15 research outputs found
CO TullyâFisher relation of star-forming galaxies at = 0.05â0.3
The TullyâFisher relation (TFR) is an empirical relation between galaxy luminosity and rotation velocity. We present here the first TFR of galaxies beyond the local Universe that uses carbon monoxide (CO) as the kinematic tracer. Our final sample includes 25 isolated, non-interacting star-forming galaxies with double-horned or boxy CO integrated line profiles located at redshifts z †0.3, drawn from a larger ensemble of 67 detected objects. The best reverse Ks-band, stellar mass and baryonic mass CO TFRs are, respectively, MKs = (â8.4 ± 2.9)[log ( W50/km sâ1 sin i ) â 2.5] + (â23.5 ± 0.5), log (M/M) = (5.2 ± 3.0)[log ( W50/km sâ1 sin i ) â 2.5] + (10.1 ± 0.5) and log (Mb/M) = (4.9 ± 2.8)[log ( W50/km sâ1 sin i ) â 2.5] + (10.2 ± 0.5), where MKs is the total absolute Ks-band magnitude of the objects, M and Mb their total stellar and baryonic masses, and W50 the width of their line profile at 50 per cent of the maximum. Dividing the sample into different redshift bins and comparing to the TFRs of a sample of local (z = 0) star-forming galaxies from the literature, we find no significant evolution in the slopes and zero-points of the TFRs since z â 0.3, this in either luminosity or mass. In agreement with a growing number of CO TFR studies of nearby galaxies, we more generally find that CO is a suitable and attractive alternative to neutral hydrogen (HI). Our work thus provides an important benchmark for future higher redshift CO TFR studies
KURVS: The outer rotation curve shapes and dark matter fractions of star-forming galaxies
We present first results from the KMOS Ultra-deep Rotation Velocity Survey
(KURVS), aimed at studying the outer rotation curves shape and dark matter
content of 22 star-forming galaxies at . These galaxies represent
`typical' star-forming discs at , being located within the
star-forming main sequence and stellar mass-size relation with stellar masses
log. We extract
individual rotation curves out to 4 times the effective radius, on average, or
kpc. Most rotation curves are flat or rising between three- and
six-disc scale radii. Only three objects with dispersion-dominated dynamics
() have declining outer rotation curves at more
than 5 significance. After accounting for seeing and pressure support,
the nine rotation-dominated discs with have
average dark matter fractions of at the effective radius, similar
to local discs. Together with previous observations of star-forming galaxies at
cosmic noon, our measurements suggest a trend of declining dark matter fraction
with increasing stellar mass and stellar mass surface density at the effective
radius. Simulated EAGLE galaxies are in quantitative agreement with
observations up to log, and over-predict the dark matter fraction of galaxies with higher
mass surface densities by a factor of . We conclude that the dynamics
of typical rotationally-supported discs at is dominated by dark
matter from effective radius scales, in broad agreement with cosmological
models. The tension with observations at high stellar mass surface density
suggests that the prescriptions for baryonic processes occurring in the most
massive galaxies (such as bulge growth and quenching) need to be reassessed.Comment: 23 pages, 9 figures. Resubmitted to MNRAS after addressing the
referee's comments. Abstract slightly modified to compile with the arXiv
formattin
From peculiar morphologies to Hubble-type spirals: the relation between galaxy dynamics and morphology in star-forming galaxies at z similar to 1.5
We present an analysis of the gas dynamics of star-forming galaxies at z ⌠1.5 using data from
the KMOS Galaxy Evolution Survey. We quantify the morphology of the galaxies using HST
CANDELS imaging parametrically and non-parametrically. We combine the H α dynamics
from KMOS with the high-resolution imaging to derive the relation between stellar mass (Mâ)
and stellar specific angular momentum (jâ). We show that high-redshift star-forming galaxies at
z ⌠1.5 follow a power-law trend in specific stellar angular momentum with stellar mass similar
to that of local late-type galaxies of the form jâ â M0.53 ± 0.10 â . The highest specific angular
momentum galaxies are mostly disc-like, 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 jâ â Mâ plane and its correlation with both the integrated
dynamical properties of a galaxy (e.g. velocity dispersion, Toomre Qg, H α star formation rate
surface density SFR) and its parametrized rest-frame UV / optical morphology (e.g. Sersic ÂŽ
index, bulge to total ratio, clumpiness, asymmetry, and concentration). We establish that the
position in the jâ â Mâ 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- 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 high-redshift systems are driven by higher star
formation rate surface densities and higher gas fractions leading to a more clumpy interstellar
medium.This work was supported by the Science and Technology Facilities Council (ST/L00075X/1). SG acknowledges the support
of the Science and Technology Facilities Council through grant
ST/N50404X/1 for support. EI acknowledges partial support from
FONDECYT through grant N⊠1171710. We thank the FMOSCOSMOS team for their invaluable contributions to the KGES target
selection. ALT acknowledges support from STFC (ST/L00075X/1
and ST/P000541/1), ERC Advanced Grant DUSTYGAL (321334),
and a Forrest Research Foundation Fellowship. LC is the recipient of
an Australian Research Council Future Fellowship (FT180100066)
funded by the Australian Government. 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
The KMOS Redshift One Spectroscopic Survey (KROSS): The origin of disc turbulence in zâ1 star-forming galaxies
We analyse the velocity dispersion properties of 472 z~0.9 star-forming galaxies observed as part of the KMOS Redshift One Spectroscopic Survey (KROSS). The majority of this sample is rotationally dominated (83 ± 5 per cent with vC/Ï0 > 1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, the median intrinsic velocity dispersion for the final sample is Ï0 =43.2 ± 0.8 kms-1 with a rotational velocity to dispersion ratio of vC/Ï0 =2.6 ± 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 (z~0.05) and an intermediate redshift MUSE sample (z~0.5). 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
First order QED and QCD radiative corrections to Higgs decay into massive fermions
SIGLECNRS RP 171 (332) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
The KMOS galaxy evolution survey (KGES): the angular momentum of star-forming galaxies over the last â10 Gyr
We present the KMOS Galaxy Evolution Survey (KGES), a K-band Multi-Object Spectrograph (KMOS) study of the Hâα and [NâII] emission from 288 K-band-selected galaxies at 1.2 âČ z âČ 1.8, with stellar masses in the range log10(Mâ/Mâ)â9âââ11.5. In this paper, we describe the survey design, present the sample, and discuss the key properties of the KGES galaxies. We combine KGES with appropriately matched samples at lower redshifts from the KMOS Redshift One Spectroscopic Survey (KROSS) and the SAMI Galaxy Survey. Accounting for the effects of sample selection, data quality, and analysis techniques between surveys, we examine the kinematic characteristics and angular momentum content of star-forming galaxies at z â 1.5, â1, and â0. We find that stellar mass, rather than redshift, most strongly correlates with the disc fraction amongst star-forming galaxies at z âČ 1.5, observing only a modest increase in the prevalence of discs between z â 1.5 and z â 0.04 at fixed stellar mass. Furthermore, typical star-forming galaxies follow the same median relation between specific angular momentum and stellar mass, regardless of their redshift, with the normalization of the relation depending more strongly on how disc-like a galaxyâs kinematics are. This suggests that massive star-forming discs form in a very similar manner across the â10âGyr encompassed by our study and that the inferred link between the angular momentum of galaxies and their haloes does not change significantly across the stellar mass and redshift ranges probed in this work
Multi-resolution angular momentum measurements of z ⌠1.5 â 2 star-forming galaxies
We present detailed stellar specific angular momentum (j*) measurements of ten star-forming galaxies at z ⌠1.5 â 2 using both high and low spatial resolution integral field spectroscopic data. We developed a code that simultaneously models the adaptive optics (AO) assisted observations from OSIRIS/SINFONI along with their natural seeing (NS) counterparts from KMOS at spatial resolutions of [0.1 â 0.4] arcsec and [0.6 â 1.0] arcsec respectively. The AO data reveals 2/10 systems to be mergers and for the remaining eight the mean uncertainties ÎÂŻjâ decrease from 49 per cent (NS), and 26.5 per cent (AO), to 16 per cent in the combined analysis. These j* measurements agree within 20 per cent with simple estimates (â jâ~â ) calculated from the Hubble Space Telescope photometry and NS kinematics, however higher resolution kinematics are required to first identify these disks. We find that the choice of surface mass density model and the measurement of effective radius from photometry are the key sources of systematic effects in the measurement of j* between different analyses. Fitting the j* versus M* relations (Fall, 1983) with a fixed power-law slope of ÎČ = 2/3, we find a zero-point consistent with prior NS results at z â„ 1 within âŒ0.3 dex. Finally, we find a âŒ0.38 dex scatter about that relation that remains high despite the AO data so we conclude it is intrinsic to galaxies at z > 1. This compares to a scatter of â€0.2 dex for disks at z â 0 pointing to a settling of the Fall relation with cosmic time
K-CLASH: Strangulation and ram pressure stripping in galaxy cluster members at 0.3 < z < 0.6
Galaxy clusters have long been theorized to quench the star formation of their members. This study uses integral-field unit observations from the K-band MultiObject Spectrograph (KMOS) â Cluster Lensing And Supernova survey with Hubble (CLASH) survey (K-CLASH) to search for evidence of quenching in massive galaxy clusters at redshifts 0.3 < z < 0.6. We first construct mass-matched samples of exclusively star-forming cluster and field galaxies, then investigate the spatial extent of their Hâα emission and study their interstellar medium conditions using emission line ratios. The average ratio of Hâα half-light radius to optical half-light radius (â re,Hα/re,Rcâ ) for all galaxies is 1.14 ± 0.06, showing that star formation is taking place throughout stellar discs at these redshifts. However, on average, cluster galaxies have a smaller re,Hα/re,Rc ratio than field galaxies: â©re,Hα/re,RcâȘ = 0.96 ± 0.09 compared to 1.22 ± 0.08 (smaller at a 98âperâcent credibility level). These values are uncorrected for the wavelength difference between Hâα emission and Rc-band stellar light but implementing such a correction only reinforces our results. We also show that whilst the cluster and field samples follow indistinguishable massâmetallicity (MZ) relations, the residuals around the MZ relation of cluster members correlate with cluster-centric distance; galaxies residing closer to the cluster centre tend to have enhanced metallicities (significant at the 2.6Ï level). Finally, in contrast to previous studies, we find no significant differences in electron number density between the cluster and field galaxies. We use simple chemical evolution models to conclude that the effects of disc strangulation and ram-pressure stripping can quantitatively explain our observations
K-CLASH: spatially resolving star-forming galaxies in field and cluster environments at z â 0.2â0.6
We present the KMOS-CLASH (K-CLASH) survey, a K-band Multi-Object Spectrograph (KMOS) survey, of the spatially resolved gas properties and kinematics of 191 (pre-dominantly blue) H α-detected galaxies at 0.2 âČ z âČ 0.6 in field and cluster environments. K-CLASH targets galaxies in four Cluster Lensing And Supernova survey with Hubble (CLASH) fields in the KMOS IZ-band, over 7 arcmin radius (â2â3âMpc) fields of view. K-CLASH aims to study the transition of star-forming galaxies from turbulent, highly star-forming disc-like and peculiar systems at z â 1â3, to the comparatively quiescent, ordered late-type galaxies at z â 0, and to examine the role of clusters in the build-up of the red sequence since z â 1. In this paper, we describe the K-CLASH survey, present the sample, and provide an overview of the K-CLASH galaxy properties. We demonstrate that our sample comprises star-forming galaxies typical of their stellar masses and epochs, residing both in field and cluster environments. We conclude K-CLASH provides an ideal sample to bridge the gap between existing large integral-field spectroscopy surveys at higher and lower redshifts. We find that star-forming K-CLASH cluster galaxies at intermediate redshifts have systematically lower stellar masses than their star-forming counterparts in the field, hinting at possible âdownsizingâ scenarios of galaxy growth in clusters at these epochs. We measure no difference between the star formation rates of H α-detected, star-forming galaxies in either environment after accounting for stellar mass, suggesting that cluster quenching occurs very rapidly during the epochs probed by K-CLASH, or that star-forming K-CLASH galaxies in clusters have only recently arrived there, with insufficient time elapsed for quenching to have occurred