Re‐started jet activity occurred in the bright nearby radio source 3C 84 in about 2005. The re‐started jet is forming a prominent component (namely C3) at the tip of jet. The component has showed an increase in radio flux density for more than 7 years while the radio spectrum remains optically thin. This suggests that the component is the head of a radio lobe including a hotspot where the particle acceleration occurs. Thus, 3C 84 is a unique laboratory to study the physical properties at the very early stage of radio source evolution. Another important aspect is that high energy and very high energy γ ‐ray emissions are detected from this source. The quest for the site of γ ‐ray emission is quite important to obtain a better understanding of γ ‐ray emission mechanisms in radio galaxies. In this paper, we review the observational results from very long baseline interferometry (VLBI) monitoring of 3C 84 reported in series of our previous papers. We argue the nature of re‐started jet/radio lobe and its relation with high‐energy emission. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We present a kinematic study of the sub-parsec-scale radio jet of the radio galaxy 3C 84/NGC 1275 with the VLBI Exploration of Radio Astrometry (VERA) array at 22 GHz for 80 epochs from 2007 October to 2013 December. The averaged radial velocity of the bright component “C3” with reference to the radio core is found to be 0.27 ± 0.02 c between 2007 October and 2013 December. This constant velocity of C3 is naturally explained by the advancing motion of the head of the mini-radio lobe. We also find a non-linear component in the motion of C3 with respect to the radio core. We briefly discuss possible origins of this non-linear motion.

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We introduce the gamma-ray emitting notable active galactic nucleus (AGN) monitoring by Japanese VLBI programme, which is the monitoring of gamma-ray bright AGNs with the VLBI Exploration of Radio Astrometry (VERA) array. This programme aims to conduct dense monitoring at 22 GHz toward the $ \gamma$-ray emitting AGNs to investigate the time variation of the radio core and possible ejection of a new radio component, the motion of jets, and their relations with the emission at other wavelengths, especially at $ \gamma$-rays. We are currently monitoring 8 notable $ \gamma$-ray-emitting AGNs (DA 55, 3C 84, M 87, PKS 1510$-$ 089, DA 406, NRAO 530, BL Lac, and 3C 454.3) about once every two weeks. This programme is promising for tracing the trend of radio time variation on shorter time scale than conventional VLBI monitoring programmes and is complementary to data of other programmes (e.g., MOJAVE; Boston University Blazar Project). In particular, we successfully carried out quick follow-up observations after the GeV $ \gamma$-ray flare in NRAO 530 and 3C 454.3 reported by the Fermi Gamma-ray Space Telescope. Here, we present the initial results of morphology and light curves for the first 7-month operation.

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We performed simultaneous measurements of the elastic constant C 11 and electrical resistance of the filled skutterudite compound PrOs 4 Sb 12 . The elastic constant C 11 shows a local minimum at around 3 K in 0 T, which shifts to low temperature in 3 T, and seems independent from the heavy fermion superconductivity (HFSC) of the present compound. The temperature and magnetic field dependences of the elastic constant C 11 are consistent with the calculated quadrupole susceptibility based on the crystalline electric field level scheme, indicating well localized 4f -electron states from Pr 3+ at low temperature. The present results strongly suggest that there is no relation between the HFSC and local charge fluctuation, due to off-center quantum tunnneling of the guest Pr 3+ , and also implies that the origin of the heavy fermion state of this compound is not a typical Kondo effect.