Particle Acceleration at Supernova Remnants and Supernovae

Transcription

1 Particle Acceleration at Supernova Remnants and Supernovae Gwenael Giacinti 1 & Tony Bell 2 1 MPIK, Heidelberg 2 Clarendon Laboratory, University of Oxford Giacinti & Bell, MNRAS 449, 3693 (2015); Bell, Schure, Reville & Giacinti, MNRAS 431, 415 (2013)

2 Cosmic ray spectrum knee ankle Galactic Transition? Extragalactic

3 CR spectrum and knee Galactic Transition? Knee (Max E sources?) Extragalactic

4 Sources, acceleration mechanism Supernova remnants shock Ejecta CISM ISM R Tycho - Composite Forward shock

5 Sources, acceleration mechanism Difusive shock acceleration (Krymskii; Axford et al. '77; Bell; Blandford & Ostriker '78) shock CR Ejecta CISM ISM j CR R Tycho - Composite CR-driven CR-driven instabilities instabilities

6 Sources, acceleration mechanism Difusive shock acceleration (Bell '78) Emax ~ Z x 3 PeV??? KNEE? - E max vs t : PeV? When? - How do CRs escape SNRs? j CR - Instabilities: Time to grow, MF ampliication,... Tycho - Composite Instabilities Instabilities self self conf. conf.

7 Pion bump Fermi-LAT collaboration, Science 339, 807 (2013) But where are the PeVatrons?

8 Outline I Cosmic Ray Acceleration at SNR / SNe How do CR escape SNR? magnetic field amplification? Can SNR accelerate CR to > 1 PeV... when? II SNe in dense winds as PeVatrons III Particle Acceleration BEFORE SN Shock Breakout When does particle acceleration start?

9 Sources, acceleration mechanism Difusive shock acceleration (Krymskii '77; Axford et al. '77; Bell '78; Blandford & Ostriker '78) Bell '78 Alfven waves E max for : τ = R/u shock D Bohm = cr g /3 E max CR precusor size D/u shock 300 yrs, B ~ 3 µg, u shock ~ 5000 km s -1 => E max ~ 10 TeV!!! = > Need for MF amplification

10 Sources, acceleration mechanism Difusive shock acceleration (Krymskii '77; Axford et al. '77; Bell '78; Blandford & Ostriker '78) Bell '78 Alfven waves E max for : τ = R/u shock D Bohm = cr g /3 E max CR precusor size D/u shock 300 yrs, B ~ 3 µg, u shock ~ 5000 km s -1 => E max ~ 10 TeV!!! = > Need for MF amplification

11 NRH instability (Bell '04) Large CR current densities : Non-resonant hybrid instability

12 CR acceleration and escape MNRAS 431, 415 (2013) Bkg plasma CRs

13 CR acceleration and escape piston

14 CR acceleration and escape piston

15 CR acceleration and escape CR charge through a unit surface, upstream ( ) r R ρ = cst Diff. / R : Cas A : T 400 TeV!!!

16 Nowadays, historical SNRs are not accelerating particles to the knee! Tycho SN 1006 Kepler Cas A

17 SNe in DENSE WINDS as PeVatrons Bell et al. MNRAS 431, 415 (2013) r R Diff. / R : ρ α r -2

18 Radio SNe SN 1993J

19 Radio SNe

20 Radio SNe

21 ARGO-YBJ : cutoff at ~ 700 TeV All-particle spectrum SN Type Ia? p+he SNe in dense winds? (Type Ib/c?, some II) Heavier nuclei?

22 Formation of a collisionless shock t 1 t 2 1 2

23 u 2 < u 1 => =>

24 Progenitor with an optically THIN wind 1D spherical T e = T p, but T e T rad Compton cooling + Bremsstrahlung Thomson scattering

25 Progenitor with an optically THIN wind

26 Progenitor with an optically THICK wind Spherical 1D

27 Progenitor with an optically THICK wind Spherical 1D

28 Progenitor with an optically THICK wind Spherical 1D

29 Observational consequences 1 10 TeV CRs possible before breakout : < ( )

30 Observational consequences 1) GG & Bell, proc. Swift 10 conf. 2) X-Ray Flash

31 Parameters of Svirski & Nakar, ApJL (2014) SN 2008D / XRF may have been an event in which a CS is formed before SB

32 Conclusions and perspectives Summary of Bell's NR instability Instability growth / saturation => Limits CR E max Tight link between CR Escape / E max / MF amplification Type Ia fall short of reaching the knee => COMPOSITION? First few decades of SNe in dense winds promising to reach knee and beyond

33 Conclusions and perspectives First few decades of SNe in dense winds very promising -> Need to search for HE neutrino / (LE) γ-rays from SNe Studied transition from a radiation mediated shock to a collisionless shock, Optically thick winds : CS can form significantly before breakout Observational consequences : - X-ray flashes - E > 100 GeV neutrinos Probe of the poorly known optically thick regions of circumstellar winds