Jets blowing bubbles in the young radio galaxy 4C 31.04. (arXiv:1811.08971v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zovaro_H/0/1/0/all/0/1">Henry R. M. Zovaro</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Sharp_R/0/1/0/all/0/1">Robert Sharp</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Nesvadba_N/0/1/0/all/0/1">Nicole P. H. Nesvadba</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Bicknell_G/0/1/0/all/0/1">Geoffrey V. Bicknell</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Mukherjee_D/0/1/0/all/0/1">Dipanjan Mukherjee</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Wagner_A/0/1/0/all/0/1">Alexander Y. Wagner</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Groves_B/0/1/0/all/0/1">Brent Groves</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Krishna_S/0/1/0/all/0/1">Shreyam Krishna</a> (1) ((1) Research School of Astronomy and Astrophysics, The Australian National University, (2) Institut d'Astrophysique Spatiale, Université Paris-Sud, (3) Dipartimento di Fisica Generale, Universita degli Studi di Torino, (4) University of Tsukuba, Center for Computational Sciences)
We report the discovery of shocked molecular and ionized gas resulting from
jet-driven feedback in the compact radio galaxy 4C 31.04 using near-IR imaging
spectroscopy. 4C 31.04 is a $sim 100$ pc double-lobed Compact Steep Spectrum
source believed to be a very young AGN. It is hosted by a giant elliptical with
a $sim 10^{9}~rm M_odot$ multi-phase gaseous circumnuclear disc. We used
high spatial resolution, adaptive optics-assisted $H$- and $K$-band integral
field Gemini/NIFS observations to probe (1) the warm ($sim 10^3~rm K$)
molecular gas phase, traced by ro-vibrational transitions of $rm H_2$, and
(2), the warm ionized medium, traced by the [Fe II]$_{1.644~rm mu m}$ line.
The [Fe II] emission traces shocked gas ejected from the disc plane by a
jet-blown bubble $300-400~rm pc$ in diameter, whilst the $rm H_2$ emission
traces shock-excited molecular gas in the interior $sim 1~rm kpc$ of the
circumnuclear disc. Hydrodynamical modelling shows that the apparent
discrepancy between the extent of the shocked gas and the radio emission can
occur when the brightest regions of the synchrotron-emitting plasma are
temporarily halted by dense clumps, whilst less bright plasma can percolate
through the porous ISM and form an energy-driven bubble that expands freely out
of the disc plane. This bubble is filled with low surface-brightness plasma not
visible in existing VLBI observations of 4C 31.04 due to insufficient
sensitivity. Additional radial flows of jet plasma may percolate to $sim rm
kpc$ radii in the circumnuclear disc, driving shocks and accelerating clouds of
gas, giving rise to the $rm H_2$ emission.
We report the discovery of shocked molecular and ionized gas resulting from
jet-driven feedback in the compact radio galaxy 4C 31.04 using near-IR imaging
spectroscopy. 4C 31.04 is a $sim 100$ pc double-lobed Compact Steep Spectrum
source believed to be a very young AGN. It is hosted by a giant elliptical with
a $sim 10^{9}~rm M_odot$ multi-phase gaseous circumnuclear disc. We used
high spatial resolution, adaptive optics-assisted $H$- and $K$-band integral
field Gemini/NIFS observations to probe (1) the warm ($sim 10^3~rm K$)
molecular gas phase, traced by ro-vibrational transitions of $rm H_2$, and
(2), the warm ionized medium, traced by the [Fe II]$_{1.644~rm mu m}$ line.
The [Fe II] emission traces shocked gas ejected from the disc plane by a
jet-blown bubble $300-400~rm pc$ in diameter, whilst the $rm H_2$ emission
traces shock-excited molecular gas in the interior $sim 1~rm kpc$ of the
circumnuclear disc. Hydrodynamical modelling shows that the apparent
discrepancy between the extent of the shocked gas and the radio emission can
occur when the brightest regions of the synchrotron-emitting plasma are
temporarily halted by dense clumps, whilst less bright plasma can percolate
through the porous ISM and form an energy-driven bubble that expands freely out
of the disc plane. This bubble is filled with low surface-brightness plasma not
visible in existing VLBI observations of 4C 31.04 due to insufficient
sensitivity. Additional radial flows of jet plasma may percolate to $sim rm
kpc$ radii in the circumnuclear disc, driving shocks and accelerating clouds of
gas, giving rise to the $rm H_2$ emission.
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