Observational Signatures of High-Redshift Quasars and Local Relics of Black Hole Seeds

TL;DR

This paper reviews observational evidence from high-redshift quasars and local dwarf galaxies to understand the origins and early growth of massive black holes in the universe.

Contribution

It synthesizes current observational constraints from different cosmic epochs to shed light on black hole seed formation and early evolution.

Findings

High-redshift quasars indicate rapid black hole growth and heavy initial seeds.

Dwarf galaxies provide limits on the initial mass of black hole seeds.

Observational data across cosmic time are crucial for understanding black hole origins.

Abstract

Observational constraints on the birth and early evolution of massive black holes (BHs) come from two extreme regimes. At high redshift, quasars signal the rapid growth of billion-solar-mass BHs and indicate that these objects began remarkably heavy and/or accreted mass at rates above the Eddington limit. At low redshift, the smallest nuclear BHs known are found in dwarf galaxies and provide the most concrete limits on the mass of BH seeds. Here we review current observational work in these fields that together are critical for our understanding of the origin of massive BHs in the Universe.