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03/08/05 12:53:09 (20 years ago)
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wittek
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  • trunk/MagicSoft/GC-Proposal/GC.tex

    r6782 r6784  
    278278
    279279Figure \ref{fig:exclusion_lmits} shows exclusion limits for MAGIC (solid straight lines) for the four most promising sources,
    280 in the plane $N_{\gamma}(E_{\gamma}>E_{\mathrm{thresh}})\langle \sigma v \rangle$ vs. $m_{\chi}$. Due to its proximity the GC yields the largest expected flux from particle dark matter annihilation. Nevertheless, this minimum measurable flux is more than one order of magnitude above the highest fluxes predicted by SUSY models. Also the flux measured by the HESS experiment is far above the theoretical expectation.
     280in the plane $N_{\gamma}(E_{\gamma}>E_{\mathrm{thresh}})\langle \sigma v \rangle$ vs. $m_{\chi}$. The energy threshold $E_th$ has been assumed to be 100 GeV. Due to its proximity the GC yields the largest expected flux from particle dark matter annihilation and thus the lowest exclusion limit. Nevertheless, this minimum measurable flux is more than one order of magnitude above the highest fluxes predicted by SUSY models (full circles). Also the flux measured by the HESS experiment is far above the theoretical expectation.
    281281
    282282
     
    285285\includegraphics[totalheight=6cm]{plot_DM_exclusion.eps}%{Dark_exclusion_limits.eps}
    286286\end{center}
    287 \caption[DM exclusion limits.]{Exclusion limits (solid straight lines) for the four most promising sources of dark matter annihilation radiation. The GC is expected to give the largest flux from all sources. For energies above 700 GeV, the flux from the GC as observed by the HESS experiment (dotted line)is within the reach of MAGIC. The solid points represent flux predictions from some typical SUSY models.  -- Figure to be updated --} \label{fig:exclusion_lmits}
     287\caption[DM exclusion limits.]{Exclusion limits (solid straight lines) for the four most promising sources of dark matter annihilation radiation. The GC is expected to give the largest flux from all sources. For energies above 700 GeV, the flux from the GC as observed by the HESS experiment (dotted line) is within the reach of MAGIC. The full circles represent flux predictions from some typical SUSY models.  -- Figure to be updated --} \label{fig:exclusion_lmits}
    288288\end{figure}
    289289
     
    300300still being analyzed. Preliminary results were presented at the MAGIC
    301301collaboration meeting in Berlin, 21-25th February 2005.\\
    302 Up to now there is only 2.9 hours of ON data available at a very large zenith
    303 angle range. Some details of the data set are shown in Table \ref{table:GC_dataset}.\\
     302Up to now only 2.9 hours of ON data are available, at zenith angles between 60.3 and 67.8 degrees. Some details of the data set are shown in Table \ref{table:GC_dataset}.\\
    304303
    305304\begin{table}[!ht]{
     
    321320ZA (65$^\circ$ ZA and 205$^\circ$ Az) Monte Carlo gammas were generated,
    32232199500 events in all, with energies between 200
    323 and 30,000 GeV. The slope of the generated spectrum is $-2.6$, conforming the
    324 energy spectrum of the Crab nebula...
    325 
    326 The MC sample is divided into training
    327 and test sample. Since there is no dedicated OFF data available, we used a
    328 subsample of Sgr A$^*$ ON data for the Random Forest training. As training
     322and 30,000 GeV. The differential spectral index of the generated spectrum is $-2.6$, conforming with the energy spectrum of the Crab nebula.
     323
     324The MC sample was divided into a training
     325and a test sample. Since no dedicated OFF data were available, we used a
     326subsample of Sgr A$^*$ ON data to represent the hadronic background in the Random Forest training. As training
    329327parameters we used SIZE, DIST, WIDTH, LENGTH, CONC, and M3Long...
    330328
     
    348346
    349347
    350 The observed differential gamma flux by the HESS collaboration is given by \cite{GC_hess}:
     348The differential gamma flux observed by the HESS collaboration is given by \cite{GC_hess}:
    351349
    352350\begin{equation}
     
    375373
    376374
    377 Thus the expected integral fluxes above 700 GeV based on the HESS and Cangaroo data agree within errors.
     375Thus the integral fluxes above 700 GeV based on the HESS and Cangaroo data agree within errors.
    378376
    379377Using MC simulations \cite{MC-Camera} for small zenith angles we conservatively estimate MAGICs sensitivity \cite{MC-Sensitivity} to the integral flux to be:
     
    383381\end{equation}
    384382
    385 Assuming this sensitivity MAGIC shall be able to get an excess at the 5
    386 $\sigma$ significance level in $1.8 \pm 0.5$ h observation time for both the
    387 Cangaroo and HESS spectrum. The observed Cangaroo and HESS spectra differ
     383Assuming this sensitivity and using the integrated flux of $3.2\cdot 10^{-12} cm^{-2}s^{-1}$ MAGIC will obtain an excess at the 5
     384$\sigma$ significance level in $1.8 \pm 0.5$ h observation time.
     385
     386The observed Cangaroo and HESS spectra differ
    388387substantially in the spectral index. While the Cangaroo spectrum only extends
    389 to about 2 TeV, the recently published HESS spectrum goes up to about 9 TeV. Figure \ref{fig:MAGIC_flux_limits} shows the HESS and Cangaroo observed fluxes together with the mimimum detectable flux with MAGIC in 20 hours observation time.
     388to about 2 TeV, the recently published HESS spectrum goes up to about 9 TeV. Figure \ref{fig:MAGIC_flux_limits} shows the HESS and Cangaroo observed fluxes together with the mimimum flux detectable by MAGIC in 20 hours observation time.
    390389
    391390MAGIC will be able to solve the obvious discrepancy between the observed fluxes. Due to the observation under high zenith angle of about 60 deg MAGIC will be able to extend the source spectrum to higher energies.
     
    396395\includegraphics[totalheight=8cm]{MAGIC_flux_limits.eps}
    397396\end{center}
    398 \caption[Flux limits.]{Observed gamma spectra of the HESS and Cangaroo experiments compared to the minimum detectable flux with the MAGIC telescope in 20 hours observation time.} \label{fig:MAGIC_flux_limits}
     397\caption[Flux limits.]{Observed gamma spectra of the HESS and Cangaroo experiments compared to the minimum flux detectable by the MAGIC telescope in 20 hours observation time.} \label{fig:MAGIC_flux_limits}
    399398\end{figure}
    400399
     
    423422Based on the above estimations a 5 $\sigma$ excess is expected to be observed in about 2 hours assuming the HESS flux. To acquire a comparable data set to the other experiments at least 20 hours of good ON data and 20 hours of good dedicated OFF data are needed.
    424423
    425 To get the lowest possible threshold all data shall be taken under the
     424To get the lowest possible threshold all data shall be taken at the
    426425smallest possible zenith angles between culmination at about 58 deg and 60
    427426deg. This limits the data taking interval to about 1 hour per night between
     
    435434
    436435In order to take part in exploring the exciting physics of the GC
    437 we propose to start taking data as soon as possible beginning in April. In this way first results may be presented in the summer conferences 2005.
     436we propose to start taking data as soon as possible, beginning in April. In this way first results may be presented at the summer conferences 2005.
    438437
    439438
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