Changeset 6762

Timestamp:

03/07/05 14:55:46 (20 years ago)

Author:

wittek

Message:

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File:

• trunk/MagicSoft/GC-Proposal/GC.tex (modified) (5 diffs)

trunk/MagicSoft/GC-Proposal/GC.tex

@@ -42 +42 @@
 %% abstract %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{abstract}  
-The Galactic Center (GC) is a very interesting region. Gamma radiation above  a few hundred GeV has been detected recently by Whipple, Cangaroo and HESS. The reconstructed spectra from Cangaroo and HESS show significant differences. Source and acceleration mechanism have still to be identified.
-
-Various possibilities for the acceleration of the very high energy gamma rays
-are discussed in the literature, like accretion flow onto the central black hole, supernova shocks in Sgr A East, proton acceleration near the event horizon of the black hole, or WIMP dark matter annihilation. Although the observed VHE gamma
-radiation from the GC is most probably not due to SUSY-neutralino particle
-dark matter (DM) annihilation, other models like Kaluza-Klein dark matter are not ruled out. Moreover, assuming a universal DM distribution profile, the GC is expected to yield the largest DM flux due to its relative vicinity.
-
-
-The GC culminates at about 58 deg ZA in La Palma. It can be observed with
-MAGIC at up to 60 deg ZA for about 150 hours per year between April and late August. The expected integral flux above 700 GeV derived from the HESS data is $(3.2 \pm 1.0)\cdot 10^{-12}\mathrm{cm}^{-2}\mathrm{s}^{-1}$. Comparing this to the expected MAGIC sensitivity from MC simulations, this could result in a 5 $\sigma$ detection in about $1.8\pm0.5$ hours. 
-
-The observations have to be conducted as early as possible to participate in the exciting physics of the Galactic Center. The main motivations are:
+Due to the wealth of sources, the region around
+the Galactic Center (GC) is very interesting. Recently, gamma radiation above 
+a few hundred GeV has been detected by the Whipple, Cangaroo and HESS 
+collaborations. The reconstructed spectra from Cangaroo and HESS show 
+significant differences. The acceleration mechanisms have still to be 
+identified.
+
+Various possibilities for the acceleration of the very high energy (VHE)
+gamma rays are discussed in the literature, like accretion flow onto the 
+central black 
+hole, supernova shocks in Sgr A East, proton acceleration near the event 
+horizon of the black hole, or WIMP dark matter annihilation. Although the 
+observed VHE gamma radiation from the GC is most probably not due to 
+the annihilation of SUSY-neutralino dark matter (DM) particles, other models 
+like Kaluza-Klein dark matter are not ruled out. Moreover, assuming a 
+universal DM density profile, the GC is expected to yield the largest DM flux 
+amongst the favoured candidates, due to its proximity.
+
+At La Palma, the GC culminates at about 58 deg zenith angle (ZA). It can be 
+observed with MAGIC at up to 60 deg ZA for about 150 hours per year, between 
+April and late August. The expected integral flux above 700 GeV derived from 
+the HESS data is $(3.2 \pm 1.0)\cdot 10^{-12}\mathrm{cm}^{-2}\mathrm{s}^{-1}$. 
+Comparing this to the expected MAGIC sensitivity from MC simulations, this 
+could result in a 5 $\sigma$ detection in about $1.8\pm0.5$ hours. 
+
+The observations have to be conducted as early as possible in order to 
+participate in the ongoing discussion about gamma radiation from the GC. 
+The main motivations for the observation of the GC are :
 
 \begin{itemize}
-\item To solve the flux discrepancies between HESS and Cangaroo, inter-calibration between the instruments.
-\item Extend the observed spectrum to higher energies due to large ZA.
-\item Determine the nature and acceleration mechanism of the source. Set constraints to models for particle dark matter annihilation.
+\item to measure the gamma flux and its energy dependence (due to the high
+zenith angles higher energies are accessible),
+\item to inter-calibrate MAGIC and HESS,
+\item to help resolving the flux discrepancies between HESS and 
+Cangaroo,
+\item to gain information about the nature and acceleration mechanism of the 
+source, 
+\item to set constraints on models for dark-matter-particle annihilation.
 \end{itemize}
 
-
-To get a comparable data set to the other experiments and to be able to reconstruct the spectrum, an observation of 20 hours plus 20 hours of dedicated OFF data would be needed and hereby applied for. Moreover due to the large threshold moon observations are envisaged and 60 hours are applied for.
+In order to collect a data sample comparable in size to those of the other 
+experiments and to be able to measure the energy spectrum, 40 hours of
+observation time are requested. The 40 hours will be split into 20 hours ON
+and 20 hours dedicated OFF data or they will be devoted to observations in
+the wobble mode. In addition, 60 hours of observation during moonshine are 
+applied for.
 \end{abstract}
 
@@ -80 +105 @@
 \section{Introduction}
 
-
-
-The Galactic Center (GC) region, excepting the famous source Sgr A$^*$, contains many unusual objects which may be responsible for the high energy processes generation gamma rays \cite{Aharonian2005,Atoyan2004,Horns2004}. The GC is rich in massive stellar clusters with up to 100 OB stars \cite{GC_environment}, immersed in a dense gas within the volume of 300 pc and the mass of $2.7 \cdot 10^7 M_{\odot}$, young supernova remnants e.g. G0.570-0.018 or Sgr A East, and nonthermal radio arcs. An overview of the sources in the GC region is given in figure \ref{fig:GC_sources}. Some data about the Galactic Center are summarized in table \ref{table:GC_properties}.
+The Galactic Center (GC) region contains many unusual objects which may be 
+responsible for the high energy processes generating gamma rays 
+\cite{Aharonian2005,Atoyan2004,Horns2004}. The GC is rich in massive stellar 
+clusters with up to 100 OB stars \cite{GC_environment}, immersed in a dense 
+gas within a radius of 300 pc and the mass of $2.7 \cdot 10^7 M_{\odot}$, 
+young supernova remnants e.g. G0.570-0.018 or Sgr A East, and nonthermal radio arcs. An overview of the sources in the GC region is given in figure \ref{fig:GC_sources}. Some data about the Galactic Center are summarized in table \ref{table:GC_properties}.
 
 \begin{table}[h]{\normalsize\center
@@ -88 +116 @@
  \hline
  (RA, dec), epoch J2000.0 & $(17^h45^m12^s,-29.01$ deg)
-\\ heliocentric distance  & $8\pm0.5$ kpc (1 deg = 24 pc)
+\\ heliocentric distance  & $8\pm0.4$ kpc \cite{Eisenhauer2003} 
+(1 deg = 140 pc)
 \\ mass of the black hole & $2\pm0.5 \cdot 10^6 M_{\odot}$ 
 \\ 
@@ -106 +135 @@
 
 
-In fact, EGRET has detected a strong source in direction of the GC, 3 EG J1745-2852 \cite{GC_egret}, which has a broken power law spectrum extending up to at least 10 GeV, with the index 1.3 below the bread at a few GeV. If in the GC, the gamma ray luminosity of this source is very large $~2 \cdot 10^{37} \mathrm{erg}/\mathrm{s}$, which is equivalent to about 10 Crab pulsars. Up to now, the GC has been observed at energies above 200 GeV by Veritas, Cangaroo and HESS, \cite{GC_whipple,GC_cangaroo,GC_hess}. Figure \ref{fig:GC_gamma_flux} shows the reconstructed spectra by the other IACTs while figure \ref{fig:GC_source_location} shows the different reconstructed positions of the GC source. Recently a second TeV gamma source only about 1 degree away from the Galactic Center has been discovered \cite{SNR_G09+01}. Its integral flux above 200 GeV represents about 2\% of the gamma flux from the Crab nebula with a photon-index of about 2.4.
+In fact, EGRET has detected a strong source in direction of the GC, 
+3 EG J1745-2852 \cite{GC_egret}, which has a broken power law spectrum 
+extending up to at least 10 GeV, with the index 1.3 below the break at a few 
+GeV. Asssuming a distance of 8.5 kpc, the gamma ray luminosity of this source 
+is very large $~2.2 \cdot 10^{37} \mathrm{erg}/\mathrm{s}$, which is 
+equivalent to about 10 Crab pulsars. An independent analysis of the EGRET data 
+\cite{Hooper2002} indicates a source position, excluded beyond 99.9 \%
+as the GC.
+
+Up to now, the GC has been observed at 
+energies above 200 GeV by Veritas, Cangaroo and HESS, \cite{GC_whipple,
+GC_cangaroo,GC_hess}. Figure \ref{fig:GC_gamma_flux} shows the reconstructed 
+spectra by the other IACTs while figure \ref{fig:GC_source_location} shows the 
+different reconstructed positions of the GC source. Recently a second TeV 
+gamma source only about 1 degree away from the Galactic Center has been 
+discovered \cite{SNR_G09+01}. Its integral flux above 200 GeV represents about 
+2\% of the gamma flux from the Crab nebula with a photon-index of about 2.4.
 
 \begin{figure}[h!]
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 \end{equation}
 
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