very high energy gamma ray observations with the magic ...scipp.ucsc.edu › seminars ›...
TRANSCRIPT
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Very High Energy Gamma Ray Observations with the MAGIC
Telescope(a biased selection)
Nepomuk Ottefor the MAGIC collaboration
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2A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
• Imaging air shower Cherenkov technique– The MAGIC telescope
• Observation of the AGN 3c279
• Observation of Neutron Stars with MAGIC
• The Crab nebula and Pulsar (young pulsar) [astro-ph/0705.3244] • PSR B1951+32 (middle aged pulsar) [astro-ph/0702077]• PSR B1957+20 (millisecond pulsar)• LS I 61+303 [Science 2006]
• Where to go next?
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3A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The non-thermal universe in VHE gamma-rays
GRBsAGNs
Origin ofcosmic rays
CosmologyDark matter
Space-time& relativity
Pulsarsand PWN
SNRs Micro quasarsX-ray binaries
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4A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
VHE gamma-ray sources status ICRC 2007
Rowell
71 known sources
detections from ground
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5A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Imaging Air Cherenkov Technique
~ 10 kmParticleshower
~ 1o
Cher
enko
vlig
ht
~ 120 m
Gammaray
Cherenkov light image of particle shower in telescope camera
• fast light flash (nanoseconds)• 100 photons per m² (1 TeV Gamma Ray)
reconstruct: arrival direction, energy
reject hadron background
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6A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
CANGAROO III(Australia & Japan)
4 telescopes 10 meters Ø
Woomera, Australia
Windhoek, NamibiaHESS
(Germany & France)4 telescopes12 meters Ø
Roque delos Muchachos, Canary Islands
MAGICMAGIC(Germany, Spain, Italy)(Germany, Spain, Italy)1 telescope 17 meters 1 telescope 17 meters ØØ
MontosaCanyon,Arizona
VERITAS(USA & England)4 (7) telescopes
10 meters Ø
Current generation Current generation CherenkovCherenkov telescopestelescopes
MAGICVeritas
H.E.S.S.
Cangaroo III
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7A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The MAGIC site
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8A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
A recent view of MAGIC
MAGIC I
MAGIC II
counting house
picture by R.Wagner
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9A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Current Status of MAGIC
First telescope in regular observation mode since fall 2004
– 236 m2 mirror area (17m Ø)– Fast repositioning (40 sec) for GRB
follow-up observations– Upgrade: 2GSamples/s FADCs
– Trigger threshold: ~ 50 GeV– Sensitivity: 2 % Crab (5σ,50h)
for E>200GeV– Using timing parameters after
installation of new 2GSamples/s FADC:=> Sensitivity improved to 1.5% Crab
MAGIC-I
http://wwwmagic.mppmu.mpg.de/gallery/pictures/La_Palma_July_2004/MAGIC10.JPG
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10A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Central Pixel for Optical Measurements
• Modified central pixel for optical measurements
• simultaneous with Gamma-ray observations
Crab pulsar in optical by MAGIC
view from back
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11A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Event Parameterization
muon ringhadronhadrongamma candidate
event parameterization with principal components
commonly known as Hillas parameters
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12A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Background Rejection
hadron shower (background)
gamma shower
Main background:- cosmic ray (hadron)showers
- >103 times more numerous than γ-ray showers
- reject based on showershape (hadrons are broader)
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13A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Gamma / Hadron Separation
differences between gammas and background events compressed into one variable:
HADRONNESS
determined with the method of Random Forests
Breimann 2001
analysis for Sizes < 200 phe is difficult
background
gamma rays
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14A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Extragalactic Sources: Active Galactic Nuclei
Jet
BlackHole
ObscuringTorus
LineRegion
LineRegion
Disk
Narrow
Broad
Accretion
Urry & Padovani (1995)
blazar
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15A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
EBL CherenkovTelescope
BL-Lac object
Red shifted stellar light Red shifted dust light
2.7K
Attenuation of VHE γ-rays
−+→ eeEBLHE γγ Eγγ ≈1.8* 2mec2( )
• Absorption leads to cutoff in AGN spectrum
• Measurement of spectral features allows to constrain EBL Models
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16A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
known extragalactic VHE-sources (19)Source Redshift Sp. Types Discovery Observation
M 87 0.004 2.9 FR-I HEGRA HESS
Mkn 421 0.031 2.2 HBL Whipple many
Mkn 501 0.034 2.4 HBL Whipple many
1ES 2344+514 0.044 2.9 HBL Whipple MAGIC
Mkn 180 0.045 3.3 HBL MAGIC
1ES 1959+650 0.047 2.4 HBL 7TA many
PKS 0548-322 0.069 HBL HESS
BL Lac 0.069 3.6 LBL MAGIC
PKS 2005-489 0.071 4.0 HBL HESS
PKS 2155-304 0.116 3.3 HBL Durham many
1ES 1426+428 0.129 3.3 HBL Whipple HEGRA
1ES 0229+200 0.139 HBL HESS
H 2356-309 0.165 3.1 HBL HESS
1ES 1218+304 0.182 3.0 HBL MAGIC VERITAS
1ES 1101-232 0.186 2.9 HBL HESS
1ES 0347-121 0.188 HBL HESS
1ES 1011+496 0.212 4.0 HBL MAGIC
3C 279 0.538 FSRQ MAGIC
PG 1553 ? 4.0 HBL HESS/MAGIC
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17A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Detection of 3C279
80-220 GeV
E> 220 GeV
PreliminaryPreliminary
PreliminaryPreliminarySky map around 3C279Sky map around 3C279
PreliminaryPreliminary
PreliminaryPreliminary
PreliminaryPreliminary
big jump into the deep universe
may deliver stringent constraint on EBL and acceleration models
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Pulsars and & pulsar nebulae
ExploringExtreme electrodynamics& GRRelativistic windsAcceleration in shocks
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19A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The Pulsar Wind Nebula Complexon the example of the Crab
magnetized, spinning neutron star (pulsar)
energy carried away by electromagnetic radiation and particles (~1038 erg/s)
particle acceleration in:
1. light cylinder2. shock front
massive object in center:
from Aharonian et al
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20A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The Crab Nebula resolved in X-Rays
NASA/CXC/ASU/J.Hester et al.
7 still images of Chandra observations taken between November 2000 and April 2001.
rich and dynamic structure in X-rays:
• wisps• knots• jets
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21A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The Crab-PWN: Broadband Emission
Aharonian & Atoyan (1998)
synchrotron emission
IC-emission
• little known at energies around the peak of the IC-emission
morphology?
variability?
spectrum?
pulsar?
studied with MAGIC at energies >60 GeV
Pulsar
Nebula Synchrotron IC
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22A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Nebula: Spectral Energy Distribution
• good agreement with other Cherenkov telescopes above 400GeV
• spectrum well described within SSC-framework
• first time determination of the IC-peak at 77±47statGeV
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23A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Nebula: Morphology
• emission region compatible with point-like source
- emission region
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24A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Nebula: Variability
no variability (>200 GeV) on time scales of:
• minutes (
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25A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The Crab Pulsar Wind Nebula Complex
from Aharonian et al
turning to the central object
the pulsar
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26A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Gamma-Ray Emission from Pulsars
• three sites favored for particle acceleration
• emission appears pulsed; lighthouse model
• complex electrodynamics; challenging for theory
spin axis magnetic dipole moment
Harding
• no pulsar detected above ~100 GeV
spectral cutoff; challenging for experiment
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27A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Pulsar in Gamma-Rays
shaded: regions of pulsed emission defined by EGRET measurements above 100 MeV (P1, P2)
significance of pulsed emission:no prior assumption about pulse profile: 1.2σguided by EGRET >100 MeV profile: 2.9σ
Fierro, 1998
events with Size
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28A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Upper limit on cutoff energy
1. assume EGRET spectrum with exponential cutoff
2. convolute spectrum with MAGIC response
3. calculate number of expected pulsed excess events
4. compare with upper limit on pulsed excess events
5. reiterate with different cutoff energy until match
MAGIC response after cuts (Size
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29A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Pulsar II
• no detection/hints of pulsed emission in differential bins of energy
• upper limits compatible with results from other experiments
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30A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1951+32 / CTB 80
pulsar detected by EGRET up to 20 GeV
at 10 GeV similar luminosity as the Crab pulsar
A different pulsar than Crab
• 100 times older (~105 years)• 10 times lower surface magnetic
field (~5x1011 G)• moves 2 times faster through ISM
(240km/s)• 100 times lower spin down
luminosity (~1036 erg/s)
radio
optical
radio and synchrotron nebula CTB80 + VHE gamma-ray predictions
a good candidate to observe with MAGIC
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31A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
In the surroundings of PSR B1951+32
No displaced gamma ray emission level of few % Crab (point source 0.1° RMS radius)
reduced sensitivity for more extended emission region
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32A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1951+32 / CTB 80
• model calculations do not take pulsar motion into account
emission smeared outover a larger volume?
• magnetic field larger than assumed
pulsar wind not particle dominated?
• can exclude flux level predicted by Bednarek & Bartosik(2003)
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33A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1951+32 Pulsar
• no pulsed emission detected
• constrain on the cutoff energy
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34A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Evolution of Pulsars in Binary systems
Lorimer, 2005
spin up of old pulsars by accretion of mass from companion star
millisecond period pulsars
Lower magnetic field:reduced screening of Gamma-rayslower acceleration voltage
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35A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1957+20: The black widow
• second fastest known pulsar (1.607 ms)
• recycled pulsar
• binary system (eccentricity
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36A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1957+20: search for steady gamma-ray emission
can not exclude predicted gamma-ray flux from pulsar [Bulik (2000)]
more sensitive pulsed analysis not possible because of invalid ephemeris of the binary system
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37A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
PSR B1957+20: Search in orbital phase
no evidence for gamma ray emission
light curve flux limits
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38A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
LSI+61 303
LSI+61 303:
• high mass x-ray binary• Be star companion with
circumstellar disc• high eccentricity (~0.7)• radio and x-ray emission
modulation: 26.5 days (orbit)
• radio jets (100AU)
Massi et al 2004
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39A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
LSI+61 303: MAGIC observations
Albert et al., SCIENCE 2006Albert et al., SCIENCE 2006
• 54 h observation from November 2005 till March 2006• 9 σ detection of point-like source (E > 200 Gev)• Spectral index = -2.6 ± 0.2 (stat) ± 0.2 (syst)• Flux clearly variable• Average emission has maximum (~16% Crab) at phase 0.6.
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40A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
LSI+61 303: models
• Microquasar: rel. electrons (& hadrons) from accretion powered jetsor• Binary Pulsar: rel. electrons from rotational energy of pulsar
Mirabel 2006
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41A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Summary and Conclusion
• MAGIC in full production
• ~1 new source every two month
• many exciting results like 3C279 or LSI 60+303
• detailed studies possible: Crab nebula in the energy range between 60GeV and 400GeV– within experimental resolution:
• emission region is point like;
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42A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Outlook into the Future
• The gamma-ray window between 10 GeV and 100 GeVis still closed
• GLAST will be a pathfinder mission but can not answer all questions– the strength of Cherenkov telescopes is a large collection area
(~104 m²)high sensitivity to transients
• short time flaring in AGNs• test stability of pulsed emission at the highest energies• ….
• Opening the 10 GeV - 100 GeV window from ground will be necessary
lower threshold Cherenkov telescopes are needed
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43A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Very near future: This Crab season
• trigger threshold of MAGIC is limited by accidental triggers caused by PMT afterpulses
• current trigger requires a 4 next neighbor coincidence
• investigate new trigger idea:– analog signals are clipped above ~6phe– analog sum of ~10 pixels– discriminate sum signal at ~20 phe
First tests on MAGIC are very encouraging
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44A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Trigger tests on La Palma
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45A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
midterm future (2008): MAGIC II
second telescope: MAGIC-II
”Improved clone”– Most fundamental parameters identical
to MAGIC-I– Use improved technology where
available:• High QE photosensors• Fast sampling readout
MAGIC-I
MAGIC-II
85m
Aim:• Increase sensitivity (particularly below 100 GeV)• Lower energy threshold further
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46A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
MAGIC II Monte Carlo Studies
Stereo Analysis:• observe shower simultaneously
with 2 telescopes
• 3D shower reconstruction• Additional shower parameters:
– Impact parameter– Shower maximum (hmax)– Eliminate ambiguity on arrival
direction
• Better reconstruction of energy and arrival direction
• Improved background rejection
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47A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Improved Reconstruction
• Energy resolution– MAGIC-I: ~25%– MAGIC-II: 14-20%
(2 telescopes)
• Angular resolution– Substantial (~50%) improvement
since source position is obtained from intersection point of both showers
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48A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Improved Sensitivity
using Stereo Analysis• better background rejection down to low energies • increase sensitivity by up to factor 3
=> reduce observation time by factor 9• Large gain in sensitivity at low energies (< 100 GeV)
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49A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
New photon detectors: The G-APD
a promising photon detector concept invented in Russia in the 80’s
P. Buzhan et al. http://www.slac-stanford.edu/pubs/icfa/fall01.html
• sensors with ~60% efficiency become available• internal gain ~105 -106• compact and robust• …
advantages
disadvantages
• small sizes (
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50A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Test on La Palma with MAGIC
4 MPPC-33-050C from Hamamatsu:
sensor size: 3x3mm²single cell size: 50x50µm²nominal bias: 70.4Vdark rate at nominal bias: ~2MHzgain at nominal bias: 7.5*105crosstalk at nominal bias: 10%
peak photon detection efficiency 55% needs to be confirmed
Array of 4 MPPCs:light catchers with factor 4 concentration; 6x6mm² onto 3x3mm²
MAGIC Pixel Size
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51A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Array mounted onto the MAGIC camera entrance window for two nights
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52A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
position of MPPC array
1 phe
MPPCs
PMTs
2 phe 4 phe 1 phe
70 phe 35 phe 35 phe 15 phe
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53A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Shower Signals: MPPC vs PMT
event selection:two PMTs next to MPPCs with more than 15 photoelectrons in each tube
signals are correlated
coun
ts
~300 events from ~30 min data
on average MPPCs detect 1.6 times more light
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54A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
End
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55A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Light recorded from Calibration Runs
UV-LEDs 375nm
Pedestal
1 phe
2 phe
3phe
…
single phe-resolution degraded due to light
from night sky background
easy calibration
some recorded showers
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56A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Key technological elements for MAGIC
17 m diameter parabolic reflecting surface (236 m2 )
Analog signal transport via optical fibers IPE
IPEIPECENET
2-level trigger system& FADC system
Active mirror control(PSF: 90% of light in 0.1o inner pixel)
high reflective diamond milled aluminum mirrors Light weight Carbon fiber
structure for fast repositioning
- 3.5o FOV camera - 576 high QE PMTs
(QEmax= 30%)
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57A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Data Set
• October – December 2005
• 16 hours ON source / 19 hours OFF source
• zenith angle 500 GeV
alpha plot for energies >200 GeV
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58A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The Crab Pulsar Wind Nebula
• standing reverse shock
• acceleration of electrons up to 1016 eV
• synchrotron emission (radio to gamma -rays) downstream of shock
• inverse Compton scattering (VHE gamma-rays)
other possible VHE gamma-ray components are pi0-decay or bremsstrahlung
influence on VHE gamma-ray spectrum, morphology and variability
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59A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
3C 279
• EGRET brightest AGN– Gamma-ray flares in 1991 and 1996– Apparent luminosity ~ 1048erg/s– First time variation △T ~ 6hr in 1996 flare
• Typical OVV quasar (Optically violent variable)– Categorized as a FSRQ (Flat Spectrum Radio
Quasar)
• Superluminal motion, γ~ 20~30• z = 0.538, Ld ~ 3Gpc
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60A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
3C 279 Flare in 1996
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61A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
SSC+EC / Hadronic
MAGIC
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62A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
EBL Absorption
Pair Creation; γHE+γEBL e+ + e-
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63A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
MAGIC Telescope
MAGIC-II is under construction and will becompleted in the fall of the next year
Improve sensitivity by a factor of threeEffectively lower the threshold energy
New technologiesto lower the threshold energy
17m diameter world largest cherenkov tel.0.1°High resolution cameraHemispherical PMT with enhanced QEAnalogue signal fiber transmission
Current MAGIC-I Performance
Fast rotation for GRB < 40secsTrigger threshold ~50GeVSensitivity ~2% of Crab (50hrs)Angular resolution ~0.1 degreesEnergy Resolution 20-30%
85m
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64A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Observation of 3C 279 with MAGIC
• Observation– In the period of January - April 2006– Observation of 9.5hrs– Zenith angle range is between 32 and 40
degrees relatively high threshold of 80GeV
• Analysis– 4 independent analyses have been done– Standard analysis and standard quality cut– Preliminary results will be presented here
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65A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Sky-map and alpha ploton 23rd Feb 2007
80-220 GeV
E> 220 GeV
PreliminaryPreliminary
PreliminaryPreliminary
Sky map around 3C279Sky map around 3C279
PreliminaryPreliminary
PreliminaryPreliminary
PreliminaryPreliminary
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66A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
3C279 VHE gamma-ray light curve
Intra-night LC
PreliminaryPreliminary
PreliminaryPreliminary
Optical light curve
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67A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Extragalactic VHE-sources (19)
Source Redshift Sp. Types Discovery ObservationM 87 0.004 2.9 FR-I HEGRA HESS
Mkn 421 0.031 2.2 HBL Whipple many
Mkn 501 0.034 2.4 HBL Whipple many1ES 2344+514 0.044 2.9 HBL Whipple MAGIC
Mkn 180 0.045 3.3 HBL MAGIC1ES 1959+650 0.047 2.4 HBL 7TA manyPKS 0548-322 0.069 HBL HESS
BL Lac 0.069 3.6 LBL MAGICPKS 2005-489 0.071 4.0 HBL HESSPKS 2155-304 0.116 3.3 HBL Durham many1ES 1426+428 0.129 3.3 HBL Whipple HEGRA1ES 0229+200 0.139 HBL HESS
H 2356-309 0.165 3.1 HBL HESS1ES 1218+304 0.182 3.0 HBL MAGIC VERITAS1ES 1101-232 0.186 2.9 HBL HESS1ES 0347-121 0.188 HBL HESS1ES 1011+496 0.212 4.0 HBL MAGIC
3C 279 0.538 FSRQ MAGIC
PG 1553 ? 4.0 HBL HESS/MAGIC
New HBL 1ES1011+496 See the presentation by D. Mazin
Big progress in AGN studyfrom z ~ 0.2 to z = 0.538
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68A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Summary
• VHE gamma-ray emission from 3C 279 was discovered by MAGIC– New class of source FSRQ, OVV-quasar
• The VHE flare at 100GeV was observed on 23 February in 2006 – 6 sigma below 220GeV, and 5 sigma above 220GeV
• The survey distance is extended up to z = 0.538 by MAGIC telescope– Big jump toward the deep Universe!
• Study of Energy spectrum– may deliver a stringent constraint on EBL and acceleration model– Analysis is ongoing; We need very careful understanding of
systematic uncertainties in the energy determination
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69A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab nebula emission region in VHE gamma-rays
• emission region determined by:• confinement of electrons by
magnetic fields• synchrotron cooling times
lower energies more extended emission region (few tens of arcseconds)
possible hadronic component (pi0 decay) could result in a more extended emission region
Atoyan & Aharonian
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70A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Nebula: Differential Energy Spectrum
• gamma-ray emission measured over two decades of energy60 GeV – 9 TeV
• simple power-law behavior disfavored; χ²: 24/8
• spectrum is well described by a curved power law fit; χ²: 8/7
( )
TeVscmGeVE
dEdF GeVE
⋅⋅⎟⎠⎞
⎜⎝⎛⋅=
−−−
2
300/log26.031.210 1
300106
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71A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab pulsar in optical
verifies analysis chain
main pulse offset by -252±64 µsto position of main pulse in radio
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72A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Search for pulsed Gamma-ray emission
BackgroundExcessQ =
Q vs. upper Size cut
Assuming exponential cutoff of the pulsar at 30 GeV
highest sensitivity for pulsed emission if events with Size
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73A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Pulsar: Broadband Emission
Thompson et al. 1999
• synchrotron radiation• curvature radiation• inverse Compton scattering
radiation processes
• no pulsar detected above ~100 GeV
MAGIC
spectroscopy of the cutoff would help to distinguish between theories
spectral cutoff; challenging for experiment
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74A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The GeV excess
EGRET observed Gamma-ray flux >1GeV can not be described by SSC
possible explanations:
• DC gamma-ray component from the pulsar
• enhanced Bremsstrahlungemission
SSC-model
GeV excess
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75A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
The GeV excess explained by Bremsstrahlung
Atoyan & Aharonian 1996
amplified Bremsstrahlung in denser regions of the nebula (knots)
can explain the GeV excess
could result in modified spectrum between 100 GeVand several TeV
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76A. Nepomuk Otte Max-Planck-Institut für Physik / Humboldt Universität Berlin
Crab Nebula: Spectral Index
• observation of energy dependent spectral index
• no deviation from SSC predictions (blue line)
• disfavor A&A 1996
• model A&A 1998 in agreement with measurement
Very High Energy Gamma Ray Observations with the MAGIC Telescope�(a biased selection)The non-thermal universe in VHE gamma-raysVHE gamma-ray sources �status ICRC 2007Imaging Air Cherenkov Technique The MAGIC siteA recent view of MAGICCurrent Status of MAGICCentral Pixel for Optical MeasurementsEvent ParameterizationBackground Rejection Gamma / Hadron SeparationExtragalactic Sources: Active Galactic NucleiAttenuation of VHE -rays known extragalactic VHE-sources (19)Detection of 3C279Pulsars and �& pulsar nebulaeThe Pulsar Wind Nebula Complex�on the example of the CrabThe Crab Nebula resolved in X-RaysThe Crab-PWN: Broadband EmissionCrab Nebula: �Spectral Energy DistributionCrab Nebula: MorphologyCrab Nebula: VariabilityThe Crab Pulsar Wind Nebula ComplexGamma-Ray Emission from PulsarsCrab Pulsar in Gamma-RaysUpper limit on cutoff energyCrab Pulsar II PSR B1951+32 / CTB 80In the surroundings of PSR B1951+32PSR B1951+32 / CTB 80PSR B1951+32 PulsarEvolution of Pulsars in Binary systemsPSR B1957+20: The black widowPSR B1957+20: search for steady gamma-ray emissionPSR B1957+20: Search in orbital phaseLSI+61 303 LSI+61 303: MAGIC observationsLSI+61 303: modelsSummary and ConclusionOutlook into the FutureVery near future: This Crab seasonTrigger tests on La Palmamidterm future (2008): MAGIC IIMAGIC II Monte Carlo StudiesImproved ReconstructionImproved SensitivityNew photon detectors: The G-APDTest on La Palma with MAGICShower Signals: MPPC vs PMTLight recorded from Calibration RunsKey technological elements for MAGICData SetThe Crab Pulsar Wind Nebula3C 2793C 279 Flare in 1996SSC+EC / HadronicEBL AbsorptionMAGIC TelescopeObservation of 3C 279 with MAGICSky-map and alpha plot�on 23rd Feb 20073C279 VHE gamma-ray �light curveExtragalactic �VHE-sources (19)SummaryCrab nebula emission region �in VHE gamma-raysCrab Nebula: Differential Energy SpectrumCrab pulsar in opticalSearch for pulsed Gamma-ray emissionPulsar: Broadband Emission The GeV excessThe GeV excess explained by BremsstrahlungCrab Nebula: Spectral Index