Origin of cosmic rays Vladimir Ptuskin IZMIRAN Russia/University of - - PowerPoint PPT Presentation

Origin of cosmic rays

Vladimir Ptuskin

IZMIRAN Russia/University of Maryland USA FFP14, Marseille

Outline

• Introduction
• Voyager 1 at the edge of interstellar space
• Cosmic ray transport in the Galaxy
• Supernova remnants – main Galactic accelerators
• Positrons in cosmic rays
• Structure of the “knee”
• Energy limit for galactic sources
• Extragalactic cosmic rays: transport and sources
• High energy neutrinos of cosmic origin

ultrafast pulsar

Sun close binary Galactic disk pulsar, PWN SNR stellar wind

AGN GRB interacting galaxies

Ncr = 10-10 cm-3

• total number density in the Galaxy

wcr = 1.5 eV/cm3

• energy density

Emax = 3x1020 eV

• max. detected energy

Qcr = 1041 erg/s – power of Galactic CR sources A1 ~ 10-3 – dipole anisotropy at 1 – 100 TeV rg ~ 1×E/(Z×3×1015 eV) pc - Larmor radius at B=3x10-6 G

Fermi bubble GC

WMAP haze

cosmic ray halo, Galactic wind

cosmological shocks 109 eV 1020 eV

JxE2

extragalactic

1/km2/century

E-2.7

LHC

CR spectrum at Earth

direct measurements of interstellar CR spectra at low energies

Voyager 1 at the edge of interstellar space

after E. Stone 2013

energy, MeV/nuc

100 101 102 103 104 105

particle /(m2 sec sr MeV/nuc)

10-5 10-4 10-3 10-2 10-1 100 101 102 103

low energies: Voyager 1

Stone et al. 2013

high energies: BESS Pamela

Sparvoli et al 2012

H He

launched in 1977, 70 kb, 22 w

Spacecrafts: Voyagers; ACE, Pamela, Fermi/LAT, AMS Balloons: BESS, CREAM, TRACER Cherenkov telescopes: HESS, MAGIC, VERITAS EAS detectors: KASCADE-Grande, MILAGRO, ARGO-YBJ, TUNKA, EAS-TOP, IceCube/IceTop, Auger, Telescope Array

“Golden age” of new CR measurements

energy balance: ~ 15% of SN kinetic energy go to cosmic rays to maintain observed cosmic ray density Ginzburg & Syrovatskii 1964

M51

Jcr(E)= Qcr(E)×T(E)

source term, SNR

steady state:

(without energy losses and nuclear fragmentation)

escape time from the Galaxy,

108 yr at 1 GeV, resonant scattering in random magnetic field 1/kres = rg traversed matter thickness X ~ 12 g/cm2 at 1 GeV/nuc (surface gas density of galactic disk ~ 2.5 10-3 g/cm2)

two power laws!

E-2.1 x E-0.6

1 1.1 27 2 1 0.55 2

v ~ 10 cm / , (3 1) / 2 2.7, at 2.1 ~ ~ ~

s s

cr p p s s ef p

B p p D s q Zm c Zm c H p p X D Zm c Z

 

   

  

                                  

galactic wind driven by cosmic rays

Zirakashvili et al. 1996, 2002, 2005, VP et al. 1997, 2000, Ipavich 1975, Breitschwerdt et al. 1991, 1993

+ cosmic ray streaming instability with nonlinear saturation CR scale height is larger then the scale height of thermal gas. CR pressure gradient drives the wind.

uinf = 500km/s Rsh = 300 kpc

why power law?

Fermi 1949, 1954

p u

2 2

,

• r
• 1st or 2nd order acceleration

v v approximate for ( ) ( ) : ; spectrum at / 1: .

a l

u u p p J E p f p p      



         

• 1

a l

Fermi formula τ γ = 1+ p τ 

Krymsky 1977, Bell 1978, …

shock u1 u2

1 2 2 1 2

... ... 3 , at compression ratio 4

a l

u u u u r u      diffusive shock acceleration 3 γ = 1+ = 2 r -1  

diffusion

sh sh

u R > 10 D(p)

    

sh max sh

u E 0.3 Ze B R c

D(р) should be anomalously small both upstream and downstream; CR streaming creates turbulence in shock precursor

Bell 1978; Lagage & Cesarsky 1983 …

“Bohm” limit DB=vrg/3:

Emax,ism = 1013…1014 Z eV

SNR

ush

shock

• condition of acceleration

and confinement

for Bism = 5 10-6 G

1051 erg

streaming instability gives B >> Bism in young SNR

Bell & Lucek 2000, Bell 2004, Pelletier et al 2006; Amato & Blasi 2006; Zirakashvili & VP 2008; Vladimirov et al 2009; Gargate & Spitkovsky 2011

confirmed by X-ray observations SN 1006, Cas A, RCW 86, RX J1713.7-3946 under extreme conditions (e.g. SN1998 bw): Emax ~ 1017Z eV, Bmax ~ 10-3 G

numerical simulations

• f particle acceleration

and radiation in SNR

radio polarization in red (VLA), X-rays in green (CHANDRA),

• ptical in blue (HST)

Cas A

Zirakashvili et al 2014 Zirakashvili & VP 2012 Berezhko et al. 1994-2006, Kang & Jones 2006 Zirakashvili & VP 2012, semianalytic models Blasi et al.(2005), Ellison et al. (2010) )

calculated spectrum of Galactic cosmic rays:

data from HEAO 3, AMS, BESS TeV, ATIC 2, TRACER experiments data from ATIC 1/2, Sokol, JACEE, Tibet, HEGRA, Tunka, KASCADE, HiRes and Auger experiments

interstellar spectrum of all particles

solar modulation

extragalactic component

hydrodynamic eqs.+ Pcr; diffusion-convection transport eq. for CR with Alfvenic drift «knee» is formed at the beginning of Sedov stage

15 1/6

• 2/3

knee sn,51 ej

E Z = 1.1×10 W n M eV

VP, Zirakashvili, Seo 2010

JxE2.75

source spectra produced by SNRs

4

4 ( ) /

sn sn

cp p    

protons

positrons in cosmic rays; pulsars, dark matter, ...

Harding & Ramaty 1987 Ting presentation 2013

collection of data Mitchell 2013

Berezhnev et al. 2012

structure above the knee

different types of nuclei, Eknee ~ Z different types of SN transition to extragalactic component

knee and beyond

p,He knee 2nd knee

JxE3

p He Fe

Kampert 2013

JxE2.7

summary by Tsunesada 2013

Kpc

EeV g μG

E r = 1× Z×B

GZK suppression?

EPOS 1.99 Kampert & Unger 2012

knee

JxE2.75

<lnA>

energy loss of ultra-high energy cosmic rays

Greisen 1966; Zatsepin & Kuzmin 1966

energy loss length z = 0

• pair production

p → pe+e-

• pion production

p → N GZK cutoff at EGZK ~ 6×1019 eV

• photodisintegration of nuclei

Stecker 1969

• Universe expansion
• (1/E) (dE/dt)adiabatic = H

H0=100h km/(s Mpc), h=0.71 EGZK

microwave & EBL photons

γ

γ

π

expansion

extragalactic sources of cosmic rays

needed in CR SN AGN jets GRB newly born accretion on at Е > 1019.5 eV fast pulsars galaxy clusters (< 5ms)

3 10-4 (Auger) 3 10-1 3 3 10- 4 10-3 10

kin. & 6 10-2 for X/gamma rotation strong shocks

8 10-3 for E>109 eV

Lkin > 1044 erg/s

energy release in units 1040 erg/(s Mpc3) AGN jets

   

 

1/2 20 1/2 45 max jet 2 19 4 max

E 10 ×Z×β × L / 10 erg / s eV E 10 ×Z× Ω / 10 sec eV

fast new born pulsars B = 1012…1013 G

Lovelace 1976, Biermann & Strittmatter 1987, Norman et al 1995, Lemoine & Waxman 2009 Gunn & Ostriker 1969, Berezinsky et al. 1990, Arons 2003, Blasi et al 2000, Fang et al. 2013

Auger

– transition to heavy elements above 1019 eV

• anisotropy

TA+HiRes

– proton dominated composition

• no significant anisotropy (?)

for heavy composition: Emax/Z = 4 x1018 eV easier to accelerate cosmic rays but difficult to identify their sources; production of neutrinos is suppressed (Berezinsky - “disappointing” model)

very high energy neutrinos of cosmic origin

IceCube neutrino detector

3-year data: excess of 37 neutrinos above atmospheric background (>5.7 sigma) at 3.1013 to 2.1015 eV

  

2

• 8
• 2
• 1
• 1

ν ν

E dN/dE (0.95±0.3)×10 GeV cm s sr

• cosmic neutrino flux per flavor with

possible suppression above 2 PeV;

• equal flavor ratio 1:1:1;
• isotropic sky distribution

100 TeV 1000 TeV

Aartsen et al. 2014

Aartsen et al. 2014

neutrino production in cosmos is possible via interactions and decay chains plus neutrino oscillations

• Galactic sources may account only for a minority of events
• cosmogenic (GZK) neutrino production is inefficient
• can be produced in extragalactic sources of UHE cosmic rays; not in GRB

WB bound? Waxman & Bahcall 1999

pγ, pp(n)

 

_ + + + + μ e μ

π μ ν , μ e ν ν

28

Razzaque 2013

JEM-EUSO (2016, Extreme Universe Observatory, > 3 1019 eV,

• 100000 km2 from space, instantaneous aperture ~100 PAO )

LHAASO (2013-2018, Large High Altitude Air Shower Observatory,

Tibet 4300 m, gamma-rays and CRs till the knee and 1 EeV, 1 km2 array of electron and muon detectors for gamma rays > 30 TeV, 90000 m2 water Cherenkov detector array for gamma rays >100 GeV, 24 wide field Cherenkov telescopes and 5000 m2 shower core detectors for CRs > 30 TeV)

CTA (2018, Cherenkov Telescope Array, 100 GeV – 100 TeV, 100

telescopes ( 5m to 23 m diameter); two arrays to cover full sky; 10 times better sensitivity makes about 200 SNRs visible)

some coming projects

Tunka-HiSCORE (wide-angle Cherenkov gamma observatory, 1-100

km2, search for PeVatrons, Ecr =1014 – 1018 eV)

CALET (2014, scintillation calorimeter on ISS, e+ e- up to 20 TeV) ISS-CREAM (2015, on ISS by Space-X)

sensitivity

Conclusions Cosmic ray origin scenario where supernova remnants serve as principle accelerators of cosmic rays in the Galaxy is strongly confirmed by recent numerical simulations. Accurate data on cosmic rays in the energy range 1017 to 1019 eV, where the transition from Galactic to extragalactic component occurs are becoming available. Eliminating the uncertainties with energy spectrum and composition is necessary for understanding of cosmic ray

• rigin at the highest energies.