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