Cosmic Ray Studies with MAGIC
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Cosmic Ray Studies with MAGIC S. R. Gozzini1 on behalf of the MAGIC Collaboration 1Deutsches Elektronen-Synchrotron (DESY) 2013 S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 1 / 28 The Connection of γ rays with cosmic rays All sites where protons and nuclei are accelerated and then interact radiating photons are candidate sources 1 pN → π0, η0 + X → γγ + X like in supernova remnant with molecular clouds 2 pγ → ∆, .... + X → γγ + X like in jets of active galactic nuclei S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 2 / 28 The Connection of γ rays with cosmic rays Cosmic ray electrons and positrons appear as diffuse emission; search cannot use direction information Lifetime 105 ly ⇒ propagation distance 1 kpc (they radiate photons through synchrotron, ionisation, bremsstrahlung or IC scattering) Spectrum is steeper than hadronic cosmic rays e±, γ generate identical shower. Off-source observations or moon shadowed S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 3 / 28 Extragalactic cosmic ray sources Candidate accelerators are AGN (engine: presumed super-massive black hole; feature: collimated relativistic jets), further classified as blazars (BL Lacs and flat spectrum radio quasars) others (radio galaxies, clusters of galaxies ....) Spectral energy distribution contains information about possible proton component S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 4 / 28 Galactic cosmic ray sources Supernova remnants are one of the preferred candidates Magneto-hydrodynamic interactions of the explosion blast wave with interstellar material originate strong shocks Some fraction of energy transferred into magnetic field Some into accelerated, non-thermal particles (Fermi acceleration) Radiation detected from radio to TeV. radio IR near IR X rays S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 5 / 28 Acceleration of particles in SNRs Free expansion phase (directly after the explosion) Sedov-Taylor or adiabatic expansion phase Radiative cooling Dispersion phase Fermi acceleration: scattering between particles and a shock front (charged matter, magnetic fields). Direct search or cosmic rays astrophysics is not feasible at TeV energies: deflections are large. S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 6 / 28 The detection of γ rays with telescopes Extensive showers induced by photons in the atmosphere emit Cherenkov light. Light is caught by a photomultiplier camera in imaging atmospheric Cherenkov telescopes (pointed according to scheduled observations) filter out background made of: atmospheric hadrons, muons, night sky light, electronic noise. reconstruct arrival direction, energy spectrum, and resolve morphology when possible. S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 7 / 28 The MAGIC telescopes MAGIC is a stereo system of two dishes (17 m diameter) located on La Palma (Canaries) with energy window: 50 GeV - 30 TeV. Its performance at energies above > 300 GeV: sensitivity 0.8% Crab in 50 hours angular resolution 0.07◦ energy resolution 17% field of view 3.5◦ S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 8 / 28 The supernova remnant W51C Sited in molecular complex with two nearby star forming regions and candidate pulsar wind nebula CX0J192318.5. age: 30000 years (Sedov phase) magnetic field of the order of 100 µG surrounding photons: cosmic microwave background, heated dust, reprocessed radiation, light of stars surrounding molecular material, partly ionised; observed interaction with the shell front of W51C with W51B Crucial point is identifying hints of hadronic origin in γ ray emission Cut-off at pion mass Morphology of the emission, molecular clouds Models of spectral energy distribution, for identifying what species of particels are responsible for the emission. S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 9 / 28 Maps in HI and CO X rays contours with shocked HI (21 cm) and CO and HCO (H2) from Koo & Moon ApJ475 (1997) Koo & Moon ApJ485 (1997) S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 10 / 28 Map in γ rays (in two energy ranges) Maximum of the emission coincides with interaction between the shock front and the molecular cloud in nearby star forming region 0.8 0.8 1.4 1.4 14.6 14.6 0.7 0.7 W51A 1.2 W51A 1.2 0.6 14.4 0.6 14.4 W51B W51B 1 0.5 0.5 14.2 0.8 14.2 0.8 0.4 0.4 DEC [deg] W51C 0.6 DEC [deg] W51C 0.6 0.3 0.3 14 14 0.4 0.4 0.2 0.2 13.8 13.8 0.1 0.1 0.2 0.2 PSF PSF 0 0 19.42 19.41 19.4 19.39 19.38 19.37 19.42 19.41 19.4 19.39 19.38 19.37 RA [h] RA [h] 300 GeV < E < 1 TeV E > 1 TeV Colours: γ ray emission measured with MAGIC [A&A 541 (2012)]; Pink contours: extension of Fermi source [ApJL, 706 (2009)]; green: radio S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 11 / 28 Map in γ rays (in two energy ranges) Maximum of the emission coincides with interaction between the shock front and the molecular cloud in nearby star forming region 0.8 1.4 14.6 14.6 0.7 1.2 14.4 0.6 14.4 1 0.5 14.2 14.2 0.8 0.4 DEC [deg] DEC [deg] DEC [deg] 0.6 [deg] DEC 0.3 14 14 0.4 0.2 13.8 13.8 0.1 0.2 PSF PSF 0 0 19.42 19.41 19.4 19.39 19.38 19.37 19.42 19.41 19.4 19.39 19.38 19.37 RA [h] RA [h] 300 GeV < E < 1 TeV E > 1 TeV Colours: γ ray emission measured with MAGIC [A&A 541 (2012)]; Pink contours: extension of Fermi source [ApJL, 706 (2009)]; green: 13CO S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 12 / 28 Spectral energy distribution 10-8 10-9 Synchrotron; B = magnetic field √ 3 ] 3e B LS (Eγ ) = ν ∞ dγ S(γ) ∞ dx K 5 (x) -2 mc 1 ν/νc 10-10 R R 3 cm -1 10-11 -12 dN/dE [erg s 10 2 E Radio [Moon and Koo ApJ, 475 (1997)] 10-13 ROSAT [Koo et al, ApJ, 447 (1995)] Fermi [ApJL, 706 (2009)] HESS [Proc. of 31st ICRC (2009)] MAGIC [AA, 541 (2012)] 10-14 10-5 100 105 1010 1015 E [eV] S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 13 / 28 Spectral energy distribution 10-8 Inverse Compton; T = temperature n = density -9 10 L 2 IC (Eγ ) = E 1∞ dγ 0∞ dν S(γ) b(ν, T , n) σ(γ,ν, Eγ ) R R ] -2 10-10 cm -1 10-11 -12 dN/dE [erg s 10 2 E Radio [Moon and Koo ApJ, 475 (1997)] 10-13 ROSAT [Koo et al, ApJ, 447 (1995)] Fermi [ApJL, 706 (2009)] HESS [Proc. of 31st ICRC (2009)] MAGIC [AA, 541 (2012)] 10-14 10-5 100 105 1010 1015 E [eV] S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 14 / 28 Spectral energy distribution 10-8 Bremsstrahlung; η = gas density -9 10 L 2 B (Eγ ) = E h 1∞ dγ S(γ) η σ(γ, Eγ ) R ] -2 10-10 cm -1 10-11 -12 dN/dE [erg s 10 2 E Radio [Moon and Koo ApJ, 475 (1997)] 10-13 ROSAT [Koo et al, ApJ, 447 (1995)] Fermi [ApJL, 706 (2009)] HESS [Proc. of 31st ICRC (2009)] MAGIC [AA, 541 (2012)] 10-14 10-5 100 105 1010 1015 E [eV] S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 15 / 28 Spectral energy distribution 10-8 Decay of π0 from hadronic interactions -9 dN Eγ dEπ 10 = c η ∞ σpp(Ep)Np (Ep)Fγ , Ep dEγ Eγ „ Ep « Ep R ] -2 10-10 cm -1 10-11 -12 dN/dE [erg s 10 2 E Radio [Moon and Koo ApJ, 475 (1997)] 10-13 ROSAT [Koo et al, ApJ, 447 (1995)] Fermi [ApJL, 706 (2009)] HESS [Proc. of 31st ICRC (2009)] MAGIC [AA, 541 (2012)] 10-14 10-5 100 105 1010 1015 E [eV] S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 16 / 28 Fits of spectral energy distribution Parameters in fits belong to different classes: constrained with measurements: B ambient magnetic field [Koo et al. (2010)] d distance of the source [Sato et al. (2010)] input: ae , ap electron, proton normalisation η particle density of cloud Se , Sp spectra (implicitly contain breaks, indices, cutoffs) output: amount of energy released in electrons and protons nature of acceleration process S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 17 / 28 Fit of broad-band data: main contribution from pion decay dN1011 protons dE1010 109 electrons 108 10-9 6 9 1000 10 10 1012 E 10-10 -11 ) 10 -2 cm -12 -1 10 /(erg s -13 ν 10 F ν -14 Archival data 10 This work pi0 decay -15 IC 10 Bremsstr. Synchrotron total 10-16 10-5 100 105 1010 1015 E/eV S. R. Gozzini (DESY) Cosmic Ray Studies with MAGIC the MAGIC Collaboration 18 / 28 Fit: main contribution from inverse Compton scattering 109 dN protons = electrons dE 7 10 105 10-9 1000 6 9 1000 10 10 1012 E 10-10 -11 ) 10 -2 cm -12 -1 10 /(erg s -13 ν 10 F ν -14 Archival data 10 This work IC -15 Synchrotron 10 Bremsstr.