A new feedback cycle in the archetypal cooling flow group NGC 5044
  The fate of cooling gas in the centers of galaxy clusters and groups is still
not well understood, as is also the case for the complex process of triggering
active galactic nucleus (AGN) outbursts in their central dominant galaxies, and
the consequent re-heating of the gas by the AGN jets. With the largest known
reservoir of cold molecular gas of any group-dominant galaxy and three epochs
of AGN activity visible as cavities in its hot gas, NGC 5044 is an ideal system
in which to study the cooling/AGN feedback cycle at the group scale. We present
VLBA observations of NGC 5044 to ascertain the current state of the central
AGN. We find a compact core and two small jets aligned almost in the plane of
the sky, and in the orthogonal direction to the location of cavities. We
construct the radio/sub-mm spectral energy distribution (SED) over more than
three orders of magnitude. We find that below 5 GHz the spectrum is best fit by
a self-absorbed continuous injection model representing emission coming from
the jets, while the higher frequencies show clear signs of an advection
dominated accretion flow. We derive a black hole mass and accretion rate
consistent with independent measurements. We conclude that the age of the jets
is much younger than the innermost cavities, marking the start of a new
feedback cycle.
