Resumen de Measurement of the invariance of the light observing the active galactic nucleus mkn421 with the magic telescope
The aim of this Thesis is the measurement of the invariance of the Speed of Light with respect to energy, using as the source the observations done by the MAGIC telescope of the Active Galactic Nuclei Markarian during the Spring of 2004. The motivation for this Thesis is the study, from an experimental point of view, of possible signatures of a Quantum formulation of Gravity using astronomical observations.
The data analysed in this study has been taken with the MAGIC Telescope, a detector that belongs to the group of new IACTs constructed in the last years with the aim of lowering both the sensitivity and the energy threshold of the previous generation of Cherenkov telescopes. The technical contributions of the author in both the slow control of the Camera and Calibration systems of the telescope are detailed, in particular the work done regarding the use of standard industrial protocols for the remote control of the telescope functionalities.
The astrophysics part of the thesis deals with the analysis of the data recorded by MAGIC of one of the most active periods of Markarian 421 in the last years. Due to the non-nominal situation MAGIC for the analysed period, dedicated studies have been necessary for the understanding of the telescope performance, which include the calculation of the Point Spread Function magnitude and the correction of the mispointing. For the analysed period, the energy spectrum and the light curves for each of the observed nights has been measured. The spectrum analysis has been performed for different emission levels, confirming the dependence of the Markarian 421 spectrum with activity state. During the studied period, Markarian 421 showed variability between consecutive nights of a factor 2.5 reaching a maximum mean integral flux for the 23rd of April, which is more than 4 times the integral flux for Crab Nebula. Rather smooth light curves have been measured for that period within each night, with the exception of the 19th of April, which showed a variability with halving times of the order of tens of minutes.
This Thesis also has implications in the Quantum Gravity phenomenology field, in particular in one of the sectors less constrained by the experimental measurements: the photon sector. A new analysis method to measure the invariance of the Speed of the Light with the energy has been developed. This new analysis method, by contrast with existing ones, uses the maximum available information from the experimental observations. It is based in the idea that the arrival time of photons from distant sources to the Earth must be statistically, correlated with their energy. The mathematical derivations as well as Monte Carlo simulations used for the understanding of the capabilities of the method has shown that the optimum scenario for its application corresponds to observations with peak structures well contained within the observational time window. In the rest of the morphologies the method shows a bias in the estimation of the time-energy correlation which reduces its sensitivity.
Using Markarian 421 data and this measurement, a limit at 95% confidence level corresponding to an energy scale of Quantum Gravity of EQG > 2.6 · 1016 GeV = EPI/460 has been obtained. This result is of the order of a factor 2 bigger than the best present best limit. In that situation, the method has shown a sensitivity at 99% confidence level of the order of EQG > 8.7 · 1016 GeV = EPI/140, which is more than 2 times smaller than the aforementioned best limit.
Our opinion is that this method could be exploited in the near future to achieve Planck mass scale sensitivities with the potential observation of GRBs emissions in the VHE domain, either by the present generation of IAC Telescopes like MAGIC or the next generation gamma-ray satellites like GLAST.
