( ( ( ( ( Cosmic(rays( Photons( Neutrinos( Only(ν(propagate( freely(through( the(cosmos( Multi-messenger astronomy

Lezioni 19 e 20 The IceCube Detector Motivation o Neutrinos: a new probe of the High Energy Universe Neutrino properties and how to detect them Construction of IceCube o Optical Modules, Ice Properties o The surface detector: IceTop o The pointing capability (Moon observation ) Evidence for astrophysical neutrinos at high energy Significance, implications, the Cosmic-Ray connection Cosmic Ray anisotropy: results from IceCube and other experiment in the Northern hemisphere. 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 1

Cosmic(rays( Photons( Neutrinos( Only(ν(propagate( freely(through( the(cosmos( Multi-messenger astronomy ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 2

Cosmic ray neutrino connection Cosmic(rays(are(accelerated(( in#galac(c#sources#such#as#supernova#remnants# In#extragalac(c#sources#such#as#ac(ve#galaxies#and# gamma6ray#bursts# Cosmic(ray(sources(produce(γ8rays(in(two(ways( From#radia(on#by#accelerated#electrons# From#decay#of#π 0 #produced#by#interac(ons#of#accelerated# cosmic6ray#protons#or#nuclei#with#gas#or#photons# High(energy(ν are(produced(only(in(hadronic(collisions:( From#decay#of#π/K#produced#when#cosmic#rays#interact# with#gas#in#or#near#their#sources# Or#from#photo6pion#produc(on#on#CMB#or#EBL # 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 3

Implications of astrophysical neutrinos Observa9ons(of(γ rays(are(oten(ambiguous( Electrons#radiate#efficiently#and#usually#explain#the# observa(ons# Signatures#of#hadronic#origin#of#photons#are#difficult# to#iden(fy#and#prove# Neutrinos(have(a(unique(implica9on( Observa(on#of#high#energy#extraterrestrial#ν requires#a#hadronic#origin# Neutrinos#can#emerge#from#deep#inside#a#compact# source#without#degrada(on#by#electromagne(c# cascading# 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 4

Cosmic Rays Energies and rates of the cosmic-ray particles Energy(content(of(CR( determines(possible( sources(of(neutrinos( Extra8galac9c(origin(is(likely( Loca9on(of(transi9on(from( galac9c(to(extra8galac9c( affects(energy(es9mate( E 2 dn/de (GeV cm -2 sr -1 s -1 ) 10 0 protons only 10-2 10-4 10-6 electrons positrons antiprotons Grigorov Akeno MSU KASCADE Tibet KASCADE-Grande IceTop73 all-particle HiRes1&2 TA2013 Auger2013 Model H4a CREAM all particle Galactic E dn d ln E 3 10 8 (at 10 10 GeV (10 19 ev) 10-10 GeV cm 2 srs 10-8 Fixed target HERA RHIC TEVATRON LHC Extra-Galactic 10 0 10 2 10 4 10 6 10 8 10 10 10 12 E (GeV / particle) 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 5

and neutrinos Φ ν dn de 1 E 2 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 6

( ( ( ( Detecting neutrinos in H 2 O Proposed#by#Greisen,#Reines,#Markov#in#1960# ( (DUMAND( (IMB( (Kamiokande( Baikal( AMANDA( Super8K( SNO( IceCube' ANTARES( Neutrino'must'interact' 'to'be'detected' 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 7

A'36D'cosmic6ray'detector:' Two different kinds of events Closely related scientifically: Cosmic rays after propagation Neutrinos from cosmic ray sources ν e :ν µ :ν τ = 1:2:0! 1:1:1 Cosmic(ray(showers(from( above( South(Pole( (2835(m.a.s.l.( IceTop Neutrinos(from(all(direc9ons( #ν µ 6induced#µ#(from#below)# #all#flavors#star(ng#inside#detector# 1450 m IceCube ( 2450 m Atmospheric(muons( Roma,(28/01/2014( Tom(Gaisser( 8( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 8

Deployment*history* 2002:'proposal' 2003604'staging' 2004605''''1'''''4' 2005606''''9'''16' 2006607''22'''26' 2007608''40'''40' 2008609''59'''59' 2009610''79'''73' 2010611'''86'''81( Deep(strings( Surface(sta9ons( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 9

south pole 2000 AMANDA South Pole Dome 1500 m 2000 m [not to scale] Amundsen-Scott south pole station 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 10

The South Pole n telescope: ICECUBE equipment on the surface 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 11

The South Pole n telescope: ICECUBE equipment on the surface The(drill(heaHng(plant IceCube(Site Thermal(power:(5(MW Pressure:(140(bar Flow:(800(L/m((90 C) 24(h(to(drill(to(2500m Most(importantly: (an(excellent(crew(of(drillers! 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 12 11

IceCube Digital Optical Module and deployment ( LED'Flasher'board' HV'board' Main'board'for'digiLzing'&'Lme'stamping' 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 13

architecture of independent DOMs 10 inch pmt LED flasher board main board HV board 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 14

each Digital Optical Module independently collects light signals like this, digitizes them, time stamps them with 2 nanoseconds precision, and sends them to a computer that sorts them events 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 15

DOMs during construction 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 16

Roma,(28/01/2014( Tom(Gaisser( 13( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 17

IceCube IceTop: dimensions Example... 5(μs( Tom(Gaisser( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 18

Properties of ice vary with depth 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 19

Ice Properties ( ( IceCube,(NIM(A(711,(73,(2013( charge on near and far strings [ p.e. ] 10 3 10 2 10 1 10-1 10-2 0 10 20 30 40 50 60 DOM number on string 63 Figure 6: Charge collected by DOMs on the six nearest strings (121.8 126.6 m away, triangles) and six next-to-nearest strings (211.4 217.9 m away, circles), observed when flashing at the same position on string 63. eff. scattering b e (400 nm) [ m -1 ] absorption a(400 nm) [ m -1 ] 0.2 SPICE MIE AHA 0.1 0.05 0.03 0.02 0.01 1400 1600 1800 2000 2200 2400 depth [ m ] 0.05 SPICE MIE AHA 0.03 0.02 0.01 0.005 5 7 10 14 20 25 33 50 70 100 20 25 33 50 70 100 125 200 250 λ e (400 nm) [ m ] λ a (400 nm) [ m ] 1400 1600 1800 2000 2200 2400 depth [ m ] 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 20

Primary spectrum from IceTop Phys.(Rev.(D(88,(042004((2013).((( sr -1 s -1 ] m -2 1.7 [GeV dn de da d dt 2.7 E 4 10 IceTop 73, SIBYLL 2.1, H4a composition assumption KASCADE-Grande, SIBYLL 2.1 KASCADE, SIBYLL 2.1 GAMMA 2008 Tunka-133 Tibet III, SIBYLL 2.1 6 6.5 7 7.5 8 8.5 9 log (E/GeV) 10 10 6( (10 8( GeV(sets(normaliza9on(for(PeV(ν$ Directly(for(background(atmospheric(ν(( At(sources(for(astrophysical(ν( 10 7 ( (10 9( GeV:(transi9on(from(galac9c(to(extragalac9c(( Model(dependent( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 21

Neutrino Interactions - 1 Charged(current(ν µ :( ν µ µ Force(carrier( q Also charged current ν e e and charged current ν τ τ and neutral current ν α ν α 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 22

Neutrino Interactions - 2 Tracks( (because(of(µ)( ν µ µ Force(carrier( q Cascades( Also charged current ν e e and charged current ν τ τ and neutral current ν α ν α 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 23

IceCube 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 24

IceCube 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 25

Upward neutrinos in IceCube be( S.P.( 10-24 Cross sections 10-26 proton-nucleon 10-28 cross section (cm -2 ) 10-30 10-32 10-34 10-36 10 2 10 3 10 4 10 5 10 6 10 7 10 8 E (GeV) neutrino-nucleon E Ν GeV 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 26 Nup Ndown 1.0 0.8 0.6 0.4 0.2 Ν e Ν e Passing(frac9on( P.(Lipari,(1308.2086( Frac9on(absorbed( 0.0 100 1000 10 4 10 5 10 6 10 7 10 8 r( 21(

IceCube 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 27

IceCube: check of track angular reconstruction capability Moon(Shadow(of(Cosmic(Rays(using(muons in(the(icecube(detector 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 28

IceCube: use the Moon to check the track angular reconstruction Moon(shadow(observed(in(muons( Check(on(IceCube(poinHng Center(of(moon(is(spot(on( to(a(precision(of(<0.1(degrees.( Sta>s>cal&significance&with& IC&59:&&>&10&sigma 20 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 29

IceCube, as an example: search for neutrinos from Galactic Sources - 1 galactic plane in 10 TeV gamma rays : supernova remnants in star forming regions Southern Hemisphere Sky Standard(DeviaHons 90 65 30 Milagro il 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 30 210

IceCube, as an example: search for neutrinos from Galactic Sources - 2 cygnus region : Milagro Milagro translahon(of TeV(gamma(rays into TeV(neutrinos 3(±(1(ν per(year(in(icecube(per(source 24 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 31

IceCube, as an example: search for neutrinos from Galactic Sources - 3 5σ(in(5(years(of(IceCube IceCube(image(of(our Galaxy(>(10(TeV 3σ 5σ time in years M.(C.(Gonzalez[Garcia,(F.(Halzen,(and(S.(Mohapatra,(Astropart.(Phys.(31,(437(2009;(e[print arxiv:0902.1176. 25 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 32

Upward neutrinos in IceCube Must(have(low(enough(energy(to(get(through( the(earth((depends(on(direc9on)( Must(produce(a(signal(in(the(detector((((((( ν µ a. (((((( (induced(muon(from(neutrino(interac9on(in( the(rock(or(ice(below(the(detector((highest(rate)( b. Neutrino(of(any(flavor(interacts(inside(detector( 1kmice=0.91 6 10 23 10 5 =5 10 28 nucleons/cm 2 σ ν 2.6 10 34 cm 2 at 10 5 GeV Product( (10 85 (is(frac9on(of(ν(of(this(energy(that(interact(in(detector( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 33

energy measurement ( > 1 TeV ) convert the amount of light emitted to measurement of the muon energy (number of optical modules, number of photons, de/dx, ) 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 34

Neutrino Events (ν8induced(µ( entering(from( below( PeV(=(10 6 (GeV(=(10 15 (ev.((these(are(the(highest(energy(neutrinos(ever(detected!( Two(PeV(cascades( star9ng(inside(the( detector(( PRL#111,#021103#(2013)' Large(energy(!(atmospheric( origin(unlikely(( 20( 14( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 35

Starting n µ à µ events ((((((((((((((((( ( Event(starts(in(fiducial(volume( Light(from(vertex(spreads( spherically(with(v=c/1.31( Muon(moves(ahead(with(v(=(c( ID(confirma9on(by(9ming( Jakob(van(Santen( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 36

( / / ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 37

Most events are not astrophysical neutrinos!!! 2.5(kHz( Astrophysical(ν( ~(1(per(million( ~(1(per(billion( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 38

Search strategy for astrophysical neutrinos 1. Look(for(a(hard,(high8energy(component( above(the(atmospheric(background( Upward(ν µ (induced(muons( Highest(rate( Events(star9ng(in(the(detector( Lower(rate,(but( Atmospheric(ν(background(is(lower( 2. Look(for(excess(of(events(in(the(ν µ (skymap( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 39

( ( ( ( ( Results from IC-59 (2009-2010) events 4 10 3 10 2 10 10-1 10 Analysis(of(ν µ induced(µ(from(below(( 1 experimental data conv. atms. ν (HKKMS07 + H3a) conv. atms. ν (best fit) prompt atms. ν (90%CL upper limit) astrophysical ν (best fit) astrophysical ν (90%CL upper limit) Cascade(search( with(ic59(finds(8( events((expected( background(of(4).( Prompt(ν?( #" ' ICRC(paper(0662( %' -2 10-2 -1.5-1 -0.5 0 0.5 1 1.5 2 2.5 3 log10(de/dx [GeV/m]) reco Sugges9on(of(hard((astrophysical?)(component( ~0.25(x(10 88 (GeV(cm 82 (sr 81 (s 81 (( (arxiv:1311.7048( Most(energe9c(event.( '1;;.*&)+*&<0.&!=.">-.&"+(('-+*'?+3& ( / / ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 40

( ( ( ( ( ( Search for cosmogenic neutrinos (also known as GZK n ) p + γ CMB n + π + nµ + ν µ Limits(from(IC879(+(IC886,(May(20108May2012( This(search(discovered(( two(pev(cascade(events,( each(with(just(over(1(pev( deposited(energy88lower( than(expected(for( cosmogenic(neutrinos.(( The(events(were(just(at(the( threshold(of(the(search.( Engel,(Seckel,(Stanev( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 41

( ( ( ( ( ( HESE: follow-up analysis of PeV events HESE(=(High(Energy(Star9ng(Events( Looks(at(same(662(days(of(data((June(2010( (May(2012),((Science,(22(Nov(2013( Require(event(to(start(inside(fiducial(volume( 6000(p.e.(threshold((((((((((((((((((((((deposited(energy,( 30 TeV lower(than(ehe(search(( Accept' 10 3 IceCube 4 averaged e (anti- e ) effective areas 10 2 EHE analysis HESE analysis A eff (m 2 ) 10 1 10 0 10-1 Comparison(of(effec9ve(areas( 10-2 10 4 10 5 10 6 10 7 Roma,(28/01/2014( Tom(Gaisser( 30( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 42 E (GeV)

High Energy Starting Event Analysis 210 TeV 70 TeV 250 TeV 220 TeV 2-year analysis: Science 342, 1242856 (2013 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 43

High Energy Starting Event Analysis 210 TeV Require that event: - Does not start in veto region - Has at least 6000 photoelectrons μ ν μ 70 TeV 220 TeV 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 44

3-Year Analysis PRL 113, 101101 (2014) 36 events in 3 years Three > PeV events seen in three years, including a 2-PeV neutrino High Energy Starting Event Analysis Big Bird 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 45

Significance of astrophysical flux: 5.7 σ High Energy Starting Event Analysis Of the 36 events, ~ half are expected to be bkg (atm. muons and atm. neutrinos) Astrophysical fit (and its significance) depends on number, direction, and energy Shape (energy and zenith distribution) of signal and background is different 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 46

Comments on backgrounds Atmospheric(muons(passing(the(veto( This(background(is(determined(experimentally(by( defining(a((smaller,(inner(veto(region(and(checking( the(rate(at(which(tagged(muons(leak(through( Atmospheric(neutrinos( Conven9onal (ν (from(k(and(π(decay)(( Prompt (ν (from(decay(of(charm)( Muons(produced(in(the(same(shower(as(ν(provide( a(par9al(self8veto(in(southern(sky( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 47

Atmospheric neutrino self veto Two(cases( 1.(Stefan(Schönert(et(al.( Phys.(Rev.(D79((2009)(043009( Can(be(evaluated(analy9cally( 2.(Veto(by(an(unrelated(μ( 88also(applies(to(ν e( Requires(Monte(Carlo(or( numerical(integra9on( Roma,(28/01/2014( Tom(Gaisser( 37( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 48

The rate of events passing the veto condition depends on n flavor Passing rate per 1 Veto(=(1( (Passing( ( Veto(is(more( effec9ve(for(ν µ than( for(ν e (and(prompt(ν((( Passing fraction 0.8 0.6 0.4 solid: includes correlated!: for! dashed: uncorrelated! only: for e & prompt cos = 0.35 cos = 0.55 cos = 0.75 cos = 0.95 0.2 0 10 3 10 4 10 5 10 6 10 7 E (GeV) ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 49

Atmospheric neutrino self-veto Interactions km 3 sr 1 yr 1 E > 100 TeV 10 1 astrophysical 10 0 10 1 10 2 10 3 Some neutrinos are absorbed in the Earth conventional µ conventional e 1.0 0.5 0.0 0.5 1.0 sin(δ) = cos( ) at the South Pole 1.5 km of ice An active muon veto removes down-going atmospheric neutrinos. Primary cosmic ray μ π- νμ Schönert, Resconi, Schulz, Phys. Rev. D, 79:043009 (2009) Gaisser, Jero, Karle, van Santen, Phys. Rev. D, 90:023009 (2014) 14 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics Jakob van Santen - ISVHECRI 2014, CERN 50

Atmospheric neutrino self-veto Interactions km 3 sr 1 yr 1 E > 100 TeV 10 1 astrophysical 10 0 10 1 10 2 10 3 Some neutrinos are absorbed in the Earth prompt µ + e conventional conventional µ conventional conventional e 1.0 0.5 0.0 0.5 1.0 sin(δ) = cos( ) at the South Pole An Prompt active atmospheric muon veto neutrinos removes are down-going vetoed, too. atmospheric neutrinos. 1.5 km of ice K 0 Primary cosmic ray μ π- D - νμ Schönert, Resconi, Schulz, Phys. Rev. D, 79:043009 (2009) Gaisser, Jero, Karle, van Santen, Phys. Rev. D, 90:023009 (2014) 14 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics Jakob van Santen - ISVHECRI 2014, CERN 52

Atmospheric neutrino self-veto Interactions km 3 sr 1 yr 1 E > 100 TeV 10 1 astrophysical 10 0 10 1 10 2 10 3 Some neutrinos are absorbed in the Earth atmospheric prompt µ + e conventional conventional µ conventional conventional e 1.0 0.5 0.0 0.5 1.0 sin(δ) = cos( ) at the South Pole The zenith distributions of high-energy Primary cosmic ray astrophysical and An Prompt active atmospheric muon veto neutrinos removes are down-going vetoed, too. atmospheric neutrinos. π- atmospheric D - K neutrinos 0 are νμ 1.5 km! of ice μ fundamentally different.! Schönert, Resconi, Schulz, Phys. Rev. D, 79:043009 (2009) Gaisser, Jero, Karle, van Santen, Phys. Rev. D, 90:023009 (2014) 14 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics Jakob van Santen - ISVHECRI 2014, CERN 53

3-Year High Energy Starting Event Analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 54

3-Year High Energy Starting Event Analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 55

3-Year High Energy Starting Event Analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 56

3-Year High Energy Starting Event Analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 57

3-Year High Energy Starting Event Analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 58

High Energy Starting Event Analysis Assuming unbroken E -2 spectrum, best-fit astrophysical normalization is: Lack of events above 2 PeV (3.1 expected in this analysis; more in the EHE analysis, PRL 111, 021103 (2013)) suggests unbroken E -2 disfavored Best power-law fit yields a spectral index of -2.3 (and fits 0 charm component): 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 59

where do they come from (3 year data)? hottest spot 7.2%: consistent with diffuse flux with fllavor 1:1:1? 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 60

diamonds: muon tracks (0.4 degree resolution) circles : electromagnetic showers : energy : angular resolution 10-40 angular resolution 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 61

too few ν µ? no, in an all flavor search ν µ tracks are rare length of τ track = 50m E ν PeV a muon track is relatively rare 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 62

mostly showers PeV showers: volume ~ 5 m 3 isotropic after 25~ 50 m 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 63

Muon Neutrino Diffuse Analysis Northern Sky Complementary analysis to Starting Event analysis Northern sky allow events to enter from outside detector, use Earth as filter against muons from cosmic rays Track events from muon neutrinos Good pointing: ~ 0.5 log 10 muon energy resolution ~ 0.3 (at energies ~ 100 TeV) 35 000 events in 2-year analysis Data Astrophysical Prompt IceCube Preliminary 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 64

Muon Neutrino Diffuse Analysis Events 35 000 events in 2-year analysis Estimated 99.9% pure muon neutrino sample Energy estimate for the muon track. Only lower-bound on neutrino energy (interacted before reaching detector) 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 65

Muon Neutrino Diffuse Analysis Best fit for E -2 astrophysical spectrum is: 0.96 ± 0.35 10-8 GeV -1 cm -2 s -1 sr -1 3.9σ evidence of astrophysical flux Starting Events Differential Spectrum Muon Neutrino E -2 fit (nearly) independent of starting track analysis Strengthens evidence that flux is allflavor and all-sky 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 66

Muon Neutrino Diffuse Analysis Events E -2 flux implies there are ~ 100 astrophysical muon neutrino events in sample at lower energies or much more, if spectrum is softer than E -2 These events are nearly hidden in diffuse analysis, but can stand out in point source analysis 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 67

the high energy neutrino flux: atmospheric and cosmic 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 68

Point Source Analysis 4 years of data including construction period arxiv:1406.6757 Optimization for point source search: looser cuts possible (typically ~ 90-95% neutrino purity) and lower energy events more useful N. sky N. sky diffuse point source sample sample 35 000 events 120 000 events (comparing same 2-year period) Background estimated robustly from off-source data at similar declination 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 69

Point Source Analysis 2008-2011 Data: Livetime 1371 days 178 000 upgoing neutrinos 216 000 downgoing CR muons Perform a search looking for significant clustering of events above random background expectation (unbinned maximum likelihood analysis) 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 70

Point Source Analysis arxiv:1406.6757 2008-2011 Data: Livetime 1371 days 178k (upgoing neutrinos) 216k (downgoing muons) No significant excess seen 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 71

Point Source Analysis IceCube Preliminary (arxiv:1406.6757) Northern Sky sensitive for TeV PeV Southern Sky sensitive mainly > PeV ANTARES sensitive to TeV PEV in both skies Southern sky Northern sky 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 72

Point Source Analysis Point-source equivalent flux if the diffuse flux came from: one point in the sky 100 points in the sky 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 73

Point Source Analysis Point-source equivalent flux if the diffuse flux came from: one point in the sky 100 points in the sky 1000 points in the sky 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 74

Papers(explaining(IceCube(neutrinos( (par9al(list)( F. Halzen: IceCube Neutrinos: From GeV to PeV Nuclear Physics B (Proc. Suppl.) 246 247 (2014) 3 17 GalacLc' Galac9c(PeV(Neutrinos, (Gupta,(arXiv: 1305.4123( Sub8PeV(Neutrinos(from(TeV(Uniden9fied( Sources(in(the(Galaxy, (Fox,(Kashiytama,( Mészarós,(arXiv:1305.6606( Pinning(down(the(cosmic(ray(source( mechanism(with(new(icecube(data, ( Anchordoqui(et(al.,(arXiv:1306.5021( The(Galac9c(Pevatron, (Neronov,(Semikoz,( Tchernin,(arXiv:1307.2158( ExtragalacLc' PeV(neutrinos(from(the(propaga9on(of(ultra8high( energy(cosmic(rays, (Roulet(et(al.,(arXiv:1209.4033( On(The(Origin(of(IceCube's(PeV(Neutrinos, (Cholis,( Hooper,(arXiv:1211.1974(( Cosmic(PeV(Neutrinos(and(the(Sources(of(Ultrahigh( Energy(Protons, ((Kistler,(Stanev,(Yuksel(,(arXiv: 1301.1703( PeV(neutrinos(from(intergalac9c(interac9ons(of( cosmic(rays(emied(by(ac9ve(galac9c(nuclei, ( Kalashev,(Kusenko,(Essey,(arXiv:1303.0300( Neutrinos(at(IceCube(from(Heavy(Decaying(Dark( Maer, (Feldstein(et(al.,(arXiv:1303.7320( Ice(Cube(Observed(PeV(Neutrinos(from(AGN( Cores, (Stecker,(arXiv:1305.7404( Demys9fying(the(PeV(Cascades(in(IceCube:(Less( (Energy)(is(More((Events)(, (Laha(et(al.,(arXiv: 1306.2309( ( On(the(Hadronuclear(Origin(of(PeV(Neutrinos( Observed(with(IceCube, (Murase,(Ahlers,(Lacki,( arxiv:1306.3417( Photohadronic(Origin(of(the(TeV8PeV(Neutrinos( Observed(in(IceCube, (Winter,(arXiv:1307.2793( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 76

Power for extragalactic cosmic rays (assuming transition at the ankle) Energy(in(extra8galac9c(cosmic(rays(per(ln(E): ( 4π EdN c d ln E = 4π { } 3 10 8 GeV 20 erg c cm 2 2 10 s sr cm 3 Divide(by(Hubble(9me(to(es9mate(power(required:( ( dl ( d ln E 2 1036 erg Mpc 3 s 1 Power(required(>(10 37 (erg/mpc 3 /s( Es9mates(depend(on(cosmology(+(extragalac9c(magne9c(fields:( 3(x(10 83 (galaxies/mpc 3 (5(x(10 39 (erg/s/galaxy( 3(x(10 86 (clusters/mpc 3 (4(x(10 42 (erg/s/galaxy(cluster( 10 87 (AGN/Mpc 3 ( (10 44 (erg/s/agn( ~300(GRB/(Gpc 3 yr)( (10 51 (erg/grb( ( ((( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 77

New limit on n from GRB (IC-40/IC-59) Note(shape(due(to( photoproduc9on:( Both(low(and(high( cutoffs(in(region( of(interest.( IceCube:(Nature,(19(April(2012( 8(events(expected(if(observed(GRB(account(for(all(UHECR( (None(seen(in(correla9on(with(GRBs(of(SWIFT(&(Fermi(GBM( Different(class(of(low(luminosity(GRB?((Cholis(&(Hooper,(1211.1974)(( ( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 78

Generic(model(I( CR(accelera9on(occurs(in(jets(( AGN(or(GRB( Intense(radia9on(fields( Models(assume(photo8produc9on:( (p(+(γ(!(δ +(!(p(+(π 0(!(p(+(γ γ( (p(+(γ(!(δ +(!(n(+(π +(!(n(+(µ(+(ν$ Ideal(case(((~( Waxman8Bahcall(limit )( Strong(magne9c(fields(retain(protons(in(jets( Neutrons(escape,(decay(to(protons(&(become(UHECR( Extra8galac9c(cosmic(rays(observed(as(protons( Energy(content(in(neutrinos( (energy(in(uhecr( This(picture(disfavored(as(limits(go(below(W8B( ( http://www.ucd.ie/math-phy /rieger/science.gif Waxman, Bahcall, PRD 59, 023002 (1998). Also TKG astro-ph/9707283v1 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 79

Generic(model(II( UHECR(are(accelerated(in(external(shocks(analogous(to( SNR( See(E.G.(Berezhko,(0809.0734(&(0905.4785( mixed(composi9on((accelerate(whatever(is(there)( Low(density(of(target(material(!((lower(level(of(TeV8PeV(neutrino(produc9on( Diagram from Begelman & Cioffi, Ap.J. (1989) L21 2016-2017 ( ( Univ. "La Sapienza" Dott. in Fisica -( High Energy ( Neutrino Astrophysics ( 80

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 81

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 82

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 83

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 84

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 85

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 86

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 87

IceCube: study of TeV-PeV Cosmic-Ray anisotropy 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 88

Ideas(for(the(future(at(South(Pole( Sunflower(paern( minimizes(entry( channels( ( Average(spacing:( ~250(m(( ( ( ( ( ( ( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 89

PINGU( 2016-2017 Univ. "La Sapienza" Dott. in Fisica - High Energy Neutrino Astrophysics 90