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

AGN interacting CR spectrum at Earth galaxies GRB ultrafast pulsar cosmological shocks cosmic ray halo, Galactic wind E -2.7 Fermi bubble pulsar, close extragalactic WMAP PWN binary JxE 2 haze Sun GC stellar SNR Galactic wind disk 1/km 2 /century 10 9 eV 10 20 eV N cr = 10 -10 cm -3 - total number density in the Galaxy LHC w cr = 1.5 eV/cm 3 - energy density E max = 3x10 20 eV - max. detected energy Q cr = 10 41 erg/s – power of Galactic CR sources A 1 ~ 10 -3 – dipole anisotropy at 1 – 100 TeV r g ~ 1 × E/(Z × 3 × 10 15 eV) pc - Larmor radius at B=3x10 -6 G

Voyager 1 at the edge of interstellar space direct measurements of interstellar launched in 1977, 70 kb, 22 w CR spectra at low energies 10 3 10 2 10 1 H particle /(m 2 sec sr MeV/nuc) 10 0 He low energies: 10 -1 Voyager 1 after E. Stone 2013 10 -2 Stone et al. 2013 high energies: 10 -3 BESS Pamela 10 -4 Sparvoli et al 2012 10 -5 10 0 10 1 10 2 10 3 10 4 10 5 energy, MeV/nuc

“Golden age” of new CR measurements 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

traversed matter thickness X ~ 12 g/cm 2 at 1 GeV/nuc (surface gas density of galactic disk ~ 2.5 10 -3 g/cm 2 ) M51 energy balance: ~ 15% of SN kinetic energy go to cosmic rays to maintain observed cosmic ray density Ginzburg & Syrovatskii 1964 two power laws! steady state: J cr (E)= Q cr (E) × T(E) (without energy E -2.1 x E -0.6 losses and nuclear fragmentation) escape time from the Galaxy, source term, 10 8 yr at 1 GeV, SNR resonant scattering in random magnetic field 1/k res = r g

galactic wind driven by cosmic rays Ipavich 1975, Breitschwerdt et al. 1991, 1993 CR scale height is larger then the scale height of thermal gas. CR pressure u inf = 500km/s R sh = 300 kpc gradient drives the wind. + cosmic ray streaming instability with nonlinear saturation Zirakashvili et al. 1996, 2002, 2005, VP et al. 1997, 2000,   1 1.1     s v B p p       27 2 D ~ 10 cm / , s     q Zm c Zm c     cr p p        (3 1) / 2 2.7, at 2.1 s s   1 s    0.55   H 2 p p ef   X ~ ~ ~       D Zm c Z   p

why power law? Fermi 1949, 1954 2   p u u        p p , or - 1st or 2nd order acceleration   v v p     u Fermi formula 2 approximate for ( ) J E p f p ( ) : τ   -1 γ = 1+ a  p ; spectrum at / 1: . τ a l l Krymsky 1977, Bell 1978, … diffusive shock acceleration u 2 u 1 ... ...     3 ,  a l u u u 1 2 2 diffusion 3 u   γ = 1+ = 2 1 at compression ratio r 4 r -1 u 2 shock

u R u sh - condition of acceleration sh sh > 10 and confinement D(p) shock 10 51 erg D( р ) should be anomalously small both upstream SNR and downstream ; CR streaming creates turbulence in shock precursor Bell 1978; Lagage & Cesarsky 1983 … u sh      “Bohm” limit D B =vr g /3: E 0.3 Ze B R max sh c for B ism = 5 10 -6 G E max,ism = 10 13 …10 14 Z eV streaming instability gives B >> B ism 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): E max ~ 10 17 Z eV, B max ~ 10 -3 G

numerical simulations of particle acceleration and radiation in SNR Berezhko et al. 1994-2006, Kang & Jones 2006 Zirakashvili & VP 2012, semianalytic models Blasi et al.(2005), Ellison et al. (2010) ) Zirakashvili & VP 2012 Zirakashvili et al 2014 Cas A radio polarization in red (VLA), X-rays in green (CHANDRA), optical in blue (HST)

calculated spectrum of solar modulation Galactic cosmic rays: JxE 2.75 VP, Zirakashvili, Seo 2010 source spectra produced by SNRs data from HEAO 3, AMS, BESS TeV, ATIC 2, TRACER experiments protons     4 4 cp ( ) / p sn sn hydrodynamic eqs.+ P cr ; extragalactic diffusion-convection component interstellar spectrum of transport eq. for CR with all particles Alfvenic drift «knee» is formed at the beginning of Sedov stage data from ATIC 1/2, Sokol, JACEE, Tibet, HEGRA, Tunka, KASCADE, HiRes and Auger experiments 15 1/6 -2/3 E Z = 1.1×10 W n M eV knee sn,51 ej

positrons in cosmic rays; pulsars, dark matter, ... collection of data Mitchell 2013 Harding & Ramaty 1987 Ting presentation 2013

p,He knee 2nd knee Berezhnev et al. 2012 knee and beyond structure above the knee different types of nuclei, E knee ~ Z JxE 3 different types of SN transition to extragalactic component p He Fe JxE 2.7 Kampert 2013

knee summary by Tsunesada 2013 GZK JxE 2.75 suppression? E r = 1× Z×B EeV Kpc g μ G <lnA> EPOS 1.99 Kampert & Unger 2012

energy loss of ultra-high energy cosmic rays E GZK microwave & EBL photons expansion • pair production γ p → pe + e - π γ • pion production p → N GZK cutoff at E GZK ~ 6 × 10 19 eV energy loss length z = 0 Greisen 1966; Zatsepin & Kuzmin 1966 • photodisintegration of nuclei Stecker 1969 • Universe expansion - (1/E) (dE/dt) adiabatic = H H 0 =100h km/(s Mpc), h=0.71

extragalactic sources of cosmic rays energy release in units 10 40 erg/(s Mpc 3 ) needed in CR SN AGN jets GRB newly born accretion on at Е > 10 19.5 eV fast pulsars galaxy clusters (< 5ms) 3 10 -4 (Auger) 3 10 -1 3 3 10 - 4 10 -3 10 & 6 10 -2 for kin . X/gamma rotation strong shocks 8 10 -3 for E>10 9 eV L kin > 10 44 erg/s   1/2  20 1/2 45 E 10 ×Z× β × L / 10 erg / s eV AGN jets max jet Lovelace 1976, Biermann & Strittmatter 1987, Norman et al 1995, Lemoine & Waxman 2009   fast new born 2  19 4 E 10 ×Z× Ω / 10 sec eV pulsars max B = 10 12 …10 13 G Gunn & Ostriker 1969, Berezinsky et al. 1990, Arons 2003, Blasi et al 2000, Fang et al. 2013

Auger – transition to heavy elements above 10 19 eV - anisotropy TA+HiRes – proton dominated composition - no significant anisotropy (?) for heavy composition: E max /Z = 4 x10 18 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 Aartsen et al. 2014 Aartsen et al. 2014 100 TeV 1000 TeV    2 -8 -2 -1 -1 E dN/dE (0.95±0.3)×10 GeV cm s sr ν ν 3-year data: excess of 37 neutrinos - cosmic neutrino flux per flavor with above atmospheric possible suppression above 2 PeV; background (>5.7 sigma) at - equal flavor ratio 1:1:1; 3.10 13 to 2.10 15 eV - isotropic sky distribution

neutrino production in cosmos is possible via interactions p γ , pp(n) and decay chains _   + + + + π μ ν , μ e ν ν μ e μ plus neutrino oscillations 28 Razzaque 2013 - 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

some coming projects JEM-EUSO (2016, Extreme Universe Observatory, > 3 10 19 eV,  100000 km 2 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 km 2 array of electron and muon detectors for gamma rays > 30 TeV, 90000 m 2 water sensitivity Cherenkov detector array for gamma rays >100 GeV, 24 wide field Cherenkov telescopes and 5000 m 2 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) Tunka-HiSCORE (wide-angle Cherenkov gamma observatory, 1-100 km 2 , search for PeVatrons, E cr =10 14 – 10 18 eV) CALET (2014, scintillation calorimeter on ISS, e+ e- up to 20 TeV) ISS-CREAM (2015, on ISS by Space-X)

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 10 17 to 10 19 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 origin at the highest energies.