Full text not available from this repository.

Abstract

We present results from a multiwavelength study of the blazar PKS 1954–388 at radio, UV, X-ray, and gamma-ray energies. A RadioAstron observation at 1.66 GHz in June 2012 resulted in the detection of interferometric fringes on baselines of 6.2 Earth-diameters. This suggests a source frame brightness temperature of greater than 2 × 1012 K, well in excess of both equipartition and inverse Compton limits and implying the existence of Doppler boosting in the core. An 8.4-GHz TANAMI VLBI image, made less than a month after the RadioAstron observations, is consistent with a previously reported superluminal motion for a jet component. Flux density monitoring with the Australia Telescope Compact Array confirms previous evidence for long-term variability that increases with observing frequency. A search for more rapid variability revealed no evidence for significant day-scale flux density variation. The ATCA light-curve reveals a strong radio flare beginning in late 2013, which peaks higher, and earlier, at higher frequencies. Comparison with the Fermi gamma-ray light-curve indicates this followed ∼9 months after the start of a prolonged gamma-ray high-state—a radio lag comparable to that seen in other blazars. The multiwavelength data are combined to derive a Spectral Energy Distribution, which is fitted by a one-zone synchrotron-self-Compton (SSC) model with the addition of external Compton (EC) emission.

Item Type:	Article
Authors/Creators:	Edwards, PG and Kovalev, YY and Ojha, R and An, H and Bignall, H and Carpenter, B and Hovatta, T and Stevens, J and Voytsik, P and Andrianov, AS and Dutka, M and Hase, H and Horiuchi, S and Jauncey, DL and Kadler, M and Lisakov, M and Lovell, JEJ and McCallum, J and Mueller, C and Phillips, C and Plotz, C and Quick, J and Reynolds, C and Schulz, R and Sokolovsky, KV and Tzioumis, AK and Zuga, V
Keywords:	galaxies: active, galaxies: jets, gamma rays: galaxies, ISM: structure, radio continuum: galaxies
Journal or Publication Title:	Publications of the Astronomical Society of Australia
Publisher:	C S I R O Publishing
ISSN:	1323-3580
DOI / ID Number:	10.1017/pasa.2017.16
Copyright Information:	© Astronomical Society of Australia 2017
Related URLs:	UTAS Profile: Lovell, JEJ UTAS Profile: McCallum, J
Item Statistics:	View statistics for this item

Actions (login required)

Item Control Page