J/A+A/614/A42 PKS B1718-649 ALMA observations (Maccagni+, 2018)
ALMA observations of AGN fuelling. The case of PKS B1718-649.
Maccagni F.M., Morganti R., Oosterloo T.A., Oonk J.B.R., Emonts B.H.C.
<Astron. Astrophys. 614, A42 (2018)>
=2018A&A...614A..42M 2018A&A...614A..42M (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Radio lines ; Carbon monoxide
Keywords: galaxies: individual: PKS B1718-649 - galaxies: active -
galaxies: ISM - galaxies: kinematics and dynamics - ISM: cloud -
submillimeter: ISM
Abstract:
We present ALMA observations of the 12CO (2-1) line of the newly
born (tradio∼102years) active galactic nucleus (AGN), PKS
B1718-649. These observations reveal that the carbon monoxide in the
innermost 15 kpc of the galaxy is distributed in a complex warped
disk. In the outer parts of this disk, the CO gas follows the rotation
of the dust lane and of the stellar body of the galaxy hosting the
radio source. In the innermost kiloparsec, the gas abruptly changes
orientation and forms a circumnuclear disk (r≲700pc) with its major
axis perpendicular to that of the outer disk. Against the compact
radio emission of PKS B1718-649 (r∼2pc), we detect an absorption line
at red-shifted velocities with respect to the systemic velocity
(Δv=+365±22km/s). This absorbing CO gas could trace molecular
clouds falling onto the central super-massive black hole. A comparison
with the near-infra red H2 1-0 S(1) observations shows that the
clouds must be close to the black hole (r≲75pc). The physical
conditions of these clouds are different from the gas at larger radii,
and are in good agreement with the predictions for the conditions of
the gas when cold chaotic accretion triggers an active galactic
nucleus. These observations on the centre of PKS B1718-649 provide one
of the best indications that a population of cold clouds is falling
towards a radio AGN, likely fuelling its activity.
Description:
The datacube was made using natural Briggs weighting and has been
smoothed to a velocity resolution of 48km/s. The r.m.s. noise per
channel of the data cube is 0.09mJy/beam. The size of the synthesized
beam of the final data cube is 0.28"x0.19" (PA=41°),
which, at the redshift of PKS B1718-649 corresponds to a spatial
resolution of ∼82pc.
Objects:
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RA (2000) DE Designation(s)
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17 23 41.03 -65 00 36.6 PKS B1718-649 = NGC 6328
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 135 1 Informations on the datacube
fits/* . 1 Datacube
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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
33- 53 A21 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.s)
55- 58 I4 km/s bVELO-OBS Lower value of observed velocity interval
60- 63 I4 km/s BVELO-OBS Upper value of observed velocity interval
65- 66 I2 km/s dVELO-OBS Observed velocity resolution
68- 73 I6 Kibyte Size Size of FITS file
75- 91 A17 --- FileName Name of FITS file, in subdirectory fits
93-135 A43 --- Title Title of the FITS file
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Acknowledgements:
Filippo Maccagni, maccagni(at)oa-cagliari.inaf.it
(End) Filippo Maccagni [INAF-OAC, Italy], Patricia Vannier [CDS] 12-Feb-2018