Markarian 421 with MAGIC telescope

Daniel Mazin for the MAGIC CollaborationMax-Planck-Institut für Physik, München

mazin@mppmu.mpg.de

Outline

The MAGIC telescope AGN Markarian 421 Data sample Analysis status Conclusion / outlook

The MAGIC Telescope

The largest imaging atmospheric Cherenkov Telescope with 236 m2 mirror surface

3.5° FoV Camera with 576 high-QE PMT’s

Design optimized for: Low energy threshold

E = 30 GeV Fast repositioning

tp < 30 sec

Canarian Island La Palma,2200 m asl

AGN Markarian 421

Right Ascension 11:04:27 (h:m:s)

Declination: +38:12:32 (deg:m:s)

BL Lac object, z=0.030 (370 MLy) Mass: 1.9 •108 M

First detected extragalactic TeV -ray source (Punch et al, 1992)

Many known flares, active in 2004 Well described by SSC models (e.g.

Konopelko et al, ApJ,597:851) Still many correlations not

understood

Aimo Sillanpaa, NOT

Advantages of simultaneous observations

One experiment: one decade in energy Two experiments: two decades Multiwavelength campaigns Correlation studies Change hardness during flares (Krennrich et al, ICRC 2003)

Light curves, look for fast flares

HEGRA, A&A,393,89

HEGRA, A&A,410,813

+ X-calibration of the instruments

MAGIC data sampleDate comments Preliminary

results (sky plot of number of excess

events):

February 2004

flare, commissioning

phase

April 2004 Strong flare, Overlap with HESS,

commissioning phase

December 2004

Overlap with HESS This talk

MAGIC data sample (December 04)

Triggered by RXTE and VERITAS (Dec 14) After a few hours: MAGIC and HESS agreed

to make simultaneous observations Due to bad weather only 2 days of MAGIC

data: 18 and 19 December

Date Obs.time Mean zenith angle (deg)

comments

18 Dec 55 min 48 30 min with HESS

18 Dec 59 min 12.5

19 Dec 30 min 51 30 min with HESS

19 Dec 79 min 21

Comparison of MC predictions and data

Good agreement between mc-gamma and excess events

Estimate of energy resolution

SIZE (total number of PEs) simplest energy estimator

improve energy estimation including other image parameters

optimized estimator using Random Forest technique

20% (30%) @ 1 TeV (100 GeV)

Log10(Eest[GeV])

Log10(Eest[GeV])(Eest -Etrue)/Etrue

Sig

ma

[%]

Lo

g10

(Etr

ue[

Ge

V])

Mrk 421: False source plot

For the whole data sample (3.7h): After cuts:

over 700 excess events

Point-like source ( < 0.15 deg )

11.07

38.1

9

11.1011.14 11.04 11.00

38.6

939

.19

37.6

9D

ec (

deg

)

RA (h)

Number of excess events

Alpha plots

For the 4 samples:

Clear signal

detection in all

of them

Energy range for this analysis:

high zenith angle:

250 GeV – 2 TeV

low zenith angle:

100 GeV – 1 TeV

18/12/05, <Zd>=48 18/12/05, <Zd>=12

19/12/05, <Zd>=51 19/12/05, <Zd>=21

Light curve (X-ray)17-20 December 2004

X-rays: no significant variation

Optical data (KVA): quiescent state

18/12 19/12

Dec 04Apr 04

Light curve (GeV, MAGIC)

Low zenith angle points only, 20 min bins

No strong variations visible

Looks like we just missed the peak of the flare (weather!)

Soon to come: Energy spectrum and full light curve for the MAGIC data Combined MAGIC – HESS data analysis

4004 4005 (mjd-49353)

Conclusions / Outlook

Coordinated ground based Cherenkov telescopes observations going on

Almost full time coverage possible (CANGAROO, HESS, VERITAS, MAGIC)

Up to 3 decades in energy due to energy threshold and different zenith angle conditions

MAGIC clearly detected a flare of Markarian 421 in December 2004

Due to bad weather: too late for the peak of the flare 3.7 hours of data: enough statistics to produce light

curves and energy spectra work in progress

Thank you