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22 papers · 2 filters
Where is the [O III]4363 emitting region in active galactic nuclei?
Tohru Nagao, Takashi Murayama, Yoshiaki Taniguchi
The emission-line flux ratio of [O III]4363/[O III]5007 (R_OIII)is a useful diagnostic for the ionization mechanism and physical properties of emission-line regions in active galac…
ISO continuum observations of quasars at z=1-4 I.Spectral energy distributions of quasars from the UV to far-infrared
S. Oyabu, K. Kawara, Y. Tsuzuki +8
Eight luminous quasars with at z = 1.4 - 3.7 have been observed in the mid- and far-infrared using ISO. All the quasars have been detected in the mid-infrared ba…
SiO Emission in the Multi-Lobe Outflow associated with IRAS 16293-2422
Naomi Hirano, Hitomi Mikami, Tomofumi Umemoto +2
We have mapped the thermal emission line of SiO (v = 0; J = 2-1) associated with the quadrupolar molecular outflow driven by the very cold far-infrared source IRAS 16293-2422. The…
Numerous Old Starburst Galaxies in the Local Universe
H. Mouri, Y. Taniguchi
Old starburst galaxies are deficient in O stars, and hence do not exhibit strong line emission in the optical regime. However, there remain many B stars, which are expected to heat…
A New interpretation of chain galaxies at high redshift
Yoshiaki Taniguchi, Yasuhiro Shioya
We propose a possible new model for the formation of chain galaxies at high redshift. Our model is summarized as follows. Step I: Successive merging of subgalactic gas clumps resul…
Photometric Properties of the Arp 220 Super Star Clusters
Yasuhiro Shioya, Yoshiaki Taniguchi, Neil Trentham
We investigate the photometric properties of six super stellar clusters (SSCs) seen in both the optical and near-infrared Hubble Space Telescope images of the local ultraluminous s…
Sub-parsec-scale Accleration of the Radio Jet in the Powerful Radio Galaxy NGC 6251
H. Sudou, Y. Taniguchi, Y. Ohyama +5
In order to investigate the genesis of powerful radio jet, we have mapped the central 10 pc region of the nearby radio galaxy NGC 6251 with a 0.2 pc resolution using Very Long Base…
Extreme Galactic-Winds and Starburst in IR Mergers and IR QSOs
S. Lipari, D. Sanders, R. Terlevich +8
We report -as a part of a long-term study of mergers and IR QSOs- detailed spectroscopic evidences for outflow (OF) and/or Wolf Rayet features in: (i) low velocity OF in the ongoin…
Deep Optical Imaging of A Compact Group of Galaxies, Seyfert's Sextet
S. Nishiura, T. Murayama, M. Shimada +5
In order to investigate the dynamical status of Seyfert's Sextet (SS), we have obtained a deep optical () image of this group. Our image shows that a faint envelope, down to…
ISO deep far-infrared survey in the "Lockman Hole" II. Power spectrum analysis: evidence of a strong evolution in number counts
H. Matsuhara, K. Kawara, Y. Sato +8
We investigate the characteristics of FIR brightness fluctuations at 90 micron and 170 micron in the Lockman Hole, which were surveyed with ISOPHOT aboard the Infrared Space Observ…
Dwarf galaxy formation induced by galaxy interactions
T. Okazaki, Y. Taniguchi
Growing evidence has been accumulated for that some gas-rich dwarf galaxies are formed from material liberated by galaxy collisions and/or mergers. Also, gas-poor dwarf elliptical…
X-ray emission from Seyfert 2 galaxies with optical polarized broad lines
Hisamitsu Awaki, Shiro Ueno, Yoshiaki Taniguchi +1
We analyze the 0.5-10 keV spectra of six Seyfert 2 galaxies observed with the X-ray satellite ASCA: Mrk 3, Mrk 348, Mrk 1210, Mrk 477, NGC 7212, and Was 49b. These galaxies were se…
Poststarburst Models of LINERs
Yoshiaki Taniguchi, Yasuhiro Shioya, Takashi Murayama
Since the discovery of low-ionization nuclear emission-line regions in many galaxies (LINERs), it has been recognized that they constitute a class of active galactic nuclei (AGNs)…
A Dynamical Study of Galaxies in the Hickson Compact Groups
S. Nishiura, M. Shimada, Y. Ohyama +2
In order to investigate dynamical properties of spiral galaxies in the Hickson compact groups (HCGs), we present rotation curves of 30 galaxies in 20 HCGs. We found as follows. 1)…
Large-Scale Regular Morphological Patterns in the Radio Jet of NGC 6251
H. Sudou, Y. Taniguchi
We report on large-scale, regular morphological patterns found in the radio jet of the nearby radio galaxy NGC 6251. Investigating morphological properties of this radio jet from t…
Detection of the VLBI-scale Counter Jet in NGC 6251
H. Sudou, Y. Taniguchi, Y. Ohyama +5
Mapping the central 5 pc region of the nearby radio galaxy NGC 6251 with a 0.2 pc resolution using VLBI at two radio frequencies, 5 GHz and 15 GHz, we have found the sub-pc-scale c…
Grain Survival in Supernova Remnants and Herbig-Haro Objects
H. Mouri, Y. Taniguchi
By using the flux ratio [FeII]8617/[OI]6300, we demonstrate that most of the interstellar dust grains survive in shocks associated with supernova remnants and Herbig-Haro objects.…
The Nuclear Activity of the Galaxies in the Hickson Compact Groups
Masashi Shimada, Youichi Ohyama, Shingo Nishiura +2
In order to investigate the nuclear activity of galaxies residing in compact groups of galaxies, we present results of our optical spectroscopic program made at Okayama Astrophysic…
The High-Ionization Nuclear Emission-Line Region of Seyfert Galaxies
Tohru Nagao, Yoshiaki Taniguchi, Takashi Murayama
Recently Murayama & Taniguchi proposed that a significant part of the high-ionization nuclear emission-line region (HINER) in Seyfert nuclei arises from the inner wall of dusty tor…
Formation of intermediate-mass black holes in circumnuclear regions of galaxies
Yoshiaki Taniguchi, Yasuhiro Shioya, Takeshi G. Tsuru +1
Recent high-resolution X-ray imaging studies have discovered possible candidates of intermediate-mass black holes with masses of $M_\bullet \sim 10^{2-4} \MO$ in circumnuclear regi…
Dusty Tori of Seyfert Nuclei
Yoshiaki Taniguchi, Takashi Murayama, Hideaki Mouri
Dusty tori around active galactic nuclei (AGNs) play an important role in the classification of Seyfert galaxies. Therefore, physical properties of dusty tori are of great interest…
Discovery of a Low Surface Brightness Object near Seyfert's Sextet
Takashi Murayama, Shingo Nishiura, Tohru Nagao +3
We report the discovery of a low surface brightness (LSB) object serendipitously found during deep CCD imaging of a compact group of galaxies, Seyfert's Sextet, in VR and I bands.…