Lyman-alpha forest -- is the absorption produced by neutral hydrogen seen in the spectra of background quasars. I am interested in using the Lyman-alpha forest to recover the linear dark matter power spectrum at scales of 1-40 comoving Mpc which are not probed by other observables.
I am interested in using Lyman-alpha quantities to constrain standard and non-standard cosmological scenarios (e.g. interactions between dark energy and dark matter) and the masses of cosmological neutrinos.
Cosmological parameters estimation -- When the dark matter power spectrum inferred from Lyman-alpha quasar spectra is combined with the Cosmic Microwave Background data we can get tight constraints on cosmological parameters (sigma_8, n and its running), on slow-roll inflationary models, on the mass of warm dark matter particles such as light gravitinos or sterile neutrinos.
Warm Hot Intergalactic Medium -- I am currently using hydro-dynamical simulations and the Tully catalog of galatic luminosity density in the local universe to study the distribution of warm-hot intergalatic medium and its detectability, focussing in particular on GRBs. I am also addressing the impact of several different feedback mechanisms on the low redshift IGM.
The UV background and metal enrichment -- I am using hydro-dynamical simulations to give constraints on the amplitude and shape of the UV background and on the metal enrichment at z=3. I rely on a modified version of the hydrodynamic code (G-II) that
incorporates a chemodynamical model with feedback recipes.
The nature of dark matter -- I am using hydro-dynamical simulations and high resolution data to constraints the properties of dark matter at the small scales (cold/warm dark matter and sterile neutrinos), in particular non cold dark matter models like: thermal WDM, fuzzy DM, mixed models, sterile neutrinos, etc. Impact on structure formation especially at high redshift.
Large-scale structure/CMB cross correlation I am investigating cross-correlation of the Lyman-alpha forest flux with CMB lensing and of the quasar distribution with CMB temperature. I am also constraining the amount of primordial non-Gaussianity in the IGM and from QSOs and radio sources. 21cm Intensity Mapping in the post-reionization era.
Constraints on neutrino masses from SDSS-III/BOSS Ly-alpha forest and other cosmological probes Palanque-Delabrouille, Yeche, Lesgourgues, Rossi, Borde, Viel et al. PREPRINT arXiv 1410.7244
Neutrino constraints: what large-scale structure and CMB data are telling us? Costanzi, Sartoris, Viel, Borgani PREPRINT arXiv 1407.8338
Cosmology with massive neutrinos I: towards a realistic modeling of the relation between matter, haloes and galaxies Villaescusa-Navarro, Marulli, Viel, Branchini, Castorina, Sefusatti, Saito PREPRINT arXiv 1311.0866 - 2014JCAP...03..011V
Kinetic or thermal AGN feedback in simulations of isolated and merging disc galaxies calibrated by the M-sigma relation Barai, Viel, Murante, Gaspari, Borgani PREPRINT arXiv 1307.5326 - 2014MNRAS.437.1456B
Warm dark matter as a solution to the small scale crisis: New constraints from high redshift Lyman-alpha forest data Viel, Becker, Bolton, Haehnelt PREPRINT arXiv 1306.2314 - 2013PhRvD..88d3502V