Presentation on theme: "R. M. Wagner: AGN observations with MAGIC – p.1 R. M. W AGNER Max-Planck-Institut für Physik, München on behalf of the MAGIC C OLLABORATION AGN Observations."— Presentation transcript:
R. M. Wagner: AGN observations with MAGIC – p.1 R. M. W AGNER Max-Planck-Institut für Physik, München on behalf of the MAGIC C OLLABORATION AGN Observations in the GeV/TeV Energy Range with the MAGIC Telescope
R. M. Wagner: AGN observations with MAGIC – p.2 Contents Blazars & jets – how can TeV observations help? MAGIC blazar observation activities Blazars observed by MAGIC, some highlights Markarian 421 1ES ES PG Markarian 501 Markarian 180 1ES BL Lacertae Conclusions 16 sources (incl M87) to date and counting seen in VHE -rays
R. M. Wagner: AGN observations with MAGIC – p.3 Jets observed under small angle Rapid variability at all wavelengths Most violent and rapid often in VHE High Doppler factors: amplified emission, deep insight into jet Kino et al. synchrotron peak Inverse Compton peak (Buckley 1999) Hadronic TeV Blazars | E>100 GeV Mkn 501 HEGRA, Kranich 2001 How can TeV observations help? -rays are crucial messengers: Dynamics of emission regions in the jets Study acceleration & energy loss timescales Decide: leptonic vs hadronic acceleration? -Hadronic models challenged by observed X/VHE correlations and by very rapid -ray variability -Variability needs to be explained: Matter crossing the jet? sub-shocks?...jet structure Decide SSC/EIC
R. M. Wagner: AGN observations with MAGIC – p.4 The MAGIC Telescope 17m Imaging Air Cherenkov Telescope: currently largest single-dish instrument 3.5° FOV Optimized for extragalactic point-like sources Trigger threshold: 50 – 60 GeV Analysis thresh: 70 – 100GeV Energy resolution 30% at 150 GeV Sensitivity: 2.5% Crab Nebula in 50 hours at E=250 GeV Enhanced duty cycle (moon observations) 2nd telescope under construction Major Atmospheric Gamma-ray Imaging Cherenkov Telescope Extensive blazar observation program: approx. 500 hours/year Simultaneous optical monitoring during observations MWL campaigns with Suzaku and other satellite experiments (results: see ICRC’07) Numerous ToO agreements with optical; X-ray, -ray satellites; telescopes, and Global Network of Cherenkov Telescopes initiative simultaneous observations w/HESS: wider energy coverage sequential observations w/VERITAS: ext’d time coverage Ongoing blazar monitoring of known bright sources: low state, flare statistics, blazar duty cycle MAGIC | AGN & blazar observation activities
R. M. Wagner: AGN observations with MAGIC – p.5 Mkn 421 | z=0.030 | Nov Apr h observations, clear diurnal signal Energy threshold: 150 GeV Source-inherent cutoff 1.4 ± 0.3 TeV ApJ 663 in press astro-ph/ historical TeV spectra MAGIC
R. M. Wagner: AGN observations with MAGIC – p.6 Mkn 421 | z=0.030 | Nov Apr 2005 Variable fluxes on day-to-day scale, 0.5–2 Crab, but no flares shorter than 1h ApJ 663 in press astro-ph/ F(E>200GeV) 2-10 keV optical Intra-night, 10 min bins: 6 nights, night-by-night Clear TeV/X-ray correlation, slope hardens with intensity: IC favored
R. M. Wagner: AGN observations with MAGIC – p.7 Mkn 501 | z=0.034 | June/July 2005 ApJ submitted astro-ph/ Clear signal each night: > 85 Energy threshold 150 GeV No strong evidence for correlated optical/X/VHE emission June 30 July 09 Clear variability in -rays Mkn501 ~ 0.5 Crab (‘low’) Unprecedented fast variations! (<3 min) Emission region severely constrained! June 30July 09 Mkn min bins Obs during moontime!
R. M. Wagner: AGN observations with MAGIC – p.8 Mkn 501 | Intra-night flares ApJ submitted astro-ph/ Two flares behave rather differently June 30 flare: No high (>600 GeV) energies July 09: all energies, “pre-flare“? June 30 July GeV GeV GeV 1200 GeV and above
R. M. Wagner: AGN observations with MAGIC – p.9 Constant fit : 2 /ndf = 76.6/25 (P=4×10 -7 ) Spectrum hardens with increasing flux Peak Peak in VHE distribution clearly observed in high-flux nights Peak location seems to depend on the source luminosity Mkn 501 | Spectral variations EBL corrected (Kneiske et al “low IR”) measured ApJ submitted astro-ph/ Flux-Spectral index correlationSED MAGIC
R. M. Wagner: AGN observations with MAGIC – p.10 1ES | z=0.044 | Aug 2005 – Dec 2005 ApJ 663 in press astro-ph/ First time-resolved observation of the low blazar emission state Energy spectrum Discovery: Whipple, Flare Dec 1995, F (>350GeV) = 63% Crab Catanese et al UL from Whipple (1997, 2000), HEGRA ( ), TACTIC ( ) MAGIC: observation Aug-Dec 2005 F(>350GeV)=6% Crab 11 - Clear detection Only marginal hints of variability
R. M. Wagner: AGN observations with MAGIC – p.11 PG | z>0.09 ApJL 654 (2007) 119 Blazar at unknown distance No emission lines: Jet outshines core? Very close alignment of jet axis to observer? High z? Small host galaxy? Discovery by H.E.S.S. & MAGIC Steepest observed –ray spectrum: spectral slope =4.2±0.3 – how much absorption is intrinsic? MAGIC VHE KVA optical SSC modeling: Models based on different z: Disfavor z>0.56 on 4.5 level Light curve: No correlation with optical flare. Time lag?
R. M. Wagner: AGN observations with MAGIC – p.12 BL Lacertae | z=0.069 | Aug – Dec 2005 LBL-type blazar: Synchrotron peak in the optical: Expect steep slope at VHE profit from low energy threshold! First LBL discovered in VHE –rays! Relatively steep –ray spectrum: spectral slope =3.6±0.5 ApJL submitted astro-ph/ Leptonic model, no EIC components necessary as required to explain 1997 flare seen by EGRET E peak =250 GeV 216 Excess events Significance: 5.1 Sky map Ravasio et al O/VHE correlation?
R. M. Wagner: AGN observations with MAGIC – p.13 Summary & Conclusions There are now 16 blazars observed in -rays above 100 GeV with more observations & detections in the pipeline VHE observations are crucial for modeling non-thermal emission regions in jets, but... Will need full time-dependent modeling & MWL observations Increased instrumental sensitivity helps precision observations of bright blazars Mkn 421, Mkn 501, 1ES Leptonic nature of acceleration? flux-hardness correlation, IC peak detected Fast blazar flaring: First time minute-scale variability in VHE! Low blazar emission state was mostly elusive before: now removing observational bias towards flaring sources in the VHE regime Many new sources discovered with interesting properties: Mkn 180: source detected upon optical trigger 1ES 1218: high redshift (now confirmed by VERITAS) PG 1553: probably very close alignment to jet axis BL Lacertæ: First LBL -ray source
R. M. Wagner: AGN observations with MAGIC – p.14 Backup slides
R. M. Wagner: AGN observations with MAGIC – p.15 Detection of E>100 GeV -rays showers Narrow images Aligned towards source direction , 100 GeV Proton, 100 GeV Cosmic rays initiate extensive air showers Cherenkov light is emitted by relativistic particles in the shower Showers induced by -rays and hadronic cosmic rays ( 10 4 times more numerous) develop differently in the atmosphere Image parametrization Background suppression: Cuts in image parameters candidate events from pointing direction hadronic showers Spread images Isotropic arrival direction
R. M. Wagner: AGN observations with MAGIC – p.16 Kino et al. synchrotron peak Typical Spectral Energy Distribution Inverse Compton peak (Buckley 1999) Inverse Compton scattering on different possible target photon fields In particular in blazars: Synchrotron Self-Compton model: synchrotron photons target field for IC process Natural explanation of X-ray / -ray correlated variability Acceleration and VHE production Primary acceleration by diffusive shock acceleration in jets Power law Electrons emit synchrotron radiation Electron Protons: 0 decay from photo-pion production or synchrotron emission from protons Difficult to accomodate X-ray / -ray correlations Should observe simultaneous -emission Hadronic acceleration models:
R. M. Wagner: AGN observations with MAGIC – p.17 Low-level blazar emission 1ES Discovery: Flare during the night of 1995/12/21 Up to now VHE -ray observations biased towards flaring states: What are the properties of blazars at non-flare times? MAGIC: Clear 11 signal from 23 observation nights MAGIC 2005 VHE -ray light curve and with previous <5 observations Profit from MAGIC’s higher sensitivity Integral flux 5.7 times lower than during 1995 flare Light curve well compatible with low emisson state of the source All-time VHE -ray light curve 1995 flare MAGIC significance well below 5 1995 flare data & 2005 MAGIC low emission data could be modeled using a one-zone SSC model. ApJ in press astro-ph/
R. M. Wagner: AGN observations with MAGIC – p.18 PG 1553 probably distant source! Possibility to constrain redshift by assumptions on EBL and acceleration mechanism: z < 0.42 (Mazin & Goebel 2007) Once distance is known: Source probably decisive for EBL determination! Attenuation of VHE -rays in the universe PG blazar with unknown distance Simultaneous discovery by MAGIC, H.E.S.S. MAGIC: 8.8 signal from 19 h observations Steepest observed –ray spectrum: spectral slope =4.2 0.3 MAGIC H.E.S.S. Crab nebula Modification of spectrum due to Extragalactic Background Light (EBL) VHE + EBL e + e – VHE is “lost” to observer IR (dust) Vis (starlight) Peak in e + e – GeV energies probe a specific energy range of the EBL spectrum Net effect in the >100 GeV range: Steepening of (power-law) spectra
R. M. Wagner: AGN observations with MAGIC – p.19 Mkn 180 | z=0.045 | 2006 March New sources discovered by IACT: Mkn 180 Successful optical trigger 11.1 h, 5.5 , F (>200GeV) = 11% Crab, spectral slope =3.3 ± 0.7 rather hard spectrum Earlier UL at comparable level No significant variability Need to understand whether O/VHE correlation ApJL 648 (2006) 105 SED Model: FO98 Model: CG02
R. M. Wagner: AGN observations with MAGIC – p.20 1ES | z=0.182 Whipple: F (>350GeV) <8% C.U. HEGRA: F (>750GeV) <12% C.U. MAGIC: DISCOVERY! Jan 2005, 8.2 h 6.4 , F >120GeV = 13% C.U., spectral slope =–3.0 ± 0.4 2 plot sky map ApJL 642 (2006) 119 SED