MULTIMESSENGER APPROACH:Using the Different Messengers

Transcription

1 MULTIMESSENGER APPROACH:Using the Different Messengers PROTONS p NUCLEI (A,Z) NEUTRINOS νµ PHOTONS

2 LECTURE PLAN: 1) COSMIC RAYS- proton interactions with photons, composition, nuclei interactions with photons, different photon targets 2) NEUTRINOS- presence of GZK-cutoff, photo-pion production mechanism, interaction rate, cosmic ray spectra, source distribution 3) PHOTONS- photon flux production, photon flux attenuation, competition of rates, e/ cascades 4) MULTIMESSENGER APPROACH (1)- using the different attenuation lengths, homogeneous sources, inhomogeneous sources

3 LECTURE PLAN: 1) COSMIC RAYS- proton interactions with photons, composition, nuclei interactions with photons, different photon targets 2) NEUTRINOS- presence of GZK-cutoff, photo-pion production mechanism, interaction rate, cosmic ray spectra, source distribution 3) PHOTONS- photon flux production, photon flux attenuation, competition of rates, e/ cascades 4) MULTIMESSENGER APPROACH (2)- candidate UHECR source, consistency check of disintegration with neutrino flux calculations

4 Different Distance Scales 20 ev particles 0 Mpc p 200 Mpc (A,Z) νµ Mpc

5 Aims- part 1 1) A recap on the interaction rates of protons and photons in the Universe 2) The source distribution typically assumed 3) An analytic description of the of the GZK feature 4) The photon fraction of cosmic rays 5) Different source distributions

6 Using the Photons and Protons p 20 ev particles 0 Mpc Mpc

7 1) Recapping on the proton and photon interaction rates

8 The Impedance of Background Radiation to High Energy Protons

9 The Impedance of Background Radiation to High Energy Photons

10 2) The source distributions typically assumed

11 High Energy Cosmic Ray Sources Distribution (Energy and Spatial) Energy Distribution of Cosmic Rays dn/de ~ E-2 motivated by first order Fermi shock acceleration theory Spatial Distribution of Cosmic Ray Sources dn/dv ~ (1+z)3 (z dependence is irrelevant here, only local UHECR contribute due to the distance scales probed)

12 Shells of Source Regions L (Mpc)

13 A Homogeneous Source Distribution The number of sources within a source shell of width dl would be proportional to dl for a local uniform source distribution The ratio of sources from the different shells- R n 1 : R n=1: 0.3

14 The GZK Feature Assumptions: E max = = ev (along with the source distribution mentioned in the previous lecture) dn E e de E E max

15 3) An analytic description of the GZK feature

16 A Simple Analytic Description of the GZK Feature for Protons N n E p, L n = m=0 N 0 E,0 l E p = where l m= n 1 0 m l l n p=0 l m l p e L lm l0 x x e 1 e l 0 is 1 Mpc and x= 20.5 ev Ep l E p 1 K p m

17 proton 20 Injecting a ev Fe Nucleus and Tracking the Subsequent Nucleiprotons

18 A Simple Analytic Description of the GZK Feature for Protons N n E p, L n = m=0 N 0 E,0 l E p = where l m= n 1 0 m l l n p=0 l m l p e The same expression describes BOTH nuclei and proton attenuation! L lm l0 x x e 1 e l 0 is 1 Mpc and x= 20.5 ev Ep l E p 1 K p m

19 Using these Distribution Functions to Obtain the Arriving Flux N n E p, L n = m=0 N 0 E,0 n 1 0 m l l n p=0 l m l p e L lm n max N tot E p, L = n=0 N n E p, L N 0 E,0 the source distribution function L' N p E p = 0 dl f L N tot E p, L

20 A Comparison of this Description with Monte Carlo

21 4) The photon fraction of cosmic rays

22 Arriving photon Flux from Different Shells Dip feature in photon flux from Mpc shell

23 The Photon Fraction

24 5) Different source distributions

25 Altering the Source Distribution Weighting the contribution from the more local sources to create a local overdensity R n 1 : R n=1 : 0.5 or R n 1 : R n=1 : 0.7

26 The Local UHECR Source Distribution- overdensity

27 Altering the Source Distribution Introducing a local void of UHECR sources

28 The Local UHECR Source Distribution- underdensity

29 The Effect of Diffusion Lcoh L For each coherent patch: L coh = R Larmor 1/ 2 L E p = Lcoh L L coh 1/ 2 = R Larmor

30 The Effect of Diffusion Lcoh L 19 E p 0.8 Ep L Mpc 1/ 2 Lcoh 1 Mpc 1/ 2 B 0.1 ng Diffusion can be expected to increase the path length of the protons more than the photons, reducing the flux contribution from distance sources. The effect diffusion introduces is thus similar to that of a local source overdensity

31 Conclusion (1) The detection of the photon fraction component of UHECR spectrum is a powerful diagnostic tool for: verifying the GZK origin of the cut-off/suppression feature in the UHECR spectrum (in conjunction with the spectral cut-off) determining the local distribution of UHECR sources

32 Aims- part 2 1) Candidate sources of UHECRs to be considered 2) A model for the AGN radiation field 3) A model for the GRB radiation field 4) A model for the Starburst Galaxy radiation field 5) A consistency check of the amount of disintegration expected under the typical optical depth assumption

33 20 Using the Nuclei to Probe Proton Interactions in the ev particles UHECR Source p 0 Mpc (A,Z) 200 Mpc

34 B [G] Source Size and B-Field Strength E ma x E ma x =1 =1 Hillas Plot 0 20 ev 0 17 ev Emax = (Bc)RLarmor GRB = sh(bc) lsource AGN starburst lsource [pc] 0 3 6

35 B [G] Source Size and B-Field Strength E ma x E ma x =1 =1 Hillas Plot 0 20 ev 0 17 ev Emax = (Bc)RLarmor GRB = sh(bc) lsource AGN starburst lsource [pc] 0 3 from equating t acc. with t esc. 6

36 44 Candidate Sources: AGN- erg s -1 (luminosity break energy) 52 GRB- erg s -1 (luminosity break energy) 42 Starburst- erg s -1 (luminosity break energy)

37 Power density of SourcesExtragalactic Cosmic Rays, E > 18 ev, have an energy density ~ ev cm erg cm 54-3 erg Mpc 17 time~ s to accumulate erg Mpc s -5 n~ Mpc erg s per source

38 AGN Model and Radiation Field Synchrotron Black Body Inverse Compton ~ 30 lsource= c t = 2 pc 16 n = cm 3

39 AGN Model and Radiation Field Black Body Synchrotron Inverse Compton NB. relativistic sources have smaller n values NNB. n in plasma frame is ~ 16 cm 3 (about 0.1% of air density in this room)

40 GRB Model and Radiation Field dn/de E, =1, E < MeV =2, E > MeV ~ 300 lsource= c t = 6 pc 17 n = cm 3

41 Starburst Galaxy Model and Radiation Field IR Black Body UV Black Body lsource= 0 pc n = 5 cm 3

42 Assuming Cosmic Rays are Protons...

43 Interactions Rates in Sources- AGN GRB Starburst

44 Interactions of Cosmic Ray Protons with CMB: Photo-Pion Productionp+ n > > n+π+/p+π0, Eγth=m m mp ~145 MeV p+e-+νe note- threshold value is in proton rest frame

45 Neutrino Production νe e+ µ+ p γ π+ νµ note- each ν takes ~0.05 of initial proton energy νµ n p νe e

46 Diffuse Neutrino Fluxes Produced by Candidate Sources GRB result synchrotron radiate AGN result dn = d d NB. Starburst flux ~ 4 WB bound

47 Cosmic Ray Interactions with Radiation opacity factor f f lsource/ linteraction lsource= c t linteraction=1/(n ) max 2 cross sections: pion production photodisintegration GRB f = 0.55 max AGN f = 550 Starburst Galaxy f max= 4 x 4

48 Interactions Rates in Sources- AGN GRB Starburst

49 Ratio Between Photo-Pion and Photo-Disintegration Rates From lecture 2: R p, = p, E p, p, 2 E p, p, 2 d n E A, A, 2 E A, A, 2 d n Applying this to photodisintegration reactions: R A, = A,

50 Ratio Between Photo-Pion and Photo-Disintegration Rates (2) with, p, =0.5 mb, E p, =3 MeV, p, =0 MeV and A 56, =81 mb, E A therefore 56, =18 MeV, A 56, =8 MeV A, R A, R p, 15 p, =160 R p,

51 AGN GRB

52 Degree of Photodisintegration in Source Regions Complete Photodisintegration: GRB EFe>17 ev AGN EFe>20 ev

53 Conclusion (2) The GRB model with near unity neutrino production opacities leads to complete disintegration of cosmic ray nuclei above 17 ev The AGN model with near unity neutrino production opacities leads to complete disintegration of cosmic ray nuclei above 20 ev. A consistency check with the typical opacities used in UHECR interaction rate calculations within the source region reveals contradiction with the presence of Fe in the UHECRs for the GRB source model

54 Finally Other messengers carrying useful diagnostic information remain available such as: the change in cosmic ray composition with energy the neutrino flavour ratios and how they change as a function of energy...all you need is imagination (and good physics groundwork)! SO LONG AND THANKS FOR ALL THE FISH!!!!!!

55 Finally Other messengers carrying useful diagnostic information remain available such as: the change in cosmic ray composition with energy the neutrino flavour ratios and how they change as a function of energy...all you need is imagination (and good physics groundwork)! SO LONG AND THANKS FOR ALL THE FISH!!!!!!

56 Origin of Dip Feature in Photon Flux 19 E p= ev 20 E p= ev