J/A+A/641/A40 S5 0836+710 Ground and Space VLBI images (Vega Garcia+, 2020)
Multiband RadioAstron space VLBI imaging of the jet in quasar S5 0836+710.
Vega Garcia L., Lobanov A.P., Perucho M., Bruni G., Ros E., Anderson J.M.,
Agudo I., Davis R., Gomez J.L., Kovalev Y.Y., Krichbaum T.P., Lisakov M.,
Savolainen T., Schinzel F.K., Zensus J.A.
<Astron. Astrophys. 641, A40 (2020)>
=2020A&A...641A..40V 2020A&A...641A..40V (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Radio sources ; VLBI
Keywords: radio continuum: galaxies - galaxies: jets - galaxies: active -
galaxies: individual: S5 0836+710
Abstract:
Detailed studies of relativistic jets in active galactic nuclei (AGN)
require high-fidelity imaging at the highest possible resolution. This
can be achieved using very long baseline interferometry (VLBI) at
radio frequencies, combining worldwide (global) VLBI arrays of radio
telescopes with a space-borne antenna on board a satellite.
We present multiwavelength images made of the radio emission in the
powerful quasar S5 0836+710, obtained using a global VLBI array and
the antenna Spektr-R of the RadioAstron mission of the Russian Space
Agency, with the goal of studying the internal structure and physics
of the relativistic jet in this object.
The RadioAstron observations at wavelengths of 18cm, 6cm, and 1.3cm
are part of the Key Science Program for imaging radio emission in
strong AGN. The internal structure of the jet is studied by analyzing
transverse intensity profiles and modeling the structural patterns
developing in the flow.
The RadioAstron images reveal a wealth of structural detail in the jet
of S5 0836+710 on angular scales ranging from 0.02mas to 200mas.
Brightness temperatures in excess of 1013K are measured in the jet,
requiring Doppler factors of ≥100 for reconciling them with the
inverse Compton limit. Several oscillatory patterns are identified in
the ridge line of the jet and can be explained in terms of the
Kelvin-Helmholtz (KH) instability. The oscillatory patterns are
interpreted as the surface and body wavelengths of the helical mode of
the KH instability. The interpretation provides estimates of the jet
Mach number and of the ratio of the jet to the ambient density, which
are found to be Mj~=12 and η~=0.33. The ratio of the jet to the
ambient density should be conservatively considered an upper limit
because its estimate relies on approximations.
Description:
RadioAstron imaging observations of S5 0836+710 were performed at two
epochs: on 24 October 2013 at L band (1.6GHz, wavelength
λ=18cm) and on 10-11 January 2014 at C band (5GHz,
λ=6cm) and K band (22GHz, λ=1.3cm), combining data
recorded at the SRT with data provided by a ground array of radio
telescopes. At each epoch the source was observed for about 18 hours,
starting from a perigee passage of the SRT, in order to ensure a
continuous coverage of Fourier domain (uv coverage) by the
ground-space baseline data.
Ground and space VLBI images.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 231 8 List of fits images
fits/* . 8 Individual fits images
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See also:
J/A+A/545/A65 : S5 0836+710 image at 1.6GHz (Perucho+, 2012)
J/A+A/631/A49 : LOFAR images of blazar S5 0836+710 (Kappes+, 2019)
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- 39 A10 "date" Obs.date Observation date
41- 48 F8.5 GHz Freq Observed frequency
50- 54 I5 Kibyte size Size of FITS file
56- 82 A27 --- FileName Name of FITS file, in subdirectory fits
84-231 A148 --- Title Title of the FITS file
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Acknowledgements:
Andrei Lobanov, alobanov(at)mpifr-bonn.mpg.de
(End) Patricia Vannier [CDS] 31-Aug-2020