154 research outputs found
Influence of star-forming galaxy selection on the galaxy main sequence
This work aims to determine how the galaxy main sequence (MS) changes using
seven different commonly used methods to select the star-forming galaxies
within VIPERS data over . The form and redshift evolution of
the MS will then be compared between selection methods. The star-forming
galaxies were selected using widely known methods: a specific star-formation
rate (sSFR), Baldwin, Phillips and Terlevich (BPT) diagram, 4000\AA\ spectral
break (D4000) cut and four colour-colour cuts: NUVrJ, NUVrK, u-r, and UVJ. The
main sequences were then fitted for each of the seven selection methods using a
Markov chain Monte Carlo forward modelling routine, fitting both a linear main
sequence and a MS with a high-mass turn-over to the star-forming galaxies. This
was done in four redshift bins of , ,
, and . The slopes of all star-forming
samples were found to either remain constant or increase with redshift, and the
scatters were approximately constant. There is no clear redshift dependency of
the presence of a high-mass turn-over for the majority of samples, with the
NUVrJ and NUVrK being the only samples with turn-overs only at low redshift. No
samples have turn-overs at all redshifts. Star-forming galaxies selected with
sSFR and u-r are the only samples to have no high-mass turn-over in all
redshift bins. The normalisation of the MS increases with redshift, as
expected. The scatter around the MS is lower than the 0.3~dex
typically seen in MS studies for all seven samples. The lack, or presence, of a
high-mass turn-over is at least partially a result of the method used to select
star-forming galaxies. However, whether a turn-over should be present or not is
unclear.Comment: 20 pages, 3 appendices, 14 figures, 5 tables, accepted for
publication in Astronomy & Astrophysic
Superintegrability with third order integrals of motion, cubic algebras and supersymmetric quantum mechanics I:Rational function potentials
We consider a superintegrable Hamiltonian system in a two-dimensional space
with a scalar potential that allows one quadratic and one cubic integral of
motion. We construct the most general cubic algebra and we present specific
realizations. We use them to calculate the energy spectrum. All classical and
quantum superintegrable potentials separable in Cartesian coordinates with a
third order integral are known. The general formalism is applied to quantum
reducible and irreducible rational potentials separable in Cartesian
coordinates in E2. We also discuss these potentials from the point of view of
supersymmetric and PT-symmetric quantum mechanics.Comment: 33 pages, references added, misprints correcte
The VIPERS Multi-Lambda Survey. II. Diving with massive galaxies in 22 square degrees since z = 1.5
We investigate the evolution of the galaxy stellar mass function (SMF) and
stellar mass density from redshift z=0.2 to z=1.5 of a <22-selected
sample with highly reliable photometric redshifts and over an unprecedentedly
large area. Our study is based on NIR observations carried out with WIRCam at
CFHT over the footprint of the VIPERS spectroscopic survey and benefits from
the high quality optical photometry from the CFHTLS and UV observations with
the GALEX satellite. The accuracy of our photometric redshifts is <
0.03 and 0.05 for the bright (22.5) samples,
respectively. The SMF is measured with ~760,000 galaxies down to =22 and
over an effective area of ~22.4 deg, the latter of which drastically
reduces the statistical uncertainties (i.e. Poissonian error & cosmic
variance). We point out the importance of a careful control of the photometric
calibration, whose impact becomes quickly dominant when statistical
uncertainties are reduced, which will be a major issue for future generation of
cosmological surveys with, e.g. EUCLID or LSST. By exploring the rest-frame
(NUV-r) vs (r-) color-color diagram separating star-forming and quiescent
galaxies, (1) we find that the density of very massive log() >
11.5 galaxies is largely dominated by quiescent galaxies and increases by a
factor 2 from z~1 to z~0.2, which allows for additional mass assembly via dry
mergers, (2) we confirm a scenario where star formation activity is impeded
above a stellar mass log() = 10.640.01, a value that
is found to be very stable at 0.2 < z < 1.5, (3) we discuss the existence of a
main quenching channel that is followed by massive star-forming galaxies, and
finally (4) we characterise another quenching mechanism required to explain the
clear excess of low-mass quiescent galaxies observed at low redshift.Comment: 22 pages, 20 figures. Accepted for publication in A&A. Version to be
publishe
The VIPERS Multi-Lambda Survey. I. UV and NIR Observations, multi-color catalogues and photometric redshifts
We present observations collected in the CFHTLS-VIPERS region in the
ultraviolet (UV) with the GALEX satellite (far and near UV channels) and the
near infrared with the CFHT/WIRCam camera (-band) over an area of 22 and
27 deg, respectively. The depth of the photometry was optimized to measure
the physical properties (e.g., SFR, stellar masses) of all the galaxies in the
VIPERS spectroscopic survey. The large volume explored by VIPERS will enable a
unique investigation of the relationship between the galaxy properties and
their environment (density field and cosmic web) at high redshift (0.5 < z <
1.2). In this paper, we present the observations, the data reductions and the
build-up of the multi-color catalogues. The CFHTLS-T0007 (gri-{\chi}^2) images
are used as reference to detect and measure the -band photometry, while
the T0007 u-selected sources are used as priors to perform the GALEX photometry
based on a dedicated software (EMphot). Our final sample reaches ~25
(at 5{\sigma}) and ~22 (at 3{\sigma}). The large spectroscopic sample
(~51,000 spectroscopic redshifts) allows us to highlight the robustness of our
star/galaxy separation, and the reliability of our photometric redshifts with a
typical accuracy 0.04 and a catastrophic failure rate {\eta} <
2% down to i~23. We present various tests on the band completeness and
photometric redshift accuracy by comparing with existing, overlapping deep
photometric catalogues. Finally, we discuss the BzK sample of passive and
active galaxies at high redshift and the evolution of galaxy morphology in the
(NUV-r) vs (r-K_s) diagram at low redshift (z < 0.25) thanks to the high image
quality of the CFHTLS. The images, catalogues and photometric redshifts for 1.5
million sources (down to 25 or 22) are released and
available at this URL: http://cesam.lam.fr/vipers-mls/Comment: 14 pages, 16 figures. Accepted for publication in A&A. Version to be
publishe
The galaxy-halo connection from a joint lensing, clustering and abundance analysis in the CFHTLenS/VIPERS field
We present new constraints on the relationship between galaxies and their
host dark matter halos, measured from the location of the peak of the
stellar-to-halo mass ratio (SHMR), up to the most massive galaxy clusters at
redshift and over a volume of nearly 0.1~Gpc. We use a unique
combination of deep observations in the CFHTLenS/VIPERS field from the near-UV
to the near-IR, supplemented by secure spectroscopic redshifts,
analysing galaxy clustering, galaxy-galaxy lensing and the stellar mass
function. We interpret our measurements within the halo occupation distribution
(HOD) framework, separating the contributions from central and satellite
galaxies. We find that the SHMR for the central galaxies peaks at with an amplitude of ,
which decreases to for massive halos (). Compared to central galaxies only, the total SHMR (including
satellites) is boosted by a factor 10 in the high-mass regime (cluster-size
halos), a result consistent with cluster analyses from the literature based on
fully independent methods. After properly accounting for differences in
modelling, we have compared our results with a large number of results from the
literature up to : we find good general agreement, independently of the
method used, within the typical stellar-mass systematic errors at low to
intermediate mass () and the statistical
errors above. We have also compared our SHMR results to semi-analytic
simulations and found that the SHMR is tilted compared to our measurements in
such a way that they over- (under-) predict star formation efficiency in
central (satellite) galaxies.Comment: 31 pages, 18 figures, 4 table. Accepted for publication in MNRAS.
Online material available at http://www.cfhtlens.or
Decoding the IRX-\beta\ dust attenuation relation in star-forming galaxies at intermediate redshift
We aim to understand what drives the IRX-\beta dust attenuation relation at
intermediate redshift (0.5 < z < 0.8) in star-forming galaxies. We investigate
the role of various galaxy properties in shaping this observed relation. We use
robust [O ii] {\lambda}3727, [O iii] {\lambda}{\lambda}4959, 5007, and H\beta
line detections of our statistical sample of 1049 galaxies to estimate the
gas-phase metallicities. We derive key physical properties that are necessary
to study galaxy evolution, such as the stellar masses and the star formation
rates, using the spectral energy distribution fitting tool CIGALE.
Equivalently, we study the effect of galaxy morphology (mainly the S\'ersic
index n and galaxy inclination) on the observed IRX-\beta scatter. We also
investigate the role of the environment in shaping dust attenuation in our
sample. We find a strong correlation of the IRX-\beta relation on gas-phase
metallicity in our sample, and also strong correlation with galaxy compactness
characterized by the S\'ersic indexes. Correlations are also seen with stellar
masses, specific star formation rates and the stellar ages of our sources.
Metallicity strongly correlates with the IRX-\beta scatter, this also results
from the older stars and higher masses at higher beta values. Galaxies with
higher metallicities show higher IRX and higher beta values. The correlation
with specific dust mass strongly shifts the galaxies away from the IRX-\beta
relation towards lower \b{eta} values. We find that more compact galaxies
witness a larger amount of attenuation than less compact galaxies. There is a
subtle variation in the dust attenuation scatter between edge-on and face-on
galaxies, but the difference is not statistically significant. Galaxy
environments do not significantly affect dust attenuation in our sample of
star-forming galaxies at intermediate redshift.Comment: 14 pages, 13 figures, accepted for publication in A&
CFHTLenS and RCSLenS cross-correlation with Planck lensing detected in fourier and configuration space
We measure the cross-correlation signature between the Planck cosmic microwave background (CMB) lensing map and the weak lensing observations from both the Red-sequence Cluster Lensing Survey and the CanadaâFranceâHawaii Telescope Lensing Survey. In addition to a Fourier analysis, we include the first configuration-space detection, based on the estimators ăÎșCMBÎșgală and ăÎșCMBÎłtă. Combining 747.2 deg2 from both surveys, we find a detection significance that exceeds 4.2Ï in both Fourier- and configuration-space analyses. Scaling the predictions by a free parameter A, we obtain APlanckCFHT=0.68±0.31 and APlanckRCS=1.31±0.33â . In preparation for the next generation of measurements similar to these, we quantify the impact of different analysis choices on these results. First, since none of these estimators probes the exact same dynamical range, we improve our detection by combining them. Secondly, we carry out a detailed investigation on the effect of apodization, zero-padding and mask multiplication, validated on a suite of high-resolution simulations, and find that the latter produces the largest systematic bias in the cosmological interpretation. Finally, we show that residual contamination from intrinsic alignment and the effect of photometric redshift error are both largely degenerate with the characteristic signal from massive neutrinos, however the signature of baryon feedback might be easier to distinguish. The three lensing data sets are publicly available
CFHTLenS and RCSLenS cross-correlation with Planck lensing detected in fourier and configuration space
We measure the cross-correlation signature between the Planck cosmic microwave background (CMB) lensing map and the weak lensing observations from both the Red-sequence Cluster Lensing Survey and the CanadaâFranceâHawaii Telescope Lensing Survey. In addition to a Fourier analysis, we include the first configuration-space detection, based on the estimators ăÎșCMBÎșgală and ăÎșCMBÎłtă. Combining 747.2 deg2 from both surveys, we find a detection significance that exceeds 4.2Ï in both Fourier- and configuration-space analyses. Scaling the predictions by a free parameter A, we obtain APlanckCFHT=0.68±0.31 and APlanckRCS=1.31±0.33â . In preparation for the next generation of measurements similar to these, we quantify the impact of different analysis choices on these results. First, since none of these estimators probes the exact same dynamical range, we improve our detection by combining them. Secondly, we carry out a detailed investigation on the effect of apodization, zero-padding and mask multiplication, validated on a suite of high-resolution simulations, and find that the latter produces the largest systematic bias in the cosmological interpretation. Finally, we show that residual contamination from intrinsic alignment and the effect of photometric redshift error are both largely degenerate with the characteristic signal from massive neutrinos, however the signature of baryon feedback might be easier to distinguish. The three lensing data sets are publicly available
Darboux Transformations for SUSY Integrable Systems
Several types of Darboux transformations for supersymmetric integrable
systems such as the Manin-Radul KdV, Mathieu KdV and SUSY sine-Gordon equations
are considered. We also present solutions such as supersolitons and superkinks.Comment: 13 pages. LaTeX209 with LamuPhys and EPSF packages, 3 figures.
Contribution to the proceedings of the "Integrable Models and Supersymmetry"
meeting held at Chicago on July'9
The VIMOS Public Extragalactic Redshift Survey (VIPERS): PCA-based automatic cleaning and reconstruction of survey spectra
Identifying spurious reduction artefacts in galaxy spectra is a challenge for
large surveys. We present an algorithm for identifying and repairing residual
spurious features in sky-subtracted galaxy spectra with application to the
VIPERS survey. The algorithm uses principal component analysis (PCA) applied to
the galaxy spectra in the observed frame to identify sky line residuals
imprinted at characteristic wavelengths. We further model the galaxy spectra in
the rest-frame using PCA to estimate the most probable continuum in the
corrupted spectral regions, which are then repaired. We apply the method to
90,000 spectra from the VIPERS survey and compare the results with a subset
where careful editing was performed by hand. We find that the automatic
technique does an extremely good job in reproducing the time-consuming manual
cleaning and does it in a uniform and objective manner across a large data
sample. The mask data products produced in this work are released together with
the VIPERS second public data release (PDR-2).Comment: Find the VIPERS data release at http://vipers.inaf.i
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