From Multiwavelength to Mass Scaling: Accretion and Ejection in Microquasars and AGN

TL;DR

This paper reviews recent observational and theoretical advances in understanding how accretion and ejection processes in black holes scale from microquasars to active galactic nuclei, highlighting the connectivity across emission regions.

Contribution

It synthesizes recent findings and proposes new tools for comparing accretion and ejection phenomena across different black hole mass scales.

Findings

Correlations between radio, infrared, and X-ray emissions reveal a unified inflow/outflow connection.

Simultaneous broadband observations have advanced understanding of accretion processes.

Scaling relations suggest similar physics govern microquasars and AGN.

Abstract

A solid theoretical understanding of how inflowing, accreting plasma around black holes and other compact objects gives rise to outflowing winds and jets is still lacking, despite decades of observations. The fact that similar processes and morphologies are observed in both X-ray binaries as well as active galactic nuclei has led to suggestions that the underlying physics could scale with black hole mass, which could provide a new handle on the problem. In the last decade, simultaneous broadband campaigns of the fast-varying X-ray binaries particularly in their microquasar state have driven the development of, and in some cases altered, our ideas about the inflow/outflow connection in accreting black holes. Specifically the discovery of correlations between the radio, infrared and X-ray bands has revealed a remarkable connectivity between the various emission regions, and argued for a more holistic approach to tackling questions about accretion. This article reviews the recent major observational and theoretical advances that focus specifically on the relation between the two "sides" of the accretion process in black holes, with an emphasis on how new tools can be derived for comparisons across the mass scale.