Structure formation of black hole jets triggered by electron-scale physics

doi:10.21203/rs.3.rs-63856/v1

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Structure formation of black hole jets triggered by electron-scale physics

https://doi.org/10.21203/rs.3.rs-63856/v1

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Jets are ubiquitous in the universe[1,2]. The radio jet is a beamed plasma flow with relativistic speed accelerated by a supermassive black hole in some galaxies. Recent observations of the relativistic jet in the elliptical galaxy M87 have discovered a triple-ridge sub-structure in the jet at a distance of one thousand Schwartzchild radius from the black hole [3,4]. The triple-ridge structure may be the first strong evidence of the spine-sheath structure consisting of the fast spine region (jet spine) and relatively slow sheath region (jet sheath), which was hypothetically introduced to explain observational features in various unresolved relativistic jets [5,6]. However, the formation mechanism of such a spine-brightened jet is quite enigmatic. Here we report that the combination of the magnetic pinching force induced by an electron-scale shear-instability called Mushroom instability[7] and the high-energy electron ejections by the subsequent magnetic reconnection leads to the drastic accumulation of high-energy electrons in the center of the cylindrical jet. The concentration of high-energy electrons towards the jet center indicates the appearance of bright jet-spine as observed in M87. Thus, the electron-scale, microscopic processes would play an important role in the structure formation and generation of high-energy components in the relativistic jets.

Rererences: [1] Frank, A. etal. Jets and Outflows from Star to Cloud: Observations ConfrontTheory. InBeuther, H., Klessen, R. S., Dullemond, C. P. & Henning, T. (eds.) Protostars and Planets VI, 451 (2014). [2] Blandford, R., Meier, D. & Readhead, A. Relativistic Jets from Active Galactic Nuclei. ARA&A 57, 467–509 (2019). [3] Asada, K., Nakamura, M. & Pu, H.-Y. Indication of the Black Hole Powered Jet in M87 by VSOP Observations. ApJ833, 56 (2016). [4] Hada, K. The Structure and Propagation of the Misaligned Jet M87. Galaxies 5, 2 (2017). [5] Laing, R. A. & Bridle, A. H. Relativistic models and the jet velocity field in the radio galaxy3C 31. MNRAS 336, 328–352 (2002). [6] Ghisellini, G., Tavecchio, F. & Chiaberge, M. Structured jets in TeV BL Lac objectsand radiogalaxies. Implications for the observed properties. A&A 432, 401–410 (2005). [7] Alves, E. P., Grismayer, T., Fonseca, R. A. & Silva, L. O. Transverse electron-scale instability in relativistic shear flows. PhRvE 92, 021101 (2015).

Astronomy

Astrophysics and Cosmology

Planetary Science

black hole

high-energy electrons

relativistic jets

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Formation of jet spine (II): electron density
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Magnetic reconnection driven by Mushroom instability
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Formation of jet spine (I): pseudo emissivity
Fig5supp.png
Figure 5: (supplementary information) Time evolution of MI of electron-proton plasma with real mass ratio in the cold plasma limit. The colour displays the dye concentration field of electrons. In the region shown in this figure, the blue/red colour is initially attached to the electrons in the upper/lower side of the velocity shear surface at y = 4.8c/ωpe. Then, the dynamics of electrons are solved via the PIC simulations with their colour information being kept. White coloured region means that the red- and blue-coloured electrons are mixed there. The initial bulk velocity of protons and electrons is vz = +0.5c and −0.5c above and below the velocity shear surface, respectively. The simulation domain is Lx × Ly = 4.8[c/ωpe] × 19.2[c/ωpe], which is divided by 192×768 grid cells, i.e., the initial electron skin depth is resolved by 40 grid cells. The density and thermal velocity of protons and electrons are initially uniform, except the y-component of velocity is perturbed in such a way that vy = −(10−4c) cos (2πx/Lx). The periodic boundary condition is imposed in x and y directions. We note that roughly the lower half of the simulation domain is shown in this figure.
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Figure 6: (supplementary information) Time evolution of energy of electromagnetic field ǫEM, electric field ǫE, magnetic field ǫM normalized by initial kinetic energy of particles (i.e., protons and electrons) ǫP(init), which are measured in the laboratory frame. The left panel shows the early stage of simulation. The black curve represents ǫEM. As a reference, the slope of maximal growth rate of MI (∝ ¯v/c√¯γ) for cold plasmas is shown by the gray dashed line. The MI grows linearly up to t ∼ 10/ωpe. The right panel shows the long term evolution of ǫEM (black), ǫE (blue), and ǫM (red).
Fig7supp.png
Figure 7: (supplementary information) The electron distribution in y–vy phase space at t = 2.5 × 102ω−1 pe , in which electrons are sampled along the line x = 46c/ωpe. The hole structure at (y, vy/c)≃(3, 0) evidently presents the appearance of the MR at this point. In this figure, the velocity in y-direction is evaluated in the co-moving frame of the bulk motion in z-direction.

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Structure formation of black hole jets triggered by electron-scale physics

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