X-ray measurement of electron and magnetic-field energy densities in the west lobe of the giant radio galaxy 3C 236

X-ray emission associated with the west lobe of the giant radio galaxy, 3C 236, was investigated with the Suzaku observatory, to evaluate the energetics in the lobe. After removing contamination from X-ray sources detected with Chandra and subtracting the X-ray and non-X-ray backgrounds, the Suzaku spectrum from the lobe was reproduced by a power-low model with a photon index of $\Gamma = 2.23_{-0.38-0.12}^{+0.44+0.14}$ where the first and second errors represent the statistical and systematic ones, respectively. Within the errors, the X-ray index was consistent with the radio synchrotron one, $\Gamma_{\rm R} = 1.74 \pm 0.07$, estimated in the 326 -- 2695 MHz range. This agreement supports that the X-ray emission is attributed to the inverse-Compton (IC) radiation from the synchrotron electrons filling the lobe, where the cosmic microwave background photons are up-scattered. This result made 3C 236 the largest radio galaxy, of which the lobe has ever been probed through the IC X-ray photons. When the photon index was fixed at $\Gamma_{\rm R}$, the X-ray flux density at 1 keV was measured as $S_{\rm X} = 12.3 \pm 2.0 \pm 1.9$ nJy. A comparison of the X-ray flux to the radio one ($S_{\rm R} = 1.11 \pm 0.02$ Jy at 608.5 MHz) yields the energy densities of the electrons and magnetic field in the west lobe as $u_{\rm e} = 3.9_{-0.7 -0.9}^{+0.6 +1.0} \times 10^{-14}$ ergs cm$^{-3}$ and $u_{\rm m} = 0.92_{-0.15 -0.35}^{+0.21 +0.52}\times 10^{-14}$ ergs cm$^{-3}$, respectively, indicating a mild electron dominance of $u_{\rm e}/u_{\rm m} = 4.2_{-1.3 -2.3}^{+1.6 +4.1}$. The latter corresponds to the magnetic field strength of $B = 0.48_{-0.04 -0.10}^{+0.05 +0.12}$ $\mu$G.These are typical among the lobes of giant radio galaxies. A compilation of the $u_{\rm e}$-size relation for the IC-detected radio galaxies implies that the west lobe of 3C 236 is still actively energized by its jet.Comment: Accepted for PASJ, 9 figures, 7 table

VLBI Imagings of Kilo-parsec Knot in 3C 380

We investigate observational properties of a kilo-parsec scale knot in radio-loud quasar 3C 380 by using two epoch archival data obtained by Very Long Baseline Interferometry (VLBI) at 5 GHz on 1998 July and 2001 April. We succeed in obtaining the highest spatial resolution image of the bright knot K1 located at 732 milliarcseconds, or more than 20 kpc de-projected, downstream from the nucleus three times better than previously obtained highest resolution image by Papageorgiou et al. (2006). Our images reveal, with new clarity, "inverted bow-shock" structure in K1 facing the nucleus and its morphology resembles a conical shock wave. By comparing the two epoch images directly, we explore the kinematics of K1 and obtain the upper limit of apparent velocity, 0.25 mas/yr or 9.8 c of K1 for the first time. The upper limit of apparent velocity is marginally smaller than superluminal motions seen in the core region. Further new epoch VLBI observations are necessary to measure the proper motion at K1.Comment: 15 pages, 4 figures, accepted for publication in PAS

ミリ波VLBI観測によるブレーザーMrk 501の電波コアの高精度位置決定

学位の種別:課程博士University of Tokyo(東京大学

Pollution by estrogens in river and estuarine waters around Kuala Lumpur, Malaysia, and their effects on the estuarine Java-medaka, Oryzias javanicus.

Estrogens (17 B-estradiol and estrone) concentrations in river and estuarine waters around Kuala Lumpur, Malaysia were determined by enzyme-linked immunosorbent assay while estrogenic potential of the waters were ascertained by three in vitro bioassays, namely E-screen, Ishikawa cell-alkaline phosphatase and yeast estrogen screen. Moreover, hepatic vitellogenin, a precursor of yolk protein that is specific to females, were examined in male and female Java-medaka collected in the same area. 17B-estradiol and estrone concentrations were less than 6.1 ng/L and 127 ng/L, respectively. The highest 17B-estradiol equivalent activity, 284 ng/L, was detected by in vitro assay in Sungai Kuyoh, which was adjacent to a sewage plant. 17B-estradiol and estrone concentrations were not equal to their estrogenic potentials determined by in vitro assay implying the presence of other estrogenic chemicals in these waters. Hepatic vitellogenin concentrations of both male and female java-medaka were the same to laboratory-cultured individuals. Although relatively high estrogen concentrations were detected in some waters of Malaysia, these were not high enough to induce hepatic vitellogenin in male fishes. Further research, however, is necessary to cover more number of sampling sites