A&A 608, A44 (2017) We carry out a joint analysis of redshift-space distortions and galaxy-galaxy
lensing, with the aim of measuring the growth rate of structure; this is a key
quantity for ...understanding the nature of gravity on cosmological scales and
late-time cosmic acceleration. We make use of the final VIPERS redshift survey
dataset, which maps a portion of the Universe at a redshift of $z \simeq 0.8$,
and the lensing data from the CFHTLenS survey over the same area of the sky. We
build a consistent theoretical model that combines non-linear galaxy biasing
and redshift-space distortion models, and confront it with observations. The
two probes are combined in a Bayesian maximum likelihood analysis to determine
the growth rate of structure at two redshifts $z=0.6$ and $z=0.86$. We obtain
measurements of $f\sigma_8(0.6) = 0.48 \pm 0.12$ and $f\sigma_8(0.86) = 0.48
\pm 0.10$. The additional galaxy-galaxylensing constraint alleviates galaxy
bias and $\sigma_8$ degeneracies, providing direct measurements of
$f(0.6),\sigma_8(0.6) = 0.93 \pm 0.22, 0.52 \pm 0.06$ and
$f(0.86),\sigma_8(0.86) = 0.99 \pm 0.19, 0.48 \pm 0.04$. These measurements
are statistically consistent with a Universe where the gravitational
interactions can be described by General Relativity, although they are not yet
accurate enough to rule out some commonly considered alternatives. Finally, as
a complementary test we measure the gravitational slip parameter, $E_G$ , for
the first time at $z>0.6$. We find values of $\smash{\overline{E}_G}(0.6) =
0.16 \pm 0.09$ and $\smash{\overline{E}_G}(0.86) = 0.09 \pm 0.07$, when $E_G$
is averaged over scales above $3 h^{-1} \rm{Mpc}$. We find that our $E_G$
measurements exhibit slightly lower values than expected for standard
relativistic gravity in a {\Lambda}CDM background, although the results are
consistent within $1-2\sigma$.
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).
We use the full VIPERS redshift survey in combination with SDSS-DR7 to explore the relationships between star-formation history (using d4000), stellar mass and galaxy structure, and how these ...relationships have evolved since z~1. We trace the extents and evolutions of both the blue cloud and red sequence, by fitting double Gaussians to the d4000 distribution of galaxies in narrow stellar mass bins, for four redshift intervals over 0<z<1. This reveals downsizing in star formation, as the high-mass limit of the blue cloud retreats steadily with time from M*~10^11.2 M_sun at z~0.9 to M*~10^10.7 M_sun by the present day. The number density of massive blue-cloud galaxies (M*>10^11 M_sun, d4000<1.55) drops sharply by a factor five between z~0.8 and z~0.5. These galaxies are becoming quiescent at a rate that largely matches the increase in the numbers of massive passive galaxies seen over this period. We examine the size-mass relation of blue cloud galaxies, finding that its high-mass boundary runs along lines of constant M*/r_e or equivalently inferred velocity dispersion. Larger galaxies can continue to form stars to higher stellar masses than smaller galaxies. As blue cloud galaxies approach this high-mass limit, they start to be quenched, their d4000 values increasing to push them towards the green valley. In parallel, their structures change, showing higher Sersic indices and central stellar mass densities. For these galaxies, bulge growth is necessary for them to reach the high-mass limit of the blue cloud and be quenched by internal mechanisms. The blue cloud galaxies that are being quenched at z~0.8 lie along the same size-mass relation as present day quiescent galaxies, and seem the likely progenitors of today's S0s.
Fatty acid profile and bacteriological quality of caiman meat subjected to high hydrostatic pressure Canto, Anna C.V.C.S; Bruno R.C. Costa-LimaauthorDepartamento de Tecnologia de Alimentos, Faculdade de Veterinaria, Universidade Federal Fluminense, Niteroi, 24230-340, Rio de Janeiro, Brazil; Surendranath P. SumanauthorDepartment of Animal and Food Sciences, University of Kentucky, Lexington, KY, 40546, USA ...
2015
Journal Article
We present the first quantitative detection of large-scale filamentary
structure at $z \simeq 0.7$ in the large cosmological volume probed by the
VIMOS Public Extragalactic Redshift Survey (VIPERS). ...We use simulations to show
the capability of VIPERS to recover robust topological features in the galaxy
distribution, in particular the filamentary network. We then investigate how
galaxies with different stellar masses and stellar activities are distributed
around the filaments and find a significant segregation, with the most massive
or quiescent galaxies being closer to the filament axis than less massive or
active galaxies. The signal persists even after down-weighting the contribution
of peak regions. Our results suggest that massive and quiescent galaxies
assemble their stellar mass through successive mergers during their migration
along filaments towards the nodes of the cosmic web. On the other hand,
low-mass star-forming galaxies prefer the outer edge of filaments, a vorticity
rich region dominated by smooth accretion, as predicted by the recent spin
alignment theory. This emphasizes the role of large scale cosmic flows in
shaping galaxy properties.
We use the final data from the VIPERS redshift survey to extract an unparalleled sample of more than 2000 massive M > 10^11 M_sun passive galaxies (MPGs) at redshift 0.5 < z < 1.0, based on their ...NUVrK colours. This enables us to investigate how the population of these objects was built up over cosmic time. We find that the evolution of the number density depends on the galaxy mean surface stellar mass density, Sigma. In particular, dense (Sigma > 2000 M_sun pc^-2) MPGs show a constant comoving number density over this redshift range, whilst this increases by a factor ~ 4 for the least dense objects, defined as having Sigma < 1000 M_sun pc^-2. We estimate stellar ages for the MPG population both fitting the Spectral Energy Distribution (SED) and through the D4000_n index, obtaining results in good agreement. Our findings are consistent with passive ageing of the stellar content of dense MPGs. We show that at any redshift the less dense MPGs are younger than dense ones and that their stellar populations evolve at a slower rate than predicted by passive evolution. This points to a scenario in which the overall population of MPGs was built up over the cosmic time by continuous addition of less dense galaxies: on top of an initial population of dense objects that passively evolves, new, larger, and younger MPGs continuously join the population at later epochs. Finally, we demonstrate that the observed increase in the number density of MPGs is totally accounted for by the observed decrease in the number density of correspondingly massive star forming galaxies (i.e. all the non-passive M > 10^11 M_sun objects). Such systems observed at z ~ 1 in VIPERS, therefore, represent the most plausible progenitors of the subsequent emerging class of larger MPGs.
We trace the evolution and the star formation history of passive galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). We extracted from the VIPERS survey a sample of ...passive galaxies in the redshift range 0.4<z<1.0 and stellar mass range 10<\(log(M_{star}/M_{\odot})\)<12. The sample was selected using an evolving cut in the rest-frame U-V color distribution and additional quality-ensuring cuts. We use the stacked spectra to measure the 4000\(\AA\) break (D4000) and the \(H\delta\) Lick index (\(H\delta_{A}\)) with high precision. We compare the results with a grid of synthetic spectra to constrain the star formation epochs of these galaxies. We characterize the formation redshift-stellar mass relation for intermediate-redshift passive galaxies. We find that at \(z\sim1\) stellar populations in low-mass passive galaxies are younger than in high-mass passive galaxies, similarly to what is observed at the present epoch. Over the full analyzed redshift and stellar mass range, the \(D4000\) index increases with redshift, while \(H\delta_{A}\) gets lower. This implies that the stellar populations are getting older with increasing stellar mass. Comparison to the spectra of passive galaxies in the SDSS survey shows that the shape of the relations of \(D4000\), and \(H\delta_{A}\) with stellar mass has not changed significantly with redshift. Assuming a single burst formation, this implies that high-mass passive galaxies formed their stars at \(z_{form}\sim2\), while low-mass galaxies formed their main stellar population more recently, at \(z_{form}\sim1\). The consistency of these results, obtained using two independent estimator of the formation redshift (\(D4000\) and \(H\delta_{A}\)), further strengthens a scenario in which star formation proceeds from higher- to lower-mass systems as time passes, i.e. what has become known as the 'downsizing' picture.
Gravitational lensing by clusters of galaxies offers a powerful probe of their structure and mass distribution. Deriving a lens magnification map for a galaxy cluster is a classic inversion problem ...and many methods have been developed over the past two decades to solve it. Several research groups have developed techniques independently to map the predominantly dark matter distribution in cluster lenses. While these methods have all provided remarkably high precision mass maps, particularly with exquisite imaging data from the Hubble Space Telescope (HST), the reconstructions themselves have never been directly compared. In this paper, we report the results of comparing various independent lens modeling techniques employed by individual research groups in the community. Here we present for the first time a detailed and robust comparison of methodologies for fidelity, accuracy and precision. For this collaborative exercise, the lens modeling community was provided simulated cluster images -- of two clusters Ares and Hera -- that mimic the depth and resolution of the ongoing HST Frontier Fields. The results of the submitted reconstructions with the un-blinded true mass profile of these two clusters are presented here. Parametric, free-form and hybrid techniques have been deployed by the participating groups and we detail the strengths and trade-offs in accuracy and systematics that arise for each methodology. We note in conclusion that lensing reconstruction methods produce reliable mass distributions that enable the use of clusters as extremely valuable astrophysical laboratories and cosmological probes.
The analysis of galaxy properties and the relations among them and the environment, can be used to investigate the physical processes driving galaxy evolution. We study the cluster A209 by using the ...CLASH-VLT spectroscopic data combined with Subaru photometry, yielding to 1916 cluster members down to a stellar mass of 10^{8.6} Msun. We determine: i) the stellar mass function of star-forming and passive galaxies; ii) the intra-cluster light and its properties; iii) the orbits of low- and high-mass passive galaxies; and iv) the mass-size relation of ETGs. The stellar mass function of the star-forming galaxies does not depend on the environment, while the slope found for passive galaxies becomes flatter in the densest region. The color distribution of the intra-cluster light is consistent with the color of passive members. The analysis of the dynamical orbits shows that low-mass passive galaxies have tangential orbits, avoiding small pericenters around the BCG. The mass-size relation of low-mass passive ETGs is flatter than that of high mass galaxies, and its slope is consistent with that of field star-forming galaxies. Low-mass galaxies are also more compact within the scale radius of 0.65 Mpc. The ratio between stellar and number density profiles shows a mass segregation in the center. The comparative analysis of the stellar and total density profiles indicates that this effect is due to dynamical friction. Our results are consistent with a scenario in which the "environmental quenching" of low-mass galaxies is due to mechanisms such as harassment out to R200, starvation and ram-pressure stripping at smaller radii, as supported by the analysis of the mass function, of the dynamical orbits and of the mass-size relation of passive early-types in different regions. Our analyses support the idea that the intra-cluster light is formed through the tidal disruption of subgiant galaxies.
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