TY - JOUR
T1 - The jet-ISM interaction in the outer filament of Centaurus A
AU - Santoro, F.
AU - Oonk, J. B. R.
AU - Morganti, R.
AU - Oosterloo, T.
PY - 2015/2
Y1 - 2015/2
N2 - Context. The interaction between the radio plasma ejected by the active
nucleus of a galaxy and the surrounding medium is a key process that can
have a strong impact on the interstellar medium (ISM) of the galaxy and
hence on galaxy evolution. The closest laboratory where we can observe
and investigate this phenomenon is the radio galaxy Centaurus A. About
15 kpc northeast of this galaxy, a particularly complex region is found:
the so-called outer filament where it has been proposed that jet-cloud
interactions occur. Aims: We investigate the signatures of
jet-ISM interaction by a detailed study of the kinematics of the ionized
gas, expanding on previous results obtained from the H i.
Methods: We observed two regions of the outer filament with VLT/Visible
MultiObject Spectrograph (VIMOS) in integral field unit (IFU) observing
mode. Emission from Hβ and [O iii]λλ4959, 5007
Å is detected in both pointings. Results: We found two
distinct kinematical components of ionized gas that closely match the
kinematics of the nearby H i cloud. One component follows the regular
kinematics of the rotating gas, while the second shows similar
velocities to those of the nearby H i component thought to be disturbed
by an interaction with the radio jet. Conclusions: We suggest
that the ionized and atomic gas are part of the same dynamical gas
structure stemming from the merger that shaped Centaurus A. It is
regularly rotating around Centaurus A, as proposed by other authors. The
gas (ionized and H i) with anomalous velocities traces the interaction
of the large-scale radio jet with the interstellar medium, suggesting
that the jet is still active although poorly collimated. However, we can
exclude that a strong shock is driving the ionization of the gas. It is
likely that a combination of jet entrainment and photoionization by the
UV continuum from the central engine is needed to explain both the
ionization and the kinematics of the gas in the outer filament.
AB - Context. The interaction between the radio plasma ejected by the active
nucleus of a galaxy and the surrounding medium is a key process that can
have a strong impact on the interstellar medium (ISM) of the galaxy and
hence on galaxy evolution. The closest laboratory where we can observe
and investigate this phenomenon is the radio galaxy Centaurus A. About
15 kpc northeast of this galaxy, a particularly complex region is found:
the so-called outer filament where it has been proposed that jet-cloud
interactions occur. Aims: We investigate the signatures of
jet-ISM interaction by a detailed study of the kinematics of the ionized
gas, expanding on previous results obtained from the H i.
Methods: We observed two regions of the outer filament with VLT/Visible
MultiObject Spectrograph (VIMOS) in integral field unit (IFU) observing
mode. Emission from Hβ and [O iii]λλ4959, 5007
Å is detected in both pointings. Results: We found two
distinct kinematical components of ionized gas that closely match the
kinematics of the nearby H i cloud. One component follows the regular
kinematics of the rotating gas, while the second shows similar
velocities to those of the nearby H i component thought to be disturbed
by an interaction with the radio jet. Conclusions: We suggest
that the ionized and atomic gas are part of the same dynamical gas
structure stemming from the merger that shaped Centaurus A. It is
regularly rotating around Centaurus A, as proposed by other authors. The
gas (ionized and H i) with anomalous velocities traces the interaction
of the large-scale radio jet with the interstellar medium, suggesting
that the jet is still active although poorly collimated. However, we can
exclude that a strong shock is driving the ionization of the gas. It is
likely that a combination of jet entrainment and photoionization by the
UV continuum from the central engine is needed to explain both the
ionization and the kinematics of the gas in the outer filament.
KW - galaxies: active
KW - ISM: jets and outflows
KW - galaxies: clusters: individual: Centaurus A
UR - http://adsabs.harvard.edu/abs/2015A%26A...574A..89S
U2 - 10.1051/0004-6361/201425103
DO - 10.1051/0004-6361/201425103
M3 - Article
VL - 574
JO - Astronomy & astrophysics
JF - Astronomy & astrophysics
SN - 0004-6361
M1 - A89
ER -