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 (in collaboration with Springel & Haehnelt).
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 (work in collaboration with Tornatore, Tescari, Borgani, Cristiani, D'Odorico)
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).
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 (in collaboration with Xia, Matarrese, Verde, De Zotti & Baccigalupi).
The High Redshift Integrated Sachs-Wolfe Effect
Xia, Viel, Baccigalupi, Matarrese, PREPRINT arXiv 0907.4753 JCAP in press.
Cosmological and astrophysical constraints from the Lyman-alpha forest flux probability distribution function
Viel, Bolton, Haehnelt, PREPRINT arXiv 0907.2927 2009 MNRAS Letters.
Damped Lyman-alpha systems in high-resolution hydrodynamical simulations Tescari, Viel, Tornatore, Borgani PREPRINT 2009 MNRAS .
Lenses in the forest: cross-correlation of the Lyman-alpha flux with CMB lensing
Vallinotto, Das, Spergel, Viel PREPRINT 2009 Physical Review Letters .
Realistic sterile neutrino dark matter with keV mass does not contradict cosmological bounds
Boyarsky, Lesgourgues, Ruchayskiy, Viel, PREPRINT 2009 Physical Review Letters .
Primordial Non-Gaussianity and the NRAO VLA Sky Survey
Xia, Viel, Baccigalupi, De Zotti, Matarrese, Verde PREPRINT 2010 ApJ Letters .
The effect of neutrinos on the matter distribution as probed by the Intergalactic Medium Viel, Haehnelt, Springel PREPRINT 2010 JCAP .
