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Fossil shell emission in dying radio loud AGNs
Kino, M.,Ito, H.,Kawakatu, N.,Orienti, M.,Nagai, H.,Wajima, K.,Itoh, R. WILEY‐VCH Verlag 2016 Astronomische Nachrichten Vol.337 No.1
<P>We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolution of shells after stopping the jet energy injection. We find that the shell emission overwhelms that of the radio lobes soon after stopping the jet energy injection because fresh electrons are continuously supplied into the shell via the forward shock, while the radio lobes rapidly fade out without jet energy injection. We find that such fossil shells can be a new class of target sources for SKA telescope. Next, we apply the model to the nearby radio source 3C84. Then, we find that the fossil shell emission in 3C84 is less luminous in the radio band while it is bright in the TeV gamma-ray band and can be detectable by CTA. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim</P>
THE FATE OF DEAD RADIO-LOUD ACTIVE GALACTIC NUCLEI: A NEW PREDICTION OF LONG-LIVED SHELL EMISSION
Ito, Hirotaka,Kino, Motoki,Kawakatu, Nozomu,Orienti, Monica IOP Publishing 2015 The Astrophysical journal Vol.806 No.2
<P>We examine the fate of a dead radio source in which jet injection from the central engine has stopped at an early stage of its evolution (t = t(j) less than or similar to 10(5) years). To this aim, we theoretically evaluate the evolution of the emission from both the lobe and the shell, which are composed of shocked jet matter and a shocked ambient medium (i.e., shell), respectively. Based on a simple dynamical model of expanding lobe and shell, we clarify how the broadband spectrum of each component evolves before and after the cessation of the jet activity. It is shown that the spectrum is strongly dominated by the lobe emission while the jet is active (t <= t(j)). On the other hand, once the jet activity has ceased (t> t(j)), the lobe emission fades out rapidly, since fresh electrons are no longer supplied from the jet. Meanwhile, shell emission only shows a gradual decrease, since fresh electrons are continuously supplied from the bow shock that is propagating into the ambient medium. As a result, overall emission from the shell overwhelms that from the lobe at a wide range of frequencies from radio up to gamma-ray soon after the jet activity has ceased. Our result predicts a new class of dead radio sources that are dominated by shell emission. We suggest that the emission from the shell can be probed in particular at radio wavelengths with the Square Kilometer Array phase 1.</P>
Discovery of off-axis jet structure of TeV blazar Mrk 501 with mm-VLBI
Koyama, S.,Kino, M.,Giroletti, M.,Doi, A.,Giovannini, G.,Orienti, M.,Hada, K.,Ros, E.,Niinuma, K.,Nagai, H.,Savolainen, T.,Krichbaum, T. P.,Pé,rez-Torres, M. Á,. Springer-Verlag 2016 Astronomy and astrophysics Vol.586 No.-
Hada, Kazuhiro,Doi, Akihiro,Wajima, Kiyoaki,D’Ammando, Filippo,Orienti, Monica,Giroletti, Marcello,Giovannini, Gabriele,Nakamura, Masanori,Asada, Keiichi American Astronomical Society 2018 The Astrophysical journal Vol.860 No.2
<P>We investigated the detailed radio structure of the jet of 1H 0323+342 using high-resolution multifrequency Very Long Baseline Array observations. This source is known as the nearest gamma-ray emitting radio-loud narrow-line Seyfert 1 (NLS1) galaxy. We discovered that the morphology of the inner jet is well characterized by a parabolic shape, indicating that the jet is continuously collimated near the jet base. On the other hand, we found that the jet expands more rapidly at larger scales, resulting in a conical shape. The location of the 'collimation break' is coincident with a bright quasi-stationary feature at mas from core (corresponding to a deprojected distance on the order of similar to 100 pc), where the jet width locally contracts together with highly polarized signals, suggesting a recollimation shock. We found that the collimation region is coincident with the region where the jet speed gradually accelerates, suggesting a coexistence of the jet acceleration and collimation zone, ending up with the recollimation shock, which could be a potential site of high-energy 7-ray flares detected by the Fermi-LAT. Remarkably, these observational features of the 1H 0323+342 jet are overall very similar to those of the nearby radio galaxy M87 and HST-1 as well as some blazars, suggesting that a common jet formation mechanism might be at work. Based on the similarity of the jet profile of the two sources, we also briefly discuss the mass of the central black hole of 1H 0323+342, which is also still highly controversial in this source and NLS in general.</P>
SAWADA-SATOH, S.,AKIYAMA, K.,NIINUMA, K.,NAGAI, H.,KINO, M.,D'AMMANDO, F.,KOYAMA, S.,HADA, K.,ORIENTI, M.,HONMA, M.,SHIBATA, K.M. The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
We present a kinematic study of the parsec-scale radio jet in OJ 287, one of the most studied BL Lac objects, during ${\gamma}$-ray flares, to explore the relation between parsec-scale radio jet activity and ${\gamma}$-ray emission. The 22-GHz light curve of OJ 287 show three obvious flare events around 2011 May, 2011 October, and 2012 March. The second radio flare occurred during the ${\gamma}$-ray flaring period, and the third radio flare seemed to precede the ${\gamma}$-ray flare by one month. One jet component moved outward with respect to the core component with an apparent superluminal speed (~ 11c) from 2010 November to 2011 November. Then it changed direction, moving apparently inward in 2011 November, when the ${\gamma}$-ray flare occurred. The observed apparent inward motion of the jet at 22 GHz could be caused by a new jet component, unresolved at 22 GHz, in the innermost region.
Probing the precise location of the radio core in the TeV blazar Mrk 501 with VERA at 43 GHz
Koyama, Shoko,Kino, Motoki,Doi, Akihiro,Niinuma, Kotaro,Hada, Kazuhiro,Nagai, Hiroshi,Honma, Mareki,Akiyama, Kazunori,Giroletti, Marcello,Giovannini, Gabriele,Orienti, Monica,Isobe, Naoki,Kataoka, Jun Astronomical Society of Japan 2015 Publications of the Astronomical Society of Japan Vol.67 No.4