NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
The Gamma-Ray Emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy PKS 2004-447 II. The Radio ViewContext. gamma-ray-detected radio-loud narrow-line Seyfert 1 (gamma-NLS1) galaxies constitute a small but interesting sample of the gamma-ray-loud AGN. The radio-loudest gamma-NLS1 known, PKS2004447, is located in the southern hemisphere and is monitored in the radio regime by the multiwavelength monitoring programme TANAMI. Aims. We aim for the first detailed study of the radio morphology and long-term radio spectral evolution of PKS2004447, which are essential for understanding the diversity of the radio properties of gamma-NLS1s. Methods. 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). Results. 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 gamma-NLS1s with the sample value varying over two orders of magnitude. We find a compact morphology with a projected large-scale size 11 kpc and a persistent steep radio spectrum with moderate flux-density variability. Conclusions. PKS2004447 appears to be a unique member of the gamma-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 gamma-NLS1s and extremely rare among gamma-ray-loud AGN.
Document ID
20170003555
Document Type
Reprint (Version printed in journal)
Authors
Schulz, R. (Erlangen-Nuernberg Univ. Bamberg, Germany)
Kreikenbohm, A. (Erlangen-Nuernberg Univ. Bamberg, Germany)
Kadler, M. (Wuerzburg Univ. Wurzburg, Germany)
Ojha, R. (Maryland Univ. Baltimore County Baltimore, MD, United States)
Ros, E. (Valencia Univ. Spain)
Stevens, J. (Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Edwards, P. G. (Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Carpenter, B. (Catholic Univ. of America Washington, DC, United States)
Elsaesser, D. (Wuerzburg Univ. Wurzburg, Germany)
Gehrels, N. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Grobberger, C. (Erlangen-Nuernberg Univ. Bamberg, Germany)
Hase, H. (Bundesamt fuer Kartographie und Geodaesie Frankfurt am Main, Germany)
Horiuchi, S. (Commonwealth Scientific and Industrial Research Organization Canberra, Australia)
Lovell, J. E. J. (Tasmania Univ. Hobart, Australia)
Mannheim, K. (Wuerzburg Univ. Wurzburg, Germany)
Markowitz, A. (California Univ. San Diego, CA, United States)
Phillips, C. (Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Ploetz, C. (Bundesamt fuer Kartographie und Geodaesie Frankfurt am Main, Germany)
Quick, J. (Hartebeesthoek Radio Astronomy Observatory Johannesburg, South Africa)
Truestedt, J. (Wuerzburg Univ. Wurzburg, Germany)
Tzioumis, A. K. (Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Wilms, J. (Erlangen-Nuernberg Univ. Bamberg, Germany)
Date Acquired
April 17, 2017
Publication Date
April 1, 2016
Publication Information
Publication: Astronomy & Astrophysics
Volume: 588
ISSN: 0004-6361
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN41695
Funding Number(s)
CONTRACT_GRANT: NNG17PT01A
Distribution Limits
Public
Copyright
Other
Keywords
galaxies: active / galaxies: individual: PKS 2004-447 / radio continuum: galaxie