Title: JWST's Little Red Dots: Masters of Disguise in the High-Redshift Universe 


This talk will explore the exciting journey to probe several populations of black holes, spanning from the distant to the local Universe. I will focus primarily on the "little red dots" (LRDs), a newly discovered and puzzling population of compact red sources at redshift z > 4, identified by JWST. These objects challenge our current astrophysical models in several ways. First, I will discuss the detection of overmassive black holes relative to the stellar mass of their host galaxies. Second, I will address the X-ray weakness problem, where these sources remain undetected in deep X-ray surveys. I will use advanced GRRMHD simulations to show how mildly super-Eddington accretion onto slowly spinning black holes can resolve this issue. Third, I will explore the extremely high stellar densities at the cores of these objects and their potential for triggering runaway stellar collisions. Throughout the talk, I will also discuss how the LRDs represent a perfect bridge to study other populations of black holes, with a focus on the role of future observatories such as HWO and AXIS. These include the search for black hole seeds at redshifts z = 20-30 and the detection of quiescent black holes in the local Universe.

Bio: Fabio Pacucci is a Clay and BHI Fellow at the Center for Astrophysics. He obtained his PhD in Physics from the Scuola Normale Superiore in Pisa, Italy.
He is an expert in the theory and observations of high-z black holes and is part of several large JWST programs.
He is also involved in planning next-generation observatories, such as NASA's AXIS in the X-ray, which was just selected for Phase A, and HWO in the UV, optical, and infrared, which will be NASA's next flagship mission.

contact: Zhaozhou