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DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 1 Observations of 1ES1959+650 with the HEGRA CT1 Cherenkov Telescope.

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Presentation on theme: "DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 1 Observations of 1ES1959+650 with the HEGRA CT1 Cherenkov Telescope."— Presentation transcript:

1 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 1 Observations of 1ES with the HEGRA CT1 Cherenkov Telescope (2000, 2001, 2002) Nadia Tonello and Daniel Kranich, Max-Planck-Institut für Physik for the HEGRA Collaboration

2 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 2 The Active Galactic Nucleus 1ES Discovered in 1993 by comparing X-ray/radio/optical fluxes of objects in the Einstein IPC Slew Survey. First  emission detected in 1998 by the Seven Telescope Array in Utah (Nishiyama et al., OG ). Not seen by EGRET. Studied in by the HEGRA System of Telescopes: weak signal seen (5.4  8% Crab). Short flare seen by the VERITAS collaboration in spring 2002 (IAU Circ. 7903). Observed with HEGRA CT1 Telescope (2000, 2001, 2002). z (= 718·10 6 ly) RA19h59m59.8s (2000) Dec+65d08´54 (2000)

3 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 3 Physics Motivation Study the physics processes in AGNs, responsible for the production of high energy gamma rays Measure energy spectrum of gamma rays Study time variability of source emission Multi-wavelength (radio, optical, X-ray) studies Study the absorption by the Extragalactic Background Light Cut-off of energy spectrum comparison with AGNs at different distances Mkn421 (z = 0.031), Mkn501 (z = 0.034)

4 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 4 The HEGRA CT1 Telescope ORM, La Palma (Canary Islands) Mirror area10.3 m 2 Camera127 pixels FOV~3°Ø threshold750 GeV (small ZA) sensitivity on CRAB

5 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 5 Observation statistics year No moon (nom)58 h86 h176 h With moon (reduced hv) hv h 8.1 h hv h16.1 h hv h 6.1 h hv h 2.9 h 2002 data: 180h preliminary analysis Zenith angle range: between 36.4 ° and 54.2 ° Data needed correction for slight mispointing (~0.1º). Correction determined from a 2d-plot, higher probability to have the source.

6 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 6 Analysis method gamma/hadron separation using dynamical cuts (determined from real on and off data ): DIST (SIZE,  ) WIDTH (SIZE, DIST,  ) LENGTH (SIZE, DIST,  ) N of events before cuts: N of events after cuts: 7565 Center of the camera

7 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 7 OFF data ON data (2002) signal region Alpha distribution Peaked at 0 deg for point like sources Flat distribution expected for cosmic ray background Estimation of the excesses: Gaussian fit in the signal region. Estimation of the background: fit the ON data with a pol.2nd order between 20 and 80 deg, extended into the signal region.

8 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 8 ON data (2002) signal region background fit region Alpha distribution Significance for ALPHA≤13.1º 11.1  Excesses: 664 ± 40 Background: 1672 ± 37

9 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München and 2001 light curves Source at low state. Signal: not significant. Average estimated flux: ~ 6 % Crab average flux 6% Crab average flux 5% Crab HEGRA CT1

10 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 10 TeV and X-ray emission, 2002 HEGRA CT1 En. range TeV All-Sky Mon. En.range: keV May July

11 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 11 TeV and X-ray emission, 2002 HEGRA CT1 En. range TeV All-Sky Mon. En.range: keV May July

12 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 12 Flares of 2002 Maximum activity: CRAB flux (above 1 TeV) reached in May. In July a less strong flare has been seen. combining nom and hv00 data

13 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 13 Spectrum preliminary result of all the data taken in 2002 (151 h, max ZA: 45°) Fitted with a power low function  = 3.49 ± 0.19   /d.o.f. = 9.1/6

14 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 14 Spectrum preliminary result of all the data taken in 2002 (151 h, max ZA: 45°) Fitted with a power low function with a fixed cutoff at E c = 2.4 TeV  = 2.54 ± 0.21   /d.o.f. = 7.1/6 Mkn421z =  2.41 ± 0.10 E c 3.24±0.50 Mkn501z =  2.03 ± 0.19 E c 6.12 ±1.31 1ES1959z =  1.5 (fixed) E c 2.4 ± 0.4 HEGRA System results for the source at high state

15 DPG Tagung, March 2003Nadia Tonello, MPI für Physik (Werner- Heisenberg-Institut), München 15 Conclusions CT1 observed 1ES in 2000 and 2001 at a low flux level (no significant signal). In 2002 two periods of increased flux have been seen ( times the Crab flux above 1 TeV). The preliminary results of the analysis reveal a spectrum compatible with a power law. Further analysis will be done: optimization for weak source at high zenith angles.


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