KINETIC MODELING OF RADIATIVE TURBULENCE IN RELATIVISTIC ASTROPHYSICAL PLASMAS: PARTICLE ACCELERATION AND HIGH-ENERGY FLARES PI: DMITRI UZDENSKY (UNIV. COLORADO) CO-IS: MITCH BEGELMAN AND GREG WERNER RELATIVISTIC ASTROPHYSICAL PLASMA ENVIRONMENTS ROUTINELY PRODUCE INTENSE HIGH-ENERGY EMISSION WHICH IS OFTEN OBSERVED TO BE NONTHERMAL AND RAPIDLY FLARING. THE RECENTLY DISCOVERED GAMMA-RAY (>100 MEV) FLARES IN CRAB PULSAR WIND NEBULA (PWN) PROVIDE A QUINTESSENTIAL ILLUSTRATION OF THIS BUT OTHER NOTABLE EXAMPLES INCLUDE RELATIVISTIC ACTIVE GALACTIC NUCLEI (AGN) JETS INCLUDING BLAZARS AND GAMMA-RAY BURSTS (GRBS). UNDERSTANDING THE PROCESSES RESPONSIBLE FOR THE VERY EFFICIENT AND RAPID RELATIVISTIC PARTICLE ACCELERATION AND SUBSEQUENT EMISSION THAT OCCURS IN THESE SOURCES POSES A STRONG CHALLENGE TO MODERN HIGH-ENERGY ASTROPHYSICS ESPECIALLY IN LIGHT OF THE NECESSITY TO OVERCOME RADIATION REACTION DURING THE ACCELERATION PROCESS. MAGNETIC RECONNECTION AND COLLISIONLESS SHOCKS HAVE BEEN INVOKED AS POSSIBLE MECHANISMS. HOWEVER THE INFERRED EXTREME PARTICLE ACCELERATION REQUIRES THE PRESENCE OF COHERENT ELECTRIC-FIELD STRUCTURES. HOW SUCH LARGE-SCALE ACCELERATING STRUCTURES (SUCH AS RECONNECTING CURRENT SHEETS) CAN SPONTANEOUSLY ARISE IN TURBULENT ASTROPHYSICAL ENVIRONMENTS STILL REMAINS A MYSTERY. THE PROPOSED PROJECT WILL CONDUCT A FIRST-PRINCIPLES COMPUTATIONAL AND THEORETICAL STUDY OF KINETIC TURBULENCE IN RELATIVISTIC COLLISIONLESS PLASMAS WITH A SPECIAL FOCUS ON NONTHERMAL PARTICLE ACCELERATION AND RADIATION EMISSION. THE MAIN COMPUTATIONAL TOOL EMPLOYED IN THIS STUDY WILL BE THE RELATIVISTIC RADIATIVE PARTICLE-IN-CELL (PIC) CODE ZELTRON DEVELOPED BY THE TEAM MEMBERS AT THE UNIV. OF COLORADO. THIS CODE HAS A UNIQUE CAPABILITY TO SELF-CONSISTENTLY INCLUDE THE SYNCHROTRON AND INVERSE-COMPTON RADIATION REACTION FORCE ON THE RELATIVISTIC PARTICLES WHILE SIMULTANEOUSLY COMPUTING THE RESULTING OBSERVABLE RADIATIVE SIGNATURES. THIS PROPOSAL ENVISIONS PERFORMING MASSIVELY PARALLEL LARGE-SCALE THREE-DIMENSIONAL SIMULATIONS OF DRIVEN AND DECAYING KINETIC TURBULENCE IN PHYSICAL REGIMES RELEVANT TO REAL ASTROPHYSICAL SYSTEMS (SUCH AS THE CRAB PWN) INCLUDING THE RADIATION REACTION EFFECTS. IN ADDITION TO MEASURING THE GENERAL FLUID-LEVEL STATISTICAL PROPERTIES OF KINETIC TURBULENCE (E.G. THE TURBULENT SPECTRUM IN THE INERTIAL AND SUB-INERTIAL RANGE) AS WELL AS THE OVERALL ENERGY DISSIPATION AND PARTICLE ACCELERATION THE PROPOSED STUDY WILL ALSO INVESTIGATE THEIR INTERMITTENCY AND TIME VARIABILITY RESULTING IN DIRECTION- AND TIME-RESOLVED EMITTED PHOTON SPECTRA AND DIRECTION- AND ENERGY-RESOLVED LIGHT CURVES WHICH CAN THEN BE COMPARED WITH OBSERVATIONS. TO GAIN DEEPER PHYSICAL INSIGHT INTO THE INTERMITTENT PARTICLE ACCELERATION PROCESSES IN TURBULENT ASTROPHYSICAL ENVIRONMENTS THE PROJECT WILL ALSO IDENTIFY AND ANALYZE STATISTICALLY THE CURRENT SHEETS SHOCKS AND OTHER RELEVANT LOCALIZED PARTICLE-ACCELERATION STRUCTURES FOUND IN THE SIMULATIONS. IN PARTICULAR IT WILL ASSESS WHETHER RELATIVISTIC KINETIC TURBULENCE IN PWN CAN SELF-CONSISTENTLY GENERATE SUCH STRUCTURES THAT ARE LONG AND STRONG ENOUGH TO ACCELERATE LARGE NUMBERS OF PARTICLES TO THE PEV ENERGIES REQUIRED TO EXPLAIN THE CRAB GAMMA-RAY FLARES AND WHERE AND UNDER WHAT CONDITIONS SUCH ACCELERATION CAN OCCUR. THE RESULTS OF THIS RESEARCH WILL ALSO ADVANCE OUR UNDERSTANDING THE ORIGIN OF ULTRA-RAPID TEV FLARES IN BLAZAR JETS AND WILL HAVE IMPORTANT IMPLICATIONS FOR GRB PROMPT EMISSION AS WELL AS AGN RADIO-LOBES AND RADIATIVELY-INEFFICIENT ACCRETION FLOWS SUCH AS THE FLOW ONTO THE SUPERMASSIVE BLACK HOLE AT OUR GALACTIC CENTER.