Interactions between UHE Particles and Protogalaxy Environments Ellis Owen Mullard Space Science Laboratory University College London United Kingdom E-mail: [email protected] Kinwah Wu, Idunn Jacobsen, Pooja Surajbali Image Credit: NASA - Adolf Schaller Hubble gallery Artist’s impression of protogalaxies HEPP/APP University of Sussex, Brighton, United Kingdom, March 2016 Outline 1. UHE Particles in Protogalaxies 2. Protogalaxy Environments 3. Interaction Mechanisms & Losses 4. Energy Deposition Lengths & ISM/IGM Heating 2 Ultra High-Energy Particles in Protogalaxies • Cosmic Rays (CRs) accelerated in high energy astrophysical environments – Supernovae explosions / shocks – Accretion • Particle energy distribution follows power law, peaks around ~10 GeV for galactic (stellar) contribution • Expected to be present in young starburst galaxies (protogalaxies) – High star formation rate (SFR) ~1000 times more than cosmic average – Rate of supernovae roughly follows SFR – Cosmic ray flux attributed to stellar sources roughly follows supernova rate 3 102 2 101 10 Protogalaxy Environment 3 − 0 Density Fields 10 101 King radius • King model 102 3 1 − 10− 101 100 ParameterMatter Value Density/cm 3 − rt 2kpc 100 r 1kpc2 K 10− 1 10− 3 Matter Density/cm 1 n0 10 cm− 10− 2 10− Matter Density/cm 3 • Red line at King radius,10− 1kpc 3 10 3 2 1 0 1 − 3 2 1 0 1 10− 1010− − 10− 1010− 10 1010 10 – Approximate radius of a Radius/kpc 2 Radius/kpc protogalaxy (e.g. from high z 10− LAE observations) 4 10 3 − 3 2 1 0 1 10− 10− 10− 10 10 Radius/kpc 102 101 Protogalaxy Environment 3 − 0 r>rgal Radiation Fields 10 7 • Uniform spherical 67 distribution of stars1 within 6 10− 1 5 protogalaxy − 1 s Matter Density/cm 5 − 2 s 2 − • High mass, low metallicity − 44 – O/B type, T~30,000K 2 10− 3 – T Spectrally characterizes 3 radiation field (BB spectrum) Flux/erg cm 2 Flux/erg cm 2 • Field approximately uniform 1 3 within the protogalaxy10− radius, 3 10 2 1 0 1 then simple inverse 10square− 100 − 2 4 10− 6 8 1010 10 Radius/kpc law at r>r Radius/kpc gal 0 0 2 4 6 8 10 Radius/kpc 5 5 10− 7 10− Protogalaxy Environment9 10− 11 10− Efficiency of energy transfer Magnetic Fields 5 10− 13 10− SNe à Turbulence à B field 7 10− 15 • Two scale components:10− 5 9 1010−− 17 -3 7 – Local viscous scale, 10~10− pc 10−11 10− 10 9 19 − 10− 1113 – Turbulent forcing ~1kpc 1010−− 21 10 13 10− − 15 10− • SN driven, B follows density 15 10− 23 17 Forcing Scale, ✏ =0.1 10− 1010 17 profile −− 19 25 10− 19 Viscous Scale, ✏ =0.1 10− 10− -20 21 • Initial B field ~10 G 10− Forcing Scale, ✏ =1 21 27 23 Forcing Scale, ✏ =0.1 10− 1010−− Protogalaxy Magnetic Field Strength/G permeates protogalaxy Viscous Scale, ✏Viscous=0.1 Scale, ✏ =1 25 29 10− 23 Forcing Scale, ✏ =0.1 10− 10− Forcing Scale, ✏ =1 27 10− Forcing Scale, ✏ = 10 Protogalaxy Magnetic Field Strength/G • Stellar processes drive 25 Viscous Scale, ✏ =1 Viscous Scale, ✏ =0.1 31 29 1010−− 10− Forcing Scale, ✏ = 10 Viscous Scale, ✏ = 10 31 Forcing Scale, ✏ =1 turbulence, which drives B 10− 27 Viscous Scale, ✏ = 10 33 10− 10− Protogalaxy Magnetic Field Strength/G 33 4 3 10− 2 1 0 1 2 3 Viscous4 Scale,5✏ =1 4 3 2 1 0 1 2 3 4 5 10− 10− 1029−10− 10− 1010− 10− 10 10 1010 10 1010 1010 10 10 10 field up to µG levels seen in 10− Age of Galaxy/Myr Forcing Scale, ✏ = 10 Age of Galaxy/Myr current epoch 31 10− Viscous Scale, ✏ = 10 10 33 – Exponential growth − 4 3 2 1 0 1 2 3 4 5 10− 10− 10− 10− 10 10 10 10 10 10 – Then linear growth of the forcing scale Age of Galaxy/Myr field after local saturation Model follows J. Schober + 2013 6 5 10− 7 10− Protogalaxy Environment9 10− 11 10− Efficiency of energy transfer Magnetic Fields 5 10− 13 10− SNe à Turbulence à B field 7 10− 15 • Two scale components:10− 5 9 1010−− 17 -3 7 – Local viscous scale, 10~10− pc 10−11 10− 10 9 19 − 10− 1113 – Turbulent forcing ~1kpc 1010−− 21 10 13 10− − 15 10− • SN driven, B follows density 15 10− 23 17 Forcing Scale, ✏ =0.1 10− 1010 17 profile −− 19 25 10− 19 Viscous Scale, ✏ =0.1 10− 10− -20 21 • Initial B field ~10 G 10− Forcing Scale, ✏ =1 21 27 23 Forcing Scale, ✏ =0.1 10− 1010−− Protogalaxy Magnetic Field Strength/G permeates protogalaxy Viscous Scale, ✏Viscous=0.1 Scale, ✏ =1 25 29 10− 23 Forcing Scale, ✏ =0.1 10− 10− Forcing Scale, ✏ =1 27 10− Forcing Scale, ✏ = 10 Protogalaxy Magnetic Field Strength/G • Stellar processes drive 25 Viscous Scale, ✏ =1 Viscous Scale, ✏ =0.1 31 29 1010−− 10− Forcing Scale, ✏ = 10 Viscous Scale, ✏ = 10 31 Forcing Scale, ✏ =1 turbulence, which drives B 10− 27 Viscous Scale, ✏ = 10 33 10− 10− Protogalaxy Magnetic Field Strength/G 33 4 3 10− 2 1 0 1 2 3 Viscous4 Scale,5✏ =1 4 3 2 1 0 1 2 3 4 5 10− 10− 1029−10− 10− 1010− 10− 10 10 1010 10 1010 1010 10 10 10 field up to µG levels seen in 10− Age of Galaxy/Myr Forcing Scale, ✏ = 10 Age of Galaxy/Myr current epoch Exponential31 growth 10− Linear growth Viscous Scale, ✏ = 10 10 33 – Exponential growth − 4 3 2 1 0 1 2 3 4 5 10− 10− Local10 −saturation10− 10 10 10 10 10 10 – Then linear growth of the forcing scale Age of Galaxy/Myr field after local saturation Model follows J. Schober + 2013 6 Interaction Mechanisms & Losses • Low energy particles – Collisions • Direct ionization • Heating • High energy particles – Proton-photon (p�) • Pion production (Photopion) • Pair production (Photopair) – Proton-proton (pp) • Pion production (Hadronuclear) 7 Interaction Mechanisms & Losses Photopion (��) Interaction 0 + p + ⇡ p +2γ + pion multiplicities at p + γ ∆ ! higher energies ! ! n + ⇡+ n + µ+ + ⌫ ( ! µ + Photopair (�e) Interaction n + e + ⌫e +¯⌫µ + ⌫µ + p + γ p + e + e− . ! 8 Interaction Mechanisms & Losses Hadronuclear (pp) Interaction p + p + ⇡0 p + ∆+ p + p + ⇡+ 8 ! 8 p + p > <>p + n + ⇡+ + pion multiplicities ! > at higher energies > + < ++ >n + p + ⇡ n + ∆ : + > ! (n + n + 2(⇡ ) > > :> 9 Interaction Mechanisms & Losses Hadronuclear (pp) Interaction p + p + ⇡0 p + ∆+ p + p + ⇡+ 8 ! 8 p + p > <>p + n + ⇡+ + pion multiplicities ! > at higher energies > + < ++ >n + p + ⇡ n + ∆ : + > ! (n + n + 2(⇡ ) > > :> Interactions of neutrons and photons à pion production n + γ ⇡’s ! 9 Interaction Mechanisms & Losses Hadronuclear (pp) Interaction p + p + ⇡0 p + ∆+ p + p + ⇡+ 8 ! 8 p + p > <>p + n + ⇡+ + pion multiplicities ! > at higher energies > + < ++ >n + p + ⇡ n + ∆ : + ! (n + n + 2(⇡ ) > > > : Pions decay to photons, muons, Interactions of neutrons and neutrinos, electrons, positrons, photons à pion production antineutrinos n + γ ⇡’s ! ⇡ γ,µ,e,⌫ ... ! 9 Cross Section/Mean Free Path � Interactions • Pair production, Bethe-Heitler 7 ✏ σ (✏ ) ↵ σ ln r process γe r ⇡ 6⇡ f T k ✓ γe ◆ – Cross Section by fitting function 10 Cross Section/Mean Free Path � Interactions • Pair production, Bethe-Heitler 7 ✏ σ (✏ ) ↵ σ ln r process γe r ⇡ 6⇡ f T k ✓ γe ◆ – Cross Section by fitting function • Photopion production – Cross section by fitting step function to data (Dermer & Menon 2009/Reimer 2007) 10 Cross Section/Mean Free Path � Interactions • Pair production, Bethe-Heitler 7 ✏ σ (✏ ) ↵ σ ln r process γe r ⇡ 6⇡ f T k ✓ γe ◆ – Cross Section by fitting function • Photopion production – Cross section by fitting step function to data (Dermer & Menon 2009/Reimer 2007) p Interactions • Hadronuclear production – Cross section by fitting to data (Kafexhiu+ 2014) 10 105 105 102 102 10 1 10 1 − UHE− Proton Loss Lengths Energy104 Deposition & IGM/ISM Heating 4 4 10− 10− Mean Free Path of UHE Protons 103 10 7 10 7 − Contributions− Magnetic Field UHE Proton Loss Lengths 104 10 2 10 5 10− 10 10− 10102 103 1010-22 2 13 10 2 13 1 10− 10 1 10− 10− 10 10-8 4 10− 101 16 16 7 10− 10− 10− 100 0 Energy Loss Mean Free Path/Mpc 10 Energy Loss Mean Free Path/Mpc 10 10− 19 Hadronuclear (p⇡) 19 1 20 13 20 10− 10− 10− 10− Seed Magnetic Field,Galactic 10 Radiation− HadronuclearG Photopion (⇡) (p⇡) Seed Magnetic10-22 Field, 10− G 1 Galactic Radiation Photopair (γe) 10 16 102 − 5 − 5 10−-2 − − SaturationEnergy10 Loss Mean Free Path/Mpc Magnetic Field, 10 G Saturation Magnetic Field, 10 G 22 CMB RadiationGalactic Photopion (⇡) Radiation Photopion22 (⇡) Energy Loss Mean Free Path/Mpc 10− 10− 19 10− 20 CMB Radiation Photopair (γe) Seed Magnetic Field, 10− G 3 No Magnetic10− Field Galactic Radiation Photopair (γe) No Magnetic Field 5 CMB Radiation Cosmological Expansion 22 Saturation Magnetic Field, 10− G 2 10− 25 10− Total 25 No Magnetic Field 10− Energy Loss Mean Free Path/Mpc CMB Radiation Photopion10− (⇡) 4 25 9 10 1110− 12 13 14 15 9 16 10 17 1110−18 12 19 13 20 14 15 16 17 18 19 20 10 10 10 109 101010 1011 101012 1013 101014 1015101016 10101710 101810101019 102010 10 109101010 101110 101012 101013 1014 101015 1016 1017 1018 101019 1020 10 10 10 CMBProton RadiationProton Energy/eV Energy/eV Photopair (γe) ProtonProton Energy/eV Energy/eV 3 Owen+(in prep) 10− CMB Radiation Cosmological Expansion • AssumeTotal products decay quickly at interaction point 4 •10− Energy of CR deposited ~at point of interaction 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 11 Proton Energy/eV 23 23 10− 10− 25 25 10− 10− 27 27 10− 10− 29 29 10− 10− 19 1 19 1 31 31 10− − 10− − 10− 10− s s 3 3 − − 33 Energy21 Deposition33 & IGM/ISM21 Heating 10− 10− 10− 10− 23 10− 35 35 Preliminary Estimated23 Heating Impact10− 25 23 10− 10− 10− 10− Local Scales 27 Large Scales 10− 37 37 19 10 23 10 10− − 10− − 25 29 25 1 10− 10− 1 1025− 10− − 21 10− − 1 Heating/erg cm s Heating/erg cm 31 s 39 − 10− 27 0Myr 39 s 10− 3 10 3 10 23 − 3 − 10− − − 27 33 − 10 29 27 1Myr 10 10− − 25− 10− 1 1 10− 31 10 Myr − − 10− s 41 s 41 35 3 3 10 − − 10− − 10−