferometric data constrains the BLR radius and central BH mass measurements for our targets and reveals outflow-dominated BLRs for Mrk 509 and PDS 456. We present an updated radius-luminosity (R-L) relation independent of that derived with reverberation mapping (RM) measurements using all the GRAVITY-observed AGNs. We find our R-L relation to be largely consistent with that derived from RM measurements except at high luminosity, where BLR radii seem to be smaller than predicted. This is consistent with RM-based claims that high Eddington ratio AGNs show consistently smaller BLR sizes. The BH masses of our targets are also consistent with the standard M BH - σ * relation. Model-independent photocentre fitting shows spatial offsets between the hot dust continuum and the BLR photocentres (ranging from ∼17 μas to 140 μas) that are generally perpendicular to the alignment of the red- and blueshifted BLR photocentres. These offsets are found to be related to the AGN luminosity and could be caused by asymmetric K -band emission of the hot dust, shifting the dust photocentre. We discuss various possible scenarios that can explain this phenomenon.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
Using integral field spectroscopy, we investigate the kinematic properties of 35 massive centrally dense and compact star-forming galaxies (SFGs; \(\mathrm{log}{\overline{M}}_{* }{M}_{\odot }=11.1\), ...\(\mathrm{log}({{\rm{\Sigma }}}_{1\mathrm{kpc}}{M}_{\odot }\,{\mathrm{kpc}}^{-2})\gt 9.5\), \(\mathrm{log}({M}_{* }/{r}_{e}^{1.5}{M}_{\odot }\,{\mathrm{kpc}}^{-1.5})\gt 10.3\)) at z ∼ 0.7–3.7 within the KMOS3D survey. We spatially resolve 23 compact SFGs and find that the majority are dominated by rotational motions with velocities ranging from 95 to 500 km s−1. The range of rotation velocities is reflected in a similar range of integrated Hα line widths, 75–400 km s−1, consistent with the kinematic properties of mass-matched extended galaxies from the full KMOS3D sample. The fraction of compact SFGs that are classified as “rotation-dominated” or “disklike” also mirrors the fractions of the full KMOS3D sample. We show that integrated line-of-sight gas velocity dispersions from KMOS3D are best approximated by a linear combination of their rotation and turbulent velocities with a lesser but still significant contribution from galactic-scale winds. The Hα exponential disk sizes of compact SFGs are, on average, 2.5 ± 0.2 kpc, 1–2נthe continuum sizes, in agreement with previous work. The compact SFGs have a 1.4נhigher active galactic nucleus (AGN) incidence than the full KMOS3D sample at fixed stellar mass with an average AGN fraction of 76%. Given their high and centrally concentrated stellar masses, as well as stellar-to-dynamical mass ratios close to unity, the compact SFGs are likely to have low molecular gas fractions and to quench on a short timescale unless replenished with inflowing gas. The rotation in these compact systems suggests that their direct descendants are rotating passive galaxies.
The detection of low-mass planets orbiting the nearest stars is a central stake of exoplanetary science, as they can be directly characterized much more easily than their distant counterparts. Here, ...we present the results of our long-term astrometric observations of the nearest binary M-dwarf Gliese 65 AB (GJ65), located at a distance of only 2.67 pc. We monitored the relative astrometry of the two components from 2016 to 2023 with the VLTI/GRAVITY interferometric instrument. We derived highly accurate orbital parameters for the stellar system, along with the dynamical masses of the two red dwarfs. The GRAVITY measurements exhibit a mean accuracy per epoch of 50−60 ms in 1.5 h of observing time using the 1.8 m Auxiliary Telescopes. The residuals of the two-body orbital fit enable us to search for the presence of companions orbiting one of the two stars (S-type orbit) through the reflex motion they imprint on the differential A–B astrometry. We detected a Neptune-mass candidate companion with an orbital period of p = 156 ± 1 d and a mass of m p = 36 ± 7 M ⊕ . The best-fit orbit is within the dynamical stability region of the stellar pair. It has a low eccentricity, e = 0.1 − 0.3, and the planetary orbit plane has a moderate-to-high inclination of i > 30° with respect to the stellar pair, with further observations required to confirm these values. These observations demonstrate the capability of interferometric astrometry to reach microarcsecond accuracy in the narrow-angle regime for planet detection by reflex motion from the ground. This capability offers new perspectives and potential synergies with Gaia in the pursuit of low-mass exoplanets in the solar neighborhood.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
Following the success of the Plateau de Bure high-z Blue Sequence Survey (PHIBSS), we present the PHIBSS2 legacy program, a survey of the molecular gas properties of star-forming galaxies on and ...around the star-formation main sequence (MS) at different redshifts using IRAM’s NOrthern Extended Millimeter Array (NOEMA). This survey significantly extends the existing sample of star-forming galaxies with CO molecular gas measurements, probing the peak epoch of star formation (z = 1 − 1.6) as well as its building-up (z = 2 − 3) and winding-down (z = 0.5 − 0.8) phases. The targets are drawn from the well-studied GOODS, COSMOS, and AEGIS cosmological deep fields and uniformly sample the MS in the stellar mass (M⋆) – star formation rate (SFR) plane with log(M⋆/M⊙) = 10 − 11.8 and SFR = 3.5 − 500 M⊙ yr−1 without morphological selection, thus providing a statistically meaningful census of star-forming galaxies at different epochs. We describe the survey strategy and sample selection before focusing on the results obtained at redshift z = 0.5 − 0.8, where we report 60 CO(2-1) detections out of 61 targets. We determine molecular gas masses between 2 × 109 and 5 × 1010 M⊙ and separately obtain disc sizes and bulge-to-total (B/T) luminosity ratios from HST I-band images. The median molecular gas-to-stellar mass ratio μgas∼ = 0.28 ± 0.04 μ gas ∼ = 0.28 ± 0.04 $ \widetilde{\mu_{\mathrm{gas}}} = 0.28 \pm 0.04 $ , gas fraction fgas∼ = 0.22 ± 0.02 f gas ∼ = 0.22 ± 0.02 $ \widetilde{f_{\mathrm{gas}}} = 0.22 \pm 0.02 $ , and depletion time t depl ∼ = 0.84 ± 0.07 Gyr $ \widetilde{t_{\mathrm{depl}}} = 0.84 \pm 0.07\,\mathrm{Gyr} $ as well as their dependence with stellar mass and offset from the MS follow published scaling relations for a much larger sample of galaxies spanning a significantly wider range of redshifts, the cosmic evolution of the SFR being mainly driven by that of the molecular gas fraction. The galaxy-averaged molecular Kennicutt–Schmidt (KS) relation between molecular gas and SFR surface densities is strikingly linear, pointing towards similar star formation timescales within galaxies at any given epoch. In terms of morphology, the molecular gas content, the SFR, the disc stellar mass, and the disc molecular gas fraction do not seem to correlate with B/T and the stellar surface density, which suggests an ongoing supply of fresh molecular gas to compensate for the build-up of the bulge. Our measurements do not yield any significant variation of the depletion time with B/T and hence no strong evidence for morphological quenching within the scatter of the MS.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
Abstract
We investigate the stellar mass and baryonic mass Tully–Fisher relations (TFRs) of massive star-forming disk galaxies at redshift
and
as part of the
integral field spectroscopy survey. Our ...spatially resolved data allow reliable modeling of individual galaxies, including the effect of pressure support on the inferred gravitational potential. At fixed circular velocity, we find higher baryonic masses and similar stellar masses at
as compared to
. Together with the decreasing gas-to-stellar mass ratios with decreasing redshift, this implies that the contribution of dark matter to the dynamical mass on the galaxy scale increases toward lower redshift. A comparison to local relations reveals a negative evolution of the stellar and baryonic TFR zero points from
z
= 0 to
, no evolution of the stellar TFR zero point from
to
, and a positive evolution of the baryonic TFR zero point from
to
. We discuss a toy model of disk galaxy evolution to explain the observed nonmonotonic TFR evolution, taking into account the empirically motivated redshift dependencies of galactic gas fractions and the relative amount of baryons to dark matter on galaxy and halo scales.
The GRAVITY young stellar object survey R. Garcia Lopez; A. Natta; Fedriani, R ...
Astronomy and astrophysics (Berlin),
04/2024, Volume:
684
Journal Article
Peer reviewed
Context. The region of protoplanetary disks closest to a star (within 1–2 au) is shaped by a number of different processes, from accretion of the disk material onto the central star to ejection in ...the form of winds and jets. Optical and near-IR emission lines are potentially good tracers of inner disk processes if very high spatial and/or spectral resolution are achieved. Aims. In this paper, we exploit the capabilities of the VLTI-GRAVITY near-IR interferometer to determine the location and kinematics of the hydrogen emission line Brγ. Methods. We present VLTI-GRAVITY observations of the Brγ line for a sample of 26 stars of intermediate mass (HAEBE), the largest sample so far analysed with near-IR interferometry. Results. The Brγ line was detected in 17 objects. The emission is very compact (in most cases only marginally resolved), with a size of 10–30 R*(1–5 mas). About half of the total flux comes from even smaller regions, which are unresolved in our data. For eight objects, it was possible to determine the position angle (PA) of the line-emitting region, which is generally in agreement with that of the inner-dusty disk emitting the K-band continuum. The position-velocity pattern of the Brγ line-emitting region of the sampled objects is roughly consistent with Keplerian rotation. The exception is HD 45677, which shows more extended emission and more complex kinematics. The most likely scenario for the Brγ origin is that the emission comes from an MHD wind launched very close to the central star, in a region well within the dust sublimation radius. An origin in the bound gas layer at the disk surface cannot be ruled out, while accreting matter provides only a minor fraction of the total flux. Conclusions. These results show the potential of near-IR spectro-interferometry to study line emission in young stellar objects.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
PDF
