Gamma-ray emission from the Perseus cluster of

galaxies observed with MAGIC

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

The Perseus cluster of galaxies (Abel 426)

• Brightest galaxy cluster in X-ray • Typical cool-core Cluster • Dominant central galaxy: NGC 1275• CR - ICM interactions expected

• Brightest galaxy cluster in X-ray • Typical cool-core Cluster • Dominant central galaxy: NGC 1275• CR - ICM interactions expected

Chandra – X-ray (0.5- 7keV) Blackbird Obs. - Optical

NGC 1275

5’ (~100 kpc)Fabian et al. 2011

3C 84 (VLBA – 15GHz)Distance: ~73 Mpc (z=0.018)

5

pc

MAGIC Telescopes in 2009-2011

85 m

At Observatorio del Roque de los Muchachos (La Palma), Altitude = 2200 m

3.5°ø 3.5°ø

17m ø

17m ø

Sensitivity: 0.8% crab in 50hEnergy threshold: ~50 GeV

576 Pixels 1039 Pixels

Map of the Perseus cluster with MAGIC

NGC 1275

IC 310

Energy >150 GeV

85h of Stereo observation from 2009 to 2011 NGC 1275 spectrum(2010-2011)

• Two point-like sources detected:- NGC 1275: the central galaxy- IC 310: a head-tail radio galaxy ??

• First “cluster” of TeV galaxies !

• Two point-like sources detected:- NGC 1275: the central galaxy- IC 310: a head-tail radio galaxy ??

• First “cluster” of TeV galaxies !

Sig

nif

ican

ce

[σ]

IC 310 spectrum(2009-2010)

Spectral index = -2.0

Spectral index = -4.1

Aleksić et al. ApJ. 723 (2010) L207

Aleksić et al. A&A 539 (2012) L2

Aleksić et al. A&A 541 (2012) A99

NGC 1275 (3C 84): a complex object

Hubble Space Telescope image

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°

Supermassive Black Hole

sub-pc

15 m

as /

5

pc

60” (~20 kpc)

http://images.nrao.edu/263

Detection of NGC 1275 with MAGIC

Source discoveryin 2010-2011 data

Recent re-analysis of 2009-2010 data

PRELIMINARY

Flux >100 GeV

Aleksić et al. A&A 539 (2012) L2

Flux >100 GeV

NGC 1275 spectrum in 2009-2010

Compatible with 2010-2011 spectrum:f0 = 3.1±1.0 and α = -4.1±0.7

NGC 1275: 39h from Oct. 2009 to Feb. 2010

NGC 1275 MWL light curves

C1

C2C3

VLBA (MOJAVE) 15GHz

~1 pc

S. Partini

2009 2010 2011

NGC 1275 SED

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 ?

Abdo at al. (2009) ApJ 699 31

Archival SED Fermi-LAT

MAGIC

Spectral break or cut-off at ~50 GeV Spectral break or cut-off at ~50 GeV SSC model like BL Lac objects ? SSC model like BL Lac objects ?

MAGIC (2010-2011)

IC 310: Head-tail radiogalaxy or Blazar ?

Radio - WENSS

Neronov et al (2010)

NRAO image, VLA

Kadler et al. (2012)

IC 3101.4 GHz

NGC 1265Head-tail radio galaxy:- Jets bent due to intra-cluster motion - NGC 1265 is a typical example

IC 310 originally classified "head-tail" but no evidence of jet bendingBlazar-like radio morphology of inner jetNo counter-jet: θ ≤ 38°

IC 310 originally classified "head-tail" but no evidence of jet bendingBlazar-like radio morphology of inner jetNo counter-jet: θ ≤ 38°

IC 310 light curve

Daily Light curve

High state

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)

Compact emission region

Confirm Blazar-like behavior

IC 310 spectrum

Very hard spectrum: Intrinsic spectral index ≤ 2 No variation of the spectral index !

Γint = 1.85 ± 0.11stat ± 0.2syst

Γint = 1.81 ± 0.13stat ± 0.2syst

EBL model: Dominguez et al. 2011

Origin of IC 310 emission ?

• 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

• 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

Fermi galaxy divideDermer, arXiv:1202.2814

Archival IC 310 SED

IC 310 ?

(2009-2010)(2009-2010)

Gamma-ray from Hadron Cosmic Rays

Perseus radio mini-halo

14

Cosmological Simulation:- High energy gamma-ray emission- Spectral index: α= ~2.2

Synchrotron Radiation from

cosmic electrons

Synchrotron Radiation from

cosmic electrons

Hadronic model

• 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)

Magnetic

field

γ + γICM

Typical cool core cluster: ~16 μG(from Faraday RM studies)

Constraints from MAGIC observation

IC 310

No gamma-ray signal above 630 GeVfrom the central region (r < 0.15°)

where ~60% of CR signal is expected

MAGICUpper limits

Minimal Flux of the hadronic model

Energy >630 GeV

Flux ULs reach optimistic CR model(50% acceleration efficiency in formation shocks)

Sig

nif

ican

ce [

σ]

CR / Thermal pressure ratio

≤ 1-2 %

CR models

from cosmologic

al simulations

CR models

from cosmologic

al simulations Hadroni

c model of radio

mini-halo

Hadronic model of radio

mini-halo

Central B-field > 4-9 μG

Aleksić et al. A&A 541 (2012) A99

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.

• 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.