Welcome to the webpage of the cosmoIGM research project. cosmoIGM is a FP7 ERC Starting Grant
that has the goal to investigate cosmology with the Intergalactic Medium.
The ERC Grant has been awarded to Matteo Viel by the European Community and will cover the period 1/12/2010 - 1/12/2015.
The IGM as a Large-Scale Structure tracer
The WMAP mission that measured the cosmic microwave
background (CMB) anisotropies and the SDSS (Sloan Digital Sky Survey) that mapped the galaxy
distribution out to large distances have allowed to get tight constraints on the matter
distribution at large scales and to enter the era of precision cosmology. In fact, the constraints in terms of the
cosmological parameters of the standard model (Cold Dark Matter, DM) have now reached an
unprecedented degree of precision. However, the information on the matter distribution at small scales is
completely missing and rely on few measurements of the linear dark matter power spectrum performed by
Croft et al. (2002, ApJ, 581, 20); Viel, Haehnelt & Springel (2004, MNRAS, 355, 23); McDonald et al.
(2005, ApJ, 635). These measurements are all based on various compilations of Lyman- quasar spectra that
probe the IGM at z=2-4 and at scales between a few and one hundred Mpc. There is a tension between the
cosmological parameters derived from Lyman- observations and those suggested by the large scale
structure: the amplitude derived from IGM data is in fact higher at the 2 level than that measured from the
CMB (Seljak et al. 2005, PhRvD, 71 3515; Viel et al. 2009, MNRAS, 393, 774). The current understanding
is that the systematic uncertainties in this pristine field of research are still preventing a fully reliable
measurement of the matter power spectrum at these scales and both observational and theoretical efforts are
needed in order to elevate the IGM to a powerful cosmological probe.
IGM and fundamental physics
The Lyman- forest is an important tool also for fundamental physics. In order to stress this point, I present
here two results that IGM data provided: 1) the tightest cosmological constraints on the upper limits on the
mass of neutrino masses have been obtained from Lyman- forest SDSS data (Seljak et al. 2005, PhRvD,
71, 3515) and give Sigma m_nu <0.17 eV at the 2 confidence level; 2) the tightest constraints on the coldness of
cold dark matter have been obtained from a compilation of SDSS and Keck HIRES data and give m>4 keV
for a thermal relic (28 keV for a sterile neutrino - Viel et al. 2008, PhRvL, 100, 041304). It is important to
notice that these limits are very stringent and, if trusted, can really open up new windows on the nature of
dark matter and on the constraints of neutrino masses from cosmological data also for particle physics
experiments. Other IGM-related fundamental aspects are: 1) the implications that a measurement of the
matter power spectrum at small scales has in terms of inflationary parameters (Seljak et al 2005, PhRvD,
71, 3515 Viel et al. 2004, MNRAS, 355, 23L); 2) impact of non-gaussian cosmological model on the flux
properties (Viel et al. 09, MNRAS, 393, 774); 3) the controversial constraints in terms of variation of fine
structure constant using metal line transition in high-resolution spectra (Levshakov et al. 2007 A&A, 466,
1077; Srianand et al. 2007, PhRvL, 99, 239002; Murphy et al. 2008, MNRAS, 384, 1053); 4) the most-direct
measurement of the cosmic expansion that can be performed with the next generation of ultra-stable
spectrograph (CODEX) on the ELT (Extremely Large Telecope, Liske et al. 2008, MNRAS, 386, 1192); 5)
modifications of gravity that could alter the high-z evolution of the growth factors and the IGM properties.
The IGM/Galaxy interplay Observations of absorption features in
high-z QSO absorption spectra have unveiled the widespread presence of
heavy elements well outside galaxies, reaching the low density IGM. In
fact, the Lyman- forest in the redshift range z = 2-3 is enriched (as
traced by ions CIV, OVI, SiIV) up to 0.003 the solar value (with about
1 dex scatter) down to small column densities of neutral hydrogen,
while reaching Z=0.1 solar in the local universe. Since the Lyman-
forest is thought to fairly trace the low density IGM, it is also
assumed as representative of the diffuse baryonic matter which traces
the filamentary dark-matter structures seen in numerical simulations
that extend well beyond the neighborhood of galaxies. Furthermore, it
has been well known for long time that the hot plasma in galaxy
clusters at low redshift is highly enriched to 0.3- 0.5 the solar
value. The favorite candidates for playing a major role are the
supernovae(SN)/Active Galactic Nuclei(AGN)-driven galactic outflows,
perhaps coupled with some larger-scale diffusion engine. Besides
enriching the IGM, galactic winds are also believed to have a crucial
role in shaping the mass-metallicity relation of galaxies and
influencing the IGM temperature structure. Winds driven by the
ram-pressure exerted on the interstellar medium by hot shells or
powered by the momentum transferred by the SN/AGN photons to dust
grains are thought to act differently in shaping the faint and the
bright end of the galactic luminosity function. The impact of outflows
on galaxy/IGM evolution depends strongly on the details of the
coupling among the energy and the interstellar/intergalactic
gas. Numerical studies at high resolution of the IGM and galactic
feedback are under way but the results are not conclusive. However,
some results allow significant constraints on the mass- load and
energy transfer on both the hot and cold ISM, providing insights into
the appropriate dynamical models of outflows and feedback that impact
on the IGM properties out to large scales.
Lyman-alpha forest and cosmic weak lensing in a warm dark matter universe
Katarina Markovic, Matteo Viel PREPRINT Accepted to PASA Review
Cosmic Degeneracies I: Joint N-body Simulations of Modified Gravity and Massive Neutrinos
Marco Baldi, Francisco Villaescusa-Navarro, Matteo Viel, Ewald Puchwein, Volker Springel, Lauro Moscardini PREPRINT submitted
Cosmology with massive neutrinos III: the halo mass function and an application to galaxy clusters
Matteo Costanzi, Francisco Villaescusa-Navarro, Matteo Viel, Jun-Qing Xia, Stefano Borgani, Emanuele Castorina, Emiliano Sefusatti
PREPRINT submitted
Cosmology with massive neutrinos II: on the universality of the halo mass function and bias
E. Castorina, E. Sefusatti, R.K. Sheth, F. Villaescusa-Navarro, M. Viel
PREPRINT submitted
Cosmology with massive neutrinos I: towards a realistic modeling of the relation between matter, haloes and galaxies
Francisco Villaescusa-Navarro, Federico Marulli, Matteo Viel, Enzo Branchini, Emanuele Castorina, Emiliano Sefusatti, Shun Saito
PREPRINT submitted
Kinetic or thermal AGN feedback in simulations of isolated and merging disk galaxies calibrated by the M-sigma relation
Barai, Paramita; Viel, Matteo; Murante, Giuseppe; Gaspari, Massimo; Borgani, Stefano
PREPRINT MNRAS in press
Galactic winds in cosmological simulations of the circumgalactic medium
Barai, Paramita; Viel, Matteo; Borgani, Stefano; Tescari, Edoardo; Tornatore, Luca; Dolag, Klaus; Killedar, Madhura; Monaco, Pierluigi; D'Odorico, Valentina; Cristiani, Stefano PREPRINT MNRAS (2013) 430 3213 .
Non-linear evolution of the cosmic neutrino background
Villaescusa-Navarro, Francisco; Bird, Simeon; Pena-Garay Carlos, Viel Matteo PREPRINT JCAP (2013) 03 019 .
Constraining neutrino properties with a Euclid-like galaxy cluster survey
Costanzi Alunno Cerbolini, M.; Sartoris, B.; Xia, Jun-Qing; Biviano, A.; Borgani, S.; Viel, M. PREPRINT JCAP (2013) 06 020
