Trieste (Italy)

Matteo Viel

Welcome to my homepage. I am Full Professor in the Astroparticle Physics Group at SISSA . Before that I was staff researcher at INAF-OATS. Before that I was a PPARC Fellow at the Institute of Astronomy of the University of Cambridge and a Research Fellow at Clare Hall College.

Research Areas     Contact and Personal Information
Intergalactic Medium: the 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 the intergalactic medium to constrain standard and non-standard cosmological scenarios (e.g. interactions between dark energy and dark matter, properties of dark matter) and the masses of cosmological neutrinos.

Intensity Mapping @ 21cm: -- is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms, it is an emission process and can probe the large scale structure in a way complementary to the IGM absorption. The signal is modelled both analytically or with hydro simulations.

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.

Structure formation from large to small scales -- I am broadly interested in structure formation using state-of-the-art data sets like BAO, galaxy redshift surveys, weak lensing, IGM data and I try hard to disentangle between astrophysical processes and fundamental physical processes by exploiting different redshifts and scales. These efforts are focussing on probing the geometrical and dynamical state of the Universe in the matter dominated era at z=2-6.

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, spectral index), on inflationary models, on the mass of warm dark matter particles such as light gravitinos or sterile neutrinos.

Warm Hot Intergalactic Medium -- I am using hydro-dynamical simulations to address the impact of several different feedback mechanisms on the low redshift IGM. In general the low-z IGM is a feedback thermometer (e.g. Viel+17) and potentially a probe of new physics via dark photon heating of the cosmic web (Bolton+22 -- see below).

The Circumgalactic Medium -- 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 and on the physical state of the CGM. I rely on a modified version of the hydrodynamic code (G-III) that incorporates a chemodynamical model with different feedback recipes (energy and momentum driven winds powered by SNe, AGN feedback).

via Bonomea, 265
I-34136 Trieste
Tel: +39 040 3787517
email: viel(at)

full CV: [pdf-file]

Publications at ADS  Publications at arXiv  Publications at INSPIRE-HEP  

cosmoIGM: ERC: cosmoIGM publications (draft version)

cosmoIGM: ERC: cosmoIGM final activity report (draft version)

Google Scholar link

NEWS: National Center of Super Computing - Official start of Astrophysics and Cosmos Observations activities

NEWS: Physics Magazine: Heating up dark matter with the IGM

NEWS: Dark photons as intergalactic heat source

Teaching @ Phd School ISAPP23 - Neutrino Cosmology - Varenna (July 2023):
Lecture 1 Linear theory
Lecture 2 Non-linearities
Lecture 3 IGM and neutrinos
Lecture 4 New neutrino probes

Teaching @ PhD Winter School 2022 - Tenerife (November 2022):
Lecture 1 Intensity Mapping
Lecture 2 IGM
Lecture 3 Galaxy Clustering
Lecture 4 Weak lensing and GCs

teaching: Structure formation lectures at SISSA (since 2011)

teaching: Lecture on neutrinos and large scale structure

outreach: Trieste next event - La scienza del futuro
outreach: local press article
outreach: Youtube interview in Italian outreach: DM LECTURE ON YOUTUBE - SISSA FREE Cosmology online course edited by P. Salucci outreach: Public conference (youtube link)

seminar: Seminar at Simons CCA - New York Feb. 2020 - youtube link

seminar: talk @ Fundamental Cosmology Meeting - Granada - Nov 22

Recent Publications     Full List of publications     Links
JWST high-z galaxies constraints on warm and cold dark matter models
Maio, Umberto; Viel, Matteo
PREPRINT eprint arXiv:2211.03620 arXiv:2211.03620

Testing gravity with gravitational waves X electromagnetic probes cross-correlations
Scelfo, Giulio; Berti, Maria; Silvestri, Alessandra; Viel, Matteo
PREPRINT eprint arXiv:2210.02460 arXiv:2210.02460

Multipole expansion for 21cm Intensity Mapping power spectrum: forecasted cosmological parameters estimation for the SKA Observatory
Berti, Maria; Spinelli, Marta; Viel, Matteo
PREPRINT eprint arXiv:2209.07595 arXiv:2209.07595

Studying the Warm Hot Intergalactic Medium in emission: a reprise
Parimbelli, G. ; Branchini, E. ; Viel, M. ; Villaescusa-Navarro, F. ; ZuHone, J.
PREPRINT eprint arxXiv:2209.00657

Hints of dark photon dark matter from observations and hydrodynamical simulations of the low-redshift Lyman-alpha forest
Bolton, James S.; Caputo, Andrea ; Liu, Hongwan ; Viel, Matteo
PREPRINT eprint arXiv:2206.13520 - Phys. Rev. Lett. 129, 211102 (2022)

The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium
Puchwein, Ewald ; Bolton, James S. ; Keating, Laura C. ; Molaro, Margherita ; Gaikwad, Prakash ; Kulkarni, Girish ; Haehnelt, Martin G. ; Irsic, Vid ; Soltinsky, Tomas ; Viel, Matteo ; Aubert, Dominique ; Becker, George D. ; Meiksin, Avery
PREPRINT eprint arXiv:2207.13098

Weighing cosmic structures with clusters of galaxies and the intergalactic medium
Esposito, Matteo; Irsic, Vid ; Costanzi, Matteo ; Borgani, Stefano ; Saro, Alexandro ; Viel, Matteo
Monthly Notices of the Royal Astronomical Society, Volume 515, Issue 1, pp.857-870 arXiv:2202.00974

Science (archives, institutes & computing centers):

RTN network "The Physics of the IGM"
INAF Istituto Nazionale di Astrofisica
INFN Istituto Nazionale di Fisica Nucleare
Physics Department Trieste University
Dipartimento di Fisica e Astronomia Padova
MPA Garching - Germany
Institute of Astronomy Cambrige - UK
COSMOS supercomputer DAMTP, Cambridge - UK
Darwin Cluster High Performance Computer Service (HPCS) Cambridge - UK
PACO VILLAESCUSA's public software