The beginning of extra-galactic neutrino astronomy:
What have we learned from IceCube’s neutrinos?E. Waxman
Weizmann Institute
arXiv:1312.0558arXiv:1311.0287
J. Bahcall, “Neutrino Astronomy” (1989): “The title is more of anexpression of hope than a description of the book’s content…”
The main driver of HE n astronomy: The origin of CRs
Cosmic-ray E [GeV]
log [dJ/dE]
1 106 1010
E-2.7
E-3
Heavy Nuclei
Protons
Light Nuclei?
Galactic
UHEX-GalacticSource: Supernovae)?(
Source?
Source?Lighter
Where is the G/XG transition?
Consider the rate of CR energy production at
UHE, >1010 GeV;Intermediate E, 1-100 PeV;“Low” E, ~10 GeV.
UHE: Composition
HiRes 2005
Auger 2010
HiRes 2010 (& TA 2011)
[Wilk & Wlodarczyk 10]*
[*Possible acceptable solution?, Auger collaboration 13]
UHE: Energy production rate & spectrum Protons
dQ/d log e =Const. =0.5(+-0.2) x 1044 erg/Mpc3 yr
Mixed compositioncteff [Mpc]
log(dQ/d log e) [erg/Mpc3 yr]
[Katz & EW 09] [Allard 12]
GZK
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-).
[Krimsky 77]
[Keshet & EW 05]
[Spitkovsky 06, Sironi & Spitkovsky 09, Keshet et al. 09, …]
200c/wp
40c/wp
Lp
thermalL Rc
R ,)(
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)
3
23448
WB2
)1(,1)(for5,1
srscm
GeV
yrerg/Mpc10
log/10
zzf
ddQ
d
dj
[EW & Bahcall 99;
Bahcall & EW 01]
WB192 )eV10(
d
dj[Berezinsky & Zatsepin 69]
BBR05
“Hidden” (n only) sources
Violating UHECR bound
Bound implications: >1Gton detector
5.0yrerg/Mpc10
log/344
ddQ
2 flavors,Fermi
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 (p deacy + cosmological prop.).
IceCube: 37 events at 50Tev-2PeV ~6s above atmo. bgnd. [02Sep14 PRL]
A new era in n astronomy
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) ~ e0 implies: p, G-XG transition at ~1019eV.
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 & 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 .
• (And also a significant fraction of
the g-bgnd, see Irene’s talk).
[Loeb & EW 06]
Low Energy, ~10GeV
• Our Galaxy- using “grammage”
• Starbursts- using radio to g observations
Q/SFR similar for different galaxy types, dQ/dlog e ~Const. at all e!
0.2-0.1yr,Mpc/ergGeV10
102~log
344
Zd
dQ
yrMpc/erg102)0 GeV,10~(log
344zd
dQ
[Katz, EW, Thompson & Loeb 14]
0
Galaxy
Galaxy /log/
log zVSFRSFR
ddQ
d
dQ
The cosmic ray spectrum
[From Helder et al., SSR 12]
The cosmic ray generation spectrum
XG CRs
XG n’sMW CRs,Starbursts(+ CRs~SFR)
[Katz, EW, Thompson & Loeb 14]
A single source?
• 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.
Source candidates & physics challenges
Energy extraction;Jet acceleration andcontent (kinetic/Poynting)
Particle acceleration,Radiation mechanisms
[Lovelace 76; EW 95, 04; Norman et al. 95]
Identifying the sources
• IC’s n’s are produced by the “calorimeters” surrounding the sources.
• DQ~1deg Identification by angular distribution impossible.
• Our only hope: Identification of transient sources by temporal - n gassociation.
• Requires: Wide field EM monitoring, Real time alerts for follow-up of high E n events, and Significant increase of the n detector mass at ~100TeV [Fn(source) may be << Fn(calorimeter)~FWB [ e.g. Fn(GRB) ~0.1
FWB]].
What will we learn from - n gassociations?
• 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 dCP, 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]
Summary
• IceCube detects extra-Galactic n’s. Fn=FWB at 50TeV-2PeV.
• Flux & spectrum of ~1010GeV CRs, ~1PeV n (and ~10 GeV CRs)
Consistent with CR p sources in galaxies, dQ/dlog e~Const., Q~SFR. * IceCube’s detection consistent with the predicted Fn(en<1PeV)~FWB
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>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.
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.
Backup Slides
UHE, >1010GeV, CRs
3,000 km2
J(>1011GeV)~1 / 100 km2 year 2p sr
Ground array
Fluorescence detector
Auger:3000 km2
Where is the G-XG transition?
@ E<1018eV ?
• Fine tuning• Inconsistent with Fermi’s XG g (<1TeV) flux
e2(dQ/de) =Const @ E~1019eV
[Katz & EW 09]
[Gelmini 11]
UHE: Do we learn from (an)isotropy?
Galaxy density integrated to 75MpcCR intensity map (rsource~rgal)
[EW, Fisher & Piran 97]
Biased (rsource~rgal for rgal>rgal )
[Kashti & EW 08]
• 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
[Kotera & Lemoine 08; Abraham et al. 08… Oikonomou et al. 13]
[Lemoine & EW 09]
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 (epeA/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 (dlog
ng/dlog eg<-1).
[Spector, EW & Loeb 14]
IceCube’s GRB limits
[Hummer, Baerwald, and Winter 12;
see also Li 12; He et al 12]
• No n’s associated with ~200 GRBs (~2 expected). • IC analyses overestimate GRB flux predictions, and ignore model uncertainties.• IC is achieving relevant sensitivity.
WBGRB
2
1
,,
2.0
1PeVTeVMeV1
5005.2
b
b
[EW & Bahcall 97]
Are SNRs the low E CR sources?
• So far, no clear evidence. Electromagnetic observations- ambiguous.
E.g.: “p decay signature” [Ackermann et al. 13]: