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Graz, 29.Nov.2007A.Biland: Cosmic Rays1 Cosmic Rays: what we do (not) know 95 years after the discovery Adrian Biland, ETH Zurich Graz, 29.Nov.2007.

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Presentation on theme: "Graz, 29.Nov.2007A.Biland: Cosmic Rays1 Cosmic Rays: what we do (not) know 95 years after the discovery Adrian Biland, ETH Zurich Graz, 29.Nov.2007."— Presentation transcript:

1 Graz, 29.Nov.2007A.Biland: Cosmic Rays1 Cosmic Rays: what we do (not) know 95 years after the discovery Adrian Biland, ETH Zurich Graz, 29.Nov.2007

2 A.Biland: Cosmic Rays2 - History - Direct CR Observations; ‘low’ Energy - Indirect CR Observations; ‘high’ Energy - Possible CR Sources & Accelerators

3 Graz, 29.Nov.2007A.Biland: Cosmic Rays3 CR History 1896 Bequerel discovers Radioactivity (birth of Nuclear Physics) 1900 Wilson measures conductivity of air (postulates extraterr. radiation that ionizes air) 1910 Gockel shows that air in 4000m still. conductive 1911 F.Zwicky postulates Supernovae as. source of radiation (since few years, we know the ‘crazy swiss’ had been [partially] correct once more)

4 Graz, 29.Nov.2007A.Biland: Cosmic Rays4 CR History 1912 Hess measures height-dependency of conductivity => more ionization at high altitudes ==> can’t be terrestrial radiation ‘Birth of CR- Physics’ 1936 Nobel Prize

5 Graz, 29.Nov.2007A.Biland: Cosmic Rays5 CR History 1919 Kolhoerster: Energy > known radioact.Elem Int. Physics Symposium accepts existence of. ‘ultraradiation of unknown origin’ 1927 Clay: less radiation at aequator than at pole. => must be affected by magnetic field => must be charged particles (*) 1930 Rossi: Air-showers; soft and hard component. (absorbed by 1cm Pb | penetrates 1m Pb) 1931 Dirac postulates e + (from QED) 1932 Anderson identifies e + in air showers ‘B irth of Particle Physics’

6 Graz, 29.Nov.2007A.Biland: Cosmic Rays6 (*) Clay indicated in 1926 that CR must be charged particles. But (at least in USA) dispute about charged particles vs. gamma-rays continued for many years Millikan vs. Compton ==> The New York Times headline in Dec. 1932:

7 Graz, 29.Nov.2007A.Biland: Cosmic Rays7 CR History 1935 Yukawa postulates ‘Meson’ (m ~300m e ) 1937 Anderson & Neddermeyer find. ‘Mesotron’ in showers (m ~ m e ). (- 1947) can’t be Yukawa particle 1938 Auger detects ‘large showers’ >500m 2. ==> Energy >1000 TeV (LHC: 14TeV ) 1947  +- found in showers =>Yukawa part.. ==> Mesotron is new particle class:  1949  0 found in showers

8 Graz, 29.Nov.2007A.Biland: Cosmic Rays8 Primary cosmic particle Primary cosmic particle Atmosphere Air shower (secondary particles) particles) Air shower (secondary particles) particles)  ±   ±     o    -> e + e - ->  … ~ 40 km ~ 15 km

9 Graz, 29.Nov.2007A.Biland: Cosmic Rays9 Since ~1950 : - Accelerators ----> SM - Understanding of shower development (Monte Carlo) - Satellites ==> more Information about Primary cosmic Radiation: -Mainly p and charged Ions -Power law, but ‘knee’ ~10 15 eV and ‘ankle’ ~10 18 eV Energy range >12 decades Flux range >32 decades

10 Graz, 29.Nov.2007A.Biland: Cosmic Rays10 Since ~1950 : - Accelerators ---> SM - Understanding of shower development (Monte Carlo) - Satellites ==> more Information about Primary cosmic Radiation: I(E) ~ E –  -Mainly p and charged Ions -Power law, but ‘knee’ ~10 15 eV and ‘ankle’ ~10 18 eV Energy range >12 decades Flux range >32 decades

11 Graz, 29.Nov.2007A.Biland: Cosmic Rays11 ( History ) 1930: Pauli postulates 1956: Cowan & Reines find (Reactor) Since 1965: Davis searches for solar flux factor ~3 too low (Astro) 1987: first (only) extrasolar (extragalagtic) -source seen: SN-1987A (Astro) 1989: exist three generations <45GeV Acceler. 1998: -oszillation ==> -mass from air-shower !!! (CR !!!)

12 Graz, 29.Nov.2007A.Biland: Cosmic Rays12 - History - Direct CR Observations; ‘low’ Energy - Indirect CR Observations; ‘high’ Energy - Possible CR Sources & Accelerators

13 Graz, 29.Nov.2007A.Biland: Cosmic Rays13 CR-particles with E < ~10TeV can (and should) be observed above atmosphere Direct observations Solar modulation Direct CR Observation Below 20 GeV: ‘solar modulation’ shielding by the (variable) solar wind and B-field must be taken into account

14 Graz, 29.Nov.2007A.Biland: Cosmic Rays14 Effect of Solar Shielding measured proton flux above (south) pole compared to calculated flux outside Heliosphere ==> difficult to compare measurements... Depending on solar activity, CR flux <20GeV can vary by more than 20%

15 Graz, 29.Nov.2007A.Biland: Cosmic Rays15 CR Abundance Chemical composition of CR shows good agreement with ‘metal’ ratios in interplanetary matter [IPM] even/odd structure: Binding Energy Large Li, Be, B, F, ‘sub-Fe’ too much in CR or too few in IPM ? CR ‘solar system’ (IPM) ~85% p ~12% He ~ 2% e - ~ 1% ‘metals’ ( E < 3GeV)

16 Graz, 29.Nov.2007A.Biland: Cosmic Rays16 integr. CR flux Solar minimum Solar maximum Abundance vs. Solar Activity While total CR flux varies with solar activity, rel. abundance stays constant ==> difference not from solar modulation...

17 Graz, 29.Nov.2007A.Biland: Cosmic Rays17 lifespan of a star with 25 solar masses: <10 7 y

18 Graz, 29.Nov.2007A.Biland: Cosmic Rays18 Production of Heavy Elements Main fusion-processes in (heavy) stars: 4 p 3 4 He 12 C +2p 12 C + 4 He 12 C + 12 C 16 O + 16 O …  4 He 12 C 14 N 16 O 20 Ne 4 He 23 Na p 24 Mg 28 Si 4 He 31 P p 32 S No (major) process to produce Li,Be,B,F  Suppressed in ‘standard’ matter Do CR-sources produce non- standard matter? + e -,e +,, ..

19 Graz, 29.Nov.2007A.Biland: Cosmic Rays19 Our Galaxy ~3  G  p: 10GeV r ~ pc eV r ~ r gal  (low-energy) CR trapped in Galaxy Interstellar Matter [ISM]:  ISM ~ 1 1 H/cm 3 ‘Rigidity’: momentum / charge [GV]  particles with same rigidity follow same trajectory in B-field 1pc=3.26Ly

20 Graz, 29.Nov.2007A.Biland: Cosmic Rays20 Spallation CR does not travel in vacuum: e.g. 12 C CR + 1 H ISM  10 B CR + X (X: p,  0  ,  +   + m  e + e m ) known cross-section (measured in lab): need ~6 g/cm 2 ISM to be traversed to explain CR abundance (C/B ratio)  ISM ~ g/cm 3 ==> CR travels ~ cm ~1 Mpc ‘secondary’‘primary’

21 Graz, 29.Nov.2007A.Biland: Cosmic Rays21 Propagation Model Goal: One model should explain all ratios, as well as antiproton- and positron- rates and diffuse gamma-flux (  0 ) Unknown details about our galaxy (exact ISM distribution, B-field, …) and CR-sources do automatically cancel if looking only at ratios !!!

22 Graz, 29.Nov.2007A.Biland: Cosmic Rays22 Leaky Box Model Occurrence for each Isotope i at Energy E: Isotope creation by Spallation or radioact. decay from Isotope k Isotope loss by: Collision | Radioact. with ISM | decay Acceleration at Source(s) Higher Energy particles can escape B-field easier, i.e. average ‘age’ of high-energy CR lower  less secondaries Energy dependent leaking out of magn. Bottle

23 Graz, 29.Nov.2007A.Biland: Cosmic Rays23 ‘extended’ Models ‘Nested Leaky-Box’: Strong B-field close to sources  CR must first leak-out source region (probably  >  ISM ) ‘Reacceleration’: CR that is accelerated at sources does already contain secondaries from ‘older’ sources

24 Graz, 29.Nov.2007A.Biland: Cosmic Rays24 ‘extended’ Models ‘Diffusion Model’: assume more physical escape- mechanism than just ‘leakage’  predict (small) density gradients  expect (small) anisotropies Others (E-loss by Ionisation, Radiation, …)

25 Graz, 29.Nov.2007A.Biland: Cosmic Rays25 B/C Ratio Reference fit, to be applied to other ratios Problems: -large experim. errors -disagreement between exp. ==> can not really test models

26 Graz, 29.Nov.2007A.Biland: Cosmic Rays26 Calculated Abundances ~1GeV/Z no Li, Be, B at source >50% of C,O,Mg Si,... destroyed by spallation

27 Graz, 29.Nov.2007A.Biland: Cosmic Rays27 Direct Measurement of CR Age Secondary Isotopes with lifetime  ~  esc can be used to directly measure the age of CR e.g.CR could stay for long time in regions with low  ISM and high B ? need more precise measurements...

28 Graz, 29.Nov.2007A.Biland: Cosmic Rays28 Some Actual Results Positron Flux need more precise measurements... excess ???

29 Graz, 29.Nov.2007A.Biland: Cosmic Rays29 Some Actual Results e + and anti-p could also be produced in decays of (hypothetical) dark-matter particles; should result in different energy spectra than in CR predictions ==> need much more precise measurements... [even if most CR physicists are more interested on the highest energy questions... ]

30 Graz, 29.Nov.2007A.Biland: Cosmic Rays30 direct cosmic ray Balloons (mainly in Antarctica) e.g.: BESS (since 1992, ~3d/year 100d/y planned) PAMELA (on russian Satellite; launch 15.June 2006) (20XY) put particle physics detectors outside of the atmosphere Satellites:

31 Graz, 29.Nov.2007A.Biland: Cosmic Rays31 AMS-02 Predicted performance … p-flux He-flux

32 Graz, 29.Nov.2007A.Biland: Cosmic Rays32 AMS-02 ==> search for new Physics

33 Graz, 29.Nov.2007A.Biland: Cosmic Rays33 Differential Fluxes Heavy elements (Fe) should show harder spectrum than light elements (He, C) because of shorter interaction length Are high-energy CR dominated by Fe instead of H ?

34 Graz, 29.Nov.2007A.Biland: Cosmic Rays34 - History - Direct CR Observations; ‘low’ Energy - Indirect CR Observations; ‘high’ Energy - Possible CR Sources & Accelerators

35 Graz, 29.Nov.2007A.Biland: Cosmic Rays35 Primary CR-Spectrum Above few 10 TeV: no longer possible to directly measure CR-particles: Flux too low ==> need too large detector CR-spectrum looks boring/feature-less except:

36 Graz, 29.Nov.2007A.Biland: Cosmic Rays36 Primary CR-Spectrum ~ 20 events..? galactic ? extragalactic ? confined not confined by gal.B-field

37 Graz, 29.Nov.2007A.Biland: Cosmic Rays37 ‘Air-Calorimeter’ Cannot use satellites or balloons to measure CR > 100 TeV: Use atmosphere as a ‘calorimeter’ Problems: -not constant density -not constant temperature -not constant composition (e.g. clouds) -… (and everything varies with time) -how to read it out ???

38 Graz, 29.Nov.2007A.Biland: Cosmic Rays38 Atmosphere Total atmosphere ~ 1000 g/cm 2 side remark: at 40km, still few g/cm 2 left For detailed calculations, have to take into account some local temperature and pressure variations (e.g: winter/summer !)

39 Graz, 29.Nov.2007A.Biland: Cosmic Rays39 CR + Atmosphere ? produce mainly  0,  +,  - do full MC study, but:

40 Graz, 29.Nov.2007A.Biland: Cosmic Rays40  0 in Atmosphere ? Decays immediately into 2 , [ c  =25.1nm ] producing electromagnetic (sub)showers pair-production Bremsstrahlung R~9/7 X 0 ~45g/cm 2 (in air, 20 o C)

41 Graz, 29.Nov.2007A.Biland: Cosmic Rays41  +- in Atmosphere ? decay:  + -->   + lifetime: c  ~ 8m Mass: 0.13 GeV ==> 150 GeV  +- : d=  c  =1150x8m ~9km ==> most would reach earth before decay but nuclear interaction (same as p or n) attenuation length in air: p,n ~120 g/cm 2  +- ~160 g/cm 2 ==> production of new p,n,  +-0

42 Graz, 29.Nov.2007A.Biland: Cosmic Rays42  +- in Atmosphere ? Upper atmosphere ~isothermal ==> ‘depth’[g/cm 2 ] ~ X e (-h/H), H~6.5km ==> E  +- >> 10 GeV: interaction before decay <~ 10 GeV: [ d < 600m ] decay before interaction ==> atmospheric , 

43 Graz, 29.Nov.2007A.Biland: Cosmic Rays43  +- in Atmosphere ? decay:  + -->  e e + ==> atmospheric e lifetime: c  ~ 600m Mass: 0.105GeV ==> 2 GeV  +- : d=  c  =19x600m ~11km ==> reach earth before decaying energy-loss: (Ionization, …) loose ~ 2GeV in atmosphere (1000g/cm 2 )

44 Graz, 29.Nov.2007A.Biland: Cosmic Rays GeV Showers:

45 Graz, 29.Nov.2007A.Biland: Cosmic Rays TeV Showers: (>1GeV)

46 Graz, 29.Nov.2007A.Biland: Cosmic Rays46 How to Readout ‘Calorimeter’ - Measure  (at sea-level or underground) - Measure shower-tails (at high altitudes) - Ionization --> Recombination Fluorescence light - Shower-particles relativistic ==> emit Cherenkov light ( nm) - (sound waves; radio waves; … ???)

47 Graz, 29.Nov.2007A.Biland: Cosmic Rays47 atmospheric  Best detectors: go to accelerator experim. also disadvantages: - not homogen. shielding (large access-shafts) - not homogen. inside (‘unneeded’ calorimeters) - … needed >10y to convince community to add cosmic-extensions

48 Graz, 29.Nov.2007A.Biland: Cosmic Rays48 atmospheric  Some results:  -spectrum (includ. syst. errors) p[GeV]

49 Graz, 29.Nov.2007A.Biland: Cosmic Rays49 atmospheric  Some results: compared with some nuclear interaction models predictions: Models or primary rate not correct ?

50 Graz, 29.Nov.2007A.Biland: Cosmic Rays50 atmospheric  Some results: comparison with models predictions: All models fail to predict highest multiplicity events ?!?!? (assumption: all primary are Protons or Iron ) (DELPHI) Similar results from L3+C & CosmoAleph

51 Graz, 29.Nov.2007A.Biland: Cosmic Rays51 Shower Tail: e.g. KASCADE Forschungszentrum Karlsruhe

52 Graz, 29.Nov.2007A.Biland: Cosmic Rays52 KASCADE: array Liquid scintillator plus photmultiplier for e,  Lead-absorber plus scintillator for 

53 Graz, 29.Nov.2007A.Biland: Cosmic Rays53 KASCADE some results Measured secondary flux vs. distance from shower center

54 Graz, 29.Nov.2007A.Biland: Cosmic Rays54 KASCADE some results Unfolding of chemical composition for two nuclear- interaction models ==> disagreement

55 Graz, 29.Nov.2007A.Biland: Cosmic Rays55 p or Fe Primaries ??? Difficult to judge … shower maximum

56 Graz, 29.Nov.2007A.Biland: Cosmic Rays56 AGASA Similar principle as KASCADE, but much larger area (less dense sampling) ==> measure >>10 15 eV

57 Graz, 29.Nov.2007A.Biland: Cosmic Rays57 GZK-cutoff ? Interaction of CR-protons with CMB: p UHE +  CMB -->  + --> p +  0 --> n +  + E threshold ~ eV   ~ 2x cm 2  CMB ~ 400 cm -3 ==> must come from ‘near’ sources (few Mpc) (i.e. local cluster ???) 15 evts ???

58 Graz, 29.Nov.2007A.Biland: Cosmic Rays58 Fly’s Eye / HiRes Completely different technique: Measure fluorescence of shower shower particles ionize air ==> recombinat. ==> fluorescence light (emitted in all directions)

59 Graz, 29.Nov.2007A.Biland: Cosmic Rays59 Fly’s Eye / HiRes First proposal: 1967 Major improvement: stereo measurements

60 Graz, 29.Nov.2007A.Biland: Cosmic Rays60 Fly’s Eye / HiRes HiRes does not confirm high trans-GZK flux observed by AGASA ?!!!!?!!! Could be, one of the observation techniques not well enough understood ????

61 Graz, 29.Nov.2007A.Biland: Cosmic Rays61 AUGER (south) Hybrid: water tanks (cherenkov) 1.5 km separation between neighbours 3000km 2 Status Oct x6 fluorescence telescopes

62 Graz, 29.Nov.2007A.Biland: Cosmic Rays62 AUGER (south) One of 1600 ‘ground stations’ 3000 gallons water, 3 Photomultipl., Electronics shower particles hitting station: produce cherenkov light in water; signal incl. GPS-time transmit. to center ==> shower reconstruction

63 Graz, 29.Nov.2007A.Biland: Cosmic Rays63 AUGER (south) One of 4x6 fluorescence telescopes: 440 Photo- multipliers each 11m 2 reflect.

64 Graz, 29.Nov.2007A.Biland: Cosmic Rays64 AUGER (south) black circles: all events >10 18 eV seen by AUGER (3 o error) red stars: position of nearby AGNs (<200Mpc) ==> seem correlated ==> nearby AGNs could be sources of >10 18 eV particles ==> no problem with GZK Science,

65 Graz, 29.Nov.2007A.Biland: Cosmic Rays65 even larger... Planned experiments: -Telescope Array TA (extend HiRes with ground stations similar to AUGER, but in north -AUGER North (3x larger than South) (similar to TA... groups do not want to combine... -EUSO search for fluorescence light from space huge area, but light-pollution problematic

66 Graz, 29.Nov.2007A.Biland: Cosmic Rays66 EUSO Look from ISS to earth Catch Fluores.& Cherenkov light from showers

67 Graz, 29.Nov.2007A.Biland: Cosmic Rays67 - History - Direct CR Observations; ‘low’ Energy - Indirect CR Observations; ‘high’ Energy - Possible CR Sources & Accelerators

68 Graz, 29.Nov.2007A.Biland: Cosmic Rays68 Key Questions Distribution of sources: - few bright point-like sources ? - many faint sources/ diffuse ? Type of sources: - astrophysical (“stars”,fields) ? - new physics (decay of heavy part.) ? Location of sources: nearby (solar system) ? galactic? extragalactic? universal?

69 Graz, 29.Nov.2007A.Biland: Cosmic Rays69 Main Problem charged particles are deflected by all kinds of magnetic fields ==> can not be traced back to their origin

70 Graz, 29.Nov.2007A.Biland: Cosmic Rays70 Location of Sources From p+X -->  0 +Y,  0 -->   Search for  with characteristic spectra (mainly at rather low energies...) ==> 1) ~same CR everywhere in our Galaxy ==> (probably) not local/solar origin 2) far less CR in LMC (Large Magellanic Cloud) ==> not extragalactic/universal origin

71 Graz, 29.Nov.2007A.Biland: Cosmic Rays71 Location of Sources From magnetic field strengths: ==> [for GeV … TeV energies] 1) CR can enter/escape solar system ==> (probably) not solar origin 2) CR confined/shielded by galactic field ==> not extragalactic origin

72 Graz, 29.Nov.2007A.Biland: Cosmic Rays72 Location of Sources Most probably, main component of CR has galactic origin (arguments not valid for highest energies: - low contribution to  0 production - can escape/enter galactic field ==> highest energy CR probably extragal.)

73 Graz, 29.Nov.2007A.Biland: Cosmic Rays73 CR Power Requirements Power needed to maintain galactic CR: CR Energy-density: ~1eV / cm 3 CR age GeV): ~10 7 years (CR density ~stable >10 8 years ) L = (Volume)*(E-density)/(lifetime) ~  (15kpc) 2 (200pc) * 1eVcm -3 / 10 7 y ~ erg/s = J/s

74 Graz, 29.Nov.2007A.Biland: Cosmic Rays74 Supernova (SN) Already 1911 (before Hess showed extraterrestrial origin !) Zwicky postulated SN as sources for CR ! Kinetic Energy emitted by typ-II SN: Typically, ~10M o ejected, v~ cm/s On average: 1 SN / 30 years in our Galaxy ==> L SN ~ erg/s = J/s ==> have to convert few% of kinetic SN Energy into CR-Energy (reasonable ?) (more than 99% of total SN Energy emitted in form of neutrinos ==> Astronomy?!) But SN do not accelerate to CR energies..

75 Graz, 29.Nov.2007A.Biland: Cosmic Rays75 Supernova Remnant (SNR) Models show that (type-II) Supernovae usually produce two shock waves; (shell-type SNR) Energy loss at outer shock:  E 1 = 2m(-v 1 v+v 1 2 ) Energy gain at inner shock:  E 2 = 2m(v 2 v+v 2 2 )  E=  E 1 +  E 2 =2m(v 1 2 +v 2 2 +v(v 2 -v 1 ))  E/E ~ (v 2 +v 1 )/v

76 Graz, 29.Nov.2007A.Biland: Cosmic Rays76 Supernova Remnant Shock waves from SN have typical lifetime  ~ 1000y Energy gain per cycle: E n+1 =E n (1+  ) Escape Probab. per cycle: P ===> spectral index  ~ P/ ... ===> Supernova Remnants (SNR) seem excellent accelerators up to ~100 TeV (B-field ~0.1G ==> larmor radius too large...)

77 Graz, 29.Nov.2007A.Biland: Cosmic Rays77 Neutron Star / Pulsar Rotational Energy: E rot ~ J Energy loss (deceleration) :  E~ J/s Lifetime:  ~ 10 8 y #NS in Galaxy: n ~ 10 6 ==> total Energy emitted: n  E ~ J/s compare  E CR ~ J/s ==> NS could maintain CR (if acceleration!) (but Pulsars expected to emit this energy mainly by gravity waves..)

78 Graz, 29.Nov.2007A.Biland: Cosmic Rays78 Neutron Star / Pulsar Fast rotation, huge B-field ( G) If B tilted relative to  ==> spinning B-field --> strong E-field max. value: E ~ V/m i.e. charged particle can gain 1000TeV/m ! NS can transform E rot into E kin … But: can CR escape NS region ???

79 Graz, 29.Nov.2007A.Biland: Cosmic Rays79 Neutron Star / Pulsar Problem: huge B-field ==> Larmor-radius) r[km] = E[MeV] / 30*B[G] i.e. E = 100 TeV = MeV B = G r = km = 3mm !!! ==> particles can not escape ! (?) But: ‘polar cap’ and ‘outer gap’ models...

80 Graz, 29.Nov.2007A.Biland: Cosmic Rays80 Binary Neutron Star (BNS) Macroscopic mass-flow from normal (or giant) star to companion Neutron Star

81 Graz, 29.Nov.2007A.Biland: Cosmic Rays81 Binary Neutron Star Constant matter flux from star speeds up the rotation of Pulsar ->‘millisecond Pulsar’ Known to emit ~10 31 J/s (per system) in X-ray If similar amount of Energy emitted in CR ==> few 100 Binaries could make major contribution to total CR Energy

82 Graz, 29.Nov.2007A.Biland: Cosmic Rays82 Binary Neutron Star Energy gain in Binary system: Gravitational acceleration of proton:  E = - ∫ G m p M NS /r 2 dr = G m p M NS /R NS ~ 70 MeV But mass flow >>10 30 protons / second ==> huge total energy to be emitted ev. secondary acceleration in shockwaves? R NS Inf.

83 Graz, 29.Nov.2007A.Biland: Cosmic Rays83 Pulsar Wind Nebula (PWN) Many Supernove remnants look not shell-type, but rather chaotic (e.g. Crab) Shell structure disturbed by outflow from central pulsar But shock waves still exist (or even enhanced) ==> PWN cosmic accelerators like SNR, but also possibility for additional processes at NS PWN from old pulsars could also collide with far away clouds ==> shock waves ==> acceleration

84 Graz, 29.Nov.2007A.Biland: Cosmic Rays84 Starburst Regions (SB) Galactic regions with high gas density: ==> many new stars created locally ==> high star density ==> combined stellar wind ? ==> many heavy stars ==> many SN / Pulsars / Binaries ==> stronger CR flux than average ???

85 Graz, 29.Nov.2007A.Biland: Cosmic Rays85 Active Galactic Nucleii (AGN) Mass flow into huge black hole (M~10 9 m  ) in the center of a large galaxy (black hole in center of our galaxy: M~ m  ) Accretion disk and two jets observed in several AGNs (jets > megaparsec ! ) ‘Blazar’: jet pointing to observer

86 Graz, 29.Nov.2007A.Biland: Cosmic Rays86 Starburst Galaxies Galaxies with very high star-forming rate (probably: high density/turbulent gas regions induced by recent galaxy-collision) ==> much higher CR flux, high leakage ???

87 Graz, 29.Nov.2007A.Biland: Cosmic Rays87 Gamma Ray Bursts (GRB) -Very short flash of extremely high X-ray flux [highest energy phenomena since Big Bang...] -Observe: ~1 GRB/day -Extragalactic Origin many have huge redshifts One GRB class seems correlated with SN (---> Black Hole ?) Other models: - Neutron Star mergers; - Black Hole mergers; - … Enormous energy released, but not known if also able to accelerate to CR energies...

88 Graz, 29.Nov.2007A.Biland: Cosmic Rays88 Galaxy Clusters High density of (large) Galaxies ==> combined ‘Galactic Wind’ could form intense shock waves with IGM ==> high extragalactic CR flux ???

89 Graz, 29.Nov.2007A.Biland: Cosmic Rays89 Cosmic Accelerators Problem: What is accelerating? But also: Why so little structure in CR spectrum ???

90 Graz, 29.Nov.2007A.Biland: Cosmic Rays90 Cosmic Accelerators Different classes of accelerators might act on completely different time scales: Typical values: GRB: ~10 -7 y (if accelerator) AGN (flares): ~10 -3 y SNR: ~10 3 y Neutron Stars/PWN: ~10 7 y (remind: CR flux featureless and ~stable since 10 8 y) (probably also different energy scales....)

91 Graz, 29.Nov.2007A.Biland: Cosmic Rays91 Conclusion CR were (and still are) important tools to investigate physics at unprecedented energy learned a lot about the physics of CR since their discovery many important experiments going on but still many open questions and much room for good peoples with brilliant ideas [ ?!!? entering ‘decade of astro-particle physics’ ?!!? ]


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