SNRs and PWNe as seen by
the MAGIC telescope
E. de Cea del Pozo
on behalf of the MAGIC Collaboration
All ® Chandra X-ray Observatory (NASA/ SAO/ CXC)
38th COSPAR Scientific Assembly
Bremen (Germany)
Outline
• Motivation for very high energies
• MAGIC telescopes
• Supernova remnants (SNR) by MAGIC
• Pulsar wind nebulae (PWN) by MAGIC
• Concluding remarks
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Elsa de Cea on behalf of MAGIC
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Motivation for VHE
• SNR long believed to be acceleration site of galactic cosmic rays.
Maximum energy ~ 1015eV.
- about 10% of SN explosion energy required.
- Diffusive shock acceleration of cosmic rays.
• PWN after SN explosion can produce TeV emission.
- γ-rays produced by inverse Compton (IC) of accelerated electrons.
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MAGIC telescopes
• Two 17m single-dish Cherenkov telescopes.
• Located in the Observatorio del Roque de los Muchachos on
Canary Island of La Palma (Spain).
• Phase I from 2004 – 2009. Phase II in operation since fall 2009.
• Stereoscopic observation mode:
– Sensitivity: < 1% Crab* in 50 h
– Angular resolution: < 0.1º
– Energy threshold: ~ 50 GeV
(*) Crab Nebula is the standard candle for TeV astronomy. Fluxes are usually expressed in terms of Crab fluxes.
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MAGIC telescopes
• Two 17m single-dish Cherenkov telescopes.
• Located in the Observatorio del Roque de los Muchachos on
Canary Island of La Palma (Spain).
• Phase I from 2004 – 2009. Phase II in operation since fall 2009.
• Stereoscopic observation mode: MAGIC stand-alone observations:
– Sensitivity: < 1% Crab* in 50 h
– Angular resolution: < 0.1º
– Energy threshold: ~ 50 GeV
- Sensitivity: 1.6% Crab in 50 h
- Angular resolution: 0.1º
- Energy threshold: 55 GeV
(*) Crab Nebula is the standard candle for TeV astronomy. Fluxes are usually expressed in terms of Crab fluxes.
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Supernova Remnants
as seen by MAGIC
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SNR IC 443 (G189.1+3.0)
• Asymmetric shell-type SNR (45’
at 1.5 kpc)
• Middle–age ~ 3 x 104 yr
• MTotal ~ 1.1 x 104 M⊙ mainly in
foreground giant molecular cloud
MAGIC J0616+225:
§ Detected at 5.7σ in 29 hr
§ 2.8% Crab above 300 GeV
§ Steep spectrum (3.1 ± 0.3)
§ Displaced from EGRET/
Fermi/AGILE centroid (0.15º)
and PWN (0.20º)
§ Confirmed by VERITAS
22nd July 2010
® Chandra X-ray: NASA/ CXC/ B.Gaensler et al; ROSAT X-ray: NASA/
ROSAT/ Asaoka & Aschenbach; Radio Wide: NRC/ DRAO/ D.Leahy;
Optical: DSS
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IC 443 with MAGIC
Albert et al. 2007, ApJ. 664, L87
First SNR detected by MAGIC I
Overlayed are:
• 12CO emission contours,
• contours of 20 cm VLA radio data,
• X-ray contours from Rosat, and
• gamma-ray contours from EGRET source
(3EG J0617+2238). Also:
• pulsar CXOU J061705.3+222127 (white star),
• 1720 MHz OH maser (black dot).
Sky map in the direction of MAGIC J0616+225 for
an energy threshold of ~150 GeV (plot in galactic
coordinates). MAGIC PSF is 0.1º.
VHE emission from gamma rays could be plausibly explained by interaction
between SNR and MC, but other possibilities are not completely ruled out.
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more
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Cassiopeia A (G111.7-2.1)
• Young: SN1680
• Very bright radio/X-ray
SNR shell.
• Size 4’ at 3.4 kpc
Confirmed detection by HEGRA
by MAGIC:
§ Detected at 5.2σ in 47 hr
§ 3% Crab above 250 GeV
§ Spectral index 2.4 ± 0.2
§ Confirmed by VERITAS
22nd July 2010
® X-ray: NASA/ CXC/ SAO; Optical: NASA/ STScI; Infrared: NASA/ JPLCaltech/ Steward/ O.Krause et al.
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Albert et al. 2007 A&A 474, 937
Cas A with MAGIC
Origin of TeV emission:
• Leptonic: low magnetic field
(Vink & Laming’03), contradicts
the high values required at
lower frequencies (X-rays).
• Hadronic: [too] hard spectrum
predicted (Berezhko’03) in the
range 100 GeV – 10 TeV.
Sky map around Cas A above ~ GeV. The red
cross indicates the MAGIC best fit position and
the black cross marks the HEGRA source
position. Error bars correspond to 1σ statistical
errors.
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Cas A with MAGIC
Albert et al. 2007 A&A 474, 937
Origin of TeV emission:
• Leptonic: low magnetic field
(Vink & Laming’03), contradicts
the high values required at
lower frequencies (X-rays).
• Hadronic: [too] hard spectrum
predicted (Berezhko’03) in the
range 100 GeV – 10 TeV.
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Carmona et al. 2009, Proc. 31st ICRC, Lodz
Other SNRs with MAGIC
• Selection criteria based on
known SNRs with detected
VHE emission:
– Flux at 1GHz ≥ 49Jy
– Radio spectral index
(Sν ~ ν-α) ≤ 0.6
– Distance ≤ 7 kpc
– Age ≤ 5 x 104 yr.
• 9 candidates from Green
Catalog: HB-9, W51,
CTB-80, W63, W66, HB-21,
G085.4+0.7, G085.9-06,
CTB-104 A.
• No detection found in 5 to
10 hr, assuming point-like
source (5 to 25 % Crab
upper limits).
22nd July 2010
Sky maps of 9 radio selected SNRs. The yellow (green) star (triangle)
marks the center of the SNR (wobble observation) and the circle is the
boundary of the radio shell.
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Other SNRs with MAGIC
W 51
W 66
VERITAS
22nd July 2010
Preliminary
Sky maps of 9 radio selected SNRs. The yellow (green) star (triangle)
marks the center of the SNR (wobble observation) and the circle is the
boundary of the radio shell.
Elsa de Cea on behalf of MAGIC
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Pulsar Wind Nebulae
as seen by MAGIC
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Albert et al. 2007 ApJ. 674, 1037
Crab Nebula with MAGIC
• Spectrum measured with high
precision between 60 GeV – 9 TeV.
• IC peak extrapolated to (77 ± 35) GeV.
• Point-like source: coincides with the
pulsar position.
® X-ray: NASA/ CXC/ ASU/ J.Hester et al.; Optical:
NASA/ ESA/ ASU/ J.Hester & A.Loll; Infrared: NASA/ JPLCaltech/ Univ. Minn./ R.Gehrz
Crab Nebula is a standard
candle for VHE astronomy.
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Aliu et al. 2008, Science 322, 1221
Crab Pulsar with MAGIC
• Detected above 25 GeV, thanks
to special trigger setup.
• Pulsed emission detected at the
6.4σ significance level.
• First pulsar detection by
Cherenkov telescopes.
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Anderhub et al. 2010 ApJ. 710, 828
Other PWNe as seen by MAGIC
• Selection of pulsar candidates based on their
spin-down flux (
, spin-down luminosity
divided by the square distance) and zenith
angles below ~50º:
– Two canonical: PSR J0205+6449 and PSR J2229
+6114 (3C58 and Boomerang, resp.)
– Millisecond: PSR J0218+4232 (first detected in γrays below 1GeV)
• No detection: upper limits for the steady and
pulsed emission above ~ 70 – 100 GeV
(consistent with model predictions).
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Upper limits on PWN/Pulsar
RXTE
30 hr
MAGIC
Left: light curve for PSR J0205+6449 at 80 – 300 GeV. Shadowed area
corresponds to RXTE pulse peaks (Ransom et al. 2004; right)
ASCA GIS
10.5 hr
MAGIC
Unpulsed flux upper limits (99% c.l.) for 3C58
and PSR J0205+6449 by MAGIC and Whipple.
Left: light curve at PSR J2229+6114 at 70 – 300 GeV. Shadowed area
corresponds to ASCA GIS pulse peaks (0.8-10keV; Halpern et al. 2001; right)
22nd July 2010
Elsa de Cea on behalf of MAGIC
Unpulsed flux upper limit (99% c.l.) for Boomerang and PSR J2229+6114 by MAGIC and
detection by Milagro (above 35 TeV).
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Upper limits on PWN/Pulsar
EGRET
20 hr
MAGIC
Left: light curve for PSR J0218+4232 at 50 – 300 GeV. Shadowed area
corresponds to EGRET pulse peaks (Kuiper et al. 2002; phase diagram on
the right)
Unpulsed flux upper limits (99% c.l.) for PSR
J0218+4232 by MAGIC. Black lines denote 0.1
CU** (dashed) and 1 CU (solid)
• 3C58: similar
to Crab Nebula
• Boomerang
nebula: flat
spectrum (≤ 2)
® NASA/CXC/SAO/S.Murray et al.
® NASA, ESA and Hubble Heritage
Team (STScI/AURA)
(**) Crab Units (CU) = ratio of the steady Crab flux
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Upper limits on PWN/Pulsar
EGRET
Fermi
20 hr
MAGIC
Left: light curve for PSR J0218+4232 at 50 – 300 GeV. Shadowed area
corresponds to EGRET pulse peaks (Kuiper et al. 2002; phase diagram on
the right)
VERITAS upper limits at
0.023 CU
Unpulsed flux upper limits (99% c.l.) for PSR
J0218+4232 by MAGIC. Black lines denote 0.1
CU** (dashed) and 1 CU (solid)
• 3C58: similar
to Crab Nebula
• Boomerang
nebula: flat
spectrum (≤ 2)
Recently detected
by VERITAS > 1 TeV
(**) Crab Units (CU) = ratio of the steady Crab flux
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Concluding remarks
• MAGIC has just finished cycle V.
• Despite being in the Northern hemisphere,
important contributions to the understanding
of SNRs (IC443, CasA) and pulsars (Crab).
• Covering energy gap between HE (Fermi)
and VHE experiments (VERITAS, H.E.S.S.)
• Now in stereoscopic mode: lower energy
ranges may be explored and new results will
come soon!
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Supernova remnants and pulsar wind nebulae with the
MAGIC telescope
BACK-UP SLIDES
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Motivation for VHE
Boomerang
3C 58
Cas A
W 51
W 66
IC443
Crab
• SNR long believed to be accelerated site of galactic cosmic rays.
Maximum energy ~ 1015eV.
- around 10% of SN explosion energy required.
- Diffusive shock acceleration of cosmic rays.
• PWN after SN explosion can produce TeV emission.
- γ-rays produced by inverse Compton (IC) of accelerated electrons.
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Everybody’s watching IC 443
• VERITAS: detection (> 300 GeV) + extension (0.16º)
– MAGIC J0616+225 (white cross)
– Optical contours,
– CO survey,
– PWN CXOU J061705.3+222127
(black star)
– 95% confidence radius of 0FGL
J0617.4+2234
– OH maser emission (filled black
triangles)
• AGILE: above 200MeV
Centroid coincident with EGRET
source (Tavani et al. 2010)
22nd July 2010
Excess map from Acciari et al 2009 for the
IC 443 field. Black cross-hair indicates
centroid position and its uncertainty.
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Everybody’s watching IC443
• Fermi: detection (200 MeV – 50 GeV) + extension (θext68
= 0.26º – 0.27º) + change in power law slope (energy
break ~ 3 GeV)
Fermi centroid
is:
- 0.05º from
EGRET
- 0.15º from
MAGIC
- 0.12º from
VERITAS
- 0.26º from
PWN
(See Abdo et el. 2010)
less
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