Speaker
Description
It is proposed that in many galaxy clusters, the energetic outflows from the active galactic nucleus (AGNs) will balance against the cooling of the diffused, hot gas through a process known as AGN feedback. Yet, in low-mass halos, researchers discovered a systematic entropy excess caused by lower-than-expected gas densities. The excess is commonly attributed to the unbalanced feedback process from an AGN population that overheats their host environment. In this work, we combined the radio AGN catalog of the second data release (DR2) of the LOFAR Two-Metre Sky Survey (LoTSS) and the host environment information estimated based on optical richness to pick out a sample of candidate overheating radio-loud AGNs. We extracted the subset by comparing the energy stored in the radio structure — calculated based on an equipartition assumption, other basic morphological assumptions, and properties given in LoTSS DR2 — with the gravitational binding energy of the host halo estimated with a universal pressure profile. This provides us with $\gtrsim$ 1000 overheating AGNs with $z\lesssim1$, on which we can carry out a more sophisticated energy computation adding hotspot extraction, and perform further classifications. We will present here a summary of the properties of this AGN population, including the radio luminosity and size distributions, characteristics of the host environments, and their morphology (FRI, FRII, compact, restarting, etc.), which will help us to learn about the differences between overheating and the general population, the incidence rate of overheating, its evolution with redshift, and the conditions that lead to its occurrence.
