Speaker
Description
Clustering measurements have always been a fundamental ingredient on which we built our understanding of the properties of quasars and galaxies, as well as their (co-)evolution with redshift. Recently, ground-breaking progress has been made in extending these studies to the high-z Universe: using JWST NIRCam-WFSS observations, the EIGER team has measured the quasar-galaxy cross-correlation function and the galaxy auto-correlation function at z~6 (soon to be published). These measurements are nicely complemented by the recent determination of the quasar auto-correlation function at the same redshift. Together, these early data suggest that high-z quasars live in moderately strong overdensities, with a large correlation length that agrees with the trend observed at z~2-4.
In this work, we use these new data to build a model jointly describing the properties of quasars and galaxies at high redshift. We run a new, large-volume cosmological simulation with more than a trillion particles, which contains halos whose abundance spans more than seven orders of magnitude. We complement the simulation with an empirical quasar/galaxy population model that has been already applied successfully to interpret quasar clustering and demographic properties at z~2-4. By matching our predictions with key observables such as the distribution of quasar overdensities, the quasar-galaxy cross-correlation function, the auto-correlation and luminosity functions of quasars and galaxies, we determine the mass distribution of quasar/galaxy-hosting halos, the luminosity-halo mass relation for quasars and galaxies and their duty cycle/occupation fraction. These are fundamental quantities that are directly connected with the formation and early growth of supermassive black holes as well as with the coevolution between such black holes and their hosting galaxies. By comparing the results of our model at different redshifts, we study how quasar activity and UV-bright star formation evolve across cosmic time. Finally, we discuss the implications of our results in light of the recent discovery of an extremely abundant population of faint and/or obscured AGN in JWST surveys.
