LABORATORY INVESTIGATIONS INTO THE EXTREME UNIVERSE

1. LABORATORY INVESTIGATIONS INTO THE EXTREME UNIVERSE Pisin Chen Stanford Linear Accelerator Center Stanford University • Introduction • Universe as Laboratory • Laboratory Studies of the Universe • Summary Second ORION Workshop, SLAC,Feb. 18-20, 2003.

2. LABORATORY ASTROPHYSICSIts relationship with Astrophysics, Particle Physics, and Plasma Physics

3. National Research Council Committee on the Physics of the Universe:Connecting Quarks with the Cosmos: Eleven Science Questions for the New Century • What is the dark matter? • What is the nature of the dark energy? • How did the universe begin? • Did Einstein have the last word on gravity? • What are the masses of the neutrinos, and how have they shaped the evolution of the universe? • How do cosmic accelerators work and what are they accelerating? • Are protons unstable? • Are there new states of matter at exceedingly high density and temperature? • Are there additional spacetime dimensions? • How were the elements from iron to uranium made? • Is a new theory of matter and light needed at highest energies?

4. High Energy-Density Physics • Long history of Plasma Astrophysics(Alfven waves, etc.) • Modern frontier: Very high density, high pressure, and high temperature astrophysical environments and plasma processes • Newly emerged discipline: High Energy-Density Physics

5. “Eleven Science Questions” and Extreme Astrophysical Conditions • Extremely high energy events, such as ultra high energy cosmic rays (UHECR), neutrinos, and gamma rays • Very high density, high pressure, and high temperature processes, such as supernova explosions and gamma ray bursts (GRB) • Super strong field environments, such as that around black holes (BH) and neutron stars (NS) Particle astrophysics and cosmology partially overlaps with high energy-density physics through some of these connections

6. Symbiosis between Direct Observations and Laboratory Investigations Classic example: Laboratory determination of stellar evolution 4p 4He + 2e+ + 2νe + ~ 25 MeV Symbiosis should still be true for Particle Astrophysics and Cosmology

7. Three Categories of LabAstro -Using Lasers and Particle Beams as Tools - 1. Calibration of observation - Precision measurements to calibrate observation processes - Development of novel approaches to astro-experimentations - Though mundane, value to astrophysics most certain 2. Investigation of dynamics - Astro-conditions hard to recreate in lab - Many MHD or plasma processes scalable by extrapolation - Value lies in revelation of dynamical underpinnings 3. Probing fundamental physics - Underlying physical principles may yet to be developed - Extreme limits render signatures faint; viability uncertain - Issues at stake too fundamental to be ignored for experimentation

8. UNIVERSE AS A LABORATORY- Extremely High Energy Events - • Ultra High Energy Cosmic Rays (UHECR) - “Knee” and “ankle” in UHECR spectrum - Events beyond GZK-limit found • Very high energy ν’s and γ’s - ν masses and oscillations - Extremely high energy γ: violation of Lorentz invariance? “Is a new theory of matter and light needed at the highest energies?”

9. UHECR: From Source to Detection “How do cosmic accelerators work and what are they accelerating?” Δ

10. Greisen-Zatsepin-Kuzmin Limit • Protons above 6×1019 eV will lose sizable energy through CMB • Super-GZK events have been found with no identifiable local sources 3×1020 eV 50 Mpc ~ Size of local super-cluster

11. Cosmic Acceleration Mechanisms • Conventional cosmic acceleration mechanisms encounter limitations: - Fermi acceleration (1949) (= stochastic accel. bouncing off B-fields) - Diffusive shock acceleration (70s) (a variant of Fermi mechanism) Limitations for UHE: field strength, diffusive scattering inelastic - Eddington acceleration (= acceleration by photon pressure) Limitation: acceleration diminishes as 1/γ • New thinking: - Zevatron (= unipolar induction acceleration) (R. Blandford) - Alfven-wave induced wakefield acceleration in relativistic plasma (Chen, Tajima, Takahashi, Phys. Rev. Lett. 89 , 161101 (2002).) - Additional ideas by M. Barring, R. Rosner, etc.

12. UNIVERSE AS A LABORATORY- Ultra High Energy-Density Processes - • Supernova explosion Neutrinosphere (proto-neutron star) Plasma pressure   Shock Neutrino-plasma coupling Bingham, Dawson, Bethe, Phys. Lett. A, 220, 107 (1996) Phys. Rev. Lett., 88, 2703 (1999)

13. Gamma Ray Burst • Release of ~ 1052 erg/sec (short bursts)! • “Standard” relativistic fireball model (Rees-Meszaros, 92, 93) • Extended model invokes quark-gluon plasma (Chen et al., 01) “Are there new states of matter at exceedingly high density and temperature?”

14. UNIVERSE AS A LABORATORY- Super Strong Field Environment - • Black holes and strong gravitational field - Testing general relativity “Did Einstein have the last word on gravity?” • Neutron stars and strong EM fields - Schwinger critical field: Bc~ 4×1013 G or Ec ~ 1016 V/m - QED Vacuum unstable

15. UNIVERSE AS A LABORATORY- Extreme Limits of Spacetime and Vacuum - Planck scale ~10-35m • ~2/3 of the present energy density of the universe is in “dark energy”. “What is the nature of dark energy?” • Quantum effects of gravity becomes sizable, or spacetime becomes unrest, at Planck scale. “Are there additional spacetime dimensions?” Human scale ~ 1m

16. LABORATORY STUDIES OF THE UNIVERSE POSSIBLE LABORATORY ASTROPHYSICS EXPERIMENTS Suggested in 2001 Workshop on Laboratory Astrophysics (very preliminary): 1. Cline (UCLA): Primordial Black Hole Induced Plasma Instability Expt. 2. Sokolsky (Utah): High Energy Shower Expt. for UHECR 3. Kirkby (CERN): CLOUD Expt. on Climate Variation 4. Chen-Tajima (SLAC-Austin): Plasma Wakefield Acceleration Expt. for UHECR 5. Nakajima (KEK): Laser Driven Dirac Acceleration for UHECR Expt. 6. Odian (SLAC): Non-Askaryan Effect Expt. 7. Rosner (Chicago): Astro Fluid Dynamics Computer Code Validation Expt. 8. Colgate-Li (LANL): Magnetic Flux Transport and Acceleration Expt. 9. Kamae (SLAC): Photon Collider for Cold e+e– Plasma Expt. 10. Begelman-Marshall (CO-MIT): X-Ray Iron Spectroscopy and Polarization Expt. 11. Ng (SLAC): Relativistic e+e– Plasma Expt. 12. Katsouleas (USC): Beam-Plasma Interaction Induced Photon Burst Expt. 13. Blandford (CalTech): Beam-Plasma Filamentation Instability Expt. 14. Scargle (NASA-Ames): Relativistic MHD Landau Damping Expt.

17. LABORATORY STUDIES OF THE UNIVERSE- Calibration of Observation - 1. Fluorescence from UHECR induced showers - Two methods of detec- tion: Fly’s eye (HiRes) & ground array(AGASA) - Next generation UHECR detector Pierre Auger invokes hybrid detections - Future space-based observatories use fluorescence detection

19. SLAC E-165 ExperimentFluorescence in Air from Showers (FLASH)HiRes-SLAC-CosPA (Taiwan) collaboration

20. 2. Neutrino Astrophysics and the Askaryan Effect- During high-energy EM cascade, γ’s and e-’s pull e-’s in from surrounding material - e+’s, on the other hand, annihilate in flight - The two effects lead to a net charge in the shower - Strong coherent radio and microwave Cherenkov emission (First observation at SLAC, Saltzberg, et al., Phys. Rev. Lett., 2000) - Novel method for UHECR and ν detections (Saltzberg-Gorham) 3. Heavy Element X-Ray SpectroscopyThree “lucky breaks” in black hole accretion: 1. (Many)accretion flows are “cold”; 2. Accretion disks are not fully ionized; 3. Accretion disks are illuminated by flaring coronae.“X-ray observations will allow us to probe the spacetimes of black holes in detail”(M. Begelman)

21. (M. Begelman, 01)

22. LABORATORY STUDIES OF THE UNIVERSE- Investigation of Underlying Dynamics - 1. Alfven-Wave induced Plasma Wakefield Accel. Expt. (Chen et al., 01) • Generation of Alfven waves in relativistic plasma flow • Inducing high gradient nonlinear plasma wakefields • Acceleration and deceleration of trapped e+/e- • Power-law (n~2) spectrum of stochastic acceleration

23. 2. Relativistic Jet Dynamics Experiments • Simulations of shock waves induced by jet-plasma interaction • (K. Nishikawa, 02) • Laboratory experiment with e+e-plasma (J. S.T. Ng)

24. LABORATORY STUDIES OF THE UNIVERSE- Probing Fundamental Physics - 1. Event Horizon Experiment (Chen and Tajima, 99)

25. A Conceptual Design of an Experiment for Detecting the Unruh Effect

26. 2. Probing Spacetime Granularity - Brownian motion: microscopic discrete nature of atom revealed in macro-structure fluctuations (Einstein, 1905) - Planck-scale spacetime fluctuations induces stochastic phase shifts of decoherent atomic wavefunction (Power and Percival, 00) A possible expt., R. Bingham, et al. (Rutherford Appleton Lab, 03)

27. SUMMARY • History has shown that symbiosis between direct observation and laboratory investigation instrumental in the progress of astrophysics. • Particle astrophysics and cosmology, an overlapping frontier between astrophysics and particle physics, faces deep and exciting fundamental issues for the new century. • Many of these issues further overlap with high energy-density physics. • Laser and particle beamsare powerful tools for LabAstro. • Three categories of LabAstro: Calibration of observation; Investigation of dynamics;andProbing fundamental physics; Each provides different value to astrophysics.