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Astroparticle physics 2. The Milky Way interstellar medium and cosmic-rays

Astroparticle physics 2. The Milky Way interstellar medium and cosmic-rays. Alberto Carramiñana Instituto Nacional de Astrofísica, Óptica y Electrónica Tonantzintla, Puebla, México Xalapa, 3 August 2004. These presentations.

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Astroparticle physics 2. The Milky Way interstellar medium and cosmic-rays

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  1. Astroparticle physics2. The Milky Way interstellar medium and cosmic-rays Alberto Carramiñana Instituto Nacional de Astrofísica, Óptica y Electrónica Tonantzintla, Puebla, México Xalapa, 3 August 2004

  2. These presentations • Available (soon!) as http://www.inaoep.mx/alberto/cursos/ap2004_1a.ppt http://www.inaoep.mx/alberto/cursos/ap2004_1b.ppt http://www.inaoep.mx/alberto/cursos/ap2004_2.ppt http://www.inaoep.mx/alberto/cursos/ap2004_3.ppt http://www.inaoep.mx/alberto/cursos/ap2004_4.ppt

  3. The interstellar medium of the Galaxy • ISM: gas, dust, magnetic field, cosmic-rays. • Feedack: {gas (SF) stars (Winds, Sne) gas} • Stars enrich (& steer) gas; gas forms new stars. • Pressure equilibrium. Halo 300 pc Disk GC 15 kpc

  4. A little note: Oort’s limit • Statistical study of motion of stars in the Solar neighborhood: first evidence of “missing mass”. • Can be baryonic (or it can be non-baryonic...).

  5. ISM clouds • Most of the ISM (70%) is HI, H2, HII: • diffuse HI clouds:30 to 80 K, 100 to 800 cm-3, 1 to 100 M. • translucent molecular clouds:15 to 50 K, 500 to 5000 cm-3, 3 to 100 M, several pc accross. • giants molecular clouds: 20 K, 100 to 300 cm-3, up to 106 M, 50 pc • GMC cores :100 to 200 K, 107 to 109 cm-3, 10 to 1000 M, 0.05 to 1 pc. • Bok globules :10 K, n>104 cm-3, 1 to 1000 M, 1pc, (all?) harbour young stars in their center. • HII regions: ionized by massive near star.

  6. Dark clouds Brighter cloud!

  7. Stars • About 1011 of them in the Milky Way (Mg > 1.5 1011M). • Form, live and die: • M<8 M: pufff... • M>8 M: bang! • M>30 M: bang!? pufff? bang!!? SN 1987A

  8. Stellar remnants • Planetary nebula + white dwarf: • Vexp  100 km/s • Supernova remnant (SNR) + neutron star: • Vexp > 1000 km/s

  9. CO@2.6mm

  10. E  1 keV

  11. At 408 MHz

  12. Cosmic-rays • Energetic particles in Earth’s environment • Basic questions: • Energy? • Composition? • Origin? • Isotropy?

  13. Cosmic-rays: measured abundances • Charged particles: 99% nuclei + 1% electrons. • Heavy nuclei more abundant in CRs than solar. • {Li, Be, B} and {Sc, V, Ti,...} high C/O and Fe spallation • Cross sections spallation  X = 5 to 10 g cm-2 L  1000 kpc

  14. Cosmic-rays: energy spectrum • Power-law: • Secondaries (B) have steeper spectra than primaries (C,O).

  15. Cosmic-rays: energy density • Local ISM Spectrum inferred ucr 1eV cm-3 (0.83 for p alone) • CR and Galactic energetics: • Are SN the sources of (Galactic) CR? • Shock acceleration models: Fermi mechanism ok! • Need the smoking gun...

  16. Cosmic-rays: propagation • Cosmic-rays do not propagate in straight lines: trapped by Galactic magnetic field (average 3G) • Transport equation: • Leaky box model: • CR travel path: • Proton injection spectrum: • 10Be (mean life 3.9 Myrs) analysis: (Garcia-Muñoz, Mason & Simpson 1977)

  17. Galactic radio emission • Galactic radio emission = e-synchrotron • Inferred electron spectrum: 1 eV cm-3 • n(E)  E-2.14 for 70 MeV to 1200 MeV • n(E)  E-3.0 above 1 GeV • Electrons 1% of Earth’sCR spectrum.

  18. Cosmic-ray nuclei and matter • Galactic -ray emission model: • e-bremssthralung • pion production (secondary e produced) • e-inverse compton • Model needs HI & CO data input. Hunter et al. 1997

  19. Galactic -ray spectrum • 0 production spectrum 68 MeV bump • Galactic emission fairly well modelled. • Evidence for electrons and nuclei. Strong, Moskalenko & Reimer 2004

  20. Nearby galaxies • Only LMC detected as (weak) -ray source. • Limits on SMC, M31, nearby starburst cosmic-rays (E<1015 eV) are Galactic (local).

  21. Cosmic-ray and -ray sources • High energy sources must accelerate particles to produce -rays.

  22. Galactic -ray sources • Solar flare • Pulsars (aside: bound on photon mass) • Unidentified Galactic sources: young & old • SNR positional coincidences (so, maybe....) • young & old radio quiet pulsars • wind nebulae • microquasars

  23. Photon mass • Crab pulsar pulse coherent from (at least) 100 MHz to 1 GeV. • Pulse period = 33 ms. • Pulse broadening < 5% • Distance = 2 kpc (1 pc = 31015 m) • What is the limit on the mass of to photon?

  24. Cerenkov observations • Certain detection of Crab nebula. • Probable PSR 1706-44, Vela, SN1006. • Results not fully consistent (Č to Č, Č to EG) Weekes (2000)

  25. Kuiper et al. (2001) Crab spectrum • Nebula: can fit synchrotron + inverse Compton. • Pulsar: syncrotron + curvature + inverse Compton.

  26. Pulsar energetics: the Crab • Rotating neutron star: R* =10 km, M* =1.44 M , I = 1045 g/cm2 

  27. Pulsars • >1000 radio pulsars know • Power: up to few 1038 erg/s (Crab) per pulsar vs 2  1040 erg/s (CRs)  Probably sufficient • Pulsar models: pure electron acceleration • in vacuum: 1016 eV available; • in e+e- magnetosphere: only a “fraction” Romani 1994

  28. What do we need? • The hadronic 0 smoking gun! • And GLAST

  29. Very high energy cosmic-rays • Pulsar and Sne models can only reach 1015 eV (the knee) • At 100 TeV gyro-radius  thickness of Galactic disc. • To continue...

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