INTERACTING GALAXIES(Proceedings of Japan-France Seminar on Chemical Evolution of Galaxies with Active Star Formation)

Three topics on interacting galaxies are presented. The first is on ring galaxies and bead instability, the second on Seyfert 1 nucelus of a new ring galaxy in Sextans, and the third on dual emission line clouds in the interacting pair Arp 90

The 6dF Galaxy Survey

The 6dF Galaxy Survey (6dFGS) is a spectroscopic survey of the entire southern sky with $|b|>10\deg$, based on the 2MASS near infrared galaxy catalog. It is conducted with the 6dF multi-fiber spectrograph attached to the 1.2-m UK Schmidt Telescope. The survey will produce redshifts for some 170,000 galaxies, and peculiar velocities for about 15,000 and is expected to be complete by June 2005.Comment: 8 pages, 4 figures, IAU 8th Asian-Pacific Regional Mettin

石炭の地下ガス化（UCG）システム開発に関する基礎実験

For Underground Coal Gasification (UCG), it is necessary to evaluate the combustion area in the coal seam precisely. We are planning to use acoustic emission/microseismicity (AE/MS) monitoring for estimation of the underground combustion area. Analyzing the AE/MS waveforms from underground rocks, fracture extension around the combustion reactor can be grasped. For this objective, laboratory experiments are conducted for the UCG model. During burning coal block molded cylindrically by mortar, temperatures inside coal and AE activity were monitored. From the experimental results, it was found that many AE events were generated during combustion of coal, and the AE activity was close related to the change of temperature inside coal block. These AE generations seems to be caused by the crack initiation and extension around coal combustion area in the influence of thermal stress. Therefore, AE/MS monitoring is expected to be a useful tool to evaluate the UCG combustion reactor.特集 : 「資源、新エネルギー、環境、防災研究国際セミナー

Japanese VLBI Network observations of radio-loud narrow-line Seyfert 1 galaxies

We performed phase-reference very long baseline interferometry (VLBI) observations on five radio-loud narrow-line Seyfert 1 galaxies (NLS1s) at 8.4 GHz with the Japanese VLBI Network (JVN). Each of the five targets (RXS J08066+7248, RXS J16290+4007, RXS J16333+4718, RXS J16446+2619, and B3 1702+457) in milli-Jansky levels were detected and unresolved in milli-arcsecond resolutions, i.e., with brightness temperatures higher than 10^7 K. The nonthermal processes of active galactic nuclei (AGN) activity, rather than starbursts, are predominantly responsible for the radio emissions from these NLS1s. Out of the nine known radio-loud NLS1s, including the ones chosen for this study, we found that the four most radio-loud objects exclusively have inverted spectra. This suggests a possibility that these NLS1s are radio-loud due to Doppler beaming, which can apparently enhance both the radio power and the spectral frequency.Comment: 8 pages, 2 figures, accepted for publication in PAS

VLBI Detections of Parsec-Scale Nonthermal Jets in Radio-Loud Broad Absorption Line Quasars

We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network (JVN). We aimed at selecting BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversial issues of whether BAL quasars are viewed nearly edge-on, and of whether BAL quasars are in a short-lived evolutionary phase of quasar population. We detected 20 out of 22 sources using the OCTAVE baselines, implying brightness temperatures greater than 10^5 K, which presumably come from nonthermal jets. Hence, BAL outflows and nonthermal jets can be generated simultaneously in these central engines. We also found four inverted-spectrum sources, which are interpreted as Doppler-beamed, pole-on-viewed relativistic jet sources or young radio sources: single edge-on geometry cannot describe all BAL quasars. We discuss the implications of the OCTAVE observations for investigations for the orientation and evolutionary stage of BAL quasars.Comment: 10 pages, no figure, 3 tables, accepted for publication in PAS

Faint 6.7um Galaxies and their Contributions to the Stellar Mass Density in the Universe

We discuss the nature of faint 6.7um galaxies detected with the mid-infrared camera ISOCAM on board the Infrared Space Observatory (ISO). The 23 hour integration on the Hawaii Deep Field SSA13 has provided a sample of 65 sources down to 6uJy at 6.7um. For 57 sources, optical or near-infrared counterparts were found with a statistical method. All four Chandra sources, three SCUBA sources, and one VLA/FIRST source in this field were detected at 6.7um with high significance. Using their optical to mid-infrared colors, we divided the 6.7um sample into three categories: low redshift galaxies with past histories of rapid star formation, high redshift ancestors of these, and other star forming galaxies. Rapidly star forming systems at high redshifts dominate the faintest end. Spectroscopically calibrated photometric redshifts were derived from fits to a limited set of template SEDs. They show a high redshift tail in their distribution with faint (1. The 6.7um galaxies tend to have brighter K magnitudes and redder I-K colors than the blue dwarf population at intermediate redshifts. Stellar masses of the 6.7um galaxies were estimated from their rest-frame near-infrared luminosities. Massive galaxies (M_star~10e11M_sun) were found in the redshift range of z=0.2-3. Epoch dependent stellar mass functions indicate a decline of massive galaxies' comoving space densities with redshift. Even with such a decrease, the contributions of the 6.7um galaxies to the stellar mass density in the universe are found to be comparable to those expected from UV bright galaxies detected in deep optical surveys.Comment: 31 pages, 15 figures, AJ (accepted), a version with color figures at http://www.ioa.s.u-tokyo.ac.jp/~ysato/pub/3/p3c-ysato.ps.g