Luminous, high redshift (z>5) quasars are formidable probes of the universe in the Epoch of Reionization. They are observed to already host supermassive black holes (BHs) in their centers, and to reside in the earliest, most massive galaxies, where they are thought to be surrounded by large galactic overdensities. How BHs and hosts get this massive in such a short amount of time after the Big Bang is one of the key open questions of current astrophysics.
In this talk, I will first present our current efforts to understand these puzzling objects by studying their innermost properties, and in particular the fueling of and feedback from their BHs, with a suite of recent, high-quality rest-frame UV spectra from VLT/X-Shooter.
Then, I will focus on the sub-sample (~10%) of high-z quasars that show strong radio-emission (radio-loud), linked with powerful relativistic jets. Jets are thought to have a critical role in driving the evolution of these quasars, by boosting the accretion efficiency but also affecting their host galaxies. I will give an overview of the recent discoveries, and then I will present new ALMA observations aimed at recovering the dust and [CII] emission line in the rest-frame FIR, both tracers of the host galaxy properties and, potentially, of the jet feedback. The data show that these galaxies already host large reservoirs of dust and that are forming stars at rates>~30 Msun/yrs. We do not observe strong differences with respect to the hosts of radio-quiet quasars, except for a decrease in the [CII] line, which could be due to a suppression of the cool gas due to jets, or boosting of the FIR due to a simultaneous contribution of dust and jet synchrotron radiation. Lastly, I will conclude with our search for signs of mergers and/or potential gas-rich galaxies around these radio-loud quasars, as expected from theoretical predictions.
Horarios: June 6, 2023 15:30
Publicado por: Claudia Aguilera