The powerful jet of an off-nuclear intermediate-mass black hole in the spiral galaxy NGC 2276

TL;DR

This paper reports the discovery of an off-nuclear intermediate-mass black hole in NGC 2276 with a powerful jet, demonstrating that jet physics is consistent across black hole mass scales and suggesting early Universe seed IMBHs had significant feedback effects.

Contribution

It presents the first detailed observation of a jet from an off-nuclear IMBH, confirming mass-invariant jet physics and its potential role in galaxy feedback.

Findings

Detected a 1.8 pc radio jet from an IMBH in NGC 2276.

Jet power is comparable to the black hole's radiative output.

Evidence of jet feedback affecting the surrounding star formation region.

Abstract

Jet ejection by accreting black holes is a mass invariant mechanism unifying stellar and supermassive black holes (SMBHs) that should also apply for intermediate-mass black holes (IMBHs), which are thought to be the seeds from which SMBHs form. We present the detection of an off-nuclear IMBH of $\sim$5 $\times$ 10$^{4}$ M$_\odot$ located in an unusual spiral arm of the galaxy NGC 2276 based on quasi-simultaneous \textit{Chandra} X-ray observations and European VLBI Network (EVN) radio observations. The IMBH, NGC2276-3c, possesses a 1.8 pc radio jet that is oriented in the same direction as large-scale ($\sim$650 pc) radio lobes and whose emission is consistent with flat to optically thin synchrotron emission between 1.6 GHz and 5 GHz. Its jet kinetic power ($4 \times 10^{40}$ erg s$^{-1}$) is comparable to its radiative output and its jet efficiency ($\geq$ 46\%) is as large as that of SMBHs. A region of $\sim$300 pc along the jet devoid of young stars could provide observational evidence of jet feedback from an IMBH. The discovery confirms that the accretion physics is mass invariant and that seed IMBHs in the early Universe possibly had powerful jets that were an important source of feedback.