Multiscale Modeling of Astrophysical Jets

James H Beall,David V Rose,John Guillory,Michael T Wolff

doi:10.14311/app.2014.01.0274

James H Beall, David V Rose + Show 2 more

Open Access

https://doi.org/10.14311/app.2014.01.0274

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Abstract

<p>We are developing the capability for a multi-scale code to model the energy deposition rate and momentum transfer rate of an astrophysical jet which generates strong plasma turbulence in its interaction with the ambient medium through which it propagates. We start with a highly parallelized version of the VH-1 Hydrodynamics Code (Coella and Wood 1984, and Saxton et al., 2005). We are also considering the PLUTO code (Mignone et al. 2007) to model the jet in the magnetohydrodynamic (MHD) and relativistic, magnetohydrodynamic (RMHD) regimes. Particle-in-Cell approaches are also being used to benchmark a wave-population models of the two-stream instability and associated plasma processes in order to determine energy deposition and momentum transfer rates for these modes of jet-ambient medium interactions. We show some elements of the modeling of these jets in this paper, including energy loss and heating via plasma processes, and large scale hydrodynamic and relativistic hydrodynamic simulations. A preliminary simulation of a jet from the galactic center region is used to lend credence to the jet as the source of the so-called the Fermi Bubble (see, e.g., Su, M. &amp; Finkbeiner, D. P., 2012)</p><p>*It is with great sorrow that we acknowledge the loss of our colleague and friend of more than thirty years, Dr. John Ural Guillory, to his battle with cancer.</p>

Highlights

Recent high-resolution (VLBA) observations of astrophysical jets reveal complex structures apparently caused by ejecta from the central engine as they interacts with both surrounding interstellar material such as Broad-Line Region (BLR) and Narrow-Line Region (NRL) clouds, and ejecta from prior episodes of activity
While the physical processes in the ambient medium can be modeled in small regions by PIC (Particle-in-Cell) codes for some parameter ranges, simulations of the larger astrophysical jet structure with such PIC codes are not possible with current or foreseeable computer systems. We have modeled these plasma processes in the astrophysical regime by means of a system of coupled differential equations which give the wave populations generated by the interaction of the astrophysical jet with the ambient medium through which it propagates
Beall (1990) has noted that plasma processes can slow the jets rapidly, and Beall and Bednarek (1999) have shown that these effects can truncate the low-energy portion of the γ-rays spectrum, A similar effect will occur for particle-particle productions of neutrinos, pions, and neutrons

Summary

Introduction

Recent high-resolution (VLBA) observations of astrophysical jets (see, e.g., Lister et al 2009) reveal complex structures apparently caused by ejecta from the central engine as they interacts with both surrounding interstellar material such as Broad-Line Region (BLR) and Narrow-Line Region (NRL) clouds, and ejecta from prior episodes of activity. A trenchant example of these complex interactions is shown by the galactic microquasar, Sco X-1 (Fomalhaut, Geldzahler, and Bradshaw, 2001) Such observations can be used to inform models of the jet-ambient-medium interactions. Large scale hydrodynamic simulations of the interaction of astrophysical jets with the ambient medium through which they propagate can be used to illuminate a number of interesting consequences of the jets’ presence. These include acceleration and entrainment of the ambient medium, the effects of shock structures on star formation rates, and other effects originating from ram pressure and turbulence generated by the jet (see, e.g., Basson and Alexander, 2002; Zanni et al 2005; and Krause and Camenzind 2003; Perucho, et al 2012). We have presented results for large scale hydrodynamic simulations and initial relativistic hydrodynamic simulations in previous works (Beall et al, 1999, 2003, 2006)

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