Jets at lowest mass accretion rates

TL;DR

This paper combines observational data and theoretical modeling to explore jet activity in black holes at very low accretion rates, revealing that outflows significantly influence their spectral energy distributions across different black hole masses.

Contribution

It introduces a new time-dependent jet model for episodic plasma ejections and demonstrates its success in explaining radio flares and IR spectra in low-luminosity black holes.

Findings

Model reproduces observed radio flare time lags and size-frequency relationships.

Residual IR emission is consistent with a non-thermal origin from jets.

Jets are present in both stellar-mass and supermassive black holes, indicating scale-invariant accretion-jet physics.

Abstract

We present results of recent observations and theoretical modeling of data from black holes accreting at very low luminosities (L/L_Edd ~ 10^{-8}). We discuss our newly developed time-dependent model for episodic ejection of relativistic plasma within a jet framework, and a successful application of this model to describe the origin of radio flares seen in Sgr A*, the Galactic center black hole. Both the observed time lags and size-frequency relationships are reproduced well by the model. We also discuss results from new Spitzer data of the stellar black hole X-ray binary system A0620-00. Complemented by long term SMARTS monitoring, these observations indicate that once the contribution from the accretion disk and the donor star are properly included, the residual mid-IR spectral energy distribution of A0620-00 is quite flat and consistent with a non-thermal origin. The results above suggest that a significant fraction of the observed spectral energy distribution originating near black holes accreting at low luminosities could result from a mildly relativistic outflow. The fact that these outflows are seen in both stellar-mass black holes as well as in supermassive black holes at the heart of AGNs strengthens our expectation that accretion and jet physics scales with mass.