J/A+A/648/A116 PKS 1830-211 OH and HI spectra (Combes+, 2021)
PKS 1830-211: OH and HI at z=0.89 and the first MeerKAT UHF spectrum.
Combes F., Gupta N., Muller S., Balashev S., Jozsa G.I.G., Srianand R.,
Momjian E., Noterdaeme P., Kloeckner H.-R., Baker A.J., Boettcher E.,
Bosma A., Chen H.-W., Dutta R., Jagannathan P., Jose J., Knowles K.,
Krogager J-.K., Kulkarni V.P., Moodley K., Pandey S., Petitjean P.,
Sekhar S.
<Astron. Astrophys. 648, A116 (2021)>
=2021A&A...648A.116C 2021A&A...648A.116C (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Spectra, radio ; Interstellar medium
Keywords: galaxies: ISM - quasars: absorption lines -
quasars: individual: PKS 1830-211
Abstract:
The Large Survey Project (LSP) "MeerKAT Absorption Line Survey" (MALS)
is a blind HI 21-cm and OH 18-cm absorption line survey in the L- and
UHF-bands, with the primary goal to better determine the occurrence of
atomic and molecular gas in the circumgalactic and inter-galactic
medium, and its redshift evolution. Here we present the first results
using the UHF-band, obtained towards the strongly lensed radio source
PKS 1830-211, detecting absorption produced by the lensing galaxy.
With merely 90 mins of data acquired on-source for science
verification and processed using the Automated Radio Telescope Imaging
Pipeline (ARTIP), we detect in absorption the known HI 21-cm and OH
18-cm main lines at z=0.89 at an unprecedented signal-to-noise ratio
(4000 in the continuum, in each 6km/s wide channel). For the first
time we report the detection at z=0.89 of OH satellite lines, so far
not detected at z>0.25. We decompose the OH lines into a thermal and a
stimulated contribution, where the 1612 and 1720MHz lines are
conjugate. The total OH 1720MHz emission line luminosity is
6100L☉. This is the most luminous known 1720MHz maser line. It
is also among the highest luminosities for the OH-main lines
megamasers. The absorption components of the different images of the
background source sample different light paths in the lensing galaxy,
and their weights in the total absorption spectrum are expected to
vary in time, on daily and monthly time scales. We compare our
normalized spectra with those obtained more than 20yrs ago, and find
no variation, in spite of the high signal-to-noise ratios. We
interpret the absorption spectra with the help of a lens galaxy model,
derived from an N-body hydro-dynamical simulation, with a morphology
similar to its optical HST image. The resulting absorption lines
depend mainly on the background continuum, and the radial distribution
of the gas surface density, for each atomic /molecular species.We show
that it is possible to reproduce the observations assuming a realistic
spiral galaxy disk, without invoking any central gas outflows. There
are, however, distinct and faint high-velocity features in the ALMA
millimeter absorption spectra, that most likely originate from
high-velocity clouds or tidal features. These clouds may contribute to
broaden the Hi and OH spectra.
Description:
The field centered at PKS 1830-211 was observed on July
13, 2020 using the MeerKAT-64 array and 32K mode of the SKA
Reconfigurable Application Board (SKARAB) correlator. For these
UHF-band science verification observations, the total observable
bandwidth of 544MHz was split into 32768 frequency channels. This
corresponds to a frequency resolution of 16.602kHz, or 6.1km/s
at the center of the band i.e., 815.9917MHz.
Objects:
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RA (2000) DE Designation(s)
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18 33 39.92 -21 03 39.9 PKS 1830-211 = QSO B1830-211
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 73 5 List of spectra
sp/* . 5 Individual spectra
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See also:
J/A+A/535/A103 : 7mm spectral survey of PKS 1830-211 (Muller+, 2011)
J/A+A/574/A108 : Molecular absorption lines in PKS 1830-211 (Schulz+, 2015)
J/A+A/595/A128 : PKS 1830-211 OH+ and H2O+ spectra (Muller+, 2016)
J/A+A/637/A7 : PKS 1830-211 HDO, ND and NH2D spectra (Muller+, 2020)
J/A+A/641/L2 : ALMA third image of lensed quasar PKS 1830-211 (Muller+, 2020)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- FileName Name of spectrum file in subdirectory sp
20- 22 I3 --- Nx Number of measurements
24- 73 A50 --- Title Title of the file
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 16 F16.10 km/s Vel Velocity
19- 30 F12.10 --- NFlux Flux normalized to continuum
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Acknowledgements:
Francoise Combes, francoise.combes(at)observatoiredeparis.psl.eu
(End) Patricia Vannier [CDS] 01-Mar-2021