J/A+A/644/A85 Sub-milliarcsecond imaging of 3C111 (Schulz+, 2020)
Sub-milliarcsecond imaging of a bright flare and ejection event in the
extragalactic jet 3C 111.
Schulz R., Kadler M., Ros E., Perucho M., Krichbaum T.P., Agudo I.,
Beuchert T., Lindqvist M., Mannheim K., Wilms J., Zensus J.A.
<Astron. Astrophys. 644, A85 (2020)>
=2020A&A...644A..85S 2020A&A...644A..85S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei; Galaxies, radio ; VLBI
Keywords: galaxies: active - galaxies: jets - galaxies: individual: 3C 111 -
techniques: high angular resolution
Abstract:
Flares in radio-loud active galactic nuclei (AGNs) are thought to be
associated with the injection of fresh plasma into the compact jet
base. Such flares are usually strongest and appear earlier at shorter
radio wavelengths. Hence, very long baseline interferometry (VLBI) at
millimeter (mm)-wavelengths is the best-suited technique for studying
the earliest structural changes of compact jets associated with
emission flares. Aims. We study the morphological changes of the
parsec-scale jet in the nearby (z=0.049) gamma-ray bright radio
galaxy 3C 111 following a flare that developed into a major radio
outburst in 2007.
We analyse three successive observations of 3C 111 at 86 GHz with the
Global mm-VLBI Array (GMVA) between 2007 and 2008 which yield a very
high angular resolution of ∼45 muas. In addition, we make use of
single-dish radio flux density measurements from the F-GAMMA and
POLAMI programmes, archival single-dish and VLBI data.
We resolve the flare into multiple plasma components with a distinct
morphology resembling a bend in an otherwise remarkably straight jet.
The flare-associated features move with apparent velocities of ∼4.0c
to ∼4.5c and can be traced also at lower frequencies in later epochs.
Near the base of the jet, we find two bright features with high
brightness temperatures up to ∼1011K, which we associate with the
core and a stationary feature in the jet.
The flare led to multiple new jet components indicative of a dynamic
modulation during the ejection. We interpret the bend-like feature as
a direct result of the outburst which makes it possible to trace the
transverse structure of the jet. In this scenario, the components
follow different paths in the jet stream consistent with expectations
for a spine-sheath structure, which is not seen during intermediate
levels of activity. The possibility of coordinated multiwavelength
observations during a future bright radio flare in 3C 111 makes this
source an excellent target for probing the radio-gamma-ray connection.
Description:
tablea4.dat with single-dish flux density measurements of 3C111 at 86
GHz obtained by the F-GAMMA and POLAMI programme; used for Fig. 1.
VLBI CLEAN-images of 3C111 obtained with the GMVA as FITS-files; used
for Fig. 2, 3 and 5.
Objects:
-------------------------------------------------------
RA (2000) DE Designation(s)
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04 18 21.28 +38 01 35.8 3C111 = QSO J0418+3801
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea4.dat 31 61 86GHz flux density measurements
list.dat 101 3 List of fits images
fits/* . 3 Individual fits images
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See also:
J/ApJ/734/43 : 3C 111 X-ray, optical and radio monitoring (Chatterjee+, 2011)
Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Date Date of the measurement (MJD)
11- 16 F6.3 Jy Flux Measured flux density at 86GHz
19- 23 F5.3 Jy e_Flux Error of the measured flux density at 86GHz
25- 31 A7 --- Project Single-dish monitoring programme which
obtained the measurement (F-GAMMA or POLAMI)
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
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- 39 A10 "date" Obs.date Observation date
41- 47 F7.4 GHz Freq Observed frequency
49- 52 I4 Kibyte size Size of FITS file
54- 67 A14 --- FileName Name of FITS file, in subdirectory fits
69-101 A33 --- 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-Oct-2020