The young radio lobe of 3C 84: inferred gas properties in the central 10 parsec

TL;DR

This study investigates the gas properties around the supermassive black hole in NGC 1275, revealing that the jet expands in a low-density environment and that Bondi accretion alone cannot explain the jet power, implying alternative accretion or jet mechanisms.

Contribution

It provides new insights into the gas density and accretion processes near the SMBH in NGC 1275, challenging the classical Bondi accretion model.

Findings

Jet expands in a low-density environment (<~1 cm^-3).

Bondi accretion is inconsistent with jet power estimates.

Jet power aligns with past average estimates from X-ray data.

Abstract

We analyse the environment of the supermassive black hole (SMBH) in the centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting the radio source 3C 84. We focus on the young radio lobe observed inside the estimated Bondi accretion radius. We discuss the momentum balance between the jet associated with the lobe and the surrounding gas. The results are compared with the proper motion of the radio lobe obtained with the very long baseline interferometry. We find that under assumption of a high-density environment >~ 100 cm^-3), the jet power must be comparable to the Eddington luminosity --- this is clearly inconsistent with the current moderate activity of 3C 84, which indicates instead that the jet is expanding in a very low density region (<~1 cm^-3), along the rotation axis of the accretion flow. The power required for the jet to expand in the low-density environment is comparable to the past average jet power estimated from the X-ray observations. We estimate the classical Bondi accretion rate, assuming that (1) gas accretion is spherically symmetric, (2) accretion is associated with the jet environment, and (3) the medium surrounding the jet is representative of the properties of the dominant accreting gas. We find that Bondi accretion is inconsistent with the estimated jet power. This means that either accretion of the cold gas in the NGC 1275 is more efficient than that of the hot gas, or the jets are powered by the SMBH spin.