Transcript Slide 1
Recent Progress in Understanding Particle Acceleration in Astrophysical Sources: Better Observations + Bigger Computers = Neither Sources nor Acceleration Theories Quite What Expected …. P. Coppi, Yale Hey, world is not 1.5D Convenient Charge Starvation and + homogenous or toroidal Current 2.5D >1.5 but still < Sheet 3D Topology – Direct – 3D + Turbulence!? Field (LINAC) Acceleration? To Guide or Not Guide Field? Drift, Kink Mode? High σ /quasiperpendicular shocks “Bad”? Kill σ! Fermi I, II, I.5? Weibel, Weibel, Weibel … Two beam instability? LAGN/GRB~ 40 c/ωp , right? Tearing Modes Ion Ring Instability On-Demand, Ultra-Fast Reconnection (Mini-jets?) me vs. mp still annoying Injection Problem? PIC Striped Jets And Winds? Wave Resonance & But Dad, MHD is so Breaking twentieth Radiation Reaction andcentury … WithFeedback/Drag? apologies to D. McCray (1979) Recent Progress in Understanding Particle Acceleration in Astrophysical Sources? Dobje, dobje … With apologies to D. McCray + K. Nalewajko (Nature 2007) From P. Blasi, Brasil lectures HADRONIC RXJ1713 RXJ1713 LEPTONIC Morlino, Amato & PB 2009 RXJ1713 with fermi data 1. 2. 3. 4. e/p Equilibration downstream? (Morlino et al. 2009) Very low value of Kep at given time Lines from non-equilibrium ionization ? (Ellison et al. 2010) What are those Fermi data points telling us? A Puzzling situation Courtesy of S. Funk • Most SNR detected by Fermi have steep spectra (some exceptions, such as RXJ1713) • The predicted spectra would naively require steep diffusion D(E)~E0.7 in conflict with anisotropy measurements Marshall et al. 2010 Pictor A rapid X-ray Variability? Centaurus A - Chandra Two components! Optical polarized Synchrotron TeV+ electrons! Uchiyama et al. 2007 Usual Observer Questions for particle acceleration people… • What fraction of free energy goes into protons vs. electrons? • What are overall acceleration efficiencies? • What’s the electron energy spectrum? [Probably there are multiple acceleration/dissipation regions – what are energy >spectra< and how do they depend on ambient parameters?] • Marek believes jet is kinetic dominated by the end (?) – is there a preferred conversion region/location? Why? Termination shock analog Crab? Pair loading (breeder)? Mass entrainment/baryon loading? • How fast can you make things go? (PKS 2155 o.k.?) • Coherent processes important or not? (High brightness temperature cores?) • Anything interesting at boundary layer ? (cf. sheath/spine geometry? Edge brightening?) • How much turbulence do you need/expect/what generates it? Tammi & Duffy 2009 – no problem with “conventional” acceleration timescales in PKS 2155? RXTE ASM TIMESCALES: TeV (and GeV) blazars appear to have discrete “flare” states… : vs. Structure Function Takahashi et al. 2001 1959 flares! (RXTE TOO) May-June 2002 6 hr rapid variability timescale in Mrk 421?? Problem: In "standard model," single blob would be at 2 t R 2ct 51019 25 cm! month Unlikely.... t months?? The stability problem… LTeV L2x (naive SSC) LTeV Lx Linear Axes! Steady X-Ray Component?? (ERC, SSC, hadronic model) Key – 3 keV flux tracks TeV flux relatively poorly N.B. June 1997 data (after main flaring) included! 3C 454.3 2009 Flare – SMARTS + Fermi (Chatterjee et al.) Oops!! -- 1ES1959 May-Aug 2002 Multiple Emission Components! Krawczynski et al. 2004 X-ray Counts In case you still thought things were simple… Mkn 421 2002 X-ray/TeV campaign (Dieter Horns, preliminary) TeV X-ray hardness ratio (spectrum) G. Senturk et al. 2011 Markarian 501 – Just after the big multi-wavelength campaign Neronov et al. 2011 One zone fit to 3C 454.3 Dec 2-3 2009, Bonoli et al. X-gamma + SMARTS NIR/opt 0235 PKS 1510 Bonning et al. (SMARTS) STATES!? Different Components?? PKS 2155 OJ 287 Radio Quiet vs. FSRQ Optical Variability (Bauer et al. 2009, QUEST) Some phenomenological observations/clues/questions – • To me, seems like we often need Emin for acceleration process? Agreed? Is it obviously γmin ~ 2σ1/2 (mp/me)? Do we actually need a large range of γ? • Except for few cases, don’t see evidence of mono-energetic particle distribution, i.e., no pile-up (usual result for tacc < tcool). How/why to separate emission/cooling region from acceleration region? • Definitely multiple emission regions? One size/mechanism need not fit all. • Blazars more dramatic than expected. Needles/mini-jets fine, but how do we avoid GRB efficiency/cannonball problems? (Really small region has to process a lot of power.)