Black hole accretion disks with outflows II. Time dependent Green's function solutions in Newtonian gravity

TL;DR

This paper derives analytical Green's function solutions for time-dependent thin accretion disks with outflows, revealing how outflows influence disk luminosity, temperature profiles, and variability, with implications for observations.

Contribution

It provides the first exact analytical Green's function solutions for Newtonian accretion disks with outflows, extending classical models to include outflow effects.

Findings

Outflows cause faster luminosity decay.

Outflows flatten temperature radial profiles.

Outflows suppress low-frequency variability.

Abstract

We present Green's function solutions of the Newtonian time-dependent thin disk equations in the presence of outflows, showing that simple and exact analytical expressions exist in various natural limits of the problem. These Green's functions are mathematically very similar to the classical Lynden-Bell & Pringle solutions in the absence of outflows, but differ strongly in their precise physical details and observational implications. Solutions are presented for phenomenological radius-dependent outflows which both do and do not torque the local accretion flow, and for outflows which are launched proportional to the local accretion rate. Generically, outflows lead to a more rapid decay of the bolometric luminosity of the disk, flatten the radial dependence of the disk temperature, and suppress variability in the accretion rate at small radii and low frequencies (on long timescales). Observational implications of these four results are discussed in detail.