J/A+A/641/A152 TANAMI radio galaxies II (Angioni+, 2020)
Gamma-ray emission in radio galaxies under the VLBI scope.
II. The relationship between gamma-ray emission and parsec-scale jets in
radio galaxies.
Angioni R. Ros E., Kadler M., Ojha R., Mueller C., Edwards P.G., Burd P.R.,
Carpenter B., Dutka M.S., Gulyaev S., Hase H., Horiuchi S., Krauss F.,
Lovell J.E.J., Natusch T., Phillips C., Ploetz C., Quick J.F.H., Roesch F.,
Schulz R., Stevens J., Tzioumis A.K., Weston S., Wilms J., Zensus J.A.
<Astron. Astrophys. 641, A152 (2020)>
=2020A&A...641A.152A 2020A&A...641A.152A (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, radio ; VLBI ; Gamma rays
Keywords: galaxies: active - galaxies: nuclei - gamma rays: galaxies -
galaxies: jets
Abstract:
This is the second paper in our series studying the evolution of
parsec-scale radio emission in radio galaxies in the southern
hemisphere. Following our study of the radio and high-energy
properties of gamma-ray-emitting sources, here we investigate the
kinematic and spectral properties of the parsec-scale jets of radio
galaxies that have not yet been detected by the Fermi Large Area
Telescope (Fermi-LAT) instrument on board NASA's Fermi Gamma-ray Space
Telescope. For many sources, these results represent the first
milliarcsecond resolution information in the literature. These studies
were conducted within the framework of the Tracking Active Nuclei with
Austral Milliarcsecond Interferometry (TANAMI) monitoring program and
in the context of high-energy gamma-ray observations from Fermi-LAT.
We take advantage of the regular 8.4GHz and 22.3GHz Very Long
Baseline Interferometry (VLBI) observations provided by the TANAMI
monitoring program, and explore the kinematic properties of six
gamma-ray-faint radio galaxies. We complement this with ∼8.5 years of
Fermi-LAT data, deriving updated upper limits on the gamma-ray
emission from this subsample of TANAMI radio galaxies. We include
publicly available VLBI kinematics of gamma-ray-quiet radio galaxies
monitored by the MOJAVE program and perform a consistent Fermi-LAT
analysis. We combine these results with those from our previous paper
to construct the largest sample of radio galaxies with combined VLBI
and gamma-ray measurements to date. The connection between
parsec-scale jet emission and high-energy properties in the misaligned
jets of radio galaxies is explored. We report for the first time
evidence of superluminal motion up to betaapp=3.6 in the jet of the
gamma-ray-faint radio galaxy PKS 2153-69. We find a clear trend of
higher apparent speed as a function of distance from the jet core,
which indicates that the jet is still being accelerated on scales of
tens of parsecs, or ∼105R☉, corresponding to the end of the
collimation and acceleration zone in nearby radio galaxies. We find
evidence of subluminal apparent motion in the jets of PKS 1258-321 and
IC 4296, and no measurable apparent motion for PKS 1549-79,
PKS 1733-565 and PKS 2027-308. For all these sources, TANAMI provides the
first multi-epoch kinematic analysis on parsec scales. We then compare
the VLBI properties of gamma-ray-detected and undetected radio
galaxies, and find that the two populations show a significantly
different distribution of median core flux density, and, possibly, of
median core brightness temperature. In terms of correlation between
VLBI and gamma-ray properties, we find a significant correlation
between median core flux density and gamma-ray flux, but no
correlation with typical Doppler boosting indicators such as median
core brightness temperature and core dominance. Our study suggests
that high-energy emission from radio galaxies is related to
parsec-scale radio emission from the inner jet, but is not driven by
Doppler boosting effects, in contrast to the situation in their blazar
counterparts. This implies that gamma-ray loudness does not
necessarily reflect a higher prevalence of boosting effects.
Description:
VLBI images at 8.4GHz and 22.3GHz of gamma-ray undetected radio
galaxies in the TANAMI sample, i.e. PKS 1258-321, IC 4296,
PKS 1549-79, PKS 1733-56, PKS 1814-63, PKS 2027-308 and PKS 2153-69.
The VLBI data has been calibrated in AIPS and imaged in Difmap
following standard procedures.
Objects:
------------------------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------------------------
13 01 00.79 -32 26 29.0 PKS 1258-321 = QSO J1301-3226
13 36 39.03 -33 57 57.1 IC 4296 = IBVS 1333-337
15 56 58.87 -79 14 04.3 PKS 1549-790 = QSO B1549-790
17 37 35.77 -56 34 03.1 PKS 1733-565 = ICRF J173735.7-563403
18 19 35.00 -63 45 48.2 PKS 1814-637 = ICRF J181935.0-634548
20 30 57.93 -30 39 24.3 PKS 2027-308 = ICRF J203057.9-303924
21 57 05.98 -69 41 23.7 PKS 2152-699 = ESO 75-41
------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 140 55 List of fits images
fits/* . 55 Individual fits images
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See also:
J/A+A/627/A148 : TANAMI radio galaxies I (Angioni+, 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- 51 E11.6 Hz Freq Observed frequency
53- 57 I5 Kibyte size Size of FITS file
59- 90 A32 --- FileName Name of FITS file, in subdirectory fits
92-140 A49 --- Title Title of the FITS file
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Acknowledgements:
Roberto Angioni, r.angioni90(at)gmail.com
References:
Angioni et al., Paper I 2019A&A...627A.148A 2019A&A...627A.148A, Cat. J/A+A/627/A148
(End) R. Angioni [ASI SSDC/INFN Roma Tor Vergata], P. Vannier [CDS] 21-Jul-2020