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Cosmic-ray accelerators: What have we learned from IceCube’s neutrinos?

Explore the latest findings on cosmic-ray accelerators from IceCube's neutrinos research by E. Waxman. Learn about the origins of cosmic rays, galactic and extragalactic transitions, sources like supernovae, and collisionless shock acceleration models. Discover implications for UHE cosmic rays, starburst galaxies as CR calorimeters, and potential source candidates. Dive into the physics challenges, electromagnetic acceleration in astrophysical sources, and identifying transient sources like AGN flares. Understand the potential of neutrino-gamma associations in resolving key physics questions.

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Cosmic-ray accelerators: What have we learned from IceCube’s neutrinos?

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  1. Cosmic-ray accelerators:What have we learned from IceCube’s neutrinos? E. Waxman Weizmann Institute arXiv:1312.0558 arXiv:1311.0287

  2. Open Qs: The origin of CRs Where is the G/XG transition? log [dJ/dE] E-2.7 Galactic Protons UHE X-Galactic E-3 Source: Supernovae(?) Heavy Nuclei Source? Light Nuclei? Lighter Source? 1 1010 106 Cosmic-ray E [GeV]

  3. UHE: Composition Auger 2010 [Wilk & Wlodarczyk 10]* HiRes2010 (& TA 2011) HiRes 2005 [*Possible acceptable solution?, Auger collaboration 13]

  4. UHE: Energy production rate & spectrum cteff [Mpc] GZK Protons dQ/d log e =Const. • =0.5(+-0.2) x 1044 erg/Mpc3yr Mixed composition log(dQ/d log e) [erg/Mpc3yr] [Katz & EW 09] [Allard 12]

  5. Collisionless shock acceleration • The only predictive model. • No complete basic principles theory, but - Test particle + elastic scattering assumptions gives v/c<<1: dQ/d log e=Const., v/c~1: dQ/d log e=Const.xe-2/9 (G>>1, isotropic scattering), - Supported by basic principles plasma simulations, - dQ/d log e=Const Observed in a wide range of sources (lower energy p’s in the Galaxy, radiation emission from accelerated e-). [Krimsky77] [Keshet & EW 05] [Spitkovsky 06, Sironi & Spitkovsky 09, Keshet et al. 09, …] 200c/wp 40c/wp

  6. Intermediate energy: Neutrinos • p + g N +p p0 2g ; p+  e+ + ne + nm + nm  Identify UHECR sources Study BH accretion/acceleration physics • For all known sources,tgp<=1: • If X-G p’s:  Identify primaries, determine f(z) [EW & Bahcall 99; Bahcall & EW 01] [Berezinsky & Zatsepin 69]

  7. “Hidden” (n only) sources Violating UHECR bound BBR05

  8. Bound implications: >1Gton detector Fermi 2 flavors,

  9. IceCube: 37 events at 50Tev-2PeV ~6s above atmo. bgnd. A new era in n astronomy e2Fn=(2.85+-0.9)x10-8GeV/cm2sr s =e2FWB= 3.4x10-8GeV/cm2sr s Consistent with Isotropy and with ne:nm:nt=1:1:1 (pdeacy + cosmological prop.).

  10. IceCube’s detection: Implications • Unlikely Galactic: Isotropy, and e2Fg~10-7(E0.1TeV)-0.7GeV/cm2s sr [Fermi]  e2Fn ~10-9(E0.1PeV)-0.7GeV/cm2s sr << FWB • DM decay? The coincidence of 50TeV<E<2PeV n flux, spectrum (& flavor) with the WB bound is unlikely a chance coincidence. • XG distribution of sources, (dQ/d log e)PeV-EeV~(dQ/d log e) >10EeV, tgp(pp)>~1 [“Calorimeters”] • Or • (dQ/d log e)PeV-EeV>>(dQ/d log e) >10EeV, tgp(pp)<<1 • & Coincidence over a wide energy range. • (dQ/d log e)~ e0implies: p, G-XG transition at ~1019eV.

  11. Starburst galaxies: CR calorimeters • Radio, IR & g-ray (GeV-TeV) observations  Starbursts are calorimeters for E/Z reaching (at least) 10PeV. • Most of the stars in the universe were formed in Starbursts. • If CR sources reside in galaxies and Q~Star Formation Rate (SFR), Then Fn(en<1PeV)~FWB . [Loeb & EW 06]

  12. Low Energy, ~10GeV • Our Galaxy- using “grammage” • Starbursts- using radio to g observations • Q/SFRsimilar for different galaxy types, dQ/dloge ~Const. at all e! [Katz, EW, Thompson & Loeb 14]

  13. The cosmic ray spectrum [From Helder et al., SSR 12]

  14. The cosmic ray generation spectrum A single source? MW CRs, Starbursts (+ CRs~SFR) XG n’s XG CRs [Katz, EW, Thompson & Loeb 14]

  15. Source candidates & physics challenges [Lovelace 76; EW 95, 04; Norman et al. 95] • Electromagnetic acceleration in astrophysical sources requires L>1014 LSun(G2/b) (e/Z 1020eV)2 erg/s • GRB: 1019LSun, MBH~1Msun, M~1Msun/s, G~102.5 AGN: 1014 LSun, MBH~109Msun, M~1Msun/yr, G~101 • No steady sources at d<dGZK  Transient Sources (AGN flares?), Charged CRs delayed compared to g’s. Energy extraction; Jet acceleration and content (kinetic/Poynting) Particle acceleration, Radiation mechanisms

  16. Identifying the sources • DQ~1deg  Identification by angular distribution impossible. • Our only hope: Identification of transient sources by temporal n-g association. • Requires: Wide field EM monitoring, Real time alerts for follow-up of high E nevents, and Significant increase of the n detector mass at ~100TeV [Fn(source) may be << Fn(calorimeter)~FWB[ e.g. Fn(GRB) ~0.1 FWB]].

  17. What will we learn from n-g associations? • Identify the CR sources. Resolve key open Qs in the accelerators’ physics (BH jets, particle acceleration, collisionless shocks). • Study fundamental/n physics: - p decay  ne:nm:nt = 1:2:0 (Osc.) ne:nm:nt = 1:1:1  t appearance, - GRBs: n-g timing (10s over Hubble distance)  LI to 1:1016; WEP to 1:106. • Optimistically (>100’s of n’s with flavor identification): Constrain flavor mixing, new phys. [Learned & Pakvasa 95; EW & Bahcall 97] [EW & Bahcall 97; Amelino-Camelia,et al.98; Coleman &.Glashow 99; Jacob & Piran 07] [Blum, Nir & EW 05; Winter 10; Pakvasa 10]

  18. Summary • IceCube detects extra-Galactic n’s. Fn=FWBat 50TeV-2PeV. • Flux & spectrum of ~1010GeV CRs, ~1PeV n(and ~10 GeV CRs) Consistent with CR p sources in galaxies, dQ/dloge~Const., Q~SFR. * IceCube’sdetection consistent with the predictedFn(en<1PeV)~FWB from sources residing in starbursts. [A flurry of models post-dictingIceCube’s results by arbitrarily choosing model parameters to match the flux, see Murase’s review.] * A single type of sources? • The sources are unknown. * UHE: L>1047(50)erg/s, GRBs or bright (to be detected) AGN flares. • Temporal n-g association is key to: CR sources identification, Cosmic accelerators’ physics, Fundamental/n physics.

  19. What is required for the next stageof the n astronomy revolution • The number of events provided by IceCube (~1/yr @ E>1 PeV, ~10/yr @ E>0.1PeV) will not be sufficient for an accurate determination of spectrum, flavor ratio and (an)isotropy. •  n telescopes Meff(100TeV) expansion to ~10Gton • (IceCube, Km3Net). • Wide field EM monitoring. • Adequate sensitivity for detecting the ~1010GeV GZK n’s.

  20. Backup Slides

  21. UHE, >1010GeV, CRs J(>1011GeV)~1 / 100 km2 year 2psr Auger: 3000 km2 3,000 km2 Fluorescence detector Ground array

  22. Where is the G-XG transition? e2(dQ/de) =Const @ E~1019eV @E<1018eV ? • Fine tuning • Inconsistent with Fermi’s XG g (<1TeV) flux [Katz & EW 09] [Gelmini 11]

  23. UHE: Do we learn from (an)isotropy? Biased (rsource~rgal for rgal>rgal ) CR intensity map (rsource~rgal) Galaxy density integrated to 75Mpc • Anisotropy @ 98% CL; Consistent with LSS • Anisotropy of Z at 1019.7eV implies Stronger aniso. signal (due to p) at (1019.7/Z) eV Not observed  No high Z at 1019.7eV [Kashti & EW 08] [EW, Fisher & Piran 97] [Kotera & Lemoine 08; Abraham et al. 08… Oikonomouet al. 13] [Lemoine & EW 09]

  24. p production: p/A—p/g • p decay  ne:nm:nt = 1:2:0 (propagation) ne:nm:nt = 1:1:1 • p(A)-p: en/ep~1/(2x3x4)~0.04 (epeA/A); - IR photo dissociation of A does not modify G; - Comparable particle/anti-particle content. • p(A)-g: en/ep~ (0.1—0.5)x(1/4)~0.05; - Requires intense radiation at eg>A keV; - Comparable particle/anti-particle content, • ne excess if dominated by D resonance (dlogng/dlogeg<-1). [Spector, EW & Loeb 14]

  25. IceCube’s GRB limits • No n’s associated with ~200 GRBs (~2 expected). • IC analyses overestimate GRB flux predictions, • and ignore model uncertainties. • IC is achieving relevant sensitivity. [EW & Bahcall 97] [Hummer, Baerwald, and Winter 12; see also Li 12; He et al 12]

  26. Are SNRs the low E CR sources? • So far, no clear evidence. Electromagnetic observations- ambiguous. E.g.: “p decay signature” [Ackermann et al. 13]:

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