Transcript Slide 1
44 th Rencontres de Moriond La Thuile, Valle d’Aosta, February 1-8, 2009
The MAGIC extragalactic sky
The telescope MWL campaigns Recent results & discoveries
Hints of new physics?
Barbara De Lotto Universit à di Udine & INFN - Italy
on behalf ot the MAGIC Collaboration
Imaging Air Cherenkov Technique
Gamma ray Particle shower ~ 10 km
Cherenkov light Image of particle shower in telescope camera
~ 1 o ~ 120 m
- reconstruct: - reject hadron background statistically in the analysis
The MAGIC site
La Palma, IAC 28 ° North, 18 ° West
~2240 m asl
•
Currently the largest diameter) single-dish Cherenkov telescope (17 m
• In operation
since fall 2004 ( starting AO-5 in Spring ’09)
•
Sensitivity : 1.6% Crab in 50 h
•
Angular resolution : 0.1 deg
•
Energy resolution : ~ 20%
•
Enhanced duty cycle thanks to moonlight & twilight observations (by 50%)
•
Substantially lower energy threshold than other installations:
• 55 GeV nominal • 25 GeV pulsar (“sum”) trigger •
Fast repositioning (~30 s)
• 2
nd 24th telescope ( MAGIC-II ) first light this winter, ceremony on April ~150 physicists, 23 institutes Germany, Italy, Spain leading
The MAGIC telescope
≈ x
Propagation of
g
-rays
x
dominant process for the g g VHE g EBL absorption:
e + e x
s ( b ) ~ Heitler 1960 maximal for: For g rays, relevant background component is optical/infrared (EBL) different models for EBL: minimum density given by cosmology/star formation
Science 2008
Measured spectrum affected by attenuation in the EBL:
~ E -2
Measurement of spectral features permits to constrain EBL models
Attenuation of
g
-rays
o e
(
E
,
z
)
optical depth
g
-ray horizon:
(E,z) = 1
Fazio & Stecker 1970 Blanch & Martinez 2005 region of opacity:
> 1 Importance of decreasing the energy threshold to look further away
Extragalactic VHE
g
-ray sources
24 AGN discovered by IACTs:
Ref.:
Extragalactic VHE
g
-ray sources:
23 blazars & 1 radio galaxy hadronic acceleration
p + (>>TeV) 0 matter + gg (TeV) e (TeV) g (eV-keV)
non-thermal emission, highly variable
CRs?
VHE
g
origin?
g B (eV) g (TeV) Inverse Compton
shape of spectrum
IC
Extragalactic Background Light Propagation mechanisms Lorentz Invariance
0 decay
energy E
Highlights in MAGIC extragalactic observations
M87 (z=0.0043) Mrk421 (z=0.031) Mrk501 (z=0.034) 1ES2344 (z=0.044) Mrk180 (z=0.045) 1ES1959 (z=0.047) BL-Lacertae (z=0.069) 1ES1218 (z=0.18) PG 1553+113 (z>0.25) MAGIC J0223
(3C66B?)
1ES1011 (z=0.212) S5 0716 (z=0.31)
Bright Blazars Multiwavelength campaigns
• • Simultaneous Multifrequency Observations covering • 15 decades in photon energy: VHE: HE: X-ray H.E.S.S., MAGIC, VERITAS Agile, Fermi : Suzaku, Swift, Chandra, Integral Optical : KVA Radio : Metsahövi, … Some recent MWL campaigns: • Mrk 421, Mrk 501, PG 1553+113, 1ES 1218+304, 1H 1426+428, M87 • Further under process, organized …
1ES 1959+650
ApJ 679 (2008) 1029 MWL campaign during May 2006 with Suzaku and Swift Two-peaked SED VHE emission (E>200 GeV) at one of the lowest ever observed states, no significant variability detected Modeled by a one-zone SSC model
Mrk 421 June ‘08 flare
Donnarumma+ ApJ 691 (2009) L13 Hard X-ray flare triggered MWL campaign: WEBT, Swift, Agile, MAGIC, VERITAS Time variability in TeV and X-ray comparable SSC modeling Interpretation paper under development
PG 1553+113
Reimer+ ApJ 682 (2008) A&A 493 (2009) MWL campaign during July 2006 with H.E.S.S., Suzaku and KVA Simultaneous MWL campaign during March April 2008 with Agile, XTE/ASM and KVA [paper in preparation]
KVA XTE/ASM AGILE U.L.
MAGIC Differential spectrum compatible with H.E.S.S. and previous measurements Spectral Energy Distributiom: homogeneous one-zone SSC model
M87
ApJ Lett. 685 (2008) L23 The first non-blazar radio galaxy observed to emit VHE g -rays • VERITAS/MAGIC/H.E.S.S. monitoring • 8 s on 2008 Feb 1 → VERITAS and H.E.S.S.
Trigger issued to • 9.9
s in overall sample (22.8 hours) between 2008 Jan 30-Feb 11 • Flux variable between 3-15% Crab • High variability > 350 GeV • Confirming day-scale variability (5.6
s ). No intra-night variability • Compatible with constant between 150 350 GeV (Crab nebula) 150-350 GeV constant flux >350 GeV α=–2.6
α=–2.2
day scale : 5.6 σ
Optical triggers
KVA optical telescope at la Palma
new discoveries
ApJ, 648 (2006) L105 ToO trigger Mkn 180 z = 0.045
March 2006 MAGIC 12.1 h S=5.5 σ
ApJ, 667 (2007) L21
March-May 07
1ES 1011+496 z = 0.212
ToO trigger
MAGIC 18.7h
S=6.2 σ
S5 0716+714 z = 0.31
S5 0716+714 MAGIC PRELIMINARY Significance 6.8 σ
The 3C 66A/B region
ApJ Lett. 692 (2009) 29
B: radio Galaxy A: distant Blazar, VHE candidate (EGRET, Crimea, VERITAS, Fermi) MAGIC observations triggered by optical outburst in 2007 3C 66B is more likely the source of emission ( MAGIC J0223+430)
3C279
the most distant
Science 320 (2008) 1752
• flat-spectrum radio-quasar at
z=0.536
• brightest EGRET source. Highly variable, fast variability (~6 hours) • MAGIC observed it in 2006 during WEBT campaign for 9.7 hours in 10 nights • Clear detection 23 rd Feb 2006 (6.2
s )
First FSRQ in TeV
g
-rays Major jump in redshift
skymap
Energy spectrum of 3C279
Measured and EBL-corrected spectrum:
3C279 and the
g
-ray horizon
Test of the transparency of the universe extended to z = 0.536!
Is there a new land just behind the horizon?
Spectral characteristics of observed AGN
Selection bias?
New physics?
adapted from De Angelis, Mansutti, Persic, Roncadelli MNRAS 2009
redshift
Limits on 3C454.3
We have also searched farther out: during summer 2007 intense emission of 3C454.3 - a well known FSRQ @ z = 0.86 detected by AGILE Upper limits derived from MAGIC data together with nearly simultaneous multifrequency data allow to constrain the SED
Flares: a way to new physics?
Energy-delayed flare of Mrk501:
Quantification of the delay: (0.030
± 0.012) s/GeV Probability of no delay: 2.6%
150-250 GeV ApJ 669 (2007) 892 Phys Lett B 668 (2008) 253
Possible explanations: • Astrophysical:
intrinsic source
effects IF photons at different energies were emitted simultaneously • Propagation effect due to
Lorentz invariance violation
:
c
'
c
1
E E s
E E s
2 Probing the Planck energy scale
250-600 GeV
July 9 ‘05
600-1200 GeV > 1200 GeV Opens the way to future population AGN studies at different z
MAGIC is producing high quality astrophysics after ~3.5
observation cycles:
Lowest energy threshold => deepest horizon
We have discovered 8 new extragalactic sources, detected and studied 5 known Important contributions to the understanding of AGN, EBL Now reaching out much further in redshift: high energy photons (often traveling through large distances) are a powerful probe of fundamental physics under extreme conditions MAGIC-II starts operations on April 24 th