Extraction of Rotation Energy from a Black Hole

Kyoto University 　（ YITP ）

S. Nagataki

１８ th July 2007, YITP

Gamma-Ray Bursts ～ the most powerful explosion in the universe～

Image of GRB ９７０２２８ by HST

Feb 　 28 ｔｈ　１９９７　　　　 Mar 　 3 ｒｄ　１９９７　

Some GRBs are known to beassociated with hypernova explosionswhose explosion energy is 10^52 erg.

= 10 times larger than the explosion energy of a supernova explosion.

= 10 times larger than the energy emitted from the sun in its whole life.

= 10^31 times larger than the atomic bomb dropped on Hiroshima.

Explosion mechanism is still unknown.

Hypernova Explosion

GRB030329 / SN2003dhGRB030329 / SN2003dh

Its spectrum is similar to that ofa core-collapse supernova (death ofa massive star).

Hypernova will be also associated withdeath of a (very) massive star.

In a core-collapase supernova, a neutronStar is formed at the center.

In a hypernova, a black hole is formedAt the center?

Extraction of Rotation Energy from a Black Hole (BZ effect)?

Rotation Energy of a central BH

=

Const.

For any stationary system, we can define conserved flux vector for energy.

Blandford and Znajek (1977)Roger and Me 2005, Banff, Canada.

I’m going to studyBZ effect numerically.

It’s an interesting project!

If an appropriate Tmunu is put around a BH, energy can be extracted from the BH.

Axisymmetry

Numerical simulation of Blandford-Znajek Process

For a << 1 Blandford and Znajek (1997)

=

a=0.95

Monopole solution

T=200, c=G=M=1

Red:Numerical

Blue:Analytical

Numerical results for energy flux with various a.

Formation of a jet (GRB?) from a Kerr BH

a=0.938, with-magnetic field N×N=150×150

T=1200R 　 < 　 60

R 　 < 　 300G=c=M=1

Beta_min=100

We are planning to include microphysics and performmore realistic simulations of GRBs in the near future.

My Collaborators on GRBsR. Blandford (KIPAC)F. Iocco 　（ KIPAC ）S. Pasquale 　（ Fermi 　 Lab ）K. Murase (Kyoto)J. Aoi (Kyoto)A. Mizuta (Chiba)R. Takahashi (U. of Tokyo)T. Kato (OSAKA)K. Asano (NAOJ)T. Yamasaki (CEA Saclay)S. Mineshige (Kyoto)

H. Takami (U. of Tokyo)T. Takiwaki (U. of Tokyo)H. Yoshiguchi (U. of Tokyo)S. Tsubaki (U. of Tokyo)K. Kohri (Lancaster)T. Shimizu (RIKEN)S. Yamada (Waseda)H. Takabe (Osaka)M. Hashimoto (Kyusyu)K. Sato (U. of Tokyo)

科学研究費　若手 B 　（ H.19 － H.21 ）「ガンマ線バーストに於けるハドロン加速及び高エネルギー放射」　代表　長瀧重博科学研究費　基盤 S 　（ H.19 － H.23 ）「超新星の爆発機構とガンマ線バースト源エンジンの統一的解明」　代表　佐藤勝彦科学研究費　特定領域　（ H.19 － H.22 ）「ガンマ線バーストで読み解く太古の宇宙 」　代表　河合誠之