Astropar(clePhysics

AlessandroDeAngelisMárioPimentaAsiago,June2017

CosmicraysGammaraysNeutrinosGravita(onalwaves???

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I-Introduc(on

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MessengersfromtheUniverse

1911/12:DomenicoPaciniandVictorHessperformtwocomplementaryexperiments:Pacinidiscoversthationizingradia(ondecreasesunderwater,andHessthatitincreasesathighal(tudes

–  20%ofthenaturalradia(onatgroundisduetocosmicradia(on!!!Canweusethese“cosmicrays”forscience?

!"

#"

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YES(thebirthofPar(clePhysics)

Positron (Anderson 1932)

µ (Anderson1937)

e+

Rossi,1940:Muonlife(me.Timedila(on!

An(ma]er!(Dirac)γ→e+e-(Einstein)

K, Λ, ... (LeprinceRinguet1944,Rochester,Bu]er1947,…)

π (La]es,Powell1947)Stronginterac(ons(Yukawa)

K+-

Strangeness

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nuclear reactor

Cosmicraysbombardtheatmosphere:thehighestenergieswecanaccess Detectedprotons108

(mesmoreenerge(cthanLHCDetectedgamma-rays10000(mesmoreenerge(cthanhuman-madeDetectedneutrinos105(mesmoreenerge(cthanhuman-made

YES,anditallowsaccessingthehighestenergies

nuclear reactor

YES,anditallowsunderstandinghigh-energyastrophysics(physicsunderextremecondi(ons)

CosmicRays(“astropar(cles”)

•  Oncepersecondpercm2ahigh-energypar(clefromtheskyhitstheEarth–  Mostly(~89%)protons–  He(~9%)nucleiandheavier

(~1%);–  Electronsare~1%–  0.01%-1%aregammarays

•  Thefluxfallsas~E-2.7asenergyincreases–  1021eVoncepersecondonEarth

•  Thehighestenergies

Knee

Ankle

LHC:1beam LHC:2beams

Mostlyfrom

Sun

MainlyGa

lac(c

Extragalac(c?

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Astropar(clephysics Amul&messengerscience1.  HEgammas2.  HEneutrinos3.  HEprotons/nuclei4.  Gravita&onalwaves

Severalpossiblefundamentalphysicsobjec&ves

1.  Extremelyhighenergycollisions

2.  DarkmaGer/energy3.  Axions,ALPs4.  Neutrinomass5.  Neutrinomixing6.  CMB

Andofcourse,astrophysics1.  Behaviorofphysics

near(SM)BHs2.  Accelera&on

mechanisms

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II-Produc(on

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?

Tevatron(p-p) LHC(p-p)13TeV

Origin!?

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PossibleUHECRSources:2scenarios

Top–DownDecay(PhysicsBeyondtheStandardModel)

DecayoftopologicaldefectsMonopolesRelicsSupersymmetricpar(clesStronglyinterac(ngneutrinosDecayofmassivenewlonglivedpar(clesEtc.

ü  anisotropyinarrivaldirec(onsü  Photons<≈1%

ü  isotropyinarrivaldirec(onsü  Photons>≈10%

BoCom-UpAccelera(on(AstrophysicalAccelera6onMechanisms)

UHECR’s are accelerated in extended objectsor catastrophic events (supernova remnants,rota(ngneutronstars,AGNs,radiogalaxies)

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IIa-Chargedpar(cleaccelera(on

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Energydensity(cosmicrays)

3

312

eV1~

erg10~~

cm

cmdEdEdNEE

−∫ρ

P ~ρEVgalaxyτ esc

~ 5.1040erg /s

E~1053erg

Origin(E~<1015eV)?

Forexample,powerdissipatedbyaSupernova(theremnantofacollapsedstar)of10Msun.

1SN~30Years~10-9s-1SupernovaeinourGalaxy

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WherecanbetheseacceleratorsintheUniverse?

Hillas-plot

R∼10km,B∼10TE∼10TeV

LargeHadronCollider

E∝∝BR

Pulsar SNR

AGN

RadioGalaxyLobe

Emax~bZBLconfinement!

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Afewnewterms•  Stellar end-products. A star heavier than the

Sun collapses at the end of its life into a neutron star (R ~ few km, which can be pulsating – a pulsar) or into a BH, and ejects material in an explosion (SuperNova Remnant). –  Very large B fields are in the pulsar; magnetic

fields also in the SNR

•  The centres of galaxies host black holes, often supermassive (millions or even billion solar masses). They might accrete at the expense of the surrounfing matter, and accelerate particles in the process. When they are active, they are called Active Galactic Nuclei.

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Theysurpasshuman-madeaccelerators

Yearofcomple(on

Energy(G

eV) The Large Hadron Collider (LHC)

~1930

~ 10 MeV

HighLuminositySophis(cateddetectorsCentralregionEnergylimited

14TeV

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Howtogeneratebo]om-upenergiesmuchhigherthanthermal?

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Accelera(onmechanismFermi2ndorder(1949)

par(clesacceleratedinstochas(ccollisionswithmassiveinterstellarclouds(collisionstoamovingdiffusivewall!)Inthecloudreferenceframe

BacktotheLabreferenceframe

Then:

But:Probability

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Accelera(onmechanismFermi1storder

Par(clesgainenergybyconsecu(vecrossingsoftheshockfront!

Now(planeshockfront):

Solar coronal mass ejection 9 Mar 2000

Shockforma(on:• SuddenreleaseofEnergy(CMEs,SNRs,GRBs,…)• Supersonicflowhitsanobstacle(AGNsjets,pulsarwinds,…)

Crossingprobabilityαcos(θ)

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Thepowerlaw γ−∝ EdEdN

( ) 1+−∝> γEENIneachcycle thepar(clegainsa small frac(onofenergyε.Ayerncycles:

En=E0(1+ε)n

Orthenumberofcyclestoa]ainanenergyEis:

n=ln(E/E0)/ln(1+ε)

The par(cle may escape from the shock region with some probability Pi .Then theprobabilitytoescapewithE>Enis:

and

7.2)(. −∝⎟⎠

⎞⎜⎝

⎛∝⎟⎠

⎞⎜⎝

⎛ EEdEdN

dEdN

escSourceEarth

τ

2−≈⎟⎠

⎞⎜⎝

⎛ EdEdN

Source

γ=α+1

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Zwickyconjectures(1933)1.  Heavyenoughstarscollapseattheendof

theirlivesintosuper-novae2.  Implosionsproduceexplosionsofcosmic

rays3.  Theyleavebehindneutronstars

(Zwickyin1930)

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Oneshouldconsideralsoenergylossesatthesource

Wheredotheycomefrom?

rLmustbesmallerthanthedimensionofthesourceLtoremainconfined.

Whateveristheaccelera(onmechanism…

ThemaximumenergypossibleonEarthis~5000TeV

R∼1015km,B∼10-10T⇒E∼1000TeV

R∼10km,B∼10T⇒E∼10TeV

LargeHadronCollider

TychoSuperNovaRemnant

E = k BR

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IIb-Produc(onofhighenergyphotons(andneutrinos)

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Theobservedphotonspectrumextendsover30decades(measurementsupto1TeV)

CMB:~400photons/cm3

EBL:~410-3photons/cm3

log(λ/cm)

Thermalradia(on:BlackbodySpectra

A Galactic gas cloud 60 K Dim star in the Orion Nebula: 600 K

The Sun: 6000 K

Clusterofverybrightstars,OmegaCentauri:60000K

CMB: 2.7 K

Accre(onnearBHs:~thekeVAsiago2017

γ rays:non-thermalUniverse•  Par(clesacceleratedinextremeenvironmentsinteractwithmedium

–  Gasanddust;Radia(onfields–Radio,IR,Op(cal,…;Intergalac(cMagne(cFields,…

•  Gammaraystravelingtous!

•  Nodeflec(onfrommagne(cfields,gammaspoint~tothesources–  Magne(cfieldinthegalaxy:~3µGGammarayscantracecosmicraysatenergies~10x

•  Largemeanfreepath–  RegionsotherwiseopaquecanbetransparenttoX/γ

StudyingGammaRaysallowsustoseedifferentaspectsoftheUniverse

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Examplesofknownextremeenvironments

~ parsecs

Accretion Disk 3- 10 rs Black Hole Diameter = 2rs ~ 4 AU

GRB SuperNovaRemnantsPulsars

Ac(veGalac(cNuclei

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Energiesabovethethermalregions

•  (LE)orMeV:0.1(0.03)-100(30)MeV•  HEorGeV:0.1(0.03)-100(30)GeV•  VHEorTeV:0.1(0.03)-100(30)TeV•  UHEorPeV:0.1(0.03)-100(30)PeV

•  LE,HEdomainofspace-basedastronomy•  VHE+domainofground-basedastronomy

•  Whennoambiguity,wecall“HE”alltheHEandVHE+

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>3kHEand>200VHEphotonemi]ers

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(1)Bo]om-up:Interac(onofacceleratedpar(cleswithradia(onandma]erfields

•  Gamma-rayproduc(onandabsorp(onprocesses:severalbutwellstudied

•  Thesephenomenagenerallyproceedunderextremephysicalcondi(onsinenvironmentscharacterizedby–  hugegravita(onal,magne(candelectricfields,–  verydensebackgroundradia(on,–  rela(vis(cbulkmo(ons(black-holejetsandpulsarwinds)–  shockwaves,highlyexcited(turbulent)media,etc.

•  Theyarerelatedto,andtheirunderstandingrequiresknowledgeof,–  nuclearandpar(clephysics,–  quantumandclassicalelectrodynamics,–  specialandgeneralrela(vity,–  plasmaphysics,(magneto)hydrodynamics,etc.–  astronomy&astrophysics

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Leptonicandhadronicproduc(onofgammarays

E2 d

N/d

E

energy E

IC

e- (TeV) Synchrotron γ (eV-keV)

γ (TeV) Inverse Compton γ (eV)

B

e.m. processes

π0decay

π-

π0

π+

γγ (TeV)

p+ (>>TeV)

matter

hadronic cascades

VHE

In the VHE region, dN/dE ~ E-ΓΓ (ΓΓ: spectral index)

To distinguish between hadron/leptonic origin study Spectral Energy Distribution (SED): (differential flux) . E2 Asiago2017

50TeVgamma-rayshadronicallyproducedtrackapupula(onofprotonsofenergy~1PeV

Thehadronicmechanismisatworkalsoforneutrinos…

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Inahadronicprocess(isospinsymmetry)•  N(π+)~N(π-)~N(π0)Sameenergies!

π+->µ+vπ-->µ-vπ0->γγ

A“typical”(V)HEγsource:CrabNebula•  TheCrabNebulaisanearby(~2kpcaway)PWNandthefirstsourcedetectedinVHEgamma-rays[Weekes1989].

•  ItisthebrighteststeadyVHEgamma-raysource,thereforeithasbecometheso-called“standardcandle”inVHEastronomy.–  Recentobserva(onofflaresintheGeVrangehavehowevershownthatoccasionallytheCrabfluxcanvary.

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(E/GeV)10

Log1 2 3 4 5 6

)-1 s-1

(GeV

2 m4

in 1

0pa

rticl

esN

15−10

13−10

11−10

9−10

7−10

5−10

3−10

1−10

10

310

510

o x 1oCosmic rays in 1

Crab

(E/GeV)10

Log1 2 3 4 5 6

o x

1o

CR

in 1

/ N

Cra

bN

5−10

4−10

3−10

2−10

1−10

γ-raydetec(on:signalvs.background

•  IsCrabNebulaeasytodetect?•  Supposetohavea100x100m2detectorwitharesolu(onof1squaredegree:

Conclusion:youneedlargeeffec(vearea,goodangularresolu(on,protonrejec(onAsiago2017

Conceicao,DeAngelis,Tome+2016)

S/B

(2)Top-down:aretherenew(heavy)par(cleswhichcanproduceHEphotons?

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•  Rota(oncurvesofspiralgalaxies

–  flatatlargeradii:iflighttracedmasswewouldexpectthemtobeKeplerianatlargeradii,v∝ r−1/2,becausethelightisconcentratedinthecentralbulge

•  anddisclightfallsoffexponen(ally•  Zwickyhadalreadynotedin1933thatthe

veloci(esofgalaxiesintheComaclusterweretoohightobeconsistentwithaboundsystem

•  Observedformanygalaxies,includingtheMilkyWay

ToassumethatinandaroundtheGalaxiesthereis

DarkMaCersubjecttogravita(onalinterac(onbutnoelectromagne(cinterac(on– Mustbe“cold”,i.e.,non-rela(vis(c(itistrappedbythegravita(onalfield),and“weakly”interac(ng:WIMP

–  Thehypothesisisnotodd:rememberthattheexistenceofNeptunewassuggestedonthebasisoftheirregularmo(onsofUranus

–  HowmuchDMdoweneed?resultstobe5(mesmorethanluminousma]er(astrophysics,evolu(onoftheUniverse)

Thecurrentlyfavoredsolu(on

M (r)∝ r⇒ vrot =GM (r)r

= const.

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HowdoWIMPsproducephotons?•  Theenergy“blob”fromχχannihila(onmight

decay:–  Directlyinto2γ,orintoZγifkinema(cally

allowed.Clearexperimentalsignature(photonline),butnotverylikely(requiresoneloop).InSUSY,theBRdependsonwhatisthelightestneutralinocomposi(on.

–  Intoagenericf-áarpair,thengenera(ngahadroniccascadewithπ0decayingintophotonsinthefinalstate.Remindthatflavorsareley-handedandan(-flavorsareright-handedwithamplitude[1+|p|/(E+mf)]/2~v/c,andinthiscaseforans-waveyouneedto“force”oneofthedecayproductstohavethe“wrong”elicity.

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=>Theχχpairwillprefertodecayintotheheaviestavailablepair–i.e.,if20GeV<mχ<80GeV,intob-bbar

ff_

=

M fi ∝121−

pE +mf

⎛

⎝⎜⎜

⎞

⎠⎟⎟=

mf

2mχ +mf

III-Propaga(on

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Propaga(onofchargedCRintheUniverse

!!

r1!pc

≅

E1!PeVB

1!µG

•  GyroradiusBintheGalaxy:afewµG;outsidetheGalaxy:1nG>B>1fG•  IfyouwanttolookattheGC(d~8kpc)youneedE>21019eV–  Butonly1par(cle/km2/year–  Andnogalac6cemi:ersexpectedatthisenergy

•  Butinprincipleonecouldlookoutsidethegalaxy,wereBissmallerandthereareSMBHs…•  No:theresonantinterac6onwiththeCMB(GZKeffect)

providesacutoffatE~1019eV

•  Conclusion:extremelydifficulttousechargedCRforastrophysics

Neutralmessengersmustbeusedforastronomy&astrophysics

•  Neutrinos:verydifficulttodetectduetothesmallinterac(oncrosssec(on(despiteakm3detectorinAntarc(ca,theonlycosmicsourceslocalizeduptonowareSN1987A,theSun,andtheEarth)–  <10neutrinosperyearfromastrophysicalsourcesiden(fiedbyIceCube(1km3)!

•  Gravita(onalwaves:juststarted•  Photons:theyhavealongtradi(oninastronomysincemillennia…Andtheyarethe“starrymessangers”bydefaultsince1610atlatest...

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IIIa-Propaga(onofphotons

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•  γ-raysareeffec(velyproducedinEMandhadronicinterac(ons–  EnergyspectrumatsourcesE-2

•  areeffec(velydetectedbyspace-andground-basedinstruments

•  effec(velyinteractwithma]er,radia(on(γγàe+e-)andB-fields

•  Theinterac(onwithbackgroundphotonsintheUniversea]enuatesthefluxofgammarays

•  The“enemies”ofVHEphotonsarephotonsneartheop(calregion(Extragalac(cBackgroundLight,EBL)

A]enua(onofγ-rays

γHEγbckàe+e-

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Galac(cCentre(9kpc)

DeAngelis,Galan(,Roncadelli2011withFranceschiniEBLmodeling

30GeV100GeV

redshiyz

γrayenergy(TeV)

τ=1(GRH)

τ  >1regionofopacity

),(emobs )(),( zEeEzE τ−×Φ≡Φ

γVHEγbck → e+e-

Maxfor:

σ(β)~

CenA(3.5Mpc)

1/nσ

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•  Thediffuseextragalac(cbackgroundlight(EBL)isalltheaccumulatedradia(onintheUniversedueessen(allytostarforma(onprocesses

•  Thisradia(oncoversawavelengthrangebetween~0.1and600µm(considertheredshiyandthereprocessing)

•  AyertheCMB,theEBListhesecond-mostenerge(cdiffusebackground

•  TheunderstandingoftheEBLisfundamental•  Toknowthehistoryofstarforma(on•  TomodelVHEphotonpropaga(onforextragalac(cVHE

astronomy.VHEphotonscomingfromcosmologicaldistancesarea]enuatedbypairproduc(onwithEBLphotons.Thisinterac(onisdependentontheSEDoftheEBL.

•  Therefore,itisnecessarytoknowtheSEDoftheEBLinordertostudyintrinsicproper(esoftheemissionintheVHEsources.

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Mea

n Fr

ee P

ath

The γ horizon: nuisance and resource

100 TeV 10 TeV 1 TeV 100 GeV 10 GeV 1 EeV 100 PeV 10 PeV 1 PeV 10 EeV 100 EeV

1 Mpc 100 kpc 10 kpc

10 Mpc

1 Gpc 100 Mpc Mrk 421

Cen A M 31 GC

z=5 z=1

CMB

UV NIR

FIR

Radio

3C 279

Can be used to measure: - EBL - EG magnetic fields - vacuum energy (search for axions) - Cosmological parameters… Data from existing detectors give many hints but are not conclusive Ground

-based detectors

γ + γ à e++ e-

(AdA,Roncadelli&Galan(2013)

EBL

TheEBLaffectsinpar(cularthesignalfromextragalac(csources

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Fermi2FHLandgammahorizon

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Areminder:EBLratherwellconstrained,andSEDextrapola(onfromFermiispossible PKS1424

Ifz=0.6

PKS1424Ifz=0.8

Padova2017

SpectralindexofAGN

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IIIb-Propaga(onofchargedpar(cles

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Thepropaga(oninourgalac(c

52

Propaga(on by:T.Gaisser

Charged cosmic rays diffuse and interact inthe Galac(c randomly magne(zed ISM .Confinement (mes are quite long (τ~107years) and direc(ons become basicallyisotropic.

Transportequa(on:

Sources

Diffusion

Convec(on

Energygainsandlosses

Spalla(ongains

Spalla(onanddecaylosses

( ) ( )( ) ∑>

+−∂∂

+−∇⋅∇+=∂∂

ij j

jji

i

iiiii

i NPNNEbE

NVNDQtN

ττ

!!!

53

Leaky-Box

A box where charged cosmic rays freelypropagates having however some probability toescape by the walls. The sources are uniformelydistributed.

⎭⎬⎫

⎩⎨⎧

++−⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

++= ∑>

esci

decayi

spallii

ijdecayji

spalljiji cNcNQ

τγτσρβ

γτσρβ

1110

Simplifiedsta(onaryequa(on:

Sources Spalla(onanddecaysgains

Spalla(on,decaysandescapelosses

54

Constraining propagation models

Secondary/primaryra(os

10Be/9BeB/C

Unstable/stableisotopos

Radioac(veclocksBoxsize,Diffusioncoef.,escape(me,...

55

D(E)∝Eδ

δ =1/ 3

δ = 0.7

Primary/Primary

CREAM2008

Energy dependence (𝜏𝜏sc) sc) CREAM2008

56

Confinementandcomposi(on

Galac(c~1-3µGIntergala(c1nG>B>1fG

LarmorRadius:

ZeBER =

Magne(cField:

Severalknees?

57

T.Stanev

Galactic Magnetic Field deflection (p)

Above1019:Astronomy!

Anuniqueopportunitytomeasurethegalac(cmagne(cfield?

58

The Greisen-Zatsepin-Kuzmin (GZK) cutoff

protons

p

γ2.7K

Δ Ｎ　

π

N

Mpc6≈

1=CMBp ρσ

λγ

eV10E 20p ≈

p Δ Ｎ　

π

N

Energyatsource

Propaga(ondistance(Mpc)

59

GZK is model dependent

Sourcestypeanddistribu(on

Magne(cfields

Primarycomposi(on

Notatruecutoff!

PileupRecoveryofthespectrumathigherenergies?

GZKcutoffEnergy–SteckerandScullyGZKandmagne(cfields(protons)Deligny,Parizot,Letessier-Selvon

1+z Energy(inEeV)

60

Par(cleshowers

Pierre Auger, 1938

d

#

Firstshowerenergyes(mates!

Coincidences

d

61

The events: Cosmic rays “rain”

62

The events: Cosmic rays “rain”

67

Theevents:firstinterac(on

68

Theevents:showerdevelopment

69

Theevents:showerdevelopment

70

Theevents:showerhitsEarthsurface

71

P(Fe)Air➝Baryons(leading,net-baryon≠0)➝π0(π0➝𝛾𝛾𝛾𝛾➝e+e-e+e-➝…)➝π±(π±➝𝜇𝜇±ifLdecay<Lint) ➝K±,D.…

Theevents:showerhitsEarthsurface

72

Particle interactions

-wellknown!

-forwardregion,smallpt,veryhigh

hadronicintera(ons-largeuncertain(es!

s-mainparameters:σin,kin,<n>,(frac(onπ0,NbofBaryons,…)

e.m.andweakintera(ons

Nuclearfragmenta(on

MissingEnergy-Nucleiarenotjustasuperposi(onofnucleons!

-5%to10%…

P(Fe)Air➝Baryons(leading,net-baryon≠0)➝π0(π0➝𝛾𝛾𝛾𝛾➝e+e-e+e-➝…)➝π±(π±➝𝜇𝜇±ifLdecay<Lint) ➝K±,D.…

73

Electromagne(cinterac(ons J. Knapp

74

Hardandsoyhadronicinterac(onsJ.Knapp

Perturba(veQCD

PomeronexchangeGRT

75

Stringfragmenta(on

u

d

u

d

d

u

u

u

π0

π-

Κ-

Κ+

Hadrons!

d

u

s

u

s

u

d

d

u

d

Inthisway,youcanseethatquarksarealwaysconfinedinsidehadrons

(that’sCONFINEMENT)!

Thinkofthegluonsbeingexchangedasaspring…whichifstretchedtoofar,willsnap!Storedenergyinspringàmass!

76

“Standard”Hadronicmodels(lowpt)

SIBYLL

QGSJET

EPOS

Minimum string configuration Ralph Engel

77

Hadronicmodelsparameters P.Tanguy

p air

78

Crosssec(onsextrapola(ons(beforeLHC)

79

Crosssec(onsextrapola(ons(ayerLHC) (P

roto

n-Pr

oton

) [

mb]

inel

σ

30

40

50

60

70

80

90

100

110

[GeV]s310 410 510

Auger 2012 (Glauber)ATLAS 2011CMS 2011ALICE 2011TOTEM 2011UA5CDF/E710TOTEM 2013This work

QGSJETII.3SIBYLL2.1EPOS1.99EPOS-LHCQGSJETII-04

80

LHC Kinematics (14 TeV)

pseudo-rapidity;η=-ln(tan(θ/2))

MulSplicity EnergyFlux

Allpar(cles

neutral

Mostoftheenergyflowsintoveryforwardregion

TakashiSAKO

81

The µs

82

Muon production

83

Muon spectrum at Earth Surface

J.Beringeretal(PDG)PRD86010001(2012)84

J.Beringeretal(PDG)PRD86010001(2012)

Fluxes in the atmosphere

85

UnderEarth

AttheEarthsurface:~70m-2s-1sr-1

~1cm-2min-1(Ω∼π)

1~7.2~Kamiokande2~5.3~GranSasso3~5~Blanc.Mt

)TeV(Threshold)KmWater(DepthPlace

86

Extensive Air Showers (EAS) 1019eV

87

EAStransverseprofiles

5.4s0

2s0

20e )r/r1()r/r(r/N)s(c)r( −− +=ρ

NKG(Nishimura,Kamata,Greisen)

r0:Moliéreradius

s:showerage

Ptdistribu(onsMul(pleCoulombsca]ering

88

EAS longitudinal profiles

⎟⎠

⎞⎜⎝

⎛ −−

−

⎟⎟⎠

⎞⎜⎜⎝

⎛

−

−= λ

λλ

λ

1max

max

1maxXX

X

ee eX

XXNN

Gaisser

Nemax∝E

Xmax∝lnE

Iron～56nucl(E/56)Smallerfluctuac(ons

SmallerXmax

89

ΔX

Xmax=X1+ΔX

Shower development

X1 Xmax

emprofilemuonic

profile

∫ dXdXdNe

E∝Ne∝

dXdXdN∫ µNμ ∝

90