J/A+A/647/A63 4C52.37 and 3C 293 parsec-scale HI outflows (Schulz+, 2021)
Parsec-scale HI outflows in powerful radio galaxies.
Schulz R., Morganti R., Nyland K., Paragi Z., Mahony E.K., Oosterloo T.
<Astron. Astrophys. 647, A63 (2021)>
=2021A&A...647A..63S 2021A&A...647A..63S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; H I data ; VLBI
Keywords: galaxies: active - galaxies: jets - galaxies: general -
techniques: high angular resolution - ISM: jets and outflows
Abstract:
Massive outflows of neutral atomic hydrogen (HI) have been observed in
absorption in a number of radio galaxies and are considered a
signature of active galactic nucleus (AGN) feedback. These outflows on
kiloparsec scales have not been investigated in great detail as they
require high-angular-resolution observations to be spatially resolved.
In some radio AGN, they are likely to be the result of the radio jets
interacting with the interstellar medium. We have used the global
very-long-baseline-interferometry (VLBI) array to map the HI outflow
in a small sample of young and restarted radio galaxies that we
previously observed with the Very Large Array (VLA) and the Westerbork
Synthesis Radio Telescope (WSRT) at a lower resolution. Here we report
on our findings for 4C 52.37 and 3C 293 and we discuss the sample
including the previously published 4C 12.50 and 3C 236.
For 4C 52.37, we present the first ever HI VLBI observations, which
recovered the majority of the outflowing HI gas in the form of clouds
toward the central 100pc of the AGN. The clouds are blueshifted by up
to ∼600km/s with respect to the systemic velocity. 3C 293 is
largely resolved out in our VLBI observation, but toward the VLBI core
we detect some outflowing HI gas blueshifted with respect to the
systemic velocity by up to ∼300km/s. We also find indications of
outflowing gas toward the other parts of the western lobe suggesting
that the HI outflow is extended.
Overall, we find that the fraction of HI gas recovered by our VLBI
observations varies significantly within our sample, ranging from
complete (4C 12.50) to marginal (3C 293). However, in all cases we
find evidence for a clumpy structure of both the outflowing and the
quiescent gas, consistent with predictions from numerical simulations.
All the outflows include at least a component of relatively compact
clouds with masses in the range of 104-105M☉. The outflowing
clouds are often already observed at a few tens of parsecs (in
projection) from the core. We find indications that the HI outflow
might have a diffuse component, especially in larger sources. Our
results support the interpretation that we observe these AGNs at
different stages in the evolution of the interaction between the jet
and the interstellar medium and this is reflected in the properties of
the outflowing gas as predicted by numerical simulations.
Description:
CLEAN-image and cube as FITS-files used for Fig. 1, 3, and 5 and to
extract the VLBI spectra in Fig. 2, 4, and A.1.
Objects:
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RA (2000) DE Designation(s)
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13 52 17.88 +31 26 46.5 3C 293 = LEDA 49258
16 02 46.44 +52 43 58.1 4C 52.37 = LEDA 2422287
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 166 5 List of fits images and datacubes
fits/* . 5 Individual fits images and datacubes
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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- 32 I3 --- Nz ?=- Number of slices for the datacubes
34- 43 A10 "date" Obs.date Observation date
45- 51 F7.5 GHz Freq Observed frequency
53- 61 F9.3 km/s bVEL ? Lower value of velocity interval
for the datacubes
63- 69 F7.2 km/s BVEL ? Upper value of velocity interval
for the datacubes
71- 77 F7.4 km/s dVEL ? Velocity resolution for the datacubes
79- 85 I7 Kibyte size Size of FITS file
87-106 A20 --- FileName Name of FITS file, in subdirectory fits
108-166 A59 --- Title Title of the FITS file
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Acknowledgements:
Robert Schulz, r.f.schulz(at)issc.leidenuniv.nl
(End) Patricia Vannier [CDS] 05-Jan-2021