13 research outputs found
The KMOS Redshift One Spectroscopic Survey (KROSS): the TullyâFisher relation at z ⌠1
We present the stellar mass (M*), and K-corrected K-band absolute magnitude (MK) TullyâFisher relations (TFRs) for subsamples of the 584 galaxies spatially resolved in H α emission by the KMOS Redshift One Spectroscopic Survey (KROSS). We model the velocity field of each of the KROSS galaxies and extract a rotation velocity, V80 at a radius equal to the major axis of an ellipse containing 80 per cent of the total integrated H α flux. The large sample size of KROSS allowed us to select 210 galaxies with well-measured rotation speeds. We extract from this sample a further 56 galaxies that are rotationally supported, using the stringent criterion V80/Ï > 3, where Ï is the flux weighted average velocity dispersion. We find the MK and M* TFRs for this subsample to be MK/mag=(â7.3±0.9)Ă[(log(V80/km sâ1)â2.25]â23.4±0.2MK/mag=(â7.3±0.9)Ă[(logâĄ(V80/km sâ1)â2.25]â23.4±0.2, and log(Mâ/Mâ)=(4.7±0.4)Ă[(log(V80/km sâ1)â2.25]+10.0±0.3logâĄ(Mâ/Mâ)=(4.7±0.4)Ă[(logâĄ(V80/km sâ1)â2.25]+10.0±0.3, respectively. We find an evolution of the M* TFR zero-point of â0.41 ± 0.08 dex over the last âŒ8 billion years. However, we measure no evolution in the MK TFR zero-point over the same period. We conclude that rotationally supported galaxies of a given dynamical mass had less stellar mass at z ⌠1 than the present day, yet emitted the same amounts of K-band light. The ability of KROSS to differentiate, using integral field spectroscopy with KMOS, between those galaxies that are rotationally supported and those that are not explains why our findings are at odds with previous studies without the same capabilities
The evolution of gas-phase metallicity and resolved abundances in star-forming galaxies at z â 0.6-1.8
We present an analysis of the chemical abundance properties of â650 star-forming galaxies at zâââ0.6â1.8. Using integral-field observations from the K-band multi-object spectrograph (KMOS), we quantify the [NâII]/Hâα emission-line ratio, a proxy for the gas-phase oxygen abundance within the interstellar medium. We define the stellar massâmetallicity relation at zâââ0.6â1.0 and zâââ1.2â1.8 and analyse the correlation between the scatter in the relation and fundamental galaxy properties (e.g. Hâα star formation rate, Hâα specific star formation rate, rotation dominance, stellar continuum half-light radius, and Hubble-type morphology). We find that for a given stellar mass, more highly star-forming, larger, and irregular galaxies have lower gas-phase metallicities, which may be attributable to their lower surface mass densities and the higher gas fractions of irregular systems. We measure the radial dependence of gas-phase metallicity in the galaxies, establishing a median, beam smearing corrected, metallicity gradient of ÎZ/ÎR = 0.002â±â0.004âdexâkpcâ1, indicating on average there is no significant dependence on radius. The metallicity gradient of a galaxy is independent of its rest-frame optical morphology, whilst correlating with its stellar mass and specific star formation rate, in agreement with an insideâout model of galaxy evolution, as well as its rotation dominance. We quantify the evolution of metallicity gradients, comparing the distribution of ÎZ/ÎR in our sample with numerical simulations and observations at zâââ0â3. Galaxies in our sample exhibit flatter metallicity gradients than local star-forming galaxies, in agreement with numerical models in which stellar feedback plays a crucial role redistributing metals
The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z â 0.9 galaxies
We present dynamical measurements for 586 Hα detected star-forming galaxies from the KMOS (K-band Multi-Object Spectrograph) Redshift One Spectroscopic Survey (KROSS). The sample represents typical star-forming galaxies at this redshift (z = 0.6â1.0), with a median star formation rate of â7 Mâ yrâ1 and a stellar mass range of logâ(Mâ[Mâ])â9â11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully-Fisher relationship) for our rotationally-dominated sources (VC/Ï0 > 1) has a consistent slope and normalisation as that observed for z = 0 disks. In contrast, the specific angular momentum (jâ; angular momentum divided by stellar mass), is â0.2â0.3 dex lower on average compared to z = 0 disks. The specific angular momentum scales as j s âM 0.6±0.2 â jsâMâ0.6±0.2 , consistent with that expected for dark matter (i.e., j DM âM 2/3 DM jDMâMDM2/3 ). We find that z â 0.9 star-forming galaxies have decreasing specific angular momentum with increasing SĂ©rsic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disk-dominated morphologies. This implies that an angular momentumâmassâmorphology relationship, similar to that observed in local massive galaxies, is already in place by z â 1
The energetics of starburst-driven outflows at z âŒÂ 1 from KMOS
We present an analysis of the gas outflow energetics from KMOS observations of 529 main-sequence star-forming galaxies at z 1 using broad, underlying Hα and forbid- den lines of [Nii] and [Sii]. Based on the stacked spectra for a sample with median star- formation rates and stellar masses of SFR=7Mâ / yr and Mâ =(1.0±0.1)Ă1010Mâ respectively, we derive a typical mass outflow rate of ËMwind =1â4Mâ yrâ1 and a mass loading of ËMwind / SFR=0.2â0.4. By comparing the kinetic energy in the wind with the energy released by supernovae, we estimate a coupling efficiency between the star formation and wind energetics of Ç« 0.03. The mass loading of the wind does not show a strong trend with star-formation rate over the range 2â20Mâ yrâ1, although we identify a trend with stellar mass such that dM/ dt / SFR/M0.26±0.07 â . Finally, the line width of the broad Hα increases with disk circular velocity with a sub-linear scal- ing relation FWHMbroad /v0.21±0.05. As a result of this behavior, in the lowest mass galaxies (Mâ ⌠1010Mâ) most of the gas will be retained, flowing back on to the galaxy disk at later times
From peculiar morphologies to Hubble-type spirals: the relation between galaxy dynamics and morphology in star-forming galaxies at z ⌠1.5
We present an analysis of the gas dynamics of starâforming galaxies at z ⌠1.5 using data from the KMOS Galaxy Evolution Survey (KGES). We quantify the morphology of the galaxies using HSTCANDELS imaging parametrically and non-parametrically. We combine the Hα dynamics from KMOS with the highâresolution imaging to derive the relation between stellar mass (M*) and stellar specific angular momentum (j*). We show that highâredshift starâforming galaxies at z ⌠1.5 follow a power-law trend in specific stellar angular momentum with stellar mass similar to that of local lateâtype galaxies of the form j* â M0.53±0.10ââ . The highest specific angular momentum galaxies are mostly discâlike, although generally, both peculiar morphologies and disc-like systems are found across the sequence of specific angular momentum at a fixed stellar mass. We explore the scatter within the j* â M* plane and its correlation with both the integrated dynamical properties of a galaxy (e.g. velocity dispersion, Toomre Qg, Hα star formation rate surface density ÎŁSFR) and its parameterised rest-frame UV / optical morphology (e.g. SĂ©rsic index, bulge to total ratio, Clumpiness, Asymmetry and Concentration). We establish that the position in the j* â M* plane is strongly correlated with the star-formation surface density and the Clumpiness of the stellar light distribution. Galaxies with peculiar rest-frame UV / optical morphologies have comparable specific angular momentum to disc â dominated galaxies of the same stellar mass, but are clumpier and have higher star-formation rate surface densities. We propose that the peculiar morphologies in highâredshift systems are driven by higher star formation rate surface densities and higher gas fractions leading to a more clumpy inter-stellar medium
The KMOS Redshift One Spectroscopic Survey (KROSS): the origin of disc turbulence in z â 1 star-forming galaxies
We analyse the velocity dispersion properties of 472 zââŒâ0.9 star-forming galaxies observed as part of the KMOS Redshift One Spectroscopic Survey (KROSS). The majority of this sample is rotationally dominated (83 ± 5âperâcent with vC/Ï0â>â1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, the median intrinsic velocity dispersion for the final sample is Ï0â=â43.2 ± 0.8âkmâsâ1 with a rotational velocity to dispersion ratio of vC/Ï0â=â2.6 ± 0.1. To explore the relationship between velocity dispersion, stellar mass, star formation rate, and redshift, we combine KROSS with data from the SAMI survey (zââŒâ0.05) and an intermediate redshift MUSE sample (zââŒâ0.5). Whilst there is, at most, a weak trend between velocity dispersion and stellar mass, at fixed mass there is a strong increase with redshift. At all redshifts, galaxies appear to follow the same weak trend of increasing velocity dispersion with star formation rate. Our results are consistent with an evolution of galaxy dynamics driven by discs that are more gas rich, and increasingly gravitationally unstable, as a function of increasing redshift. Finally, we test two analytic models that predict turbulence is driven by either gravitational instabilities or stellar feedback. Both provide an adequate description of the data, and further observations are required to rule out either model
KROSS-SAMI: A Direct IFS Comparison of the Tully-Fisher Relation Across 8 Gyr Since z â 1
We construct TullyâFisher relations (TFRs), from large samples of galaxies with spatially resolved Hâα emission maps from the K-band Multi-Object Spectrograph (KMOS) Redshift One Spectroscopic Survey (KROSS) at z â 1. We compare these to data from the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph (SAMI) Galaxy Survey at z â 0. We stringently match the data quality of the latter to the former, and apply identical analysis methods and sub-sample selection criteria to both to conduct a direct comparison of the absolute K-band magnitude and stellar mass TFRs at z â 1 and 0. We find that matching the quality of the SAMI data to that of KROSS results in TFRs that differ significantly in slope, zero-point, and (sometimes) scatter in comparison to the corresponding original SAMI relations. These differences are in every case as large as or larger than the differences between the KROSS z â 1 and matched SAMI z â 0 relations. Accounting for these differences, we compare the TFRs at z â 1 and 0. For disc-like, star-forming galaxies we find no significant difference in the TFR zero-points between the two epochs. This suggests the growth of stellar mass and dark matter in these types of galaxies is intimately linked over this â8 Gyr period
Lipocalina associada à gelatinase de neutrófilos (NGAL) e calprotectina no tecido laminar de equinos após obstrução jejunal, tratados ou não com hidrocortisona
A laminite Ă© uma doença podal grave que acomete os equĂdeos, sendo responsĂĄvel por intenso sofrimento. Neste estudo foram pesquisadas a presença de calprotectina por meio da imunoistoquĂmica, e de lipocalina associada Ă gelatinase de neutrĂłfilos (NGAL), por zimografia, no tecido laminar do casco de equinos apĂłs obstrução intestinal. Os animais foram divididos em quatro grupos: Grupo controle (Gc), contendo sete animais normais, sem procedimento cirĂșrgico; Grupo Instrumentado (Gi), contendo cinco animais, os quais passaram por todo o procedimento cirĂșrgico sem sofrerem obstrução intestinal; Grupo NĂŁo Tratado (Gnt), contendo quatro equinos submetidos a obstrução intestinal do jejuno por distensĂŁo de balĂŁo intraluminal, sem tratamento; e Grupo Tratado (Gt), contendo quatro equinos submetidos a obstrução intestinal, e tratados preventivamente com hidrocortisona. Houve imunomarcação de calprotectina em todos os grupos experimentais, com aumento nos equinos do grupo distendido em relação ao Gc. Com relação ao NGAL, houve aumento tambĂ©m do Gnt e do Gi em relação ao Gc. O Gt nĂŁo diferiu dos demais. Conclui-se que a distensĂŁo do intestino delgado pode promover acĂșmulos de leucĂłcitos nos cascos de equinos e que o NGAL Ă© um mĂ©todo viĂĄvel para se detectar infiltração neutrofĂlica em equinos. Novos estudos deverĂŁo ser realizados para se verificar possĂvel benefĂcio anti-inflamatĂłrio da hidrocortisona no casco de equinos com obstrução intestinal