Intergalactic Medium - Observations

Researchers at the Observatory are involved in the analysis of QSO spectra of medium to high-resolution (in particular obtained with X-shooter and UVES at the ESO-VLT, but also from SDSS-III BOSS) and the comparison with the predictions of hydro-dynamical simulations in order to study: the physical conditions of the intergalactic medium (IGM, in particular the temperature and the relation between temperature and overdensity), the chemical enrichment from low to high redshift, the nature of galactic feedback (from SNe and AGNs) through its effects on the physical and chemical properties of the IGM, the UV background, the processes of Hydrogen and Helium reionization, the Baryonic Acoustic Oscillations (BAO), the values of cosmological parameters, the matter power spectrum on small scales and the mass of neutrinos.

Contact Person: S. Cristiani

Staff: V. D'Odorico, M. Viel

PostDocG. Cupani

PhD Students: S. Di Gioia


















The XQR-30 survey

Our group is heavily involved in the XQR-30 survey (P.I. V. D'Odorico) which is collecting spectroscopic observations with the X-shooter instrument at the ESO VLT telescope of a sample of 30 quasars at redshift 5.8 <z <6.6.

This sample will allow us to determine the conditions of the Universe during the final stages of the neutral hydrogen reionization process, in particular it will be possible to:

  • Measure the evolution with redshift and the scatter of the opacity of the IGM due to the presence of neutral hydrogen in the redshift interval z = 5.0-6.5 to discriminate between different reionization models.
  • Measure the statistical properties of the absorption lines due to elements heavier than He (dubbed metals) to further determine the state of ionization of the gas, but also the nature of the ionizing sources.
  • Look for the imprint of chemical enrichment due to the first generations of stars by studying the absorption systems that trace the interstellar medium of the first galaxies.
  • Measure the mass of black holes and the metallicity of the quasars in our sample to discriminate between the formation and accretion patterns of supermassive black holes.

Master's degree and doctoral theses are proposed on these topics.

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