J/A+A/640/A104 NGC 1377 ALMA CO 3-2 and 0.8mm continuum images (Aalto+, 2020)
ALMA resolves the remarkable molecular jet and rotating wind in the extremely
radio-quiet galaxy NGC 1377.
Aalto S., Falstad N., Muller S., Wada K., Gallagher J.S., Koenig S.,
Sakamoto K., Vlemmings W., Ceccobello C., Dasyra K., Combes F.,
Garcia-Burillo S., Oya Y., Martin S., van der Werf P., Evans A.S.,
Kotilainen J.
<Astron. Astrophys. 640, A104 (2020)>
=2020A&A...640A.104A 2020A&A...640A.104A (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Radio lines
Keywords: galaxies: evolution - galaxies: individual: NGC 1377 -
galaxies: active - galaxies: nuclei - ISM: molecules -
ISM: jets and outflows
Abstract:
Submillimetre and millimetre line and continuum observations are
important in probing the morphology, column density, and dynamics of
the molecular gas and dust around obscured active galactic nuclei
(AGNs) and their mechanical feedback. With very high resolution
(0.02"x0.03" (2x3pc)) ALMA 345GHz observations of CO 3-2, HCO+ 4-3,
vibrationally excited HCN 4-3 ν2=1f , and continuum we have
studied the remarkable, extremely radio-quiet, molecular jet and wind
of the lenticular galaxy NGC 1377. The outflow structure is resolved,
revealing a 150pc long, clumpy, high-velocity (600km/s), collimated
molecular jet where the molecular emission is emerging from the spine
of the jet with an average diameter of 3-7pc. The jet widens to
10-15pc about 25pc from the centre, which is possibly due to jet-wind
interactions. A narrow-angle (50-70), misaligned and rotating
molecular wind surrounds the jet, and both are enveloped by a
larger-scale CO-emitting structure at near-systemic velocity. The jet
and narrow wind have steep radial gas excitation gradients and appear
turbulent with high gas dispersion (>40km/s). The jet shows velocity
reversals that we propose are caused by precession, or more episodic
directional changes. We discuss the mechanisms powering the outflow,
and we find that an important process for the molecular jet and narrow
wind is likely magneto-centrifugal driving. In contrast, the
large-scale CO-envelope may be a slow wind, or cocoon that stems from
jet-wind interactions. An asymmetric, nuclear r∼2pc dust structure
with a high inferred molecular column density N(H2)=1.8x1024cm-2
is detected in continuum and also shows compact emission from
vibrationally excited HCN. The nuclear dust emission is hot (Td>180K)
and its luminosity is likely powered by a buried AGN. The lopsided
structure appears to be a warped disk, which is responsible for a
significant part of the nuclear obscuration and possibly formed as a
result of uneven gas inflows. The dynamical mass inside r=1.4pc is
estimated to 9+23x106M☉, implying that the supermassive
black hole (SMBH) has a high mass with respect to the stellar velocity
dispersion of NGC 1377. We suggest that the SMBH of NGC 1377 is
currently in a state of moderate growth, at the end of a more intense
phase of accretion and also evolving from a state of more extreme
nuclear obscuration. The nuclear growth may be fuelled by low-angular
momentum gas inflowing from the gas ejected in the molecular jet and
wind. Such a feedback-loop of cyclic outflows and central accretion
could explain why there is still a significant reservoir of molecular
gas in this ageing, lenticular galaxy. A feedback-loop would be an
effective process in growing the nuclear SMBH and thus would
constitute an important phase in the evolution of NGC 1377. This also
invites new questions as to SMBH growth processes in obscured, dusty
galaxies.
Description:
Observations of the CO J=3-2 line (at 0.25"x0.18" resolution)
have been previously obtained with the Atacama Large Millimeter /submm
Array (ALMA) in August 2014 and reported in Aalto et al.
(2016A&A...590A..73A 2016A&A...590A..73A). Here we present new ALMA observations, with the
same spectral tuning but with more extended array configurations,
taken in November 2017.
ALMA data continuum substracted FITS file of CO 3-2 and 0.8mm
continuum.
Objects:
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RA (2000) DE Designation(s)
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03 36 39.08 -20 54 08.1 NGC 1377 = ESO 548-51
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 146 2 List of fits files
fits/* . 2 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 31 I2 --- Nz ? Number of slices for the datacube
33- 42 A10 "date" Obs.date Observation date
44- 50 F7.3 GHz Freq ? Observed frequency for 0.8mm continuum image
51- 61 E11.5 m/s bVELO-LSR ? Lower value of bVELO-LSR interval
for the datacube
63- 73 E11.5 m/s BVELO-LSR ? Upper value of bVELO-LSR interval
for the datacube
75- 81 F7.1 m/s dVELO-LSR ? VELO-LSR resolution
83- 88 I6 Kibyte size Size of FITS file
90-110 A21 --- FileName Name of FITS file, in subdirectory fits
112-146 A35 --- Title Title of the FITS file
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Acknowledgements:
Susanne Aalto, saalto(at)chalmers.se
(End) Patricia Vannier [CDS] 27-Jul-2020