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The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447: II. the radio view

Citation

Schulz, R and Kreikenbohm, A and Kadler, M and Ojha, R and Ros, E and Stevens, J and Edwards, PG and Carpenter, B and Elsasser, D and Gehrels, N and Grossberger, C and Hase, H and Horiuchi, S and Lovell, JEJ and Mannheim, K and Markowitz, A and Mueller, C and Phillips, C and Ploetz, C and Quick, J and Truestedt, J and Tzioumis, AK and Wilms, J, The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447: II. the radio view, Astronomy and Astrophysics, 588 Article A146. ISSN 0004-6361 (2016) [Refereed Article]


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Copyright ESO 2016

DOI: doi:10.1051/0004-6361/201527404

Abstract

As part of the TANAMI multiwavelength progam, we discuss new X-ray observations of the γ-ray and radio-loud Narrow Line Seyfert galaxy (γ-NLS1) PKS 2004-447. The active galaxy is a member of a small sample of radio-loud NLS1s detected in γ-rays by the Fermi Large Area Telescope. It is the radio-loudest and only southern-hemisphere source in this sample. We present results from our X-ray monitoring program comprised of Swift snapshot observations from 2012 through 2014 and two new X-ray observations with XMM-Newton in 2012. We analyze the X-ray spectrum and variability of this peculiar source using supplementary archival data from 2004 and 2011. The (0.5-10) keV spectrum is well described by a flat power law, which can be interpreted as non-thermal emission from a relativistic jet. The source exhibits moderate flux variability on timescales of both months and years. Correlated brightness variations in the (0.5-2) keV and (2-10) keV bands are explained by a single variable spectral component, such as the jet. A possible soft excess seen in the data from 2004 cannot be confirmed by the new \xmm{} observations in 2012. Any contribution to the total flux in 2004 is less than 20% of the power-law component. The (0.5-10) keV luminosities of PKS 2004-447 are in the range of (0.5--2.7)1044ergs−1. A comparison of the X-ray properties among the known γ-NLS1 galaxies shows that X-ray spectrum is typically dominated by a flat power law without intrinsic absorption. These objects are moderately variable in their brightness, while spectral variability is observed in at least two sources. The major difference across the X-ray spectra of γ-NLS1s is the luminosity, which spans a range of almost two orders of magnitude, from 1044ergs−1 to 1046ergs−1 in the (0.5-10) keV band.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:High Energy Astrophysics; Cosmic Rays
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:115225
Year Published:2016
Deposited By:Mathematics and Physics
Deposited On:2017-03-10
Last Modified:2017-04-07
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