Recent observations of UV/optically selected, massive star-forming galaxies at image indicate that the baryonic mass assembly and star formation history is dominated by continuous rapid accretion of ...gas and internal secular evolution, rather than by major mergers. We use the Millennium Simulation to build new halo merger trees and extract halo merger fractions and mass accretion rates. We find that, even for halos not undergoing major mergers, the mass accretion rates are plausibly sufficient to account for the high star formation rates observed in image disks. On the other hand, the fraction of major mergers in the Millennium Simulation is sufficient to account for the number counts of submillimeter galaxies (SMGs), in support of observational evidence that these are major mergers. When following the fate of these two populations in the Millennium Simulation to image, we find that subsequent mergers are not frequent enough to convert all image turbulent disks into elliptical galaxies at image. Similarly, mergers cannot transform the compact SMGs/red sequence galaxies at image into observed massive cluster ellipticals at image. We argue therefore, that secular and internal evolution must play an important role in the evolution of a significant fraction of image UV/optically and submillimeter-selected galaxy populations.
We present ∼1″ resolution (∼2 kpc in the source plane) observations of the CO (1–0), CO (3–2), Hα, and N ii lines in the strongly lensed z = 2.26 star-forming galaxy SDSS J0901+1814. We use these ...observations to constrain the lensing potential of a foreground group of galaxies, and our source-plane reconstructions indicate that SDSS J0901+1814 is a nearly face-on (i ≈ 30°) massive disk with r 1/2 ≳ 4 kpc for its molecular gas. Using our new magnification factors (μ tot ≈ 30), we find that SDSS J0901+1814 has a star formation rate (SFR) of \({268}_{-61}^{+63}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}\), \({M}_{\mathrm{gas}}=({1.6}_{-0.2}^{+0.3})\times {10}^{11}({\alpha }_{\mathrm{CO}}/4.6)\,{M}_{\odot }\), and \({M}_{\star }=({9.5}_{-2.8}^{+3.8})\times {10}^{10}\,{M}_{\odot }\), which places it on the star-forming galaxy “main sequence.” We use our matched high angular resolution gas and SFR tracers (CO and Hα, respectively) to perform a spatially resolved (pixel-by-pixel) analysis of SDSS J0901+1814 in terms of the Schmidt–Kennicutt relation. After correcting for the large fraction of obscured star formation (\({\mathrm{SFR}}_{{\rm{H}}\alpha }/{\mathrm{SFR}}_{\mathrm{TIR}}={0.054}_{-0.014}^{+0.015}\)), we find that SDSS J0901+1814 is offset from “normal” star-forming galaxies to higher star formation efficiencies independent of assumptions for the CO-to-H2 conversion factor. Our mean best-fit index for the Schmidt–Kennicutt relation for SDSS J0901+1814, evaluated with different CO lines and smoothing levels, is \(\bar{n}=1.54\pm 0.13;\) however, the index may be affected by gravitational lensing, and we find \(\bar{n}=1.24\pm 0.02\) when analyzing the source-plane reconstructions. While the Schmidt–Kennicutt index largely appears unaffected by which of the two CO transitions we use to trace the molecular gas, the source-plane reconstructions and dynamical modeling suggest that the CO (1–0) emission is more spatially extended than the CO (3–2) emission.
The two-dimensional (2D) distribution and kinematics of the molecular, ionized, and highly ionized gas in the nuclear regions of Seyfert 1 galaxies have been measured using high spatial resolution ( ...similar to 0.09 double prime ) near-infrared spectroscopy from NIRSPEC with adaptive optics on the Keck telescope. Molecular hydrogen, H sub(2), is detected in all nine Seyfert 1 galaxies and, in the majority of galaxies, has a spatially resolved flux distribution. In contrast, the narrow component of the Br gamma emission has a distribution consistent with that of the K-band continuum. In general, the kinematics of the molecular hydrogen is consistent with thin disk rotation, with a velocity gradient of over 100 km s super(-1) measured across the central 0.5 double prime in three galaxies, and a similar gradient across the central 1.5 double prime in an additional two galaxies. The kinematics of Br gamma is in agreement with the H sub(2) rotation, except that in all four cases the central 0.5 double prime is either blue- or redshifted by more than 75 km s super(-1). The highly ionized gas, measured with the Ca VIII and Si VII coronal lines, is spatially and kinematically consistent with Br gamma in the central 0.5 double prime . In addition, the velocity dispersion of both the coronal and Br gamma emission is greater than that of H sub(2) (by 1.3-2.0 times), suggesting that both originate from gas that is located closer to the nucleus than the H sub(2) line emitting gas. Dynamical models have been fitted to the 2D H sub(2) kinematics, taking into account the stellar mass distribution, the emission line flux distribution, and the point spread function. For NGC 3227 the modeling indicates a black hole mass of M sub(BH) = 2.0 super(+) sub(-) super(1) sub(0) super(.) sub(.) super(0) sub(4) x 10 super(7) M unk, and for NGC 4151 M sub(BH) = 3.0 super(+) sub(-) super(0) sub(2) super(.) sub(.) super(7) sub(2) super(5) x 10 super(7) M unk. In NGC 7469 the best-fit model gives M sub(bh) < 5.0 x 10 super(7) M unk. In all three galaxies, modeling suggests a near face-on disk inclination angle, which is consistent with the unification theory of active galaxies. The direct black hole mass estimates verify that masses determined from technique of reverberation mapping are accurate to within a factor of 3 with no additional systematic errors.
Using SINFONI Halpha, NII, and SII AO data of 27 z ~ 2 star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, we explore the dependence of outflow strength (via the broad flux fraction) on ...various galaxy parameters. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius (~a few kpc). Decomposition of the SII doublet into broad and narrow components suggests that this outflowing gas probably has a density of ~10-100 cm super(-3), less than that of the star-forming gas (600 cm super(-3)). There is a strong correlation of the Halpha broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 M sub(middot in circle) yr super(-1) kpc super(-2). Above this threshold, we find that SFGs with log m sub(*) > 10 have similar or perhaps greater wind mass-loading factors (eta = M sub(out)/SFR) and faster outflow velocities than lower mass SFGs, suggesting that the majority of outflowing gas at z ~ 2 may derive from high-mass SFGs. The mass-loading factor is also correlated with the star formation rate (SFR), galaxy size, and inclination, such that smaller, more star-forming, and face-on galaxies launch more powerful outflows. We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk.
Abstract We report new radio observations of SDSS J090122.37+181432.3, a strongly lensed star-forming galaxy at z = 2.26. We image 1.4 GHz ( L -band) and 3 GHz ( S -band) continuum using the Very ...Large Array (VLA) and 1.2 mm (band 6) continuum with Atacama Large Millimeter/submillimeter Array, in addition to the CO(7–6) and C i ( 3 P 2 → 3 P 1 ) lines, all at ≲1.″7 resolution. Based on the VLA integrated flux densities, we decompose the radio spectrum into its free–free (FF) and nonthermal components. The infrared–radio correlation parameter q TIR = 2.65 − 0.31 + 0.24 is consistent with expectations for star-forming galaxies. We obtain radio continuum-derived star formation rates (SFRs) that are free of dust extinction, finding 620 − 220 + 280 M ⊙ yr − 1 , 230 − 160 + 570 M ⊙ yr − 1 , and 280 − 120 + 460 M ⊙ yr − 1 from the FF emission, nonthermal emission, and when accounting for both emission processes, respectively, in agreement with previous results. We estimate the gas mass from the C i ( 3 P 2 → 3 P 1 ) line as M gas = (1.2 ± 0.2) × 10 11 M ☉ , which is consistent with prior CO(1–0)-derived gas masses. Using our new IR and radio continuum data to map the SFR, we assess the dependence of the Schmidt–Kennicutt relation on choices of SFR and gas tracer for ∼kpc scales. The different SFR tracers yield different slopes, with the IR being the steepest, potentially due to highly obscured star formation in J0901. The radio continuum maps have the lowest slopes and overall fidelity for mapping the SFR, despite producing consistent total SFRs. We also find that the Schmidt–Kennicutt relation slope is flattest when using CO(7–6) or C i ( 3 P 2 → 3 P 1 ) to trace gas mass, suggesting that those transitions are not suitable for tracing the bulk molecular gas in galaxies like J0901.
We present Very Large Telescope SINFONI near-infrared (NIR) integral field spectroscopy of six z ∼ 0.2 Lyman break galaxy "analogs" (LBAs) from which we detect H i, He i, and Fe ii recombination ...lines and multiple H2 rovibrational lines in emission. The Pa kinematics reveal high velocity dispersions and low rotational velocities relative to random motions ( ). Matched-aperture comparisons of Hβ, H , and Pa reveal that the nebular color excesses are lower relative to the continuum color excesses than is the case for typical local star-forming systems. We compare observed He i/H i recombination line ratios to photoionization models to gauge the effective temperatures (Teff) of massive ionizing stars, finding that the properties of at least one LBA are consistent with extra heating from an active galactic nucleus (AGN) and/or an overabundance of massive stars. We use H2 1−0 S( ) rovibrational spectra to determine a rotational excitation temperature Tex ∼ 2000 K for warm molecular gas, which we attribute to UV heating in dense photon-dominated regions. Spatially resolved NIR line ratios favor excitation by massive young stars, rather than supernova or AGN feedback. Our results suggest that the local analogs of Lyman break galaxies are primarily subject to strong feedback from recent star formation, with evidence for AGNs and outflows in some cases.
We present new optical GTC/MEGARA seeing-limited (0.9″) integral-field observations of NGC 5506, together with ALMA observations of the CO(3 − 2) transition at a 0.2″ (∼25 pc) resolution. NGC 5506 is ...a luminous (bolometric luminosity of ∼10
44
erg s
−1
) nearby (26 Mpc) Seyfert galaxy, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS). We modelled the CO(3 − 2) kinematics with
3D
B
AROLO
, revealing a rotating and outflowing cold gas ring within the central 1.2 kpc. We derived an integrated cold molecular gas mass outflow rate for the ring of ∼8
M
⊙
yr
−1
. We fitted the optical emission lines with a maximum of two Gaussian components to separate rotation from non-circular motions. We detected high OIII
λ
5007 projected velocities (up to ∼1000 km s
−1
) at the active galactic nucleus (AGN) position, decreasing with radius to an average ∼330 km s
−1
around ∼350 pc. We also modelled the OIII gas kinematics with a non-parametric method, estimating the ionisation parameter and electron density in every spaxel, from which we derived an ionised mass outflow rate of 0.076
M
⊙
yr
−1
within the central 1.2 kpc. Regions of high CO(3 − 2) velocity dispersion, extending to projected distances of ∼350 pc from the AGN, appear to be the result from the interaction of the AGN wind with molecular gas in the galaxy’s disc. Additionally, we find the ionised outflow to spatially correlate with radio and soft X-ray emission in the central kiloparsec. We conclude that the effects of AGN feedback in NGC 5506 manifest as a large-scale ionised wind interacting with the molecular disc, resulting in outflows extending to radial distances of 610 pc.
High signal-to-noise, representative spectra of star-forming galaxies at z ~ 2, obtained via stacking, reveal a high-velocity component underneath the narrow H Delta *a and N II emission lines. When ...modeled as a single Gaussian, this broad component has FWHM 1500 km s-1; when modeled as broad wings on the H Delta *a and N II features, it has FWHM 500 km s-1. This feature is preferentially found in the more massive and more rapidly star-forming systems, which also tend to be older and larger galaxies. We interpret this emission as evidence of either powerful starburst-driven galactic winds or active supermassive black holes (SMBHs). If galactic winds are responsible for the broad emission, the observed luminosity and velocity of this gas imply mass outflow rates comparable to the star formation rate. On the other hand, if the broad-line regions of active black holes account for the broad feature, the corresponding black holes masses are estimated to be an order of magnitude lower than those predicted by local scaling relations, suggesting a delayed assembly of SMBHs with respect to their host bulges.
Context.
The
M
BH
–
σ
⋆
relation is considered a result of coevolution between the host galaxies and their supermassive black holes. For elliptical bulge hosting inactive galaxies, this relation is ...well established, but there is still discussion concerning whether active galaxies follow the same relation.
Aims.
In this paper, we estimate black hole masses for a sample of 19 local luminous active galactic nuclei (AGNs; LLAMA) to test their location on the
M
BH
–
σ
⋆
relation. In addition, we test how robustly we can determine the stellar velocity dispersion in the presence of an AGN continuum and AGN emission lines, and as a function of signal-to-noise ratio.
Methods.
Supermassive black hole masses (
M
BH
) were derived from the broad-line-based relations for H
α
, H
β
, and Pa
β
emission line profiles for Type 1 AGNs. We compared the bulge stellar velocity dispersion (
σ
⋆
) as determined from the Ca II triplet (CaT) with the dispersion measured from the near-infrared CO (2-0) absorption features for each AGN and find them to be consistent with each other. We applied an extinction correction to the observed broad-line fluxes and we corrected the stellar velocity dispersion by an average rotation contribution as determined from spatially resolved stellar kinematic maps.
Results.
The H
α
-based black hole masses of our sample of AGNs were estimated in the range 6.34 ≤ log
M
BH
≤ 7.75
M
⊙
and the
σ
⋆CaT
estimates range between 73 ≤
σ
⋆CaT
≤ 227 km s
−1
. From the so-constructed
M
BH
−
σ
⋆
relation for our Type 1 AGNs, we estimate the black hole masses for the Type 2 AGNs and the inactive galaxies in our sample.
Conclusions.
We find that our sample of local luminous AGNs is consistent with the
M
BH
–
σ
⋆
relation of lower luminosity AGNs and inactive galaxies, after correcting for dust extinction and the rotational contribution to the stellar velocity dispersion.
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