M. Kino

Global e-VLBI observations of the gamma-ray narrow line Seyfert 1 PMN J0948+0022

Context. There is growing evidence of relativistic jets in radio-loud narrow-line Seyfert 1 (RL-NLS1) galaxies. nAims. We constrain the observational properties of the radio emission in the first RL-NLS1 galaxy ever detected in gamma-rays, nPMN J0948+0022, i.e., its flux density and structure in both total intensity and polarization, its compactness, and variability. nMethods. We performed three real-time e-VLBI observations of PMN J0948+0022 at 22 GHz, using a global array including telescopes nin Europe, East Asia, and Australia. These are the first e-VLBI science observations ever carried out with a global array, nreaching a maximum baseline length of 12 458 km. The observations were part of a large multiwavelength campaign in 2009. nResults. The source is detected at all three epochs. The structure is dominated by a bright component, more compact than 55 ¥ias, nwith a fainter component at a position angle ¥e ixad 35◦. Relativistic beaming is required by the observed brightness temperature of n3.4 i? 1011 K. Polarization is detected at a level of about 1%. nConclusions. The parameters derived by the VLBI observations, in addition to the broad-band properties, confirm that PMN nJ0948+0022 is similar to flat spectrum radio quasars. Global e-VLBI is a reliable and promising technique for future studies.

The kinematic of HST-1 in the jet of M 87

Aims. We aim to constrain the structural variations within the HST-1 region downstream of the radio jet of M87, in general as well as in connection to the episodes of activity at very high energy (VHE). Methods. We analyzed and compared 26 VLBI observations of the M87 jet, obtained between 2006 and 2011 with the Very Long Baseline Array (VLBA) at 1.7 GHz and the European VLBI Network (EVN) at 5 GHz. Results. HST-1 is detected at all epochs; we model-fitted its complex structure with two or more components, the two outermost of which display a significant proper motion with a superluminal velocity around ∼4c. The motion of a third feature that is detected upstream is more difficult to characterize. The overall position angle of HST-1 has changed during the time of our observations from −65 ◦ to −90 ◦ , while the structure has moved by over 80 mas downstream. Our results on the component evolution suggest that structural changes at the upstream edge of HST-1 can be related to the VHE events.

Radio-to-[gamma]-ray monitoring of the narrow-line Seyfert 1 galaxy PMN J0948+0022 from 2008 to 2011

We present more than three years of observations at different frequencies, from radio to high-energy γ-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z = 0.585). This source is the first NLS1 detected at energies above 100 MeV and therefore can be considered the prototype of this emerging new class of γ-ray emitting active galactic nuclei (AGN). The observations performed from 2008 August 1 to 2011 December 31 confirmed that PMN J0948+0022 generates a powerful relativistic jet, which is able to develop an isotropic luminosity at γ-rays of the order of 10 48 erg s −1 , at the level of powerful quasars. The evolution of the radiation emission of this source in 2009 and 2010 followed the canonical expectations of relativistic jets with correlated multiwavelength variability (γ-rays followed by radio emission after a few months), but it was difficult to retrieve a similar pattern in the light curves of 2011. The comparison of γ-ray spectra before and including 2011 data suggested that there was a softening of the highenergy spectral slope. We selected five specific epochs to be studied by modelling the broad-band spectrum, which are characterised by an outburst at γ-rays or very low/high flux at other wavelengths. The observed variability can largely be explained by changes in the injected power, the bulk Lorentz factor of the jet, or the electron spectrum. The characteristic time scale of doubling/halving flux ranges from a few days to a few months, depending on the frequency and the sampling rate. The shortest doubling time scale at γ-rays is 2.3 ± 0.5 days. These small values underline the need of highly sampled multiwavelength campaigns to better understand the physics of these sources.

EVIDENCE OF NON-THERMAL X-RAY EMISSION FROM RADIO LOBES OF CYGNUS A

Using deep Chandra Advanced CCD Imaging Spectrometer (ACIS) observation data for Cygnus A, we report evidence of non-thermal X-ray emission from radio lobes surrounded by a rich intracluster medium (ICM). The diffuse X-ray emission, which is associated with the eastern and western radio lobes, was observed in a 0.7-7 keV Chandra ACIS image. The lobe spectra are reproduced with not only a single-temperature Mekal model, such as that of the surrounding ICM component, but also an additional power-law (PL) model. The X-ray flux densities of PL components for the eastern and western lobes at 1 keV are derived as 77.7+28.9 –31.9 nJy and 52.4+42.9 –42.4 nJy, respectively, and the photon indices are 1.69+0.07 –0.13 and 1.84+2.90 –0.12, respectively. The non-thermal component is considered to be produced via the inverse Compton (IC) process, as is often seen in the X-ray emission from radio lobes. From a re-analysis of radio observation data, the multiwavelength spectra strongly suggest that the seed photon source of the IC X-rays includes both cosmic microwave background radiation and synchrotron radiation from the lobes. The derived parameters indicate significant dominance of the electron energy density over the magnetic field energy density in the Cygnus A lobes under the rich ICM environment.

New prediction of extragalactic GeV γ-ray emission from radio lobes of young AGN jets

We present a new prediction of GeV γ -ray emission from radio lobes of young active galactic nuclei jets. In the previous work of Kino, Kawakatu & Ito, MeV γ -ray bremsstrahlung emission was predicted from young cocoons/radio lobes in the regime of no coolings. In this study, we include cooling effects of bremsstrahlung emission and adiabatic loss. With the initial conditions determined by observed young radio lobes, we solve a set of equations describing the expanding lobe evolution. Then, we find that the lobes initially have electron temperature of ∼GeV, and they cool down to ∼MeV by the adiabatic loss. Correspondingly, the lobes initially yield bright bremsstrahlung luminosity in ∼GeV range and they fade out. We estimate these γ -ray emissions and show that nearby young radio lobes could be detected with Fermi Gamma-ray Space Telescope.

Enhanced Polarized Emission from the One-parsec-scale Hotspot of 3C 84 as a Result of the Interaction with the Clumpy Ambient Medium

We present Very Long Baseline Array polarimetric observations of the innermost jet of 3C

A wide and collimated radio jet in 3C84 on the scale of a few hundred gravitational radii

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KVN observations suggest multiple

84 (NGC

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-ray emission regions in 3C 84

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