K. Shibata

S. Koide

T. Kudoh

National Institute for Fusion Science (NIFS-Repository)

§36. General Relativistic Simulations of Jet Formation by a Rapidly Rotating Black Hole Koide, S. (Toyama Univ. Eng.) Shibata, K., Kudoh, T. (NAO) The radio observations have revealed the com-pelling evidence of existence of relativistic jets not only from active galactic nuclei (AGNs) but also from "mi-croquasars" in our Galaxy [1]. It is believed that in the cores of these objects a rapidly rotating black hole exists and magnetic phenomena occur near the black hole to form the relativistic jets [2,3, 4, 5]. To simulate the jet formation in the magnetosphere, we have newly developed the Kerr general relativistic magnetohydro-dynamic (KGRMHD) code [6, 7]. We report here the numerical result of the jet formation. Our study is based on the general relativistic equations of conservation laws about mass, momentum, and energy of conductive fluids and Maxwell equations. We use the Kerr metric with spin parameter a = 0.95, 6 5 4 < N 3 2 1 0 1 2 3 4 5 6 R/rs ---.. C 0.01 0.10 100 1000 10000 100000 which provides the space-time around the near maxi- Fig. 1. The plasma beta (gray-scale) and the azimuthal mumly rotating black hole. We employ simplified total component of the magnetic field B¢ (contour) of the variation diminishing (TVD) method. As the initial counter-rotating disk case at t = 4778. The solid lines condition, we assume a transonic free fall corona and show the positive value of B¢ and the dashed lines neg-a relativistic Keplerian disk with a uniform magnetic ative B¢. The vector indicates the velocity. The black field. fan-shaped region at the origin shows the horizon of the Figure 1 shows the result of the case of the Kerr black hole. The dashed line near the horizon is the counter-rotating disk to the black hole rotation at t = inner boundary of the calculation region. 4778. The disk falls toward the black hole rapidly be-cause of no stable-orbit at R < 4.5. A part of the disk Reference enters the ergospher. The jet has two layers; the plasma beta of the head and skin of the jet is high and the mag- [1] netic field azimuthal component B¢ is negative, while that of the root and the center of the jet is low and B¢ is positive. The high beta jet is gas pressure driven jet due to the shock in the disk. On the other hand, the low beta jet is the magnetically driven jet caused by strong magnetic field and the rapid frame dragging almost inside the ergospher. This acceleration mecha-nism is thought to be identical to the Blandford-Znajek mechanism [2]. We thank M. Koide for her important comments for this study and also thank NIFS for the use of super-computers. 310 [2] [3] [4] [5] [6] [7] Mirabel, 1. F. and Rodriguez, L. F., Nature, 371, (1994) 46. Blandford, R. D. and Znajek, R., MNRAS, 179, (1977) 433. Blandford, R. D. and Payne, D. G., MNRAS, 199, (1982) 883. Shibata, K. and Uchida, Y., PASJ, 38, (1986) 63l. Kudoh, T. and Shibata, K., ApJ, 476, (1997) 632. Koide, S., Shibata, K., and Kudoh, T., ApJ, 495, (1998) L63. Koide, S., Shibata, K., and Kudoh, T., ApJ, in press. 

General Relativistic Simulations of Jet Formation by a Rapidly Rotating Black Hole

Abstract

Similar works

Full text

Available Versions

National Institute for Fusion Science (NIFS-Repository)