The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447. I. The X-ray View

Kreikenbohm A, Schulz R, Kadler M, Wilms J, Markowitz A, Chang CS, Carpenter B, Elsaesser D, Gehrels N, Mannheim K, Mueller C, Ojha R, Ros E, Truestedt J (2016)


Publication Type: Journal article, Original article

Publication year: 2016

Journal

Book Volume: 585

Article Number: A91

DOI: 10.1051/0004-6361/201424818

Abstract

As part of the TANAMI multiwavelength progam, we discuss new X-ray observations of the γ-ray and radio-loud narrow line Seyfert 1 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 st and s out for being the radio-loudest and the 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. Supplemented by archival data from 2004 and 2011, our data set allows for a careful analysis of the X-ray spectrum and variability of this peculiar source. The (0.5-10) keV spectrum is described well by a power law (Γ ∼ 1.6), 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 b and s are explained by a single variable spectral component, such as the one from the jet. A possible soft excess seen in the data from 2004 cannot be confirmed by the new XMM-Newton observations taken during low-flux states. 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) × 10 erg s. A comparison of the X-ray properties among the known γ-NLS1 galaxies shows that in four out of five cases the X-ray spectrum is 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 10 erg s to 10 erg s in the (0.5-10) keV b and .

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APA:

Kreikenbohm, A., Schulz, R., Kadler, M., Wilms, J., Markowitz, A., Chang, C.S.,... Truestedt, J. (2016). The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447. I. The X-ray View. Astronomy & Astrophysics, 585. https://dx.doi.org/10.1051/0004-6361/201424818

MLA:

Kreikenbohm, A., et al. "The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447. I. The X-ray View." Astronomy & Astrophysics 585 (2016).

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