A New Code for Relativistic Hydrodynamics and Studies of Radio Jets

Abstract

We developed a new special relativistic hydrodynamic (RHD) code that can simulate ultra-relativistic flows with Lorentz factors of up to ~ 100 with high-order accuracy. It employs the finite-difference weighted essentially non-oscillatory (WENO) scheme, a highorder scheme for numerical flux calculation, and the strong stability preserving Runge-Kutta (SSPRK), a high-order time integration method. In addition, the code includes an equation of state (EOS) that closely approximates the EOS of the singlecomponent perfect gas in the relativistic regime, and is optimized for reproducing complex structures in ultra-relativistic flows. Using this code, we simulated the dynamical evolution of relativistic jets with a wide range of model parameters covering both FR I and FR II radio galaxies. As in previous studies, we confirm that the jet power mainly governs flow dynamics, while the jet-tobackground density and pressure ratios play secondary roles. We also find that jet-induced flows contain numerous structures involving shocks, shear, and turbulence. Furthermore, through Monte Carlo simulations, we followed the transport and acceleration of energetic particles in the jet-induced flows. We find that the particles can be boosted into ultra-high energy cosmic rays (UHECRs) with energies of up to E ~ 10^{20} - 10 10^{21} eV via diffusive shock acceleration (DSA), turbulence shear acceleration (TSA), relativistic shear acceleration (RSA). In this talk, we present the new RHD code and studies of radio jets using the code.