Kentaro Aoki

Spectropolarimetry of Extremely Luminous Type Ia Supernova 2009dc: Nearly Spherical Explosion of Super-Chandrasekhar Mass White Dwarf (2009)

Tanaka, Masaomi, Kawabata, Koji S., Yamanaka, Masayuki, Maeda, Keiichi, Hattori, Takashi, Aoki, Kentaro, ...

We present the first spectropolarimetric observations of a candidate of super-Chandrasekhar mass Type Ia supernova (SN): SN 2009dc. The observations were performed at 5.6 and 89.5 days after the...

Lyman Break Galaxies at z~5: Rest-Frame UV Spectra. III (2009)

Kajino, Hiroki, Ohta, Kouji, Iwata, Ikuru, Yabe, Kiyoto, Yuma, Suraphong, Akiyama, Masayuki, ...

We present results of optical spectroscopic observations of candidates of Lyman Break Galaxies (LBGs) at $z \sim 5$ in the region including the GOODS-N and the J0053+1234 region by using GMOS-N and...

The Stellar Populations of Lyman Break Galaxies at z~5 (2008)

Yabe, Kiyoto, Ohta, Kouji, Iwata, Ikuru, Sawicki, Marcin, Tamura, Naoyuki, Akiyama, Masayuki, ...

We present the results of Spectral Energy Distribution(SED) fitting analysis for Lyman Break Galaxies(LBGs) at z~5 in the GOODS-N and its flanking fields (the GOODS-FF). With the publicly available...

No Evidence for Variability of Intervening Absorption Lines toward GRB 060206: Implications for the Mg II Incidence Problem (2008)

Aoki, Kentaro, Totani, Tomonori, Hattori, Takashi, Ohta, Kouji, Kawabata, Koji S., Kobayashi, Naoto, ...

We examine variability of absorption line strength of intervening systems along the line of sight to GRB 060206 at $z = 4.05$, by the low-resolution optical spectra obtained by the Subaru telescope...

Differential Evolution of Lyman Break Galaxies from $z$=5 to 3 (2008)

Iwata, Ikuru, Ohta, Kouji, Sawicki, Marcin, Tamura, Naoyuki, Akiyama, Masayuki, Aoki, Kentaro

We briefly summarize our findings from the unbiased surveys for $z$$\sim$5 LBGs based on Subaru/Suprime-Cam and follow-up optical spectroscopy.

The Stellar Populations of Lyman Break Galaxies at $z\sim5$ (2008)

Yabe, Kiyoto, Ohta, Kouji, Iwata, Ikuru, Sawicki, Marcin, Tamura, Naoyuki, Akiyama, Masayuki, ...

We present the results of Spectral Energy Distribution (SED) fitting analysis for Lyman Break Galaxies (LBGs) at $z\sim5$ in the GOODS-N and its flanking fields. From the SED fitting for $\sim100$...

Asphericity in Supernova Explosions from Late-Time Spectroscopy (2008)

Maeda, Keiichi, Kawabata, Koji, Mazzali, Paolo A., Tanaka, Masaomi, Valenti, Stefano, Nomoto, Ken'ichi, ...

Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important...

Lyman Break Galaxies at z~5: Rest-frame UV Spectra II (2007)

Ando, Masataka, Ohta, Kouji, Iwata, Ikuru, Akiyama, Masayuki, Aoki, Kentaro, Tamura, Naoyuki

We present the results of spectroscopy of Lyman Break Galaxies (LBGs) at z~5 in the J0053+1234 field with the Faint Object Camera and Spectrograph on the Subaru telescope. Among 5 bright candidates...

CO Observations of a FeLoBAL Quasar with an H alpha Absorption Line at z=2.3 (2007)

Ohta, Kouji, Kiuchi, Gaku, Nakanishi, Kouichiro, Aoki, Kentaro, Iwata, Ikuru, Akiyama, Masayuki, ...

SDSS J083942.11+380526.3 is an Iron Low-ionization Broad Absorption Line (FeLoBAL) quasar at z = 2.3, and Aoki et al. (2006) recently found the presence of an H alpha absorption line in the broad H...

The Long Faint Tail of the High-Redshift Galaxy Population (2006)

Sawicki, Marcin, Iwata, Ikuru, Ohta, Kouji, Thompson, David, Tamura, Naoyuki, Akiyama, Masayuki, ...

We study the properties of very faint, sub-L* Lyman break galaxies at z~2-5 - thus far a largely neglected but numerically and energetically very important population. We find that the LBG luminosity...

Discovery of H alpha absorption in the unusual broad absorption line quasar SDSS J083942.11+380526.3 (2006)

Aoki, Kentaro, Iwata, Ikuru, Ohta, Kouji, Ando, Masataka, Akiyama, Masayuki, Tamura, Naoyuki

We discovered an H alpha absorption in a broad H alpha emission line of an unusual broad absorption line quasar, SDSS J083942.11+380526.3 at z=2.318, by near-infrared spectroscopy with the Cooled...

Deficiency of large equivalent width Lyman-alpha emission in luminous Lyman break galaxies at z~5-6? (2006)

Ando, Masataka, Ohta, Kouji, Iwata, Ikuru, Akiyama, Masayuki, Aoki, Kentaro, Tamura, Naoyuki

We report a deficiency of luminous Lyman break galaxies (LBGs) with a large rest-frame equivalent width (EW_rest) of Lyman-alpha emission at z~5-6. Combining our spectroscopic sample of LBGs at z~5...

Host Galaxies of Hard X-ray Selected Type-2 Active Galactic Nuclei at Intermediate Redshifts (2006)

Kiuchi, Gaku, Ohta, Kouji, Akiyama, Masayuki, Aoki, Kentaro, Ueda, Yoshihiro

We study properties of the host galaxies of 15 hard X-ray selected type-2 active galactic nuclei (AGNs) at intermediate redshifts (0.05$

Implications for the Cosmic Reionization from the Optical Afterglow Spectrum of the Gamma-Ray Burst 050904 at z = 6.3 (2005)

Totani, Tomonori, Kawai, Nobuyuki, Kosugi, George, Aoki, Kentaro, Yamada, Toru, Iye, Masanori, ...

The gamma-ray burst (GRB) 050904 at z = 6.3 provides the first opportunity of probing the intergalactic medium (IGM) by GRBs at the epoch of the reionization. Here we present a spectral modeling...

An Observational Pursuit for Population III Stars in a Ly_alpha Emitter at z=6.33 through HeII Emission (2005)

Nagao, Tohru, Motohara, Kentaro, Maiolino, Roberto, Marconi, Alessandro, Taniguchi, Yoshiaki, Aoki, Kentaro, ...

We present a very deep near-infrared spectroscopic observation of a strong Ly_alpha emitter at z=6.33, SDF J132440.6+273607, which we used to search for HeII 1640. This emission line is expected if...

The Largest Blueshifts of [O III] emission line in Two Narrow-Line Quasars (2004)

Aoki, Kentaro, Kawaguchi, Toshihiro, Ohta, Kouji

We have obtained optical intermediate resolution spectra (R = 3000) of the narrow-line quasars DMS 0059-0055 and PG 1543+489. The [O III] emission line in DMS 0059-0055 is blueshifted by 880 km/s...

Lyman Break Galaxies at $z\sim5$: Rest-Frame UV Spectra (2004)

Ando, Masataka, Ohta, Kouji, Iwata, Ikuru, Watanabe, Chisato, Tamura, Naoyuki, Akiyama, Masayuki, ...

We report initial results for spectroscopic observations of candidates of Lyman Break Galaxies (LBGs) at $z\sim5$ in a region centered on the Hubble Deep Field-North by using the Faint Object Camera...

Current performance and on-going improvements of the 8.2 m Subaru Telescope (2004)

Iye, Masanori, Karoji, Hiroshi, Ando, Hiroyasu, Kaifu, Norio, Kodaira, Keiichi, Aoki, Kentaro, ...

An overview of the current status of the 8.2m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept...

Dusty ERO Search behind Two Massive Clusters (2003)

Takata, Tadafumi, Kashikawa, Nobunari, Nakanishi, Kouichiro, Aoki, Kentaro, Asai, Ryo, Ebizuka, Noboru, ...

We performed deep K'-band imaging observations of 2 massive clusters, MS 0451.6-0305 at z = 0.55 and MS 0440.5+0204 at z = 0.19, for searching counterparts of the faint sub-mm sources behind these...

Decomposition of the Superwind in M82 (2002)

Ohyama, Youichi, Taniguchi, Yoshiaki, Iye, Masanori, Yoshida, Michitoshi, Sekiguchi, Kazuhiro, Takata, Tadafumi, ...

We present new optical images ($B$, $V$, and H$\alpha$) of the archetypical starburst/superwind galaxy M82 obtained with the 8.2 m Subaru Telescope to reveal new detailed structures of the...

Subaru Deep Survey III. Evolution of Rest-Frame Luminosity Functions Based on the Photometric Redshifts for A K'-band Selected Galaxy Sample (2002)

Kashikawa, Nobunari, Takata, Tadafumi, Ohyama, Youichi, Yoshida, Michitoshi, Maihara, Toshinori, Iwamuro, Fumihide, ...

We have constructed a very deep K'-selected multicolor BVRIz'JK' sample of 439 field galaxies. Photometric redshifts for sample galaxies were estimated. The overall redshift distribution N(z) for the...

Subaru Spectroscopy of the Gravitational Lens HST 14176+5226: Implications for a Large Cosmological Constan (2002)

Ohyama, Youichi, Hamana, Takashi, Kashikawa, Nobunari, Chiba, Masashi, Futamase, Toshifumi, Iye, Masanori, ...

We present new optical spectroscopy of the lens elliptical galax in the ``Einstein Cross'' lens system HST 14176+5226, using the Faint Object Camera and Spectrograph (FOCAS) of the Subaru t Our...

Discovery of Very Extended Emission-Line Region around the Seyfert 2 Galaxy NGC 4388 (2001)

Yoshida, Michitoshi, Yagi, Masafumi, Okamura, Sadanori, Aoki, Kentaro, Ohyama, Youichi, Komiyama, Yutaka, ...

We found a very large, 35 kpc, emission-line region around the Seyfert type 2 galaxy NGC 4388, using deep narrow-band imaging with the prime focus camera (Suprime-Cam) of the Subaru telescope. This...

A Shock-Induced Pair of Superbubbles in the High-Redshift Powerful Radio Galaxy MRC 0406-244 (2001)

Taniguchi, Yoshiaki, Ohyama, Youichi, Murayama, Takashi, Yoshida, Michitoshi, Kashikawa, Nobunari, Iye, Masanori, ...

We present new optical spectroscopy of the high-redshift powerful radio galaxy MRC 0406$-$244 at redshift of 2.429. We find that the two extensions toward NW and SE probed in the rest-frame...

The Central Gas Systems of Early-Type Galaxies Traced by Dust Feature: Based on the HST WFPC2 Archival Images (2000)

Tomita, Akihiko, Aoki, Kentaro, Watanabe, Masaru, Takata, Tadafumi, Ichikawa, Shin-ichi

We investigated the central gas systems of E/S0 galaxies by making use of the WFPC2 images of the Hubble Space Telescope archive. We searched the gas systems that were traced by the dust with a new...