SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION
Abstract
A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nucleus power and host galaxy properties, is presented to test the predictions of the unified scheme hypothesis. Our sample sources have core flux densities greater than 8 mJy at 5 GHz on arcsec scales due to the feasibility requirements. These simultaneous parsec-scale and kiloparsec-scale radio observations reveal (1) that Seyfert 1 and Seyfert 2 galaxies have an equal tendency to show compact radio structures on milliarcsecond scales, (2) the distributions of parsec-scale and kiloparsec-scale radio luminosities are similar for both Seyfert 1 and Seyfert 2 galaxies, (3) there is no evidence for relativistic beaming in Seyfert galaxies, (4) similar distributions of source spectral indices in spite of the fact that Seyferts show nuclear radio flux density variations, and (5) the distributions of the projected linear size for Seyfert 1 and Seyfert 2 galaxies are not significantly different as would be expected in the unified scheme. The latter could be mainly due to a relatively large spread in the intrinsic sizes. We also find that a starburst alone cannot power these radio sources. Finally, an analysismore »
- Authors:
-
- Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)
- Department of Physics, University College Cork, Cork (Ireland)
- Publication Date:
- OSTI Identifier:
- 21574738
- Resource Type:
- Journal Article
- Journal Name:
- Astrophysical Journal
- Additional Journal Information:
- Journal Volume: 731; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/731/1/68; Journal ID: ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTRIBUTION; FLUX DENSITY; LUMINOSITY; RADIOWAVE RADIATION; SEYFERT GALAXIES; SIZE; VARIATIONS; ELECTROMAGNETIC RADIATION; GALAXIES; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; RADIATIONS
Citation Formats
Lal, Dharam V, Shastri, Prajval, and Gabuzda, Denise C. SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION. United States: N. p., 2011.
Web. doi:10.1088/0004-637X/731/1/68.
Lal, Dharam V, Shastri, Prajval, & Gabuzda, Denise C. SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION. United States. https://doi.org/10.1088/0004-637X/731/1/68
Lal, Dharam V, Shastri, Prajval, and Gabuzda, Denise C. 2011.
"SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION". United States. https://doi.org/10.1088/0004-637X/731/1/68.
@article{osti_21574738,
title = {SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION},
author = {Lal, Dharam V and Shastri, Prajval and Gabuzda, Denise C},
abstractNote = {A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nucleus power and host galaxy properties, is presented to test the predictions of the unified scheme hypothesis. Our sample sources have core flux densities greater than 8 mJy at 5 GHz on arcsec scales due to the feasibility requirements. These simultaneous parsec-scale and kiloparsec-scale radio observations reveal (1) that Seyfert 1 and Seyfert 2 galaxies have an equal tendency to show compact radio structures on milliarcsecond scales, (2) the distributions of parsec-scale and kiloparsec-scale radio luminosities are similar for both Seyfert 1 and Seyfert 2 galaxies, (3) there is no evidence for relativistic beaming in Seyfert galaxies, (4) similar distributions of source spectral indices in spite of the fact that Seyferts show nuclear radio flux density variations, and (5) the distributions of the projected linear size for Seyfert 1 and Seyfert 2 galaxies are not significantly different as would be expected in the unified scheme. The latter could be mainly due to a relatively large spread in the intrinsic sizes. We also find that a starburst alone cannot power these radio sources. Finally, an analysis of the kiloparsec-scale radio properties of the CfA Seyfert galaxy sample shows results consistent with the predictions of the unified scheme.},
doi = {10.1088/0004-637X/731/1/68},
url = {https://www.osti.gov/biblio/21574738},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 731,
place = {United States},
year = {Sun Apr 10 00:00:00 EDT 2011},
month = {Sun Apr 10 00:00:00 EDT 2011}
}