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The beginning of extra-galactic neutrino astronomy: What have we learned from IceCube’s neutrinos? E. Waxman Weizmann Institute arXiv:1312.0558 arXiv:1311.0287 J. Bahcall, “Neutrino Astronomy” (1989): “The title is more of an expression of hope than a description of the book’s content…”
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Cosmic-ray accelerators: What have we learned from IceCube’s neutrinos? E. Waxman Weizmann Institute arXiv:1312.0558 arXiv:1311.0287
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The main driver of HE astronomy: The origin of CRs Cosmic-ray E [GeV] log [dJ/dE] 1 10 6 10 E -2.7 E -3 Heavy Nuclei Protons Light Nuclei? Galactic UHE X-Galactic Source: Supernovae(?) Source? Lighter Where is the G/XG transition?
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Consider the rate of CR energy production at UHE, >10 10 GeV; Intermediate E, 1-100 PeV; “Low” E, ~10 GeV.
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UHE: Composition HiRes 2005 Auger 2010 HiRes 2010 (& TA 2011) [Wilk & Wlodarczyk 10]* [*Possible acceptable solution?, Auger collaboration 13]
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UHE: Energy production rate & spectrum Protons dQ/d log =Const. =0.5(+-0.2) x 10 44 erg/Mpc 3 yr Mixed composition ct eff [Mpc] log(dQ/d log ) [erg/Mpc 3 yr] [Katz & EW 09] [Allard 12] GZK
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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 =Const., v/c~1: dQ/d log =Const.x -2/9 ( >>1, isotropic scattering), - Supported by basic principles plasma simulations, - dQ/d log =Const Observed in a wide range of sources (lower energy p’s in the Galaxy, radiation emission from accelerated e - ). [Krimsky 77] [Keshet & EW 05] [Spitkovsky 06, Sironi & Spitkovsky 09, Keshet et al. 09, …] 200c/ p 40c/ p
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Intermediate energy: Neutrinos p + N + 0 2 ; + e + + e + + Identify UHECR sources Study BH accretion/acceleration physics For all known sources, p <=1: If X-G p ’ s: Identify primaries, determine f(z) [EW & Bahcall 99; Bahcall & EW 01] [Berezinsky & Zatsepin 69]
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BBR05 “Hidden” ( only) sources Violating UHECR bound
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Bound implications: >1Gton detector 2 flavors, Fermi
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=(2.85+-0.9)x10 -8 GeV/cm 2 sr s = WB = 3.4x10 -8 GeV/cm 2 sr s Consistent with Isotropy and with e : : =1:1:1 ( deacy + cosmological prop.). IceCube: 37 events at 50Tev-2PeV ~6 above atmo. bgnd. [02Sep14 PRL] A new era in astronomy
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IceCube’s detection: Implications Unlikely Galactic: Isotropy, and 2 ~10 -7 (E 0.1TeV ) -0.7 GeV/cm 2 s sr [Fermi] 2 ~10 -9 (E 0.1PeV ) -0.7 GeV/cm 2 s sr << WB DM decay? The coincidence of 50TeV<E<2PeV flux, spectrum (& flavor) with the WB bound is unlikely a chance coincidence. XG distribution of sources, (dQ/d log ) PeV-EeV ~ (dQ/d log ) >10EeV, p(pp) >~1 [“Calorimeters”] Or (dQ/d log ) PeV-EeV >> (dQ/d log ) >10EeV, p(pp) <<1 & Coincidence over a wide energy range. (dQ/d log ) ~ 0 implies: p, G-XG transition at ~10 19 eV.
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Candidate CR calorimeters: Starburst galaxies Candidate UHECR sources are NOT expected to be “calorimeters” for <100PeV p’s [e.g. Murase et al. 2014]. Radio, IR & -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 ( <1PeV)~ WB. (And also a significant fraction of the -bgnd, see Irene’s talk). [Loeb & EW 06]
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Low Energy, ~10GeV Our Galaxy- using “grammage” Starbursts- using radio to observations Q/SFR similar for different galaxy types, dQ/dlog ~Const. at all ! [Katz, EW, Thompson & Loeb 14]
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The cosmic ray spectrum [From Helder et al., SSR 12]
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The cosmic ray generation spectrum XG CRs XG ’s MW CRs, Starbursts (+ CRs~SFR) [Katz, EW, Thompson & Loeb 14] A single source?
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Electromagnetic acceleration in astrophysical sources requires L> 10 14 L Sun ( 2 / ) ( /Z 10 20 eV) 2 erg/s GRB: 10 19 L Sun, M BH ~1M sun, M~1M sun /s, ~10 2.5 AGN: 10 14 L Sun, M BH ~10 9 M sun, M~1M sun /yr, ~10 1 No steady sources at d<d GZK Transient Sources (AGN flares?), Charged CRs delayed compared to ’s. Source candidates & physics challenges Energy extraction; Jet acceleration and content (kinetic/Poynting) Particle acceleration, Radiation mechanisms [Lovelace 76; EW 95, 04; Norman et al. 95]
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Identifying the sources IC’s ’s are produced by the “calorimeters” surrounding the sources. ~1deg Identification by angular distribution impossible. Our only hope: Identification of transient sources by temporal association. Requires: Wide field EM monitoring, Real time alerts for follow-up of high E events, and Significant increase of the detector mass at ~100TeV (source) may be << (calorimeter)~ WB [ e.g. (GRB) ~0.1 WB ] ].
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What will we learn from associations? Identify the CR sources. Resolve key open Qs in the accelerators’ physics (BH jets, particle acceleration, collisionless shocks). Study fundamental/ physics: - decay e : : = 1:2:0 (Osc.) e : : = 1:1:1 appearance, - GRBs: - timing (10s over Hubble distance) LI to 1:10 16 ; WEP to 1:10 6. Optimistically (>100’s of ’ s with flavor identification): Constrain CP, 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; … Ng & Beacom 14; Ioka & Murase 14; Ibe & Kaneta 14; Blum, Hook & Murase 14]
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Summary IceCube detects extra-Galactic ’s. = WB at 50TeV-2PeV. Flux & spectrum of ~10 10 GeV CRs, ~1PeV (and ~10 GeV CRs) Consistent with CR p sources in galaxies, dQ/dlog ~Const., Q~SFR. * IceCube’s detection consistent with the predicted ( <1PeV)~ WB from sources residing in starbursts. [A flurry of models post-dicting IceCube’s results by arbitrarily choosing model parameters to match the flux.] * A single type of sources? The sources are unknown. * UHE: L>10 47(50) erg/s, GRBs or bright (to be detected) AGN flares. Temporal association is key to: CR sources identification, Cosmic accelerators’ physics, Fundamental/ physics.
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What is required for the next stage of the 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. telescopes M eff (100TeV) expansion to ~10Gton (IceCube, Km3Net). Wide field EM monitoring. Adequate sensitivity for detecting the ~10 10 GeV GZK ’s.
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Backup Slides
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UHE, >10 10 GeV, CRs 3,000 km 2 J(>10 11 GeV)~1 / 100 km 2 year 2 sr Ground array Fluorescence detector Auger: 3000 km 2
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Where is the G-XG transition? @ E<10 18 eV ? Fine tuning Inconsistent with Fermi’s XG (<1TeV) flux 2 (dQ/d ) =Const @ E~10 19 eV [Katz & EW 09] [Gelmini 11]
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UHE: Do we learn from (an)isotropy? Galaxy density integrated to 75Mpc CR intensity map ( source ~ gal ) [EW, Fisher & Piran 97] Biased ( source ~ gal for gal > gal ) [Kashti & EW 08] Anisotropy @ 98% CL; Consistent with LSS Anisotropy of Z at 10 19.7 eV implies Stronger aniso. signal (due to p) at (10 19.7 /Z) eV Not observed No high Z at 10 19.7 eV [Kotera & Lemoine 08; Abraham et al. 08… Oikonomou et al. 13] [Lemoine & EW 09]
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production: p/A—p/ decay e : : = 1:2:0 (propagation) e : : = 1:1:1 p(A)-p: / p ~1/(2x3x4)~0.04 ( p A /A); - IR photo dissociation of A does not modify ; - Comparable particle/anti-particle content. p(A)- : / p ~ (0.1—0.5)x(1/4)~0.05; - Requires intense radiation at >A keV; - Comparable particle/anti-particle content, e excess if dominated by resonance (dlog n /dlog <-1). [Spector, EW & Loeb 14]
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IceCube’s GRB limits [Hummer, Baerwald, and Winter 12; see also Li 12; He et al 12] No ’ 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]
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Are SNRs the low E CR sources? So far, no clear evidence. Electromagnetic observations- ambiguous. E.g.: “ decay signature” [Ackermann et al. 13] :
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