Data analysis with Cherenkov Telescopes: MAGIC
Problematiche astrofisica VHE
Antonio StamerraUniversità di Siena & INFN Pisa
JC - 10 febbraio 2010 Pisa
Istituto Nazionaledi Fisica Nucleare
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 2
IACT detector
IACT Imaging Atmospheric Cherenkov Telescope
Atmosphere is opaque to γ-rays
IACT detector IACT detector = =
Atmosphere + telescopeAtmosphere + telescope
Satellite: direct detection of γ-ray
Ground-based: indirect detection
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 3
Electromagnetic atmospheric shower
pair-production
Bremsstrahlung
R~9/7 X0~45g/cm2
(in air, 20oC)
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 4
MAGIC17 m diameter reflecting surface (240 m2 )
Analog signal transport via optical fibers 2-level trigger
system& 300 MHz FADC system
Active mirror control
high reflective diamond milled aluminum mirrors
Light weight Carbon fiber structure for
fast repositioning
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 5
Stereoscopic mode: Improved sensitivity Better angular and energy
resolution New technologies:
Camera: Photo-detectors with higher QE (HPDs in near future)
Faster Digitalization: 4 GHz Analogue to Digital Converts (Domino)
MAGIC-IIFlorian Goebel
Telescopes
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 6
QuickTimeᆰ e undecompressore
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Imaging Air Cherenkov Telescopes
Direction reconstruction Particle-id Energy reconstruction
Showertop
Showertail
×
γ -ray direction
A telescope placed inside the Cherenkov light A telescope placed inside the Cherenkov light pool can obtain an image of the development pool can obtain an image of the development of the shower above the night sky background of the shower above the night sky background (NSB) fluctuations(NSB) fluctuations
Distances in camera
= Angular Distances
on sky
Shower top
N1 ,θ C1
Shower tail
n2>n1 ⇒ θC2> θC1
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 7
Background
Cosmic-ray background γ-rays have a definite direction
(source position on sky) CR are isotropically distributed
ON-OFF selection? CR flux overwhelms γ-ray flux…
Night-Sky background (NSB, LONS)
Field stars
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 8
Gamma/hadron separationgamma proton
300 GeV gamma 1 TeV proton
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 9
Modelli emissione adronica
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 10
Cosmic rays
“All-particle” spectrum Power law spectrum (~E-
2.7) Particles decrease with
energy
Two breaks in the power law Knee ~3 PeV (3x1015 eV) Ankle ~1 EeV (1018 eV)
Underlying physical processes?
Acceleration mechanism?
Acceleration sites?
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 11
Cascade showerCascade shower
100GeV gamma ray 300GeV Proton
By M. Hayashida
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 12
EAS simulation - uncertainties
Reliability of simulation of hadronic interactions (extrapolation of accelerator data and/or theoretical assumptions) - partially solved by IACTs using real hadrons…
Forward physics unexplored (LHC? E.g. TOTEM)Physical Intrinsic shower fluctuations
Enviromental Weather condition (Calima, high clouds,…) Night sky light (Bright stars, Moon, city, …)
Instrumental Calibration (absolute QE, mirror aging, …) Background estimation (inhomogeneity, …) Telescopes condition (dead pixels, misspointing, …)
Analysis Simulation (atmospheric model, trigger, …) Analyzer choices (optimizations, binning, …)
Generally, IACTs claim 20% systematics !
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 13
Sensitivity in 50h5σ & 10 evts
For 5σ: Sensitivity ∝ 1/sqrt(time)
For 10 evt: Sensitivity ∝ 1/time
Sensitivity
Depends on the Effective area and CR Background rejection (and background uncertainty)
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 14
MAGIC-II
Overall sensitivity will be Overall sensitivity will be improved by a factor of 2-3improved by a factor of 2-3
Energy resolutionEnergy resolution ~25% ~25% 15-20% 15-20%
Angular resolutionAngular resolution Substantial improvementSubstantial improvement
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 15
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 16
Sites of particle acceleration
Hillas plot
Compact sites and high B Diffuse objects and low B
The acceleration site environment plays a key role…
A deeper (astrophysical) knowledge of candidate sites is mandatory
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 17
Exploring extreme accelerators with gamma-rays
VHEγ-astronomy address diversity of topics related to the nonthermal Universe:
acceleration, propagation and radiation of ultrarelativistic protons/nuclei and electrons
generally under extreme physical conditions in environments characterized with
huge gravitational, magnetic and electric fields, highly excited media, shock waves
and very often associated with relativistic bulk motions linked, in particular, to
jets in black holes (AGN, Microquasars, GRBs) and cold ultrarelativistic pulsar winds
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 18
Goal 0: Detection!
Gammas are not for free…
Signal reconstruction Background rejection Sensitivity
Minimum flux detectable Shortest time variation Observation time
In the following we assume we are lucky and we always get gammas.
We focus on goals 1, 2, 3. We’ll tackle goal 0 later on (slide 35 ff).
S s »Rate
g
RateB
T
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 19
Standard candle: Crab Nebula
Crab broad-band spectrum
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 20
UVUV
OpticalOptical
RadioRadio
X-RayX-Ray
MWMW
γγ -ray-ray
VHEVHE
Energy Energy
Flu
x
Flu
x
sincrotrone
IC
100Mev-10GeV
>100GeV
BBe-
γ
e-
e- γ
γ
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 21
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 22
Goals summary
Spectrum #ph in ∆E
Energy reconstruction
E’ energy resolution
Skymap #ph in ∆Ω
Angular resolution - PSF
F.o.V.
Lightcurve #ph in ∆ t
Time resolution
Pulsar ⇒ ms AGN ⇒ min.
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 23
Gamma/Neutrino astronomy
Fermi acceleration processes create secondary particles, among them neutral particles
γ and ν bring direct information on the acceleration site
But…. Their emission, and
propagation depends on the environment and source details
A deep (astrophysical) knowledge of the source is mandatory!
Chargedparticles
Acceleratedparticles
Bpp
HeHeIonsIonsππnnµµee
γγνν
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 24
γ-ray production
Synchrotron radiation
Bremstrahlung
Inverse Compton
Annihiliation
p/nuclei interaction with ISM (proton induced cascade)
Proton-synchrotron
ISM
e-
γ
BBe-
γ
e-
e- γγ
e+
γ
γ
e-
P (RC)π +
π0
γ
γHadro
nic
pro
ces s
es
Lep
toni
c pr
oces
ses
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 25
Hadronic or leptonic?
Emissione γ ray emission from π0 decay and interaction with molecular clouds
Signature: π0 decay spectrum
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 26
Hadronic or leptonic?
modelli leptonici modelli leptonici (IC)(IC)modelli
adronici Yet no “smoking gun” evidence of γ-rays stemmed from hadronic acceleration and π0 decay!
But many hints….
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 27
WHAT DO WE LEARN FROM GAMMA RAYS?
courtesy P. Blasi
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 28
WHY IS IT INTERESTING:II. Large B observed?
TYPICAL THICKNESS OF FILAMENTS: 10-2 pc
The synchrotron limited thickness is:
Dx 4 D E tsyn
E »4 pc Bm3/2
B»100 m Gauss courtesy P. Blasi
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 29
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 30
RXJ1713
EFFICIENT ACCELERATION – LARGE B FIELDS
PROBLEMS: 1. LARGE THERMAL X-RAYS (BUT…) 2. VERY LOW RATIO OF ELECTRONS AND PROTONS
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 31
INEFFICIENT ACCELERATION – LOW B FIELDS
PROBLEMS: 1. VERY HIGH PHOTON DENSITY FOR ICS 2. LOW B FIELDS (IGNORES X-RAY OBSERVATIONS) 3. BAD FIT TO HIGHEST-E HESS DATA POINTScourtesy P. Blasi
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 32
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 33
Kep~0.01
Kep~0.1
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 34
AGN - blazars
Intense and variable emission up to ~10 TeVObserved structures: accretion disk; obscuring thorus Relativistic Jet Broad/Narrow line regions (NLR, BLR)
TeV emitting zone: jet with high relativistic bulk motion Particle acceleration at shock
boundaries bundled in a magnetic field (Fermi acceleration processes)
Gamma-ray emission from accelerated electrons (synchrotron and inverse-Compton scattering) or hadronic interactions
Unified AGN model: different AGN classes depending on viewing angle FRI, FR-II, Radio quasars, BL-Lac
(HBL-LBL)
FR-I, FR-II Radio quasars
BL-Lac
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 35
γ-ray emission from AGN: SSC a (minimal)
standard model
Blazar: collimated emission from jet (relativistic amplification) Environment: B, δ, R
Observed emission (SED) well described by leptonic models, such as SSC and EC. Expected X-ray / Tev time
correlation Synchrotron peak: IR to x-ray IC peak: UV to γ-rays LBL, IBL, HBL Outbursts of e.m. radiation
Synchrotron IC Em
itte
d po
wer
Energy
BBe-
γ
e-
e- γγγ min γbr γmax γ br γmaxKN
Relativistic electrons injection/acceleration/cooling
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 36
Blazar Multiwavelength campaigns
ExtremeExtreme (~>1 order of magnitude in flux) and (~>1 order of magnitude in flux) and fast fast (~hours, minutes) (~hours, minutes)
vvaarriiaabbiilliittyy Simultaneous Multifreq. Observations covering 15 decades in photon
energy:VHE: H.E.S.S., MAGIC, VERITASHE: Agile, FermiX-ray: Suzaku, Swift, Chandra, IntegralOptical: KVARadio: Metsahövi, VLBI…
Methods: Monitoring (optical, x-ray, radio) Intensive planned campaigns Target of Opportunity (ToO): react to alerts (internal/external)
• MAGIC Monitoring program of bright blazars (Mrk421, Mrk501, 1ES1959, 1ES2344+514….)
Some recent MWL campaigns: • Mrk 421, Mrk 501, OJ287, PG 1553+113, 1ES 1218+304, 1H 1426+428, M87• …and other campaigns organized…
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 37
Mrk 421 2008 activity
MWL campaigns on Mrk421 in flaring stateoptical to TeV energies
Simultaneous data strong SSC model constraints time evolution of the SEDs
New 2009 campaign on Mrk421 and Mrk501
Bonnoli G. et al. (MAGIC Coll.) arXiV:0907.0831Bonnoli G. et al. (MAGIC Coll.) arXiV:0907.0831Publication in preparationPublication in preparation
preliminary
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 38
Mrk421 - 2009 campaign
4.5 months Jan 20th - June 1st
~20 instruments
2-day sampling
Complete coverage 0.1 GeV-10 TeV
preliminary
Fermi
MAGIC
Swift/XRT
D.Paneque, Fermi symposium
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 39
S5 0716+714IBL z=0.31(?)
Bright in optical ⇒ trigger MWL campaign (opt-X-γ) Clear signal in 2.6 h: 6.9σ
1st VHE detection F(>400 GeV) =7.5x10-12 ph/cm²/s (≈9% Crab)
Significance 6.8 σ
ApJ - accepted arXiv:0907.2386MAGIC collab. 2008, Atel #1500
SSC model predicts an unplausible IC γ -ray flux⇒ Spine-layer model Ghisellini et al. 2005, A&A, 432, 401
High redshift Nilsson,A&A 487(2008)L29 reports the detection of the host galaxy: z=0.31±0.08
2008
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 40
S5 0716+714IBL z=0.31
Rotation of positional angle of polarization (EVPA) during maximum (60deg/day) Larionov et al.,ATel #1502
propagation of a polarized knot spiraling down the jet, following helical magnetic field (e.g. BLLac, Marscher et al., 2008, Nature, 452, 966)
Similar behavior (degree of polarization) during Fermi campaign on 3C279: polarization degree a good precursor of γ-flares?
X-ray spectrum shows synchrotron component: transition between LBL-HBL states? E.g. reported on PKS2155-304
Y.H.Zhang, ApJ,682(2008)789
QuickTimeᆰ e undecompressore H.264
sono necessari per visualizzare quest'immagine.
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 41
BL Lacertae
MAGIC detection in 2005-2006flare end October 2005 ~MJD 53670
MAGIC Coll., ApJL 666 (2007) L17MAGIC Coll., ApJL 666 (2007) L17
A. Marscher et al., Nature 452 (2008) 966A. Marscher et al., Nature 452 (2008) 966
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 42
M87 RG z=0.0043, 16.7 Mpc
RadioVLBA 8 GHz
X-raysChandra
nucleus
HST-1
knot Dknot A
Harris+07
“misaligned blazar” (15-25o); 17 Mpc HEGRA hint; HESS/VERITAS detection
Candidate nearby CR site (hadronic emission?)
Variability?Site for TeV emission (core/HST-1)?
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 43
M87 MWL campaign jan-feb 2008
(triggered by MAGIC detection on 1st February flare)
9.9σ detection; 8.0σ single night 1st-feb First spectrum at E>100 GeV
Marginal hint of spectral hardening
Clear <~daily variability at E>350GeV Chandra observations ⇒ core/HST-1
contribution (core active / HST1 dim)
Science, 325 (2009) 444
Joint paper MAGIC-VERITAS-HESS-VLBI-Chandra MAGIC coll. ApJL, 685 (2008)
Apr07 Jul07 Oct07 Jan08 Apr08
VHE
HST-1
nucleus
X-ray
radio
jet
Nucleus ~100Rs
Nucleus radiobrightening
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 44
Goal 2: lightcurve
AGN, µQSO ⇒ days, minutes
Pulsar ⇒ ms
#ph / ∆T Time resolution
X-ray
TeV
Crab pulsar
33 ms
26 days
LS I+61 303
0.15-0.25 TeV
0.25-0.6 TeV
0.6-1.2 TeV
1.2-10 TeV 4 min lag
Mrk 501
20 minutes
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 45
Crab pulsar Cutoff depends on the acceleration
and radiation process (outer gap/polar cap) Absorption in magnetosphere
(magnetic/photon pair production) Maximum acceleration energy
First hint at E~>60 GeV
Albert et al. 2008, ApJ, 674, 1037
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 46
Crab pulsar
Lower trigger threshold: new trigger system (sum-trigger)
M. Teshima et al. 2008, Atel #1421MAGIC coll., Science 322 (2008) 1221
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 47
LS I +61 303o High Mass X-ray Binary (2kpc)
o Be star orbiting unknown object (NS-BH)
o P=26.5d; e=0.72
o X-ray emission at
o Φ~0.5
o GeV-emitter (3EG 0241+6103)
⇒ Candidate for TeV emission
Mirabel 2006
Relativistic electrons from accretion powered jet
Relativistic electrons from rotational energy of pulsar
Relativistic Jet radio structures: µ-QSO nature? (Massi et al. 2004)
Cometarylike radio structure: interaction of pulsar/jet wind Massi et al 2004
M. Massi et al., A&A 414, L1 (2004) J.Albert et al., ApJ, 684, 1351 (2008)
10 mas100 mas
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 48
LS I +61 303
MAGIC observations 2005-2006 (54 hrs, 6 orbits)
8.7 sigma; point-like; max at Φ~0.6-0.7
MAGIC Coll. 2006, Science, 312, 1771
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 49
F
(E
> 4
00 G
eV)
LS I +61 303
2nd campaign - sep-dec 2006; 112 hrs
Hint of X-ray/TeV emission correlation
No time correlation with radio Highest emission at Φ=0.65 Periodicity: 26.8±0.2 days No significant spectral changes
with phase
Swift/XRT0.3-10 keV
P.Esposito et al 2007
MAGICE>400GeV
æ 1stcampaignPhase 0.6 - 0.7Phase 0.5 - 0.6Phase 0.4 - 0.7 (1st campaign)
Periastron
MAGIC coll. 2009, ApJ, 693, 303
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 50
LS I+61 303
Simultaneous MWL campaign, single period
XMM, Swift, MAGIC - sep 2007; Clear X-ray/TeV emission
correlation No radio-TeV(X-ray) correlation Highest emission at Φ=0.65 No significant spectral changes
with phase X-ray
TeV
MAGIC coll. 2009, ApJ Lett. 706, L27
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 51
⇒⇒ Interaction with Extragalactic Background Interaction with Extragalactic Background Light (EBL)Light (EBL)
⇒ energy dependent energy dependent γγ -ray absorption -ray absorption
⇒ modification of original spectrummodification of original spectrum
Î ¦Î ³o b s e r v e d E Î ¦
Î ³u n a b s o r b e dE e
Ï„ EÎ ³
, z
ττ (E,z): Optical Depth(E,z): Optical DepthGamma Ray Horizon (GRH): Gamma Ray Horizon (GRH):
ττ=1=1
EBLEBL
EHEε EBL=3.6(mec2)2
Emitted spectrum
observed spect.
High absorption
Low absorption
Energy
Energ
y flux
Energy
Energy
λ 1 .2 4m mE
g
1 T e V1 z2
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 52
Cosmic backgrounds
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 53
CIB: modelli
Primack (2005)
Data analysis with Cherenkov Telescopes: MAGIC
Perugia, 22 ottobre 2009 MAPS school a.Stamerra 54
http://wwwmagic.mppmu.mpg.de/[email protected]@pi.infn.ithttp://www.pi.infn.it/magic/http://www.pi.infn.it/magic/