J/A+A/588/A146 The gNLS1 galaxy PKS 2004-447. VLBI images (Schulz+, 2016)
The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447.
II. The radio view.
Schulz R., Kreikenbohm A., Kadler M., Ojha R., Ros E., Stevens J.,
Edwards P. G., Carpenter B., Elsasser D., Gehrels N., Grossberger C.,
Hase H., Horiuchi S., Lovell J. E. J., Mannheim K., Markowitz A.,
Muller C., Phillips C., Plotz C., Quick J., Trustedt J., Tzioumis A. K.,
Wilms J.
<Astron. Astrophys. 588, A146 (2016)>
=2016A&A...588A.146S 2016A&A...588A.146S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, radio ; VLBI
Keywords: galaxies: active - galaxies: individual: PKS 2004-447 -
radio continuum: galaxies - techniques: interferometry -
galaxies: jets
Abstract:
Gamma-ray-detected radio-loud narrow-line Seyfert 1 (g-NLS1) galaxies
constitute a small but interesting sample of the g-ray-loud AGN. The
radio-loudest g-NLS1 known, PKS 2004-447, is located in the southern
hemisphere and is monitored in the radio regime by the multiwavelength
monitoring programme TANAMI.
We aim for the first detailed study of the radio morphology and
long-term radio spectral evolution of PKS 2004-447, which are
essential for understanding the diversity of the radio properties of
g-NLS1s.
The TANAMI VLBI monitoring program uses the Australian Long Baseline
Array (LBA) and telescopes in Antarctica, Chile, New Zealand, and
South Africa to monitor the jets of radio-loud active galaxies in the
southern hemisphere. Lower resolution radio flux density measurements
at multiple radio frequencies over four years of observations were
obtained with the Australia Telescope Compact Array (ATCA).
The TANAMI VLBI image at 8.4GHz shows an extended one-sided jet with
a dominant compact VLBI core. Its brightness temperature is consistent
with equipartition, but it is an order of magnitude below other
g-NLS1s with the sample value varying over two orders of magnitude. We
find a compact morphology with a projected large-scale size <11kpc
and a persistent steep radio spectrum with moderate flux-density
variability.
PKS 2004-447 appears to be a unique member of the g-NLS1 sample. It
exhibits blazar-like features, such as a flat featureless X-ray
spectrum and a core-dominated, one-sided parsec-scale jet with
indications for relativistic beaming. However, the data also reveal
properties atypical for blazars, such as a radio spectrum and
large-scale size consistent with compact-steep-spectrum (CSS) objects,
which are usually associated with young radio sources. These
characteristics are unique among all g-NLS1s and extremely rare among
g-ray-loud AGN.
Description:
Flux density measurements of ATCA observations (Table A.1) and four
naturally weighted CLEAN-images as FITS-files (Fig. 3 and 4).
Objects:
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RA (2000) DE Designation(s)
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20 07 55.18 -44 34 44.3 PKS 2004-447 = PMN J2007-4434
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 35 58 Flux density measurements of ATCA
list.dat 120 4 List of FITS images
fits/* . 4 Individual VLBI FITS images of PKS 2004-447
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 F4.1 GHz Freq Frequency
6- 15 A10 "date" Obs.Date Observation date
17- 20 F4.2 Jy Flux Flux density
22- 25 F4.2 Jy e_Flux Uncertainty of Flux density
27- 35 F9.1 d JD Julian date
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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)
11- 19 F9.5 deg DEdeg Declination of center (J2000)
21- 28 F8.3 mas/pix Scale Scale of the image
30- 33 I4 --- Nx Number of pixels along X-axis
34 A1 --- --- [x]
35- 38 I4 --- Ny Number of pixels along Y-axis
40- 43 F4.2 GHz Freq Frequency
45- 54 A10 "date" Obs.Date Observation date
56- 59 I4 Kibyte size Size of FITS file
61- 78 A18 --- FileName Name of FITS file in subdirectory fits
80-120 A41 --- Title Title of the file
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Acknowledgements:
Robert Schulz, robert.schulz(at)physik.uni-wuerzburg.de
References:
Kreikenbohm et al., Paper I 2016A&A...585A..91K 2016A&A...585A..91K
(End) Patricia Vannier [CDS] 17-Mar-2016