The Properties and Environment of Luminous Quasars in the Epoch of Reionization
Luminous quasars at high redshift (z > 6, i.e. in the first Gyr of cosmic history) are formidable probes of the state of the universe in the Epoch of Reionization. Already hosting supermassive black holes (SMBHs) in their centers, their very presence represents a crucial challenge to current theories of SMBHs formation, and theoretical models predict them to reside in biased regions, embedded in large overdensities of galaxies.
In this talk, I will briefly report on our search for high-redshift quasars, based on data from large-area sky surveys (e.g., Pan-STARRS1, UKIDSS, WISE, DECaLS), which resulted in the discovery of ~100 quasars at z > 6. I will focus on several properties of a sample of quasars at z>6.5, e.g. their virial black hole masses, accretion rates, near zone sizes and metallicity ratios, and place them in the context of observations at lower redshift.
Finally, I will report on our current, multi-wavelength study of the environments of high-redshift quasars, from our search for Lyman Alpha Emitters and Lyman Break Galaxies in quasars fields, to our latest ALMA observations of gas-rich companions around few quasars at z~6.