Affiliation: International Centre for Radio Astronomy Research

Contribution: Oral

Title: Cosmic odyssey of star formation and AGN

Abstract: The James Webb Space Telescope (JWST) is revolutionising our understanding of star formation and the growth of super massive black holes. However, the interface of these two processes (SF and AGN), especially beyond z=5, is not well understood as their contributions to the spectral energy distributions (SED) of galaxies are almost equivalent and requires careful disentangling. Reconciling the coevolution of these two processes is critical if we are to further advance our understanding of how galaxies formed and evolved since the Big Bang. I will discuss our photometric measurements of z>5 galaxies obtained from 400 square arcminutes of JWST surveys, with a particular focus on the PEARLS survey. This photometry was carefully prepared by a custom data reduction pipeline and leverages the full strength of JWST+HST imaging. We then analysed the light distributions using the SED fitting software ProSpect that simultaneously accounts for star formation and active galactic nuclei (AGN) when interpreting the SEDs of our JWST detected, distant galaxies. We found that accounting for an AGN component is critical to explain the physics underpinning the SEDs of the first galaxies to exist in the Universe. We found that accounting for AGN can reduce the inferred stellar masses by as much as 4 dex and the resultant cosmic star formation density by 0.4 dex at z>5. Finally, I will discuss our multi-survey catalogue of 2000 z>5 objects with ProSpect derived stellar masses, star formation rates and AGN luminosities. From these data we have constructed the cosmic SF history, the cosmic AGN luminosity history and the evolution of the stellar mass function from z=12 to 5. Our results have significant implications for the abundance of AGN at z>5, the progenitors of massive quasars and the sources of reionisation.

This contribution can be found here (pdf).