WG4 joint session with WG3 (radio) Bone * FMS? CS? Trapping below a CS? Thick-target coronal or chromospheric? * Veronig-Brown event * X3.3 20 Jul 2002 LDE with slow "impulsive" emission (Kane says 10,000 km occultation height) * CLEAN and PIXON maps - latter show rather nice loops even @ 50 keV * Non-thermal fits, HXR @ 3.0 and similar OVRO * GOES 28e49 => 2.2e11 density => 28-41 keV thick, not good enough? * Need more data... need interpretation... Schwartz, Krucker, Fletcher, Hudson, Dennis, St-Hilaire - this event is the most extreme coronal event in RHESSI data perhaps Battaglia * Motivation: flare energy release, electron propagation... * Parks-Winckler 1969 SHS cf Grigis: acceleration or transport? * Events selected to have 3 HXR sources, 1 minute duration, well separated, no strong pileup, >M1 => 5 events * CLEAN, OSPEX tools * Event list 1-Nov-03, 4-Dec-02, 30-Jul-05, 24-Oct-03, 13-Jul-05; each with peculiarities * 35 keV vs gamma analysis +> 2 events SHS in all 3, 2 in one source, 1 anticorrelated * All coronal sources show SHS to some extent (?) * "Pivot point" Grigis-Benz 2004, 2005 not necessarily physically significant; found in 4 events (footpoints in 2); E_piv larger in corona; E_piv increases with T * Gamma differences avoid 2; footpoints 0.33+-0.04 from absolute "about the same" * "So what" slide: Source intrinsic property? Grigis result on SHS from stochastic model Fletcher, Fivian.. discussion of how to relate the coronal sources White, Fletcher - how about looptop/footpoint identification? Dennis - possibility of pileup? Have avoided "pretty bad" pileup cases via attenuator motions and from Smith model. Krucker concurs Dennis - crosstalk from sidelobes? Sidelobe conservative level shown in spectra Warmuth * Two topics: the outflow shock and propagating shocks. Aurass, Mann. * Cartoon: Forbes, Tsuneta-Naito 1998. Observations Vrstnak-Mann, Aurass-Mann * 7-Apr-97 lovely example of two-band herringbone morphology of a type II, but with no drift. Images show it to be stationary as well * Have as many as 10 events now... * Objections: why so few, why not impulsive phase? Suggest fragmented source. * Lucky to have found the right event 28-Oct-2003 11:03 herringbone at 280 MHz, coincident with INTEGRAL/Coronas-F gamma-rays (7.5 MeV) and >100 keV HXR White, Pick comments - no backbone, broad scattering source * Claim shock _can_ be there in some cases * Relativistic shock drift acceleration theory, mirroring (but assuming planar QP shock) * Mann et al. 2006 (A&A) SDA theory of particle acceleration and reflection * From a Maxwellian into a loss-cone distribution at a specific angle * Fluxes per unit upstream density, preheating by slow-mode shocks; Mach 2 and model compression ratio X = 2, V_s = 1500 km/s * Compare with RHESSI electron fluxes and powers (23-Jul-02 event) * Density and area estimates to get flux: @ 10MK neeed NA = 1.8e30 20 7.6e28 40 ... * NRH spectroheliogram does not look right? * Observations and theory look pretty good, including quantitative agreement within reasonable parameters * Problem with spectra being too steep at high energies, starting with Maxwellian; working on kappa distributions; thinking about stochastic acceleration in the outflow itself * protons? SDA independent of charge... Khan: Nancay source morphology looks wrong... Van Driel: filament eruption Hudson: McKenzie flows? White: Oct. 28 does not look like a type II. Herringbone almost never seen... perhaps QP condition required. White: substructure within type IV? But see harmonic as well as fundamental Pick: See type III and RS instead of herringbone? Kundu: motion parallel to density contours? Ruled out in this case... Khan: CME signature, even CME-driven shock? Ask Henry Fletcher: number/density estimates Dennis: Enlarged view of radio signature shows down/flat/up motions. Backbone "very problematic", ask Henry Pick: Overview, 164 MHz observation shows systematic radial motions - Moreton wave clearly observed in movie; do not like termination-shock picture - See the process between CME and open-field regions Warmuth: we think we see a stationary source, but Moreton wave quite unusual Van Driel * Goff thesis work? 16 Apr 02, 3rd of homologous "coronal thick target" series * TRACE, RHESSI, MDI, EIT, CDS, LASCO, magnetic modeling Hudson question regarding identification of erupting filament * CDS sit-and-stare FeXIX red/blue observation of same feature, loop + legs with opposite flow senses (cf Mason-Pike OV observation) * Synthetic TRACE image looks the same (Lyida, Helen) or looks different (others) Much discussion! * Magnetic extrapolations based on 14-Apr MDI data rotated to the time of the flare * Conclude downflows along two legs consistent with loop tilts (Mandrini) * RHESSI "thick target" loop plus coronal source with rising motion (recall Sui-Holman decreasing motion * Photometry of looptop/coronal sources near dynamic range limit * Map erupting filament and RHESSI position over same time range, parallel tracks * Height-time plots show mismatch between CME and low-coronal motions, would require exponential acceleration to coincide Discussion (Dennis, Hudson, Pick, Warmuth, Fletcher, Khan) about 3D and structural relationships among components of ejecta * Interpretation in terms of standard cartoon; add kink instability to explain apparent acceleration to link filament and CME motions but not at the impulsive phase. Identify RHESSI coronal source with bottom of rising filament. A&A 434, 761, 2005 Ji * Loop-top source downwards motions in M-class flare, NRO, PMO, RHESSI * Shear angle vs time (observational, not theoretical but would like to relate) shows correlated change with HXR lightcurve, including fine structure * Displacement of NRO microwave source also correlated, but perhaps with confusion of phase reference motions * Shear relaxation, collapsing trap, current-sheet formation, implosion Fletcher: Bogachev-Somov, general discussion of nature of reconnection development Krucker: studied related events for particle relationships. Such events tend to have three footpoints (cf Sakao emerging-flux idea => converging footpoints?) Discussion of reconnection in HPR geometry, no real concensus - Sa"m points out that the unmatched footpoint often is the brightest HXR source in such events Dennis - does the cartoon explain decreasing altitude? Veronig * Graduate student Miklenic * Reconnection cartoons, E = vxB from Forbes-Priest; Poynting flux Isobe et al. 2002 in terms of observables - the 2D picture * Global reconnection rate from activated area - the 3D view * In any case the more reconnection, the more hard X-rays would be expected * 18-Nov-03 event TRACE 1600A observations, HXR 20-60 keV * overlay on MDI shows more rapid ribbon motion in weak-field regions * Four peaks in RHESSI HXR matched with ribbon separation at HXR location, usually almost perpendicular to neutral line * Find inferred E(t) to match HXR(t), especially with imaged HXR light curves * 3D cartoon shows patchy motions within arcade * Activation area movie... lovely. Flux balance to 10% Fletcher - is there a time delay between E and HXR? Hudson - is there a complete mismatch? Probably not * Conclusion: Agreement with local reconnection rate, but not quantitatively. But a perhaps surprisingly good agreement with the model Discussion - Dennis, Hudson, Fletcher, Krucker, Van Driel