Results of MAGIC first observation cycle on Galactic sources Javier Rico for the MAGIC Collaboration...

Results of MAGIC first Results of MAGIC first observation cycle on observation cycle on

Galactic sourcesGalactic sources

Javier Rico for the MAGIC CollaborationJavier Rico for the MAGIC CollaborationInstitut de Física d’Altes EnergiesInstitut de Física d’Altes Energies

Barcelona, SpainBarcelona, Spain

THE MULTI-MESSENGER APPROACH TO UNIDENTIFIED GAMMA-RAY SOURCES

Barcelona (Spain) July 4 - 7, 2006

J. Rico (IFAE)Results of MAGIC fist observation cycle on Galactic sources

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on Major Atmospheric Gamma-Ray Imaging

Cherenkov Telescope International collaboration of 16 institutions from more than

10 countries, about 150 collaborators: Barcelona IFAE, Barcelona UAB, Barcelona UB, Crimean

Observatory, U.C. Davis, U. Lodz, UCM Madrid, MPI Munich, INFN/ U. Padua, INFN/ U. Siena, U. Humboldt Berlin, Tuorla Observatory, Yerevan Phys. Institute, INFN/U. Udine, U. Würzburg, ETH Zürich, INR Sofia, Univ. Dortmund

Summary Introduction:

MAGIC Cycle I galactic targets

LS I +61 303 Previous data Discovery at VHE Emission models


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• MAGIC is a Imaging Air Cherenkov telescope operating in the energy range 50 GeV – 50 TeV

• Located in the Roque de los Muchachos observatory, La Palma, Canary Island (Spain) at 28.8 N

• Largest single-dish (17 m Ø) lowest energy threshold

• 576 high QE PMT camera with 3.5 Ø FOV

• Good angular resolution ~ 0.1

• Determination of point-like sources position within 2’

• Energy resolution 20-30%

• Flux sensitivity: 2.5% Crab Nebula flux with 5 in 50h

• Fast repositioning (<40s average) for GRB observation

• Observations under moonlight possible 50% extra observation time


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Observations from November 2004 to May 2006

About 25% total observation time for Galactic targets (apart from Crab Nebula)

Targets include: SNR:

Intense EGRET sources HESS galactic scan sources (HESS J1834, HESS

J1813) PWN Pulsars: limits to Crab and PSR B1957 Microquasars (low and high mass)

LS I +61 303 variable source Galactic Center HEGRA Unidentified TeV2032 Cataclysmic variable (AE Aquari)

HESS J1834

MAGIC

CRAB pulsar


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Microquasars: REXB displaying relativistic radio jets Compact object Neutron Star or a Black Hole In BH, the length and time scales are proportional to the mass, M. The maximum temperature of the accretion disk is Tcol ~ 2107 M1/4

Laboratories of jet physics Possible contributors to galactic cosmic rays

Compacts jetsRadio IR X? gamma?

(synchrotron)

Disc + corona ?

X therm +

non therm

Large scale ejectionRadio & Xgamma?

Interaction with environment


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X-ray and radio spectral states: High/soft state steep power-law state. No radio emission. Low/hard state (power-law state). Compact radio jet. Intermediate and very high states transitions. Transient radio emission.


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LS I +61 303: High Mass x-ray binary at a distance of 2 kpc Optical companion is a B0 Ve star of 10.7 mag with a circumstellar disc Compact object probably a neutron star High eccentricity or the orbit (0.7) Modulation of the emission from radio to x-rays with period 26.5 days attributed to orbital period Secondary modulation of period 4 years attributed to changes in the wind flow Compact jets (100 AU) resolved with radio observations microquasar

0.20.1

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0.70.4 AU

To observer


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Periodic radio outbursts at phases 0.5-0.8 (close to apastron), with intensity and peak position modulated with a 4 yr period X-ray outburst observed ~10 days ( ~ 0.4) before radio outbursts A significant hardening of the x-ray spectrum is observed on the radio onset

Photon index

X-ray flux

Radio flux

Greiner & Rau 2001

Paredes et al. 1990

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Massi et al 2004

= 0.67-0.68 = 0.71-0.72

Double sided jets at milli-arsec scale (~200 AU) are resolved with radio interferometer MERLIN (5 GHz)

The jets display fast precession

The feature on the second day can be associated with the jet of the day before compatible with a velocity of 0.6c

The projected angle changes by ~60 in 24 hours


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Hartman et al. 1999

A HE -ray (100 MeV – 10 GeV) source detected by EGRET is marginally associated with the position of LS I +61 303. The emission is variable and peaking at periastron passage (=0.2) and ~ 0.5-0.6

Interpreted as stellar photons upscattered (inverse Compton) by relativistic electrons in the jet

Tavani et al. 1998Massi et al. 2004


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ies MAGIC has observed LS I +61 303 for 54 hours from November 2005

to March 2006 (6 orbital cycles)

A point-like source (E>200GeV) detected with significance of ~9 Position: RA=2h40m34s, DEC=6115’ 25” [0.4’ (stat), 2’ (syst)] in agreement with LSI position identification of -ray source The source is quiet at periastron passage and at relatively high emission level (16% Crab Nebula flux) at later phases [0.5-0.7]

Albert et al. 2006


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Albert et al. 2006

MAGIC has observed LSI during 6 orbital cycles A variable flux (probability of statistical fluctuation 310-5) detected Marginal detections at phases 0.2-0.4 Maximum flux detected at phase 0.6-0.7 with a 16% of the Crab Nebula flux Strong orbital modulation the emission is produced by the interplay of the two objects in the binary No emission at periastron, two maxima in consecutive cycles at similar phases hint of periodicity!


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Albert et al. 2006

The average emission has a maximum at phase 0.6. Search for intra-night flux variations (observed in radio and x-rays) yields negative result Marginal detections occur at lower phases. We need more observation time at periastron passage Parts of the orbit not covered due to similarities between orbital period (26.5 days) and Moon period


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We perform contemporaneous radio observations (Ryle telescope 15GHz) during the last observed orbital cycle Two maxima are detected: just before periastron and higher at phase 0.7 TeV peak is observed one day before

Albert et al. 2006


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Albert et al. 2006

The average energy spectrum from 200 GeV to 4 TeV is well fitted by a power law with spectral index = -2.6 0.2 (stat) 0.2 (syst) The luminosity above 200 GeV is ~7 x 1033 erg s-1 (assuming a distance of 2 kpc) ~ 6 times that of QSR LS 5039 (average) It displays more luminosity at TeV energies than at x-rays


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Chernyakova et al. 2006

The absence of a spectral feature between 10 and 100 keV goes against an accretion scenario Contemporaneous multiwavelength observations are needed to understand the nature of the object


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Mirabel 2006

1. Microquasar: Particles accelerated in the jet collide with stellar or synchrotron photons by inverse Compton scattering, boosting their energies to the TeV range. Similar to quasar.

Pros: steady, double sided radio jets resolved; similar object known (LS 5039)

Cons: No spectral cut-off from accretion disk is observed. No emission at periastron 2. Binary pulsar: the -rays are produced by the interaction of the winds of a young pulsar with that of the Be star

Pros: spectral shape and time variability resembles that of young pulsars; similar object known PSR B1259-63

Cons: no pulsed emission; radio jets;

More multi-wavelength

observations are

needed, mainly

VHE+radio

Mirabel 2006


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In the microquasar scenario, two alternative -ray production mechanisms are possible:

Inverse Compton scattering: e + → e +

relativistic electrons from the jet with the star of synchrotron photons Hadron interactions: p + p → X + 0

└→ relativistic protons in the jet interact with non-relativistic stellar wind ions, producing gamma-rays via neutral pion decay

Our result seems to favor the leptonic scenario since -rays are produced at phase 0.5-0.6 i.e far from the companion star, and there the efficiency of the leptonic process is likely higher that that of the hadronic process In either case opacity seems to play a major role near periastron (e.g. by gamma-ray cascading) Neutrinos are expected to be produced in a hadronic scenario (from the decay of charged pions and muons) and would be unabsorbed. Differences in the spectral shape are also expected. More -ray data and

Multi-messenger observations are

needed!


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The MAGIC IACT has completed its first observation cycle in May 2006

25% of the observation time has been devoted to Galactic objects

We have detected 5 TeV sources out of which a new discovery

The microquasar LS I +61 303 has been detected at TeV energies The emission is variable Possible hint of periodicity The maximum of the emission happens 1/3 of

the orbit away from periastron New MAGIC+multi-wavelength/messenger

will establish LSI nature and the mechanism of VHE -ray production

Results of MAGIC first observation cycle on Galactic sources Javier Rico for the MAGIC Collaboration...

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