Absolute calibration of the MAGIC telescope using muon images

1
Long term monitoring of bright TeV Blazars with
the MAGIC telescope
F. Goebel1, M. Backes2, T. Bretz3, M. Hayashida1,
C. Hsu1, K. Mannheim3, A. Moralejo4, W. Rhode2,
K. Satalecka5, M. Shayduk1,6, M. Teshima1, R.
Wagner1 for the MAGIC
collaboration

• Max-Planck-Institut für Physik, Munich, Germany
• Universität Dortmund, Germany
• Universität Würzburg, Germany

• IFAE, Spain
• DESY, Zeuthen, Germany
• Humboldt Universität zu Berlin, Germany

International Cosmic Ray Conference Merida,
Mexico 2007
Abstract The MAGIC telescope has performed long
term monitoring observations of the bright TeV
Blazars Mrk421, Mrk501 and 1ES1959650. Up to 40
observations, 30 to 60 minutes each have been
performed for each source evenly distributed over
the observable time period. The sensitivity of
MAGIC is sufficient to establish a flux level of
25 of the Crab flux for each measurement. These
observations are well suited to trigger
multiwavelength ToO observations and the overall
collected data allow an unbiased study of the
flaring statistics of the observed AGNs.
TeV Blazars
The MAGIC Telescope
Blazar Monitoring with MAGIC

• Galaxies harboring super-massive black holes
• Relativistic plasma outflows (jets) pointing
  towards the Earth
• No emission lines
• Continuous Spectral Energy Distribution (SED)
  with a peak in the UV to soft X-ray band and a
  second peak in the GeV-TeV range
• Strong variability in all frequencies
• Flux doubling times at the order of minutes at
  Very High Energies (VHE gt 100 GeV - 100 TeV)

MAGIC 1 is currently the largest single dish
Imaging Air Cherenkov telescope (IACT) for high
energy ?- ray astronomy. It has been in
scientific operation on the Canary Island La
Palma since summer 2004.

• Monitor Mrk421, Mrk501 and 1ES1959650
• Up to 40 short observations per source
• Observations evenly distributed over observable
  time during MAGIC Cycle II observation period

Preliminary Results

• Preliminary light curves of Mrk421, Mrk501 and
  1ES1959 for the period from April 2006 until
  January 2007 are shown below
• The data has been analyzed with the Standard
  MAGIC analysis tools
• Few observation days have been removed due to
  poor observation conditions
• Multiwavelength MWL observations 3 (also
  unbiased since scheduled in advance) are included
  in the plots as green points
• The background rate shown below the light curve
  shows stable analysis conditions

The energy threshold of MAGIC is 60 GeV. A
source emitting ?-rays at a flux level of 2.5
of the Crab Nebula can be detected with 5 sigma
significance within 50 h observation time. The
sensitivity is sufficient to establish a flux
level of 25 of the Crab flux above 300 GeV for
a 20 min observation. MAGIC can observe under
moderate moon and twilight conditions with only
slightly lower sensitivity 4.
jet
Urry Padovani 1995
?
observer

• Models for particle acceleration in jets
• Leptonic models
• Relativistic electrons produce Synchrotron
  (X-ray) and inverse Compton radiation (GeV/TeV
  ?-rays)
• Correlation between Synchrotron IC expected
• Hadronic models
• GeV/TeV ?-rays from ?0-decay
• Simultaneous emission of high energy neutrinos

• Mrk 421

2006/07
Mrk421 (z0.030), Mrk501 (z0.034) and
1ES1959650 (z0.047) are bright and close TeV
blazars and therefore well suited to study jet
acceleration mechanisms.
TeV Blazar Monitoring

• Monitor flux state of TeV blazars in VHE ?-rays
  to
• Measure long term flux variabilities
• Input to constrain jet emission models
• Determine flaring probabilities
• Estimate statistical significance of correlations
  with other observables such as neutrinos
• Requires unbiased observations (in particular
  not triggered by high flux measurements)
• Trigger Target of Opportunity (ToO) observations
• multiwavelength observations during high flux
  (most violent blazar state, high flux allows
  precise and high statistics observations)
• ?-ray (instead of X-ray) triggered ToO are
  sensitive to orphan flares
• Perform detailed studies using combined data set
• Low flux data still rare

Online Analysis

• Mrk 501

A quick online analysis estimates the flux level
of each source during data taking. The
sensitivity of the online analysis allows to
detect a flux of 30 of the Crab flux within 30
min. The results of the online analysis can be
used to trigger ToO observations.

• 1ES 1959650

Monitoring Strategies

• IACT observation time is very precious, therefore
  several monitoring strategies have been
  developed.
• Use previous generation IACTs 2
• Build small and inexpensive dedicated IACTs
• Short sampling observations (adopted here)
• Use latest generation high sensitivity IACTs
• Short observations evenly distributed over the
  observable time of year
• Require typically 20-60 min to detect moderate
  flaring states
• Moderate impact on observation schedule
• For MAGIC also schedule moon and twilight
  observations
• Sensitive to short flares but low duty cycle

Constantly updating Alpha plot in MAGIC Online
Analysis
References 1 E. Lorenz, New Astron. Rev. 48
(2004), 339 2 D. Horan, 2007 AAS/AAPT Joint
Meeting 209, 109.09 3 M. Hayashida, this
conference 4 J. Albert, astro-ph/0702475v1

• Mrk 421 was observed in flaring state during the
  commissioning phase of monitoring program in
  April/May 2006
• Further analysis of the data is ongoing