Nobuhiro Okabe

The Mass Structure of the Galaxy Cluster Cl0024+1654 from a Full Lensing Analysis of Joint Subaru and ACS/NIC3 Observations (2009)

Umetsu, Keiichi, Medezinski, Elinor, Broadhurst, Tom, Zitrin, Adi, Okabe, Nobuhiro, Hsieh, Bau-Ching, ...

We derive an accurate mass distribution of the rich galaxy cluster Cl0024+1654 (z=0.395) based on deep Subaru BR_{c}z' imaging and our recent comprehensive strong lensing analysis of HST/ACS/NIC3...

LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters (2009)

Okabe, Nobuhiro, Takada, Masahiro, Umetsu, Keiichi, Futamase, Toshifumi, Smith, Graham P.

(Abridged) We use Subaru data to conduct a detailed weak-lensing study of the dark matter distribution in a sample of 30 X-ray luminous galaxy clusters at 0.15

Suzaku Observation of the Ophiuchus Galaxy Cluster: One of the Hottest Cool Core Clusters (2008)

Fujita, Yutaka, Hayashida, Kiyoshi, Nagai, Masaaki, Inoue, Susumu, Matsumoto, Hironori, Okabe, Nobuhiro, ...

We present the analysis of a Suzaku observation of the Ophiuchus galaxy cluster. We confirmed that the cluster has a cool core. While the temperature of the intracluster medium (ICM) decreases toward...

High Metallicity of the X-Ray Gas up to the Virial Radius of a Binary Cluster of Galaxies: Evidence of Galactic Superwinds at High-Redshift (2007)

Fujita, Yutaka, Tawa, Noriaki, Hayashida, Kiyoshi, Takizawa, Motokazu, Matsumoto, Hironori, Okabe, Nobuhiro, ...

We present an analysis of a Suzaku observation of the link region between the galaxy clusters A399 and A401. We obtained the metallicity of the intracluster medium (ICM) up to the cluster virial...

Subaru Weak Lensing Study of Seven Merging Clusters: Distributions of Mass and Baryons (2007)

Okabe, Nobuhiro, Umetsu, Keiichi

We present and compare projected distributions of mass, galaxies, and the intracluster medium (ICM) for a sample of merging clusters of galaxies based on the joint weak-lensing, optical photometric,...

Observational Constraints on the ICM Temperature Enhancement by Cluster Mergers (2007)

Okabe, Nobuhiro, Umetsu, Keiichi

We present results from a combined weak lensing and X-ray analysis of the merging cluster A1914 at a redshift of $z=0.1712$ based on $R_{\rm}$-band imaging data with Subaru/Suprime-Cam and archival...

Magnetic field generation by the Weibel instability at temperature gradients in collisionless plasmas (2006)

Fujita, Yutaka, Kato, Tsunehiko N., Okabe, Nobuhiro

The Weibel instability could be responsible for the generation of magnetic fields in various objects such as gamma-ray bursts, jets from active galactic nuclei, and clusters of galaxies. Using...

A Direct Method for Measuring Heat Conductivity in Intracluster Medium (2005)

Hattori, Makoto, Okabe, Nobuhiro

The inverse Compton scattering of the cosmic microwave background (CMB) radiation with electrons in the intracluster medium which has a temperature gradient, was examined by the third-order...

A Spontaneous Generation of the Magnetic Field and Suppression of the Heat Conduction in Cold Fronts (2003)

Okabe, Nobuhiro, Hattori, Makoto

We have determined the physical mechanism responsible for the plasma instabilities, which was first found by Ramani and Laval (1978), associated with anisotropic velocity distributions induced by the...