Sylvie Foucaud

A test of the nature of cosmic acceleration using galaxy redshift distortions

Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the equations of cosmic expansion, accounting for about 75 per cent of the total energy density in the Universe. The simplest option for this ‘dark energy’ corresponds to a ‘cosmological constant’, perhaps related to the quantum vacuum energy. Physically viable alternatives invoke either the presence of a scalar field with an evolving equation of state, or extensions of general relativity involving higher-order curvature terms or extra dimensions. Although they produce similar expansion rates, different models predict measurable differences in the growth rate of large-scale structure with cosmic time. A fingerprint of this growth is provided by coherent galaxy motions, which introduce a radial anisotropy in the clustering pattern reconstructed by galaxy redshift surveys. Here we report a measurement of this effect at a redshift of 0.8. Using a new survey of more than 10,000 faint galaxies, we measure the anisotropy parameter β = 0.70 ± 0.26, which corresponds to a growth rate of structure at that time of f = 0.91 ± 0.36. This is consistent with the standard cosmological-constant model with low matter density and flat geometry, although the error bars are still too large to distinguish among alternative origins for the accelerated expansion. The correct origin could be determined with a further factor-of-ten increase in the sampled volume at similar redshift.

The SWIRE-VVDS-CFHTLS surveys: stellar mass assembly over the last 10 Gyr. Evidence for a major build up of the red sequence between z = 2 and z = 1

(abridged abstract) We present an analysis of the stellar mass growth over the last 10 Gyrs using a large 3.6

The VIMOS-VLT Deep Survey: Evolution of the galaxy luminosity function up to z=2 in first epoch data

\mu

The GALEX VIMOS-VLT Deep Survey Measurement of the Evolution of the 1500 Å Luminosity Function

selected sample. We split our sample into active (blue) and quiescent (red) galaxies. Our measurements of the K-LFs and LD evolution support the idea that a large fraction of galaxies is already assembled at

The VIMOS VLT Deep Survey - Evolution of the major merger rate since z ~ 1 from spectroscopically confirmed galaxy pairs

z\sim 1.2

The VIMOS-VLT deep survey - evolution of the luminosity functions by galaxy type up to z = 1.5 from first epoch data

. Based on the analysis of the evolution of the stellar mass-to-light ratio (in K-band) for the spectroscopic sub-sample, we derive the stellar mass density for the entire sample. We find that the global evolution of the stellar mass density is well reproduced by the star formation rate derived from UV dust corrected measurements. Over the last 8Gyrs, we observe that the stellar mass density of the active population remains approximately constant while it gradually increases for the quiescent population over the same timescale. As a consequence, the growth of the stellar mass in the quiescent population must be due to the shutoff of star formation in active galaxies that migrate into the quiescent population. From

The VLA-VIRMOS Deep Field I. Radio observations probing the microJy source population

z=2

The cosmic star formation rate evolution from z = 5 to z = 0 from the VIMOS VLT deep survey

to

Physical properties of galaxies and their evolution in the VIMOS VLT Deep Survey - I. The evolution of the mass-metallicity relation up to z ~ 0.9

z=1.2

The VIMOS VLT Deep Survey - Evolution of the non-linear galaxy bias up to z = 1.5

, we observe a major build-up of the quiescent population with an increase by a factor of 10 in stellar mass, suggesting that we are observing the epoch when an increasing fraction of galaxies are ending their star formation activity and start to build up the red sequence.