TeVPA, SLAC, 2009

Pratik MajumdarPratik MajumdarDESY, ZeuthenDESY, Zeuthen

(for the MAGIC Collaboration)(for the MAGIC Collaboration)

Outline: MAGIC Telescope Observations of High

redshift AGNs Conclusions

MAGIC Observations of High Redshift AGNs

Instituto de Astrofisica, Andalucia, Barcelona IFAE, UA Barcelona, U. Barcelona, HU Berlin, Instituto Astrofisica Canarias, R.B. Inst., Croatia, U.C. Davis, U. Dortmund, DESY Zeuthen, IEEC-CSIC, Spain, U. Lodz, UCM Madrid, MPI München, INFN/ U. Padua, INAF, INFN/ U. Siena, INR Sofia, Tuorla Observatory, Yerevan Phys. Institute, INFN/ U. Udine, U. Würzburg, ETH Zürich

TeVPA, SLAC, 2009

The MAGIC telescope

• Largest single dish Cherenkov Telescope: 17 m Ø mirror dish, mirror surface (241 m2 )

• 3.5° FoV Camera with 577 enhanced QE PMT’s

• Fast repositioning for GRBs: average < 40 s

• Low energy trigger threshold: 50 - 60 GeV

• Sensitivity: 1.6% Crab / 50 h (improvement with 2 GHz sampling and timing parameters in g/h

separation)

• -PSF: ~ 0.1° ( E > 500 GeV )• Energy resolution: 20 - 30%

Canary Island La Palma 2200 m asl

First telescope in regular observation mode since fall 2004 Extended observations during Moon

TeVPA, SLAC, 2009

MAGIC AGN Physics Program Strategy

MWL campaigns on known TeV sources to MWL campaigns on known TeV sources to make precision studies of spectrum, make precision studies of spectrum, variability variability

Discover new sources at high redshifts, Discover new sources at high redshifts, test EBL test EBL

(extragalactic background light) models (extragalactic background light) models Vigorously pursued owing to its low Vigorously pursued owing to its low

threshold threshold

Long term monitoring of TeV blazarsLong term monitoring of TeV blazars

Why do we see high z objects

at all? Is the universe more transparent to VHE -rays than assumed?

Limits on EBL ?

Can VHE data give vital inputs to distinuish

between different models ?

TeVPA, SLAC, 2009

VHE detections using Optical Triggers

Regular optical monitoring of candidate sources by KVA optical telescope at LaPalma Continuing the success stories of Mrk180 and 1ES1011+496

S5 0716+714Trigger in April

2008

Preliminary

Optical trigger on S50716+714: MAGIC observations in 2008 April

→ 2.6h of data, clear signal (6.8 σ): DISCOVERY ‣April 28: Swift reports F(0.3-10 keV) = 4x10-11 erg/cm²/s,

about 50% larger than that observed in 2007

‣Apr 29: ATel #1500, MAGIC reports 6.8 discovery Apr 23-25F(>400 GeV) ≈ 10-11 ph/cm²/s (≈25% Crab) : (paper in prep.)

Host Galaxy detected Z=0.31+/-0.08

(Nilson 08), 2nd farthest VHE emitter

Host Galaxy detected Z=0.31+/-0.08

(Nilson 08), 2nd farthest VHE emitter

3rd low-peaked

VHE Blazarafter BL Lac

&W Comae

3rd low-peaked

VHE Blazarafter BL Lac

&W Comae

arXiv:0907.2386

TeVPA, SLAC, 2009

S50716+714 ( Contd.)

Collecting all data from 2007 to 2008

SSC model predicts a huge GeV flux

Structured jet model could be an interesting alternative

( Ghisellini et al (2005) )

Preliminary

Preliminary

Preliminary

10.3 good hrs in 2007, 2.8 in 2009 (Zd ~ 42 to 55 deg )

TeVPA, SLAC, 2009

3C 279 (z = 0.536)Wehrle et al. 1998

x100

• EGRET brightest AGN ( Wehrle et. al 1998)EGRET brightest AGN ( Wehrle et. al 1998)• Gamma-ray flares in 1991 and 1996 Gamma-ray flares in 1991 and 1996 • Apparent luminosity ~ 10Apparent luminosity ~ 10erg/serg/s• Fast time variation T ~ 6hr in 1996 flareFast time variation T ~ 6hr in 1996 flare

• 9.7 hours, 10 nights from 9.7 hours, 10 nights from January to April January to April

• Clear detection on 23Clear detection on 23rdrd Feb Feb

(5.8(5.8 after trial), after trial), marginal on 22marginal on 22ndnd. .

• No short scale variability in No short scale variability in opticaloptical

• VHE distance champion !!!VHE distance champion !!!

MAGIC observations

TeVPA, SLAC, 2009

Implications on Extragalactic Background Light

• Powerlaw Powerlaw =- 4.11+/-0.68=- 4.11+/-0.68• Spectrum sensitive to 0.2 to 2 Spectrum sensitive to 0.2 to 2 mm• Deabsorption using Low Deabsorption using Low

density model ( Primack ) and high density model ( Primack ) and high one ( Stecker fast evolution)one ( Stecker fast evolution)

• Assuming Assuming model model parameters based on Kneiske parameters based on Kneiske et.al can be tuned to give EBL et.al can be tuned to give EBL upper limitupper limit No internal absorption taken into No internal absorption taken into

accountaccount

TeVPA, SLAC, 2009

Caveats and Open Issues

• Alternative emission models can produce spectra Alternative emission models can produce spectra

• Internal absorption by photon fieldsInternal absorption by photon fields can produce hard spectra can produce hard spectra (Bednarek(Bednarek

1997, Aharonian et.al 2008,Tavecchio1997, Aharonian et.al 2008,Tavecchio

and Mazin 2008and Mazin 2008 ) )

• SSC model with narrow electron distribution can SSC model with narrow electron distribution can

produce produce

spectra ~ 0.7 spectra ~ 0.7

Intrinsic absorption is redshift Intrinsic absorption is redshift

dependent and can mimic EBL evolution dependent and can mimic EBL evolution ( Reimer 2007 )( Reimer 2007 )

Position of the emitting region crucial for internal absorption studies ( Liu, Bai etal 2009)

Presence of ALP ? ( Roncadelli et al ) ( see D. Paneque’s talk )

R = rBLRin

R = rBLRout

arXiv:0905.1447v1

TeVPA, SLAC, 2009

Implications on SED

• Optical (BVRI) and X-ray (RXTE) Optical (BVRI) and X-ray (RXTE) data available , X-ray flare follows data available , X-ray flare follows VHE flare by about 5-7 VHE flare by about 5-7 days,optical state high, but little days,optical state high, but little variabilityvariability

• One zone EC model : steep One zone EC model : steep optical spectrum, soft X-ray optical spectrum, soft X-ray spectrum spectrum unusually low B ( ~ unusually low B ( ~ 0.03 G)0.03 G)

or high or high factors , X-ray flux factors , X-ray flux cannot be reproduced. cannot be reproduced.

• Multizone emission regionMultizone emission region• Hadronic model seems to Hadronic model seems to

describe the data well with or describe the data well with or without external radiation field as without external radiation field as target for ptarget for p interactions interactions

• Future MWL campaigns will be key to constrain emission models

arXiv:0810.4864

TeVPA, SLAC, 2009

3c279 Observations in 2007

• New observations after an optical New observations after an optical outburst in January 2007outburst in January 2007

• 9 nights from 149 nights from 14thth till 22 till 22ndnd January January• Only 16Only 16thth shows significant signal shows significant signal

at 5.6 sigma ( 150 mins of data )at 5.6 sigma ( 150 mins of data )

( not corrected for trials ) ( not corrected for trials )

Preliminary

• No significant emission on other No significant emission on other nightsnights

TeVPA, SLAC, 2009

3c279 Observations in 2007

• Extensive MWL campaign Extensive MWL campaign organised in 2009organised in 2009

Data analysis close to finish, Data analysis close to finish,

stay tuned…… stay tuned……

Preliminary

• Spectrum hard as in 2006Spectrum hard as in 2006• SED and physics SED and physics

interpretetion sooninterpretetion soon

Gamma ray flare seems to come Gamma ray flare seems to come

during optical decay !!!during optical decay !!!

X-ray data sparseX-ray data sparse

• Challenge for conventional Challenge for conventional modelsmodels

Preliminary

MAGIC

RXTE

Optical, KVA

Chatterjee et al

TeVPA, SLAC, 2009

Upper Limits on 3C454.3• Well known AGN ( z =0.859), many observations Well known AGN ( z =0.859), many observations

by EGRET, highly variable emissionby EGRET, highly variable emission• in 2007 intense flaring observed in 2007 intense flaring observed

in opticalin optical, triggerred observations , triggerred observations

in X-rays (Swift), in X-rays (Swift),

AGILE : intense emission in summer 2007 AGILE : intense emission in summer 2007

and in November-December 2007and in November-December 2007• Triggerred by these observations, Triggerred by these observations,

MAGIC observations : MAGIC observations :

9.6 hours (July to August),9.6 hours (July to August),

6.8 hours ( Nov-Dec)6.8 hours ( Nov-Dec)

No emission seen, UL derived.No emission seen, UL derived.

Consistent with leptonic Consistent with leptonic

EC models, cutoff at 20-30 GeVEC models, cutoff at 20-30 GeV

( Maraschi & Tavecchio , 2003)( Maraschi & Tavecchio , 2003)

arXiv:0809.1737v1

TeVPA, SLAC, 2009

Conclusions Highly successful AGN program, discovered Highly successful AGN program, discovered

few high redshift objectsfew high redshift objects

1515 detections under detections under Extragalactic sourceExtragalactic source

program, program, 8 discoveries8 discoveries, Active monitoring and MWL , Active monitoring and MWL campaigns organised on known sources to study campaigns organised on known sources to study them deeply. them deeply.

22ndnd MAGIC telescope almost end of commissioning MAGIC telescope almost end of commissioning phase => will improve sensitivity of the MAGIC phase => will improve sensitivity of the MAGIC system. system.

Preliminary

Mrk421 in June 2009

First Stereo Signal

TeVPA, SLAC, 2009

Backup

TeVPA, SLAC, 2009

What is EBL?

• Unique imprint of the Unique imprint of the history of the history of the universeuniverse

• Test of star Test of star formation and galaxy formation and galaxy evolution modelsevolution models

• Cosmological Cosmological evolution models evolution models have to explain have to explain current EBLcurrent EBL

• Opacity source of Opacity source of GeV-TeV photonsGeV-TeV photonsRed shifted stellar

light Red shifted dust light

Dwek&Krennrich 05, Kneiske et al. 04

2.7K

TeVPA, SLAC, 2009

EBL Absorption

e-e+

EBL

VH

E

blazarIACT

TeVPA, SLAC, 2009

Extragalactic VHE -ray sources:

• AGN with relativistic jet aligned with observer’s line of sight

(exception M87, Cen A, 3c66B…)• non-thermal emission, highly variable• High Doppler factors, jets may attain

high luminosities

Blazars:

Jet

Black

Hole

Obscuring

Torus

NarrowLineRegion

BroadLineRegion

AccretionDisk

Urry & Padovani (1995)

blazar

E2 d

F/d

E

energy E

0decay

IC

• discriminate hadronic vs leptonic acceleration

• leptonic models (SSC or EC) favoured due to X-ray/TeV correaltions in some objects

• Still not well known : - Variability scales - correlations with other

wavelengths : optical/radio

TeVPA, SLAC, 2009

Observations in the vicinity of 3c66A• 3C66A blazar at z = 0.44 3C66A blazar at z = 0.44

(controversial )(controversial )• In September 2008, In September 2008,

VERITAS reported detection VERITAS reported detection

at > 100 GeV (see ATEL # 1753 )at > 100 GeV (see ATEL # 1753 )• 3C66B : a large FRI radio galaxy, 6’ 3C66B : a large FRI radio galaxy, 6’

away from 3C66A ( z = 0.0215 ) away from 3C66A ( z = 0.0215 ) • MAGIC observations after an MAGIC observations after an

optical outburst in Augustoptical outburst in August• Total time : 54.2 hrs, 6Total time : 54.2 hrs, 6 signal signal

( 5.4( 5.4 after trial correction ), 2.2% after trial correction ), 2.2% Crab > at 150 GeV , Spectrum : -Crab > at 150 GeV , Spectrum : -3.1+/-0.313.1+/-0.31

• Excess 6.1’ away from 3C66A Excess 6.1’ away from 3C66A

MAGIC J0233+430• From simulations of skymaps, From simulations of skymaps,

exclusion probability from 3C66A is exclusion probability from 3C66A is 85.4% ( including systematics in 85.4% ( including systematics in pointing accuracy ) pointing accuracy )

Published in ApJL