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Gamma-ray emission from the Perseus cluster of galaxies observed with MAGIC

Gamma-ray emission from the Perseus cluster of galaxies observed with MAGIC.

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Gamma-ray emission from the Perseus cluster of galaxies observed with MAGIC

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  1. Gamma-ray emission from the Perseus cluster of galaxies observed with MAGIC P. Colin*,D. Eisenacher, D. Hildebrand, S. Lombardi, E. Lindorfs, D. Paneque, S. Partini, F. Prada, J. Sitarek, F. Zandanel for the MAGIC collaboration, and T. Dauser, M. Kadler, F. Krauss, J. Kataoka, C. Pfrommer, A. Pinzke, Y. Takahashi, S. Wilbert, J. Wilms *Max-Planck-Institut für Physik

  2. The Perseus cluster of galaxies (Abel 426) Chandra – X-ray (0.5- 7keV) Blackbird Obs. - Optical NGC 1275 3C 84 (VLBA – 15GHz) Distance: ~73 Mpc (z=0.018) 5’ (~100 kpc) Fabian et al. 2011 • Brightest galaxy cluster in X-ray • Typical cool-core Cluster • Dominant central galaxy: NGC 1275 • CR - ICM interactions expected 5 pc

  3. MAGIC Telescopes in 2009-2011 Sensitivity: 0.8% crab in 50h Energy threshold: ~50 GeV 3.5°ø 3.5°ø 17m ø 576 Pixels 1039 Pixels 17m ø 85 m At Observatorio del Roque de los Muchachos (La Palma), Altitude = 2200 m

  4. Map of the Perseus cluster with MAGIC NGC 1275 spectrum (2010-2011) 85h of Stereo observation from 2009 to 2011 Energy >150 GeV Significance [σ] Spectral index = -4.1 NGC 1275 Aleksić et al. A&A 539 (2012) L2 IC 310 IC 310 spectrum (2009-2010) Aleksić et al. A&A 541 (2012) A99 • Two point-like sources detected: • NGC 1275: the central galaxy • IC 310: a head-tail radio galaxy ?? • First “cluster” of TeV galaxies ! Spectral index = -2.0 Aleksić et al. ApJ. 723 (2010) L207

  5. NGC 1275 (3C 84): a complex object Supermassive Black Hole 15 mas / 5 pc sub-pc http://images.nrao.edu/263 • Unclear classification: • Seyfert 1.5 in Veron&Veron (2006) • - FR I radio galaxy ? • - Strong variability: BL Lac suggested in 1978 • - Counter-jet visible: Jet orientation = 30°- 55° 60” (~20 kpc) Hubble Space Telescope image

  6. Detection of NGC 1275 with MAGIC PRELIMINARY Source discovery in 2010-2011 data Recent re-analysis of 2009-2010 data Aleksić et al. A&A 539 (2012) L2 Flux >100 GeV Flux >100 GeV

  7. NGC 1275 spectrum in 2009-2010 NGC 1275: 39h from Oct. 2009 to Feb. 2010 Compatible with 2010-2011 spectrum: f0 = 3.1±1.0 and α = -4.1±0.7

  8. NGC 1275 MWL light curves 2010 2009 2011 VLBA (MOJAVE) 15GHz S. Partini C1 C2 C3 ~1 pc

  9. NGC 1275 SED Spectral break or cut-off at ~50 GeV SSC model like BL Lac objects ? Fermi-LAT Archival SED MAGIC MAGIC (2010-2011) Abdo at al. (2009) ApJ 699 31 • Broad-band emission model: • Fast variability: need contemporaneous data ! • Compact emission region: inner-jet ? • Synchrotron peak not well defined • Need HST image to resolve the inner-jet optical emission ?

  10. IC 310: Head-tail radiogalaxy or Blazar ? NGC 1265 NRAO image, VLA • Head-tail radio galaxy: • Jets bent due to intra-cluster motion • NGC 1265 is a typical example Radio - WENSS IC 310 1.4 GHz Neronov et al (2010) Kadler et al. (2012) IC 310 originally classified "head-tail" but no evidence of jet bending Blazar-like radio morphology of inner jet No counter-jet: θ≤ 38°

  11. IC 310 light curve • Variability: • Published results: • Hints of week and month scale variability • Year scale confirmed in Aug 2010- Jan 2011 data • New analysis: • (Poster of Eisenacher et al) • - Day scale variability established (>5σ) Daily Light curve High state Compact emission region Confirm Blazar-like behavior

  12. IC 310 spectrum Very hard spectrum: Intrinsic spectral index ≤ 2 No variation of the spectral index ! EBL model: Dominguez et al. 2011 Γint = 1.85 ± 0.11stat ± 0.2syst Γint = 1.81 ± 0.13stat ± 0.2syst

  13. Origin of IC 310 emission ? Archival IC 310 SED (2009-2010) (2009-2010) Fermi galaxy divide Dermer, arXiv:1202.2814 • Very extreme BL Lac object • Need very low accretion rate • Powerful enough for the kpc structure ??? • Misaligned extreme BL Lac • Mrk 501 or H 1426+428 with ~10° angle ? • M87 type models ? • Multi-zones jet • Black Hole magnetosphere • Hadronic models IC 310 ?

  14. Gamma-ray from Hadron Cosmic Rays • Theoretical predictions: • CR acceleration in cluster formation (merging) shocks • CR injection by the AGNs and galaxies of the cluster • CR accumulation in the cluster (lifetime ≈ Hubble time) • Observation: Radio Halo (mini-Halo) from High energy electrons • Re-acceleration of existing electrons by MHD turbulences ? • Secondary electrons from CR/ICM interactions (Hadronic model) Perseus radio mini-halo Hadronic model Magnetic field Synchrotron Radiation from cosmic electrons • Cosmological Simulation: • High energy gamma-ray emission • Spectral index: α= ~2.2 γ + γ ICM 14

  15. Constraints from MAGIC observation Energy >630 GeV No gamma-ray signal above 630 GeV from the central region (r < 0.15°) where ~60% of CR signal is expected Significance [σ] IC 310 Flux ULs reach optimistic CR model (50% acceleration efficiency in formation shocks) CR models from cosmological simulations CR / Thermal pressure ratio ≤ 1-2 % MAGIC Upper limits Hadronic model of radio mini-halo Central B-field > 4-9μG Minimal Flux of the hadronic model Typical cool core cluster: ~16 μG (from Faraday RM studies) Aleksić et al. A&A 541 (2012) A99

  16. Summary • MAGIC searches for new classes of VHE emitter • Deep observation of Perseus cluster (85h) • Discovery of 2 peculiar AGNs • Double the TeV radio galaxies known (2 → 4) • Blazar-like emissions (but unusual - misaligned ?) • Need MWL campaign to probe emission models • No signal from CR-ICM interactions • First constraints on CR physics in cluster • Interesting B-constraint in Hadronic model of radio (mini-)Halo, perspective to probe this model with more observation or with CTA.

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