Outline:

1
(No Transcript)
2
The MAGIC VHE ?-ray telescope- Prospects for the
observationof Gamma Ray Bursts -

• Outline
• VHE domain
• Cherenkov radiation
• The MAGIC telescope
• Observation of GRBs

• MAGIC key parameters
• MAGIC GRB catalogue
• MAGIC II
• Outlook

Markus Garczarczyk Max-Planck-Institute for
Physics Centro Astrofisica La Palma
CALP December 3rd 2007
3
The Universe in visible light

• Dominant light contribution by our Galaxy
• More than 1012 Galaxies in the background

4
The Universe in X-rays

• In X-rays the Universe shines also outside our
  Galaxy
• In the last decade more than 105 new sources found

5
The Universe in gamma rays

• Big contribution by the galactic plane in MeV
• Few point like sources at GeV

6
The Gamma Ray Burst distribution

• More than 2700 GRB during 10y observation
• GRBs do not repeat

7
How do we detect cosmic gamma rays?

• At high fluxes and low energies with satellite
  experiments
• At low fluxes and high energies with ground based
  detectors
• Large detectors only on the Earth possible
• Earth atmosphere not transparent for X-rays and
  ?s

8
Detection of HE gamma rays
Using Cherenkov telescopes
?-shower
hadron shower
For comparison night sky background 1012
photons/m2?sr?s
9
How to extract signal from background?-
parametrisation of the images -
Hillas Parameter
Hillas A., Proceedings 19th ICRC, 445 (1985)
10
Cherenkov telescopes worldwide
11
The MAGIC ?-ray telescope
Barcelona IFAE, UA Barcelona, U. Barcelona, IEEC
Barcelona, HU Berlin, Instituto Astrofisica
Canarias,U.C. Davis, U. Dortmund, U. Lodz, UCM
Madrid, MPI München, INFN/ U. Padova, INFN/ U.
Siena, INAF, INR Sofia, Tuorla Observatory,
Yerevan Phys. Institute, INFN/ U. Udine, U.
Würzburg, DESY Zeuthen, ETH Zürich

• Largest Cherenkov telescope 17 m Ø mirror dish
• 3.5 FoV camera with 576enhanced QE PMTs
• Analogue signal transmission
• Fast repositioning for GRBsaverage lt 42 s
• Trigger threshold 50 - 60 GeV
• Sensitivity 2 Crab / 50 h
• ?-PSF 0.1
• Energy resolution 20 - 30

Canary Island La Palma, 2200 m a.s.l.
12
MAGIC key technological elements
Camera with 576 enhanced QE PMTs

• 17m diameter mirror surface (236m2)

13
MAGIC The reflector

• 964 spherical mirror elements
• 49.5 x 49.5 cm2
• All-aluminum, diamond milled, quartz coated,
  internal heating
• gt82 reflectivity (300-650nm)

• 4 mirrors mounted on 1 panel
• Mirror spot d901cm (pixelinner d3cm)

• Overall reflector
• Parabolic (f/d1)
• Isochronous, maintain time structure of
  Cherenkov light flashes (2 nsec)
• Better bkg light rejection

14
MAGIC The telescope frame

• Carbon fiber epoxy structure
• Lightweightdish mirrors 20 tonstelescope
  65 tons
• Stiff

• Allows fast slewing time(180º in both axes in
  lt42 s)
• Fast follow-up of aGamma Ray Burst

15
Fast repositioning of the telescope
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
t sec

• Current status
• For safety reason maximal speed 50s
• No reverse mode ? 2x longer for ?Az ? 360

Mirror dish deformations at varying telescope
orientations
16
The Active Mirror Control

• 964 Al-mirrors mounted on 247 panels
• Fixed on three points to the mirror dish
  structure
• Two actuators per panel
• Laser module
• CCD camera
• Software control
• Look-up tables 10s for refocussing
• Resulting PSF ?7.6 mm

17
Enhanced QE PMT camera

• Matrix of 576 PMTs
• Field of View 3.5o

236 m2 ? 276 m2 !!!
18
Status of the MAGIC telescope

• 2003-2004 Commissioning
• September 2004Start regular data taking

• Smooth data takingif weather allows

19
VHE ?-ray physics overview
gt 40 sources above 100 GeV, rapid growth in
recent years
20
Observation of GRBs

• GRBs are most energetic phenomena
• Bright flashes in ?-rays
• Short lasting (40sec)
• Unpredictable position at the sky
• Satellite alerts distributed over GCN

• Requirements
• Fast reaction time
• Low energy thredshold
• High sensitivity

21
Sensitivity of MAGIC in GRB mode

• Tested on a fake alert by INTEGRAL
• October 11th 2005 Crab Nebula observation
• 46min observation time
• 14? detection _at_ 350 GeV
• Sensitivity of MAGIC5? from a source of 5 C.U.
• 40s for E above 300 GeV
• 90s for E below 300 GeV

22
GCN activity

• For the time between January 2005 and May 2007
• 352 acceptable GCN GRB alerts
• 276 alerts from SWIFT
• 12 fake alert rate by SWIFT
• MAGIC observation rate 9.7 GRBs/month by the
  SWIFT satellite

23
MAGIC GRB observations
24
(No Transcript)
25
Prompt emission of GRB 050713a

• Duration 129.1 s
• Start MAGIC observation at T040s
• No ? emission seen
• Detection at broad energy range
• No redshift measurement

• Compatible with ?E-2.14 synchrotron extrapolation
• EBL absorption not included
• Max. 10 of the GRB emissionin VHE domain

Albert J. et al., ApJL 641, L69 (2006)
26
(No Transcript)
27
The Universe is nottransparent for VHE gamma
rays
28
Next Step MAGIC-II

• Aim
• Increase sensitivity by factor 3?
• Lower energy threshold further
• Better energy and angular resolution

• Second telescope MAGIC-II under construction
• Planed completion beginning 2008