35 research outputs found
The KMOS3D Survey: Rotating Compact Star-forming Galaxies and the Decomposition of Integrated Line Widths
Using integral field spectroscopy, we investigate the kinematic properties of 35 massive centrally dense and compact star-forming galaxies (SFGs; logM[Ṁ] = 11.1, log (σ 1kpc[Ṁ kpc-2]) > 9.5 log (M∗/re1.5 (Ṁ kpc1.5])> 10.3) at z ∼ 0.7-3.7within 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 1DUMMYα line widths, 75400 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 lineof-sight gas velocity dispersions from KMOS3Dare best approximated by a linear combination of their rotation and turbulent velocities with a lesser but still significant contribution from galactic-scale winds. The 1DUMMYα exponential disk sizes of compact SFGs are, on average, 2.5 ± 0.2 kpc, 1-2 × the continuum sizes, in agreement with previous work. The compact SFGs have a 1.4 × higher 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.DJW and MF acknowledge
the support of the Deutsche Forschungsgemeinschaft via
Project IDs 3871/1-1 and 3871/1-2. EW acknowledges the
support of ASTRO 3D funding for the writing retreat used to
bring this paper to completion. Parts of this research were
conducted by the Australian Research Council Centre of
Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO
3D) through project number CE170100013
Kiloparsec Scale Properties of Star Formation Driven Outflows at z~ 2.3 in the SINS/zC-SINF AO Survey
We investigate the relationship between star formation activity and outflow properties on kiloparsec scales in a sample of 28 star-forming galaxies at z ~ 2–2.6, using adaptive optics assisted integral field observations from SINFONI on the Very Large Telescope. The narrow and broad components of the Hα emission are used to simultaneously determine the local star formation rate surface density (), and the outflow velocity and mass outflow rate , respectively. We find clear evidence for faster outflows with larger mass loading factors at higher . The outflow velocities scale as ∝ 0.34±0.10, which suggests that the outflows may be driven by a combination of mechanical energy released by supernova explosions and stellar winds, as well as radiation pressure acting on dust grains. The majority of the outflowing material does not have sufficient velocity to escape from the galaxy halos, but will likely be re-accreted and contribute to the chemical enrichment of the galaxies. In the highest regions the outflow component contains an average of ~45% of the Hα flux, while in the lower regions only ~10% of the Hα flux is associated with outflows. The mass loading factor, η = /SFR, is positively correlated with but is relatively low even at the highest : η lesssim 0.5 × (380 cm−3/n e ). This may be in tension with the η gsim 1 required by cosmological simulations, unless a significant fraction of the outflowing mass is in other gas phases and has sufficient velocity to escape the galaxy halos.S.T. is supported by the Smithsonian Astrophysical Observatory through the CfA Fellowship
The SINS/zC-SINF survey of z~2 galaxy kinematics: Outflow properties
Based on SINFONI Ha, [NII] and [SII] AO data of 30 z \sim 2 star-forming
galaxies (SFGs) from the SINS and zcSINF surveys, we find a strong correlation
of the Ha broad flux fraction with the star formation surface density of the
galaxy, with an apparent threshold for strong outflows occurring at 1 Msun
yr^-1 kpc^-2. Above this threshold, we find that SFGs with logm_\ast>10 have
similar or perhaps greater wind mass loading factors (eta = Mdotout/SFR) and
faster outflow velocities than lower mass SFGs. This trend suggests that the
majority of outflowing gas at z \sim 2 may derive from high-mass SFGs, and that
the z \sim 2 mass-metallicity relation is driven more by dilution of enriched
gas in the galaxy gas reservoir than by the efficiency of outflows. The mass
loading factor is also correlated with the SFR and inclination, such that more
star-forming and face-on galaxies launch more powerful outflows. For galaxies
that have evidence for strong outflows, we find that the broad emission is
spatially extended to at least the half-light radius (\sim a few kpc). 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. Using the ratio of the [SII]
doublet in a broad and narrow component, we find that outflowing gas has a
density of \sim10-100 cm^-3, significantly less than that of the star forming
gas (600 cm^-3).Comment: 7 pages, 3 figures, accepted by Ap
Millimeter Mapping at z~ 1: Dust-obscured Bulge Building and Disk Growth
A randomly chosen star in today's universe is most likely to live in a galaxy with stellar mass between the Milky Way and Andromeda. It remains uncertain, however, how the structural evolution of these bulge-disk systems proceeded. Most of the unobscured star formation we observe by building Andromeda progenitor s at 0.7 < z < 1.5 occurs in disks, but gsim90% of their star formation is reprocessed by dust and remains unaccounted for. Here we map rest-500 μm dust continuum emission in an Andromeda progenitor at z = 1.25 to probe where it is growing through dust-obscured star formation. Combining resolved dust measurements from the NOthern Extended Millimeter Array interferometer with Hubble Space Telescope Hα maps and multicolor imaging (including new data from the Hubble Deep UV Legacy Survey, HDUV), we find a bulge growing by dust-obscured star formation: while the unobscured star formation is centrally suppressed, the dust continuum is centrally concentrated, filling the ring-like structure that is evident in the Hα and UV emission. Reflecting this, the dust emission is more compact than the optical/UV tracers of star formation with r e (dust) = 3.4 kpc, r e (Hα)/r e (dust) = 1.4, and r e (UV)/r e (dust) = 1.8. Crucially, however, the bulge and disk of this galaxy are building simultaneously; although the dust emission is more compact than the rest-optical emission (r e (optical)/r e (dust) = 1.4), it is somewhat less compact than the stellar mass (r e (M *)/r e (dust) = 0.9). Taking the rest-500 μm emission as a tracer, the expected structural evolution can be accounted for by star formation: it will grow in size by Δr e /ΔM * ~ 0.3 and in central surface density by ΔΣcen/ΔM * ~ 0.9. Finally, our observations are consistent with a picture in which merging and disk instabilities drive gas to the center of galaxies, boosting global star formation rates above the main sequence and building bulges
The KMOS3D Survey: Demographics and Properties of Galactic Outflows at z=0.6-2.7
We present a census of ionized gas outflows in 599 normal galaxies at redshift 0.6 < z < 2.7, mostly based on integral field spectroscopy of H alpha, [N II], and [S II] line emission. The sample fairly homogeneously covers the main sequence of star-forming galaxies with masses 9.0 < log(M-*/M-circle dot) < 11.7, and probes into the regimes of quiescent galaxies and starburst outliers. About one-third exhibits the high-velocity component indicative of outflows, roughly equally split into winds driven by star formation (SF) and active galactic nuclei (AGNs). The incidence of SF-driven winds correlates mainly with SF properties. These outflows have typical velocities of similar to 450 km s(-1), local electron densities of n(e) similar to 380 cm(-3), modest mass loading factors of similar to 0.1-0.2 at all galaxy masses, and energetics compatible with momentum driving by young stellar populations. The SF-driven winds may escape from log(M-*/M-circle dot) less than or similar to 10.3 galaxies, but substantial mass, momentum, and energy in hotter and colder outflow phases seem required to account for low galaxy formation efficiencies in the low-mass regime. Faster AGN-driven outflows (similar to 1000-2000 km s(-1)) are commonly detected above log(M-*/M-circle dot) similar to 10.7, in up to similar to 75% of log(M-*/M-circle dot) greater than or similar to 11.2 galaxies. The incidence, strength, and velocity of AGN-driven winds strongly correlates with stellar mass and central concentration. Their outflowing ionized gas appears denser (n(e) similar to 1000 cm(-3)), and possibly compressed and shock-excited. These winds have comparable mass loading factors as the SF-driven winds but carry similar to 10 (similar to 50) times more momentum (energy). The results confirm our previous findings of high-duty-cycle, energy-driven outflows powered by AGN above the Schechter mass, which may contribute to SF quenching.E.S.W. and J.T.M. acknowledge
support by the Australian Research Council Center of
Excellence for All Sky Astrophysics in Three Dimensions
(ASTRO 3D), through project number CE170100013. D.J.W.
and M.F. acknowledge the support of the Deutsche Forschungsgemeinschaft via Project ID 3871/1-1 and 3871/1-2.
G.B.B. acknowledges support from the Cosmic Dawn Center,
which is funded by the Danish National Research Foundation
The 3D-HST Survey: <i>Hubble Space Telescope</i> WFC3/G141 Grism Spectra, Redshifts, and Emission Line Measurements for ~ 100,000 Galaxies
We present reduced data and data products from the 3D-HST survey, a 248-orbit Treasury program. The survey obtained WFC3 G141 grism spectroscopy in four of the five CANDELS fields: AEGIS, COSMOS, GOODS-S, and UDS, along with WFC3 imaging, parallel ACS G800L spectroscopy, and parallel imaging. In a previous paper, we presented photometric catalogs in these four fields and in GOODS-N, the fifth CANDELS field. Here we describe and present the WFC3 G141 spectroscopic data, again augmented with data from GO-1600 in GOODS-N (PI: B. Weiner). We developed software to automatically and optimally extract interlaced two-dimensional (2D) and one-dimensional (1D) spectra for all objects in the Skelton et al. (2014) photometric catalogs. The 2D spectra and the multi-band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxies explicitly into account. The resulting catalog has redshifts and line strengths (where available) for 22,548 unique objects down to (79,609 unique objects down to ). Of these, 5459 galaxies are at and 9621 are at , where Hα falls in the G141 wavelength coverage. The typical redshift error for galaxies is , i.e., one native WFC3 pixel. The limit for emission line fluxes of point sources is erg . All 2D and 1D spectra, as well as redshifts, line fluxes, and other derived parameters, are publicly available
Cross-calibration of CO- versus dust-based gas masses and assessment of the <i>dynamical </i>mass budget in <i>Herschel</i>-SDSS Stripe82 galaxies
We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22μm) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500μm). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the Hi reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for
Cross-calibration of CO- versus dust-based gas masses and assessment of the dynamical mass budget in Herschel-SDSS Stripe82 galaxies
We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22 μ m) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500 μ m). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the HI reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for
Ionized and Molecular Gas Kinematics in a z=1.4 Star-forming Galaxy
We present deep observations of a z = 1.4 massive, star-forming galaxy (SFG) in molecular and ionized gas at comparable spatial resolution (CO 3–2, NOrthern Extended Millimeter Array (NOEMA); Hα, Large Binocular Telescope (LBT)). The kinematic tracers agree well, indicating that both gas phases are subject to the same gravitational potential and physical processes affecting the gas dynamics. We combine the one-dimensional velocity and velocity dispersion profiles in CO and Hα to forward-model the galaxy in a Bayesian framework, combining a thick exponential disk, a bulge, and a dark matter halo. We determine the dynamical support due to baryons and dark matter, and find a dark matter fraction within one effective radius of . Our result strengthens the evidence for strong baryon-dominance on galactic scales of massive z ~ 1–3 SFGs recently found based on ionized gas kinematics alone