Intermittent activity of radio sources. Accretion instabilities and jet precession

TL;DR

This paper investigates how accretion disk instabilities and jet precession can cause intermittent activity in radio sources, explaining their observed short lifespans and complex morphologies.

Contribution

It demonstrates that radiation pressure instability can account for the short ages and morphological features of certain radio sources, linking accretion processes to jet behavior.

Findings

Radiation pressure instability timescales match observed source ages.

Intermittent activity explains the morphology of sources like 1045+352.

Jet precession may result from internal jet flow instabilities.

Abstract

We consider the radiation pressure instability operating on short timescales 10^3 - 10^6 years in the accretion disk around a supermassive black hole as the origin of the intermittent activity of radio sources. We test whether this instability can be responsible for short ages (<10^4 years) of Compact Steep Spectrum sources measured by hot spots propagation velocities in VLBI observations and statistical overabundance of Gigahertz Peaked Spectrum sources.The implied timescales are consistent with the observed ages of the sources. We aslo discuss possible implications of the intermittent activity on the complex morphology of radio sources, such as the quasar 1045+352, dominated by a knotty jet showing several bends. It is possible that we are whitnessing an ongoing jet precession in this source due to internal instabilities within the jet flow.