Pickup Ions and Reservoir for Energetic Particles George Gloeckler & Eberhard Möbius

PUI Session PUI Production Rates Didkowski et al. PUI Sources Drews et al., Schwadron, Bochsler & Möbius Evolution of PUI Distributions Roelof, Möbius et al. PUI Generated Waves Jian et al., Smith et al. Tails and Energetic Particle Reservoirs Gloeckler, Popecki et al., Lario et al.

~ 14.5 Years of SEM EUV data Didkowski et al.

SEM-based He Photoionization Rates Black: this work with SOLERS22 reference spectrum Magenta: same as black but with SOLAR spectrum Rates match those calculated by McMullin et al. (SOHO 11 Symp) using SOLERS22 This work uses SOLERS22 and SOLAR-2000 reference spectra Didkowski et al.

ISM Ne Cone & Inner Source C, N, O, H 2 O STEREO PLASTIC sees ISM Ne & He, showing the Focusing Cones C, N, O, and H 2 O group ions are identified and do not show cone structure -> Inner Source Drews et al.

2/7/04Outer Heliosphere Wkshp – Riverside - N A Schwadron Prediction vs Observed ENA H Roughly constant density outside the ionization boundary 50 eV ENAs survive inside ~0.5 AU, higher energy move even closer n ENA-PUI ~  i r 1 2 n ENA /(r u) = n p1 (r 1 /r) n ENA-PUI ~ 2.3x10 -4 cm -3 calculated at 3 AU n ENA-PUI ~ 1.7x10 -4 cm -3 observed at 3 AU Schwadron

IBEX_GRUSI_4May 6, 2015IBEX_GRUSI_47 Bochsler & Möbius Simulation of ENA-Generated PUIs

IBEX_GRUSI_4May 6, 2015IBEX_GRUSI_48 Bochsler & Möbius ENA Generated PUIs vs Inner Source

IBEX_GRUSI_4 PUI Sources ISM Ne PUI Ions found at 1 AU New suggestion for Inner Source: from ENAs - Fluxes seem to agree - Can’t explain molecules - Produce suprathermal distribution rather than cold Inner Source distribution - Has difficulty to explain latitude distribution

IBEX_GRUSI_4 Conclusions for guiding center energy loss in a Parker magnetic field (applicable to “scatter-free” propagation) Outside Earth’s orbit: rsin  >V/  ~1AU  -2V/3r“adiabatic cooling” Inside Earth’s orbit: rsin  <V/  ~1AU dlnp/dt = (1-  2 )/2  lnB/  t-(1+  2 ) (V/2r)(1-cos 4  )  -(1+  2 )(  sin  ) 2 (r/V)  0 as r  0 No “adiabatic deceleration” near the Sun!—for any nearly “scatter-free” particle (PUIs or GCRs) Roelof

E. Möbius UNH-SSC9 th Annual Intl Astrophysics Conference, Maui March 2010 Influence of Ionization & Cooling PUI Distribution Determined by Ionization & Cooling ACE SWICS PUI PSDs June 2001 & Along Inflow Axis  = 0.85 AU (SolMax)  = 0.34 AU (SolMin) Use  = 2.0, 1.5 & 1.2 in Model Looks Tantalizing! Acceptable V/V sw To Do PSD Integration!! PUI Distribution Determined by Ionization & Cooling ACE SWICS PUI PSDs June 2001 & Along Inflow Axis  = 0.85 AU (SolMax)  = 0.34 AU (SolMin) Use  = 2.0, 1.5 & 1.2 in Model Looks Tantalizing! Acceptable V/V sw To Do PSD Integration!!

IBEX_GRUSI_4 Evolution of PUI Distributions For scatterfree propagation, PUI cooling is reduced Preliminary observations with ACE SWICS seem to support a visible deviation from standard adiabatic cooling behavior PUI fluxes are highly modulated by SW streams STEREO & ACE data provide excellent opportunity for detailed study

IBEX_GRUSI_4 Distribution of LH vs. RH in S/C Frame LH (~ 70%) RH Because all the waves are intrinsically LH in plasma frame, the RH waves in s/c frame should be due to inward propagation with respect to the solar wind Both the inward and outward propagating ICWs can be carried out by the super- Alfvénic solar wind We use the Doppler shift relation to get f sw from f sc Jian et al.

Power Spectrum Magnetic power spectrum computed for 4.5 hr interval shown on previous slide. Note broad spectral enhancement at the proton cyclotron frequency. Note, too, the added enhancement, lower in frequency consistent with He + resonance. Both waves are left-hand polarized in the s/c frame. f pc /4 Smith et al.

IBEX_GRUSI_4 PUI Generated Waves PUI generated waves are preferentially observed during radial B Event rate decreases with r At AU LH & RH circular polarization observed Outside 3 AU events are rare Linear polarization is observed

IBEX_GRUSI_4 Suprathermal Tails observed in Large Spatially Homogenous Regions in the Solar System In the solar wind frame the suprathermal tail spectrum has the form f (v ) = f o v –5 exp[–(v/v o ) 1.26 ], where v o = cm/s w ≈ 40 Pickup protons GCRs Quiet times at 1 AU Rollover could be exponential or power steeper power law 15 Gloeckler et al.

He + Suprathermal Tail Jan-Oct 2008: SW speeds < V maxHe+ in the SW Frame PSD averaged over total time with SW speeds < V maxHe+ ~SW frame by subtracting Vsw Spectral index over the speed range 2 < V/Vsw < 5 : -5.2 ± 0.1 Popecki et al.

IBEX_GRUSI_4 Lario et al. Correlation between ACE and Ulysses Decay Times of SEP Electrons Fluxes of SEP Electrons Nearly homogeneous fluxes and decay rates over wide range of Longitude, Latitude, and footpoint sep.

IBEX_GRUSI_4 Suprathermal Tails & Energetic Particle Reservoirs Common spectra (v -5 & high-E Rollover) for H +, He +, and He 2+ observed in different heliospheric regions Large SEP events populate a spatially extended reservoir in the inner heliosphere during the decay phase Various sources probably contribute to energetic particle reservoirs: suprathermal tails, ENA-generated PUIs, SEP events

IBEX_GRUSI_4 Open Questions What are the sources of Inner Source PUIs? Why are not more PUI-generated waves observed? ….?

2/7/04Outer Heliosphere Wkshp – Riverside - N A Schwadron Estimating Density of H ENAs j 0 ~200 cm -2 s -1 sr -1 keV -1 at E 0 =1 keV [McComas et al., 2009] j=j 0 (E/E 0 ) -  with  ~2 Lower energy bound of E 1 =50 eV (Survival prob. < 60% inside 1 AU) n ENA ~4  j 0 E 0 (E 1 / E 0 ) 1/2-  /[(  -1/2) v 0 ] ~ cm -3 v 0 =440 km/s is the particle speed associated with E 0 =1 keV