Ian Richardson HILARY CANE Bruny Island and Tycho von Rosenvinge RADIO SPECTROMETER Ian Richardson and Tycho von Rosenvinge NASA/GSFC

SOLAR ENERGETIC PARTICLES (SEPs) What we know (observe) and what is under debate

OBSERVATIONS ASSOCIATIONS INTENSITY-TIME PROFILES ANISOTROPIES TIMING CHARGE STATES SPECTRA RELATIVE ABUNDANCES

WHAT IS INFERRED WHEN, WHERE AND HOW PARTICLES ARE ACCELERATED HOW THEY GET TO THE OBSERVER (CHARGE STATES)

WHAT NEEDS TO BE DETERMINED How are particles accelerated in flares? What are the characteristics e.g. sizes of regions on the sun that produce flare particles? How do CME shocks evolve? e.g. size and strength with longitude and radial distance

WHAT NEEDS TO BE DETERMINED What populations do shocks accelerate? How much scattering (parallel and perpendicular) is there? How does the scattering vary with radial distance?

1960’s to 1980’s 30 mins Metre Wavelength Radio (MHz) Microwaves H alpha Soft Xrays Hard Xrays Gamma rays Impulsive Gradual phase Phase

METRE WAVELENGTH RADIO BURSTS Drift from high to low frequencies shows presence of a disturbance travelling out from the sun Type III – fast drift produced by flare-accelerated electrons (2- 50 keV?) Type II - slow drift produced by shock-accelerated electrons ( a few keV) Stationary type IV – Flare continuum produced by trapped electrons (gyrosynchrotron~1 MeV? Plasma emission keV?)

1960’s to 1980’s Metre Wavelength Radio (MHz) Microwaves H alpha Soft Xrays Hard Xrays Gamma rays protons Impulsive Gradual phase Phase

DECA and HECTO METRIC RADIO Interplanetary type II NOW Metre wavelength radio (MHz) CME height Microwaves H alpha Soft Xrays Hard Xrays Gamma rays Impulsive Gradual phase Phase

DECA and HECTO METRIC RADIO Interplanetary type II NOW Metre wavelength radio (MHz) CME height Microwaves Nonthermal electrons ≤200 keV and ~MeV H alpha Soft Xrays Hard Xrays Gamma rays Impulsive Gradual phase Phase Electrons (20 keV-1 GeV), protons (up to ~10GeV) and ions (up to ~100 MeV/nuc)

SEP EVENT ASSOCIATIONS SEP EVENTS ARE (USUALLY) PRECEDED BY CORONAL MASS EJECTIONS and FLARES THEY ARE OFTEN IN PROGRESS WHEN AN INTERPLANETARY (IP) (CME-DRIVEN) SHOCK PASSES THE OBSERVER LARGEST EVENTS ACCOMPANIED BY IP RADIO EMISSION FROM THE CME-DRIVEN SHOCK

RELATIONSHIP BETWEEN SEPS AND XRAY AND GAMMA RAY EMISSION WILL BE DISCUSSED IN SESSIONS TODAY AND TOMORROW

PROTON EVENTS AND XRAY SPECTRAL HARDENING (SHH) 2009 Th t Th t 3 ESSENTIALLY NO OPEN FIELD LINES 2 PROBABLY POORLY CONNECTED 1 SLOW SEP EVENT

Meter wavelength dynamic spectrum Coronagraph W26 Meter wavelength dynamic spectrum Soft Xrays

W

Measurements near Earth INTENSITY VS TIME 1, 5, 25, 70 MeV protons Measurements near Earth

SCATTER FREE

SCATTER FREE ELECTRON EVENT

An event from the east limb

IF PARTICLES ACCELERATED AT A FLARE, ASSUMED TO BE A POINT SOURCE, AND CONFINED TO A FIELD LINE HOW DO WE SEE THEM FROM THE EAST LIMB? CORONAL “PROPAGATION”

INTENSITY TIME PROFILES IMP 8 SHOCK ICME 5, 15, 25 MeV protons Helios 1 Helios 2

TIMING electrons In order to compare particle onsets with solar phenomena need to be able to account for interplanetary propagation. Would be much more reliable if observing close to the sun. Good luck PSP!! Event to right seen at Helios 1 when at 0.38 AU and the s/c well connected to solar source. Note protons delayed relative to electrons electrons

CHARGE STATES >10 MeV/nuc

SPECTRA Different functions have been fitted with a double power law seeming to be best for large events. Models are developed to try to predict the spectra. Note that the ones illustrated are fluences i.e. the total particle increase.

RELATIVE ABUNDANCES From observations in the 1970s it was known that some SEP events are enhanced in heavy ions. Enhancement was more common in small events and less common in large events. Extreme enhancements of 3He relative to 4He were found in small events.

“Two classes of solar energetic particle events …..” CANE, MCGUIRE AND VON ROSENVINGE ApJ 1986

DAILY AVERAGED INTENSITY OF OXYGEN VS. THAT OF IRON AT 1. 9-2 DAILY AVERAGED INTENSITY OF OXYGEN VS. THAT OF IRON AT 1.9-2.8 MEV/NUC FROM ISEE-3 (LAUNCHED 1978) Reames (1990)

BIMODAL?

Reames (1992)

SA EVENTS / TYPE III-l ISEE-3, launched in 1978, carried particle detectors and radio antennae and receivers. It was found that at the time of an SEP event the radio experiment saw strong, long lasting type III emission at the time when a type II burst was reported from the ground. Cane et al. (1981) called the type III-like radio bursts “shock accelerated” or later “shock associated”. The association between strong, long lasting, low frequency type III bursts and SEP events was confirmed with Wind Waves data (Cane et al. 2002). HOWEVER it was realised that there was type III emission at times when no type II burst was seen from the ground plus the starting frequencies were higher than the backbone of the type II, when present. Thus the association with shocks was not correct. The phenomenon was renamed type III-l; Low starting frequency, Long duration and LATE.

It was thus suggested that particles accelerated in the gradual phase of flares can make a significant contribution in gradual particle events in contradiction to the current paradigm that “shocks do it all”.

0.25-0.7 MeV Electrons 0.67-3.0 MeV “ 25.9-32.2 MeV Protons 50.8-87.3 MeV “ 25.9-32.2 MeV/n Helium 50.8-67.3 MeV/n “ 0.32- 0.64 MeV/n Oxygen 1.28-3.07 MeV/n “ 14 MeV /n “ 34 MeV/n “ 0.32- 0.64 MeV/n Iron Example of a small (electron-rich) event observed by instruments on ACE and SOHO.

ACE/SOHO observations of a big event at W76°. It is Fe-rich at high energies where shock effect not important.

ARGUMENTS AGAINST POSSIBILITY OF FLARE PARTICLES IN “GRADUAL” EVENTS 1 Flares particles cannot escape 2 Flare particles confined to a small cone 3 Composition not quite right 4 Timing wrong- initiation times too late 5 Properties not centred on the flare

LONGITUDE SPREAD OF FLARE PARTICLES Three s/c (Helios 1 & 2 and near-Earth) Flare electron events (~1 MeV) Three s/c 3He Wibberenz and Cane, (2006)

ARGUMENTS AGAINST POSSIBILITY OF FLARE PARTICLES IN “GRADUAL” EVENTS 1 Flares particles cannot escape 2 Flare particles confined to a small cone 3 Composition not quite right 4 Timing wrong- initiation times too late 5 Properties not centred on the flare

ARGUMENTS AGAINST POSSIBILITY OF FLARE PARTICLES IN “GRADUAL” EVENTS 1 Flares particles cannot escape 2 Flare particles confined to a small cone 3 Composition not quite right 4 Timing wrong- initiation times too late 5 Properties not centred on the flare

ARGUMENTS AGAINST POSSIBILITY OF FLARE PARTICLES IN “GRADUAL” EVENTS 1 Flares particles cannot escape 2 Flare particles confined to a small cone 3 Composition not quite right 4 Timing wrong- initiation times too late 5 Properties not centred on the flare

CONNECTIVITY IS INDICATED BY DRIFT RATE OF TYPE III EMISSION

TWO HOUR DELAY CROSS FIELD TRANSPORT? CANE AND ERICKSON (2003)

STEREO A EARTH (WIND) STEREO B Observations at Earth and STEREO A and B for the event on May 17, 2012.

CONCLUSIONS DESPITE THE FACT THAT WE HAVE OVER 4 SOLAR CYCLES OF REASONABLE DATA COVERAGE AND TWO WITH GOOD (SPECIES AND ENERGY RANGES) THERE IS STILL MUCH MORE INFORMATION NEEDED TO UNDERSTAND THE GENERATION OF SEPS. THIS IS UNLIKELY TO BE ACHIEVED WITHOUT GOING CLOSE TO THE SUN.

CONCLUSIONS DESPITE THE FACT THAT WE HAVE OVER 4 SOLAR CYCLES OF REASONABLE DATA COVERAGE AND TWO WITH GOOD (SPECIES AND ENERGY RANGES) THERE IS STILL MUCH MORE INFORMATION NEEDED TO UNDERSTAND THE GENERATION OF SEPS. THIS IS UNLIKELY TO BE ACHIEVED WITHOUT GOING CLOSE TO THE SUN. HOWEVER PLEASE COME TO THE SESSIONS TODAY AND TOMORROW AND CONTRIBUTE TO A LIVELY DEBATE

SUN SUN SUN NO CONNECTION POOR CONNECTION GOOD CONNECTION

Three (controversial) proposals were made based on analysis of Cycle 23 events: That flares contribute significant particles in the majority of SEP events and that this is determined by the presence of Type III radio emissions [Cane et al., JGR 2002; Cane et al. JGR 2010 and references therein]. That the very low frequency behaviour of these radio bursts indicates whether the flare particles will reach an observer and how quickly [Cane and Erickson, JGR 2003]. That since flare particles do reach spacecraft that are nominally poorly connected there must be some interplanetary cross field transport [Cane and Erickson, JGR 2003, Wibberenz and Cane, ApJ 2006 ].

THREE PHASES OF PARTICLE ACCELERATION FLARE IMPULSIVE PHASE (FIRST) FLARE LATE PHASE (SECOND) SHOCK CME SHOCK ACCELERATION THIRD PHASE

This event clearly has two components; the first is Fe-rich i. e This event clearly has two components; the first is Fe-rich i.e. flare-like, the second is Fe-poor. Even at 34 MeV/nuc OXYGEN peaks at shock passage; there was no local effect in IRON. Obviously O is more efficiently accelerated, presumably because it has a lower mass to charge ratio than Fe. SHOCK 34 MeV/nuc Particles/(cm2- sec- ster- MeV/nuc)

first GLE (Forbush) Feb GLE (Meyer et al.) Two phase acceleration (Wild et al.) 3He enrichment (Hiseh and Simpson) Gamma-ray lines (Chupp et al.) CMEs and SEPS (Kahler et al.) Neutrons SEP charge states 3He events and type III/electrons Two classes 1990 Workshop I

1999 Reames and colleagues propose that high Fe charge states and enhancements of high-Z particles in certain large events are caused by electron stripping before shock acceleration. Cliver (2000) The Reames picture implies “(1) that two quite different acceleration/transport processes can produce identical SEP composition; (2) and that the stripping process results in an Fe charge state similar to that observed in impulsive flares. The need for such coincidences gives one pause and suggests and alternative picture: simply that flare accelerated SEPs account for the observed composition and high Fe charge states in these events…….. It is hard to argue that none of the flare-accelerated particles escape in large gradual flares

Pinter STIP 1977 Apr 12 1969 P6 to P9 183⁰ Nov 20 1968 P8 to flare 113⁰ Jan 26 1971 P8 to flare 116⁰

Hα