7 March 2008 Nicola Galante, DPG - Freiburg 1

Observation of GRBs with the MAGIC Telescope

Nicola Galante (MPI für Physik - München)

for the MAGIC Collaboration

7 March 2008 Nicola Galante, DPG - Freiburg 2

Observations at VHE

• BATSE: 2704 GRB up to ~2 MeV• EGRET: 4 GRBs above 1 GeV (up to 18 GeV)• No more detections above GeV

(only 1 evidence of excess by MILAGRO)• (too) Many emission models• New phenomenology recently discovered

(GRB late X-ray flares 103 - 104 s later)• VHE observations necessary to constrain models

• GeV/TeV emission present in late activity?

AGILE already in orbit, GLAST will be launched soon - GeV observations time!

GeV/TeV observation possible by new generation IACTs too

7 March 2008 Nicola Galante, DPG - Freiburg 3

Constraints on IACT

Isotropic GRB distribution: IACT Duty-Cycle ~10%

Duration

Short T90 < 2s, T90 0.7s, 1/3 Tot

Long T90 > 2s, T90 30s, 2/3 Tot

Fast repositioning time required!

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Constraints on IACT

Band functionvalid up to GeVEbreak 300 keVhard-to-soft evolution

well described by Shock Synchrotron Model (SSM)

moreover…Tavani M., Ap.J. 466, 768-778 (1996)

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Afterglow and redshift

GRB970228: first fading X-ray counterpart by Beppo-SAX. From X to O up to several days

adjacent galaxies: red-shift measurement 0.01 ≤ z ≤ 6.29

Jakobsson P., Levan A., et al., A&A 447, 897-903, 2006

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Interaction with EBL

cosmological horizon

Observed flux is attenuated

zmax 1for 50 GeV threshold

K. Mannheim et al., A&A, 413,807-815 (2006)

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GRB Alarm System

GCN

Alert System

Central Control

Communication:

•e-mail

•web

•Acoustic alarm

Outside

MAGIC systems

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The MAGIC Telescope

Analog signal transport via optical fibers IPE

IPEIPECENET

2-level trigger system& 2 GHz FADC system

Active mirror control

(PSF: 90% of light in 0.1o inner pixel)

high reflective diamond milled aluminum mirrorsLight weight

Carbon fiber structure for

fast repositioning

- 3.5o FOV camera - 576 high QE PMTs (QEmax= 30% 330 – 450 nm)

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Sensitivity

Since February 2007 a fast 2GHz Multiplexed FADC DAQ system is working improved sensitivity

Current Sensitivity for E>300 GeV

1.57% Crab in 50 h

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Sensitivity

Test on Crab Nebula:

measured sensitivity as a function of observation time

70 GeV < E < 300 GeV

~3.6 Crab in 20 s

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Observed GRBs 2005-2006GRB t0 talert toss t90 <ZA>

050421 04:11:52 58 s 108 s 10 s 50°

050502a 02:13:56 40 s 269 s 20 s 42°

050505 23:22:21 540 s 717 s 60 s 55°

050509a 01:46:29 16 s 131 s 12 s 50°

050713a 04:29:02 13 s 40 s 70 s 49°

050904 01:51:44 82 s 145 s 225 s 20°

060121 22:24:54 15 s 583 s 2 s 42°

060203 23:55:35 171 s 259 s 83 s 44°

060206 04:46:53 16 s 52 s 11 s 10°

Typical repointing40÷50 s

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Two Prompt Emissions

GRB 050713a

GRB 050904

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Flux Upper Limits 2005-2006GRB Eth Flux UL (30 min)

050421 212 GeV 0.2 CU

050502a 152 GeV 0.3 CU

050505 213 GeV 0.8 CU

050509a 215 GeV 0.4 CU

050713a 170 GeV 0.8 CU

050904 86 GeV 0.3 CU

060121 151 GeV 0.4 CU

060203 151 GeV 1.7 CU

060206 86 GeV 0.4 CU

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Flux Upper Limits 2006-2007GRB t0 talert toss t90 <ZA>

060825 02:59:58 19 s 57 s 8 s 28°

061028 01:26:22 140 s 169 s 106 s 38°

061217 03:40:08 13 s 786 s 0.4 s 56°

070412 01:27:03 674 s 701 s 34 s 35°

070920a 04:00:13 539 s 680 s 56 s 52°

GRB Eth Flux UL (30 min)

060825 80-125 GeV 0.7 CU

061028 100-125 GeV 0.8 CU

061217 300-500 GeV 0.5 CU

070412 80-125 GeV 0.2 CU

070920a 225-300 GeV 0.4 CU

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ConclusionsMAGIC features (TESTED!):Flux sensitivity: 3.6 Crab @ 5 LiMa in 20s @ 70 GeV < E < 300 GeVAngular resolution: 0.1°Slewing capabilities: 40÷50 s, ~20x than other CherenkovEth: 50 GeV at zenith, lowest attained E at Cherenkov

Publishing GCN circular within 1 week!Paper on 2005-2006 observations already published

J. Albert, et al., Ap. J. 667, 358, 2007

Measurements in VHE crucial but... ... need a near (but not so much) GRB!

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Fast Slewing Time!

QuickTime™ and aCinepak decompressor

are needed to see this picture.