We make publicly available a catalog of calibrated environmental measures for galaxies in the five 3D-Hubble Space Telescope (HST)/CANDELS deep fields. Leveraging the spectroscopic and grism ...redshifts from the 3D-HST survey, multiwavelength photometry from CANDELS, and wider field public data for edge corrections, we derive densities in fixed apertures to characterize the environment of galaxies brighter than mag in the redshift range . By linking observed galaxies to a mock sample, selected to reproduce the 3D-HST sample selection and redshift accuracy, each 3D-HST galaxy is assigned a probability density function of the host halo mass, and a probability that it is a central or a satellite galaxy. The same procedure is applied to a z = 0 sample selected from Sloan Digital Sky Survey. We compute the fraction of passive central and satellite galaxies as a function of stellar and halo mass, and redshift, and then derive the fraction of galaxies that were quenched by environment specific processes. Using the mock sample, we estimate that the timescale for satellite quenching is it is longer at lower stellar mass or lower redshift, but remarkably independent of halo mass. This indicates that, in the range of environments commonly found within the 3D-HST sample ( ), satellites are quenched by exhaustion of their gas reservoir in the absence of cosmological accretion. We find that the quenching times can be separated into a delay phase, during which satellite galaxies behave similarly to centrals at fixed stellar mass, and a phase where the star formation rate drops rapidly ( Gyr), as shown previously at z = 0. We conclude that this scenario requires satellite galaxies to retain a large reservoir of multi-phase gas upon accretion, even at high redshift, and that this gas sustains star formation for the long quenching times observed.
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 Hα, 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 ⊙) < 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 ∼450 km s−1, local electron densities of n e ∼ 380 cm−3, modest mass loading factors of ∼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 ⊙) ≲ 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 (∼1000–2000 km s−1) are commonly detected above log(M */M ⊙) ∼ 10.7, in up to ∼75% of log(M */M ⊙) ≳ 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 ∼ 1000 cm−3), and possibly compressed and shock-excited. These winds have comparable mass loading factors as the SF-driven winds but carry ∼10 (∼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.
We present the completed KMOS3D survey, an integral field spectroscopic survey of 739 \(\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 9\) galaxies at 0.6 < z < 2.7 using the K-band Multi Object ...Spectrograph (KMOS) at the Very Large Telescope. The KMOS3D survey provides a population-wide census of kinematics, star formation, outflows, and nebular gas conditions both on and off the star-forming galaxy main sequence through the spatially resolved and integrated properties of Hα, N ii, and S ii emission lines. We detect Hα emission for 91% of galaxies on the main sequence of star formation and 79% overall. The depth of the survey has allowed us to detect galaxies with star formation rates below 1 M ⊙ yr−1, as well as to resolve 81% of detected galaxies with ≥3 resolution elements along the kinematic major axis. The detection fraction of Hα is a strong function of both color and offset from the main sequence, with the detected and nondetected samples exhibiting different spectral energy distribution shapes. Comparison of Hα and UV+IR star formation rates reveal that dust attenuation corrections may be underestimated by 0.5 dex at the highest masses (\(\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 10.5\)). We confirm our first year results of a high rotation-dominated fraction (monotonic velocity gradient and v rot/\({\sigma }_{0}\gt \sqrt{3.36}\)) of 77% for the full KMOS3D sample. The rotation-dominated fraction is a function of both stellar mass and redshift, with the strongest evolution measured over the redshift range of the survey for galaxies with \(\mathrm{log}({M}_{\star }/{M}_{\odot })\lt 10.5\). With this paper, we include a final data release of all 739 observed objects (http://www.mpe.mpg.de/ir/KMOS3D).
We study a set of 3319 galaxies in the redshift interval 0.04 < z < 0.15 with far-infrared (FIR) coverage from the Herschel Stripe 82 survey (HerS), and emission-line measurements, redshifts, stellar ...masses and star formation rates (SFRs) from the Sloan Digital Sky Survey (SDSS) (DR7) MPA/JHU data base. About 40 per cent of the sample are detected in the Herschel/SPIRE 250 μm band. Total infrared (TIR) luminosities derived from HerS and Wide-field Infrared Survey Explorer (WISE) photometry allow us to compare infrared and optical estimates of SFR with unprecedented statistics for diverse classes of galaxies. We find excellent agreement between TIR-derived and emission line-based SFRs for H ii galaxies. Other classes, such as active galaxies and evolved galaxies, exhibit systematic discrepancies between optical and TIR SFRs. We demonstrate that these offsets are attributable primarily to survey biases and the large intrinsic uncertainties of the Dn
4000- and colour-based optical calibrations used to estimate the SDSS SFRs of these galaxies. Using a classification scheme which expands upon popular emission-line methods, we demonstrate that emission-line galaxies with uncertain classifications include a population of massive, dusty, metal-rich star-forming systems that are frequently neglected in existing studies. We also study the capabilities of infrared selection of star-forming galaxies. FIR selection reveals a substantial population of galaxies dominated by cold dust which are missed by the long-wavelength WISE bands. Our results demonstrate that Herschel large-area surveys offer the means to construct large, relatively complete samples of local star-forming galaxies with accurate estimates of SFR that can be used to study the interplay between nuclear activity and star formation.
Abstract Background context The evidence-based clinical guideline on the diagnosis and treatment of degenerative lumbar spinal stenosis by the North American Spine Society (NASS) provides ...evidence-based recommendations to address key clinical questions surrounding the diagnosis and treatment of degenerative lumbar spinal stenosis. The guideline is intended to reflect contemporary treatment concepts for symptomatic degenerative lumbar spinal stenosis as reflected in the highest quality clinical literature available on this subject as of July 2010. The goals of the guideline recommendations are to assist in delivering optimum efficacious treatment and functional recovery from this spinal disorder. Purpose Provide an evidence-based educational tool to assist spine care providers in improving quality and efficiency of care delivered to patients with degenerative lumbar spinal stenosis. Study design Systematic review and evidence-based clinical guideline. Methods This report is from the Degenerative Lumbar Spinal Stenosis Work Group of the NASS's Evidence-Based Clinical Guideline Development Committee. The work group consisted of multidisciplinary spine care specialists trained in the principles of evidence-based analysis. The original guideline, published in 2006, was carefully reviewed. A literature search addressing each question and using a specific search protocol was performed on English language references found in MEDLINE, EMBASE (Drugs and Pharmacology), and four additional, evidence-based, databases to identify articles published since the search performed for the original guideline. The relevant literature was then independently rated by a minimum of three physician reviewers using the NASS-adopted standardized levels of evidence. An evidentiary table was created for each of the questions. Final recommendations to answer each clinical question were arrived at via work group discussion, and grades were assigned to the recommendations using standardized grades of recommendation. In the absence of Levels I to IV evidence, work group consensus statements have been developed using a modified nominal group technique, and these statements are clearly identified as such in the guideline. Results Sixteen key clinical questions were assessed, addressing issues of natural history, diagnosis, and treatment of degenerative lumbar spinal stenosis. The answers are summarized in this document. The respective recommendations were graded by the strength of the supporting literature that was stratified by levels of evidence. Conclusions A clinical guideline for degenerative lumbar spinal stenosis has been updated using the techniques of evidence-based medicine and using the best available clinical evidence to aid both practitioners and patients involved with the care of this condition. The entire guideline document, including the evidentiary tables, suggestions for future research, and all references, will be available electronically at the NASS Web site ( www.spine.org ) and will remain updated on a timely schedule.
Abstract
We analyse age–velocity dispersion relations (AVRs) from kinematics of individual stars in eight Local Group galaxies ranging in mass from Carina (M* ∼ 106 M⊙) to M31 (M* ∼ 1011 M⊙). ...Observationally the σ versus stellar age trends can be interpreted as dynamical heating of the stars by giant molecular clouds, bars/spiral arms or merging subhaloes; alternatively the stars could have simply been born out of a more turbulent interstellar medium (ISM) at high redshift and retain that larger velocity dispersion till present day – consistent with recent integral field unit kinematic studies. To ascertain the dominant mechanism and better understand the impact of instabilities and feedback, we develop models based on observed star formation histories (SFHs) of these Local Group galaxies in order to create an evolutionary formalism that describes the ISM velocity dispersion due to a galaxy's evolving gas fraction. These empirical models relax the common assumption that the stars are born from gas that has constant velocity dispersion at all redshifts. Using only the observed SFHs as input, the ISM velocity dispersion and a mid-plane scattering model fits the observed AVRs of low-mass galaxies without fine tuning. Higher mass galaxies above Mvir ≳ 1011 M⊙ need a larger contribution from latent dynamical heating processes (for example minor mergers), in excess of the ISM model. Using the SFHs, we also find that supernovae feedback does not appear to be a dominant driver of the gas velocity dispersion compared to gravitational instabilities – at least for dispersions σ ≳ 25 km s−1. Together our results point to stars being born with a velocity dispersion close to that of the gas at the time of their formation, with latent dynamical heating operating with a galaxy mass-dependent efficiency. These semi-empirical relations may help constrain the efficiency of feedback and its impact on the physics of disc settling in galaxy formation simulations.
The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band H
α
+ NII imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot ...observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass (
M
*
≃ 10
9.8
M
⊙
) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous H
α
observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness ~10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped ~500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H
2
gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.
We analyze the angular momenta of massive star-forming galaxies (SFGs) at the peak of the cosmic star formation epoch (z~ 0.8-2.6). Our sample of ~360 log(M sub(*)/M sub(middot in circle)) ~ 9.3-11.8 ...SFGs is mainly based on the KMOS super(3D) and SINS/zC-SINF surveys of Halpha kinematics, and collectively provides a representative subset of the massive star-forming population. The inferred halo scale angular momentum distribution is broadly consistent with that theoretically predicted for their dark matter halos, in terms of mean spin parameter left angle bracketlambdaright angle bracket ~ 0.037 and its dispersion (sigma sub(loglambda)~ 0.2). Spin parameters correlate with the disk radial scale and with their stellar surface density, but do not depend significantly on halo mass, stellar mass, or redshift. Our data thus support the long-standing assumption that on average, even at high redshifts, the specific angular momentum of disk galaxies reflects that of their dark matter halos (j sub(d)= j sub(DM)). The lack of correlation between lambda x (j sub(d)/j sub(DM)) and the nuclear stellar density Sigma sub(*)(1 kpc) favors a scenario where disk-internal angular momentum redistribution leads to "compaction" inside massive high-redshift disks. For our sample, the inferred average stellar to dark matter mass ratio is ~2%, consistent with abundance matching results. Including the molecular gas, the total baryonic disk to dark matter mass ratio is ~5% for halos near 10 super(12)M sub(middot in circle), which corresponds to 31% of the cosmologically available baryons, implying that high-redshift disks are strongly baryon dominated.
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.
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