The main question asked at the beginning of this thesis was: Is the VHE γ-ray source at the direction of the Galactic Center variable and at least partially linked to the black hole Sgr A* ? It would be daring to answer this question with a clear yes since the analysis performed here was at the limit of what was doable with H.E.S.S. from the systematic and statistical perspective. However, several observations, which were
presented in this work favor the scenario that at least one component of the signal from HESS J1745-290 is in fact connected to Sgr A*. Further components could still be from the PWN G359.95-0.0 and the diffuse emission in the Galactic plane. Although the significance levels, which were found during this analysis, were too low to claim a detection of a variability of HESS J1745-290 at the 5σ level, this work revealed evidence for both a short-term variability of HESS J1745-290 at timescales of minutes and also for a long-term variability of this source.
These observations clearly support the assumption of a link between the GC VHE γ-ray source HESS J1745-290 and Sgr A*, since the only known objects to show variable behavior at timescales like the observed ones are black holes. Furthermore, the findings presented here are similar to the known behavior of Sgr A* in terms of time structure for both the short-term variability and the long-term variability. When putting them into a common context, the H.E.S.S. results fit well into the overall picture of Sgr A* and might give a new insight into the nature of this black hole at so-far unreached energies from the VHEγ-ray range. It is hard to imagine that all the effects which are reported here are due to an unknown systematic origin, although this cannot fully be excluded at the time of this writing. However, the parallelism to MWL observations of Sgr A* disfavors the systematic explanation since the effects observed here have counterparts at different wavelength: Both the long-term flux modulation which is of the order of 110 days and the hints of quasi-periodic behavior have counterparts from the radio band (long-term behavior) to the X-ray band (quasi-periodic) behavior. Furthermore, control sources like G 0.9+0.1 did not show any comparable effects. There is no plausible explanation why systematic effects should mimic known behavior with respect to the time structure of the variability only at the position of Sgr A* but nowhere else in the FoV.
The assumption that HESS J1745-290 and Sgr A* are linked raises the question how large the contribution of Sgr A* to the overall flux of HESS J1745-290 is. From the stud-ies, which were summarized in this thesis, the following limits can be given: Concerning the short-term variability which appears to be present in less than 10% of all runs a luminosity of 1033 –1035erg/s could be derived which on average is corresponding to a flux increase of△Φγ = 0.88±0.72×10−11cm−2s−1which is 17.6% of the total integrated flux>100 GeV and implies that the contribution of Sgr A* to the HESS J1745-290 flux is≥17.6% during runs showing a short-lived variability.
In case the reported long-term variability is caused by the precession of the accretion disk of Sgr A* there should also be a steady VHEγ-ray flux component from the vicinity of Sgr A*, which is partially shielded by the disk precession. This steady flux component should be larger than the flux modulation. Therefore, a lower limit for the expected
VHE γ-ray flux can be derived from the result of the fit of the Sgr A* light curve with Eq. 4.2.1 in Sec. 4.2.4.2.3. About twice the amplitude of the sinusodial component of the fit function should be equivalent to the maximum flux which is shielded by the preceding disk. This value was calculated to be 1.29±0.24·10−11cm−2s−1 for energies
>100 GeV which corresponds to 26.5% of the total integrated flux of HESS J1745-290.
This allows the conclusion that the flux component which Sgr A* is contributing to the HESS J1745-290 flux is ≥26.5%.
Trying to give a detailed, quantitative model explaining the VHE γ-ray emission would go beyond the scope of this thesis and requires further combined efforts by theo-rists and experimentalists.
In order to confirm the VHE γ-ray variability of Sgr A*, which was reported in this thesis at the 5σ level, follow-up observations and dedicated MWL campaigns are needed.
Therefore, the Galactic Center remains an extremely interesting target for H.E.S.S. II and of course also future observatories like CTA may play a crucial role here. The results on a VHEγ-ray variability of Sgr A* presented in this work may already now be helpful for theorists in finding the correct model for the not yet fully understood variability of Sgr A* at different wavelengths bands, which from now on are also expected to include the VHE γ-ray range.
There are many people who were important for realizing this work and it is certainly not possible to mention them all. However, there are some people I would like to thank in particular: First of all I would like to mention Professor Thomas Lohse for giving me the opportunity to do my PHD in his working group. I really appreciated the inspiring atmosphere and also the good conversations about scientific and non-scientific adventures at lunch. The work certainly would not have been possible without the input by Ulli Schwanke who always had time to discuss any doubts. Furthermore, I would like to thank Loise Oakes for the good collaboration and the cross-check analyses. Also many thanks to Veronika Schneider for being patient when handing in my travel expense reports late and Tim Holch for proof-reading some chapters and also buying an excellent coffee machine for the office - better late than never. Not to forget about the numerous discussions with Gerrit Spengler about physics and systematics at H.E.S.S. and the good collaboration in the beginning of my PHD when I was working at indirect Dark Matter searches. There were also many people who indirectly supported me during this work and made the past four years unforgettable experience in my life. Many thanks to my parents and brother, my grand parents and of course also my friends Andres, Andrew, Clara, Elias, Johannes, Letizia, Laia, Robin for the great time. Also not to forget about Sven, Michael, Lars and the other guys for some inspiring weekends and everybody else I forgot to mention here. Last but not least I would also like to thank Professor Elisa Bernardini and Professor Markus Böttcher for volunteering to review this thesis.
[1] Fiona A. Harrison, Steven Boggs, Finn Christensen, William Craig et al. . The Nuclear Spectroscopic Telescope Array (NuSTAR). ArXiv:1008.1362 [astro-ph.IM], 2010.
[2] T. Antoni A, W. D. Apel B, F. Badea A, K. Bekk B, A. Bercuci B, H. Bl. Umer B, H. Bozdog B, I. M. Brancus C, C. B. Uttner A, A. Chilingarian D, K. Daumiller A, P. Doll B, J. Engler B, F. Fexler B, H. J. Gils B, R. Glasstetter A, R. Haeusler A, A. Haungs B, D. Heck B, J. R. H. Or, El A, A. Iwan A, K. h. Kampert A, H. O. Klages B, G. Maier B, H. J. Mathes B, H. J. Mayer B, J. Milke B, M. M. Uller B, R. Obenl, J. Oehlschl. Ager B, S. Ostapchenko A, M. Petcu C, H. Rebel B, M. Risse B, M. Roth A, G. Schatz B, H. Schieler B, J. Scholz B, T. Thouw B, H. Ulrich B, A. Vardanyan D, J. Weber B, A. Weindl B, J. Wentz B, J. Wochele B, J. Zabierowski E, and S. Zagromski B. Investigating cosmic rays of primary...
Nuclear Instruments and Methods in Physics Research Section A.
[3] A. Balzer, M. Fuessling et al. The H.E.S.S. central data acquisition system. arxiv:1311.3486, 2013.
[4] A. Abramowski, F. Aharonian, F. Ait Benkhali, A. G. Akhperjanian, E. O.
Angüner, M. Backes, S. Balenderan, A. Balzer, A. Barnacka, Y. Becherini, and et al. Diffuse Galactic gamma-ray emission with H.E.S.S. prd, 90(12):122007, December 2014.
[5] F. Acero, F. Aharonian, A. G. Akhperjanian, G. Anton, U. Barres de Almeida, A. R. Bazer-Bachi, Y. Becherini, B. Behera, K. Bernlöhr, A. Bochow, C. Bois-son, J. Bolmont, V. Borrel, J. Brucker, F. Brun, P. Brun, R. Bühler, T. Bulik, I. Büsching, T. Boutelier, P. M. Chadwick, A. Charbonnier, R. C. G. Chaves, A. Cheesebrough, L.-M. Chounet, A. C. Clapson, G. Coignet, M. Dalton, M. K.
Daniel, I. D. Davids, B. Degrange, C. Deil, H. J. Dickinson, A. Djannati-Ataï, W. Domainko, L. O. ’. Drury, F. Dubois, G. Dubus, J. Dyks, M. Dyrda, K. Egberts,
D. Emmanoulopoulos, P. Espigat, C. Farnier, S. Fegan, F. Feinstein, A. Fiasson, A. Förster, G. Fontaine, M. Füßling, S. Gabici, Y. A. Gallant, L. Gérard, D. Ger-big, B. Giebels, J. F. Glicenstein, B. Glück, P. Goret, D. Göring, D. Hauser, M. Hauser, S. Heinz, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, A. Hoffmann, W. Hofmann, P. Hofverberg, S. Hoppe, D. Horns, A. Jacholkowska, O. C. de Jager, C. Jahn, I. Jung, K. Katarzyński, U. Katz, S. Kaufmann, M. Kerschhaggl, D. Khangulyan, B. Khélifi, D. Keogh, D. Klochkov, W. Kluź-niak, T. Kneiske, N. Komin, K. Kosack, R. Kossakowski, G. Lamanna, J.-P.
Lenain, T. Lohse, V. Marandon, O. Martineau-Huynh, A. Marcowith, J. Mas-bou, D. Maurin, T. J. L. McComb, M. C. Medina, J. Méhault, R. Moder-ski, E. Moulin, M. Naumann-Godo, M. de Naurois, D. Nedbal, D. Nekrassov, B. Nicholas, J. Niemiec, S. J. Nolan, S. Ohm, J.-F. Olive, E. d. O. Wilhelmi, K. J.
Orford, M. Ostrowski, M. Panter, M. P. Arribas, G. Pedaletti, G. Pelletier, P.-O.
Petrucci, S. Pita, G. Pühlhofer, M. Punch, A. Quirrenbach, B. C. Raubenheimer, M. Raue, S. M. Rayner, O. Reimer, M. Renaud, F. Rieger, J. Ripken, L. Rob, S. Rosier-Lees, G. Rowell, B. Rudak, C. B. Rulten, J. Ruppel, V. Sahakian, A. San-tangelo, R. Schlickeiser, F. M. Schöck, U. Schwanke, S. Schwarzburg, S. Schwem-mer, A. Shalchi, M. Sikora, J. L. Skilton, H. Sol, Ł. Stawarz, R. Steenkamp, C. Stegmann, F. Stinzing, G. Superina, A. Szostek, P. H. Tam, J.-P. Tavernet, R. Terrier, O. Tibolla, M. Tluczykont, C. van Eldik, G. Vasileiadis, C. Venter, L. Venter, J. P. Vialle, P. Vincent, M. Vivier, H. J. Völk, F. Volpe, S. J. Wag-ner, M. Ward, A. A. Zdziarski, and A. Zech. Detection of Gamma Rays from a Starburst Galaxy. Science, 326:1080, November 2009.
[6] F. Aharonian, A. G. Akhperjanian, K.-M. Aye, A. R. Bazer-Bachi, M. Beil-icke, W. Benbow, D. Berge, P. Berghaus, K. Bernlöhr, C. Boisson, O. Bolz, C. Borgmeier, I. Braun, F. Breitling, A. M. Brown, J. Bussons Gordo, P. M.
Chadwick, L.-M. Chounet, R. Cornils, L. Costamante, B. Degrange, A. Djannati-Ataï, L. O’C. Drury, G. Dubus, T. Ergin, P. Espigat, F. Feinstein, P. Fleury, G. Fontaine, S. Funk, Y. A. Gallant, B. Giebels, S. Gillessen, P. Goret, C. Had-jichristidis, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, W. Hofmann, M. Holleran, D. Horns, O. C. de Jager, I. Jung, B. Khélifi, N. Komin, A. Konopelko, I. J. Latham, R. Le Gallou, A. Lemière, M. Lemoine, N. Leroy, T. Lohse, A. Marcowith, C. Masterson, T. J. L. McComb, M. de Naurois, S. J.
Nolan, A. Noutsos, K. J. Orford, J. L. Osborne, M. Ouchrif, M. Panter, G. Pel-letier, S. Pita, G. Pühlhofer, M. Punch, B. C. Raubenheimer, M. Raue, J. Raux, S. M. Rayner, I. Redondo, A. Reimer, O. Reimer, J. Ripken, L. Rob, L.
Rol-land, G. Rowell, V. Sahakian, L. Saugé, S. Schlenker, R. Schlickeiser, C. Schuster, U. Schwanke, M. Siewert, H. Sol, R. Steenkamp, C. Stegmann, J.-P. Tavernet, R. Terrier, C. G. Théoret, M. Tluczykont, G. Vasileiadis, C. Venter, P. Vincent, B. Visser, H. J. Völk, and S. J. Wagner. Very high energy gamma rays from the composite SNR G 0.9+0.1. aap, 432:L25–L29, March 2005.
[7] F. Aharonian, A. G. Akhperjanian, A. R. Bazer-Bachi, B. Behera, M. Beilicke, W. Benbow, D. Berge, K. Bernlöhr, C. Boisson, O. Bolz, V. Borrel, T. Boutelier, I. Braun, E. Brion, A. M. Brown, R. Bühler, I. Büsching, T. Bulik, S. Carri-gan, P. M. Chadwick, A. C. Clapson, L.-M. Chounet, G. Coignet, R. Cornils, L. Costamante, B. Degrange, H. J. Dickinson, A. Djannati-Ataï, W. Domainko, L. O. Drury, G. Dubus, J. Dyks, K. Egberts, D. Emmanoulopoulos, P. Espigat, C. Farnier, F. Feinstein, A. Fiasson, A. Förster, G. Fontaine, S. Funk, S. Funk, M. Füßling, Y. A. Gallant, B. Giebels, J. F. Glicenstein, B. Glück, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, A. Hoffmann, W. Hofmann, M. Holleran, S. Hoppe, D. Horns, A. Ja-cholkowska, O. C. de Jager, E. Kendziorra, M. Kerschhaggl, B. Khélifi, N. Komin, K. Kosack, G. Lamanna, I. J. Latham, R. Le Gallou, A. Lemière, M. Lemoine-Goumard, J.-P. Lenain, T. Lohse, J. M. Martin, O. Martineau-Huynh, A. Mar-cowith, C. Masterson, G. Maurin, T. J. L. McComb, R. Moderski, E. Moulin, M. de Naurois, D. Nedbal, S. J. Nolan, J.-P. Olive, K. J. Orford, J. L. Osborne, M. Os-trowski, M. Panter, G. Pedaletti, G. Pelletier, P.-O. Petrucci, S. Pita, G. Pühlhofer, M. Punch, S. Ranchon, B. C. Raubenheimer, M. Raue, S. M. Rayner, M. Renaud, J. Ripken, L. Rob, L. Rolland, S. Rosier-Lees, G. Rowell, B. Rudak, J. Ruppel, V. Sahakian, A. Santangelo, L. Saugé, S. Schlenker, R. Schlickeiser, R. Schröder, U. Schwanke, S. Schwarzburg, S. Schwemmer, A. Shalchi, H. Sol, D. Spangler, Ł. Stawarz, R. Steenkamp, C. Stegmann, G. Superina, P. H. Tam, J.-P. Taver-net, R. Terrier, C. van Eldik, G. Vasileiadis, C. Venter, J. P. Vialle, P. Vincent, M. Vivier, H. J. Völk, F. Volpe, S. J. Wagner, M. Ward, and A. A. Zdziarski. An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304. apjl, 664:L71–
L74, August 2007.
[8] F. Aharonian, A. G. Akhperjanian, A. R. Bazer-Bachi, M. Beilicke, W. Ben-bow, D. Berge, K. Bernlöhr, C. Boisson, O. Bolz, V. Borrel, I. Braun, F. Bre-itling, A. M. Brown, R. Bühler, I. Büsching, S. Carrigan, P. M. Chadwick, L.-M.
Chounet, R. Cornils, L. Costamante, B. Degrange, H. J. Dickinson, A. Djannati-Ataï, L. O’C. Drury, G. Dubus, K. Egberts, D. Emmanoulopoulos, P.
Espi-gat, F. Feinstein, E. Ferrero, A. Fiasson, G. Fontaine, S. Funk, S. Funk, Y. A.
Gallant, B. Giebels, J. F. Glicenstein, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, W. Hofmann, M. Holleran, D. Horns, A. Jacholkowska, O. C. de Jager, B. Khélifi, N. Komin, A. Konopelko, K. Kosack, I. J. Latham, R. Le Gallou, A. Lemière, M. Lemoine-Goumard, T. Lohse, J. M. Martin, O. Martineau-Huynh, A. Marcowith, C. Mas-terson, T. J. L. McComb, M. de Naurois, D. Nedbal, S. J. Nolan, A. Nout-sos, K. J. Orford, J. L. Osborne, M. Ouchrif, M. Panter, G. Pelletier, S. Pita, G. Pühlhofer, M. Punch, B. C. Raubenheimer, M. Raue, S. M. Rayner, A. Reimer, O. Reimer, J. Ripken, L. Rob, L. Rolland, G. Rowell, V. Sahakian, L. Saugé, S. Schlenker, R. Schlickeiser, U. Schwanke, H. Sol, D. Spangler, F. Spanier, R. Steenkamp, C. Stegmann, G. Superina, J.-P. Tavernet, R. Terrier, C. G.
Théoret, M. Tluczykont, C. van Eldik, G. Vasileiadis, C. Venter, P. Vincent, H. J.
Völk, S. J. Wagner, and M. Ward. Observations of the Crab nebula with HESS.
aap, 457:899–915, October 2006.
[9] F. Aharonian et al. Calibration of cameras of the H.E.S.S. detector. Astropart.
Phys., 22:109–125, 2004.
[10] F. Aharonian et al. Very high-energy gamma rays from the direction of Sagittarius A*. Astron. Astrophys., 425:L13–L17, 2004.
[11] F. Aharonian et al. A Low level of extragalactic background light as revealed by gamma-rays from blazars. Nature, 440:1018–1021, 2006.
[12] Dermer, Charles Aharonian, Felix, Bergstroem, Lars. Astrophysics at Very High Energies. Swiss Society for Astrophysics and Astronomy, 2013.
[13] Tal Alexander. Stellar processes near the massive black hole in the Galactic Center.
Phys. Rept., 419:65–142, 2005.
[14] V. Allevato, M. Paolillo, I. Papadakis, and C. Pinto. Measuring X-Ray Variability in Faint/Sparsely Sampled Active Galactic Nuclei. apj, 771:9, July 2013.
[15] Galactic Center Group/W. M. Keck Observatory Andrea Ghez, Gunther Witzel.
Science and Technology News Since. http://scitechdaily.com/, 2013.
[16] B. Aschenbach, N. Grosso, D. Porquet, and Predehl. X-ray flares reveal mass and angular momentum of the Galactic Center black hole. aap, 417:71–78, April 2004.
[17] B. Aschenbach, N. Grosso, Delphine Porquet, and P. Predehl. X-ray flares reveal mass and angular momentum of the Galactic Center black hole.Astron. Astrophys., 417:71–78, 2004.
[18] A. Bamba, R. Yamazaki, K. Kohri, H. Matsumoto, S. Wagner, G. Pühlhofer, and K. Kosack. X-ray Observation of Very High Energy Gamma-Ray Source, HESS J1745-303, with Suzaku. apj, 691:1854–1861, February 2009.
[19] F. J. M. Barning. The numerical analysis of the light-curve of 12 Lacertae. bain, 17:22, August 1963.
[20] Nicolas M. Barriere, John A. Tomsick, Frederick K. Baganoff, Steven E. Boggs, Finn E. Christensen, William W. Craig, Jason Dexter, Brian Grefenstette, Charles J. Hailey, Fiona A. Harrison, Kristin K. Madsen, Kaya Mori, Daniel Stern, William W. Zhang, Shuo Zhang, and Andreas Zoglauer. Nustar detec-tion of high-energy x-ray emission and rapid variability from sagittarius a flares.
The Astrophysical Journal, 786(1):46, 2014.
[21] G. Bélanger, R. Terrier, O. C. de Jager, A. Goldwurm, and F. Melia. Periodic Modulations in an X-ray Flare from Sagittarius A*. Journal of Physics Conference Series, 54:420–426, December 2006.
[22] D. Berge, S. Funk, and J. Hinton. Background modelling in very-high-energyγ-ray astronomy. aap, 466:1219–1229, May 2007.
[23] K. Bernlöhr. Simulation of imaging atmospheric Cherenkov telescopes with COR-SIKA and sim_ telarray. Astroparticle Physics, 30:149–158, October 2008.
[24] C. Bigongiari. The MAGIC telescope. In International Europhysics Conference on High Energy Physics, HEP2005, page 20, 2005.
[25] A. E. Broderick and A. Loeb. Imaging optically-thin hotspots near the black hole horizon of Sgr A* at radio and near-infrared wavelengths. mnras, 367:905–916, April 2006.
[26] Rene Brun and Fons Rademakers. ROOT - An Object Oriented Data Analysis Framework. Proceedings AIHENP’96 Workshop, Lausanne, Sep. 1996, Nucl. Inst.
and Meth. in Phys. Res. A 389 (1997) 81-86.
[27] CANGAROO-II collaboration. Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II. ApJ 606 pL115-L118, 2004.
[28] B. Cerutti, G. Dubus, J. Malzac, A. Szostek, R. Belmont, A. A. Zdziarski, and G. Henri. Absorption of high-energy gamma rays in Cygnus X-3. aap, 529:A120, May 2011.
[29] Fermi Collaboration. Overview: LAT Data Analysis Tools. 2005.
[30] O. C. de Jager and I. Büsching. The H-test probability distribution revisited:
Improved sensitivity. ArXiv e-prints, May 2010.
[31] M. de Naurois. Analysis methods for Atmospheric Cerenkov Telescopes. ArXiv Astrophysics e-prints, July 2006.
[32] A. Eckart, R. Schödel, M. García-Marín, G. Witzel, A. Weiss, F. K. Baganoff, M. R. Morris, T. Bertram, M. Dovčiak, W. J. Duschl, V. Karas, S. König, T. P. Krichbaum, M. Krips, D. Kunneriath, R.-S. Lu, S. Markoff, J. Mauerhan, L. Meyer, J. Moultaka, K. Mužić, F. Najarro, J.-U. Pott, K. F. Schuster, L. O.
Sjouwerman, C. Straubmeier, C. Thum, S. N. Vogel, H. Wiesemeyer, M. Zamani-nasab, and J. A. Zensus. Simultaneous NIR/sub-mm observation of flare emission from Sagittarius A*. aap, 492:337–344, December 2008.
[33] P. Esquej, R. D. Saxton, M. J. Freyberg, A. M. Read, B. Altieri, M. Sanchez-Portal, and G. Hasinger. Candidate tidal disruption events from the XMM-Newton slew survey. aap, 462:L49–L52, February 2007.
[34] Gajdus M. et al. for the H.E.S.S. collaboration. Proc. of the 34th International Cosmic Ray Conference. ID841, 2015.
[35] F. K. Baganoff, M. W. Bautz, W. N. Brandt et al. The 3 Ms Chandra Cam-paign on Sgr A*: A Census of X-ray Flaring Activity from the Galactic Center. arXiv:1311.6818, 2013.
[36] Fermi/LAT Collaboration: W. B. Atwood, et al. The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission. arXiv:0902.1089 [astro-ph.IM], 2009.
[37] G. Ponti, B. De Marco, M. R. Morris, A. Merloni, T. Munoz-Darias et al. Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate. arXiv:1507.02690 [astro-ph.HE], 2015.
[38] G. Spengler, H. Prokoph. Private Communication. 2015.
[39] R. Genzel, R. Schödel, T. Ott, A. Eckart, T. Alexander, F. Lacombe, D. Rouan, and B. Aschenbach. Near-infrared flares from accreting gas around the supermas-sive black hole at the Galactic Centre. nat, 425:934–937, October 2003.
[40] Ott, T Genzel, R, Schodel, R. Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre. nature, 425:0028–0836, 10 2003.
[41] Fritz T. K. Gillessen S., Genzel R. A gas cloud on its way towards the supermassive black hole at the Galactic Centre. Nature 2012/01/05/, 2012.
[42] J. H. V. Girard, M. Kasper, S. P. Quanz, M. A. Kenworthy, S. Rengaswamy, R. Schödel, A. Gallenne, S. Gillessen, N. Huerta, P. Kervella, N. Kornweibel, R. Lenzen, A. Mérand, G. Montagnier, J. O’Neal, and G. Zins. Status and new operation modes of the versatile VLT/NaCo. In Society of Photo-Optical Instru-mentation Engineers (SPIE) Conference Series, volume 7736 of Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, page 2, July 2010.
[43] I. J. Goodfellow, Y. Bulatov, J. Ibarz, S. Arnoud, and V. Shet. Multi-digit Number Recognition from Street View Imagery using Deep Convolutional Neural Networks.
ArXiv e-prints, December 2013.
[44] D. F. Gray and K. Desikachary. A new approach to periodogram analyses. apj, 181:523–530, April 1973.
[45] H. Prokoph. Presentation on Systematics at H.E.S.S. at the 2015 H.E.S.S. CM in Parys, South Afrika. 2015.
[46] J. Hahn, R. de los Reyes, K. Bernlöhr, P. Krüger, Y. T. E. Lo, P. M. Chadwick, M. K. Daniel, C. Deil, H. Gast, K. Kosack, and V. Marandon. Data quality monitoring in the presence of aerosols and other adverse atmospheric conditions with H.E.S.S. ArXiv e-prints, February 2015.
[47] F. A. Harrison, W. W. Craig, F. E. Christensen, C. J. Hailey, W. W. Zhang, S. E.
Boggs, D. Stern, W. R. Cook, K. Forster, P. Giommi, B. W. Grefenstette, Y. Kim, T. Kitaguchi, J. E. Koglin, K. K. Madsen, P. H. Mao, H. Miyasaka, K. Mori, M. Perri, M. J. Pivovaroff, S. Puccetti, V. R. Rana, N. J. Westergaard, J. Willis, A. Zoglauer, H. An, M. Bachetti, N. M. Barriere, E. C. Bellm, V. Bhalerao, N. F.
Brejnholt, F. Fuerst, C. C. Liebe, C. B. Markwardt, M. Nynka, J. K. Vogel, D. J.
Walton, D. R. Wik, D. M. Alexander, L. R. Cominsky, A. E. Hornschemeier, A. Hornstrup, V. M. Kaspi, G. M. Madejski, G. Matt, S. Molendi, D. M. Smith,
J. A. Tomsick, M. Ajello, D. R. Ballantyne, M. Baloković, D. Barret, F. E. Bauer, R. D. Blandford, W. N. Brandt, L. W. Brenneman, J. Chiang, D. Chakrabarty, J. Chenevez, A. Comastri, F. Dufour, M. Elvis, A. C. Fabian, D. Farrah, C. L.
Fryer, E. V. Gotthelf, J. E. Grindlay, D. J. Helfand, R. Krivonos, D. L. Meier, J. M.
Miller, L. Natalucci, P. Ogle, E. O. Ofek, A. Ptak, S. P. Reynolds, J. R. Rigby, G. Tagliaferri, S. E. Thorsett, E. Treister, and C. M. Urry. The Nuclear Spectro-scopic Telescope Array (NuSTAR) High-energy X-Ray Mission. apj, 770:103, June 2013.
[48] R. C. Haymes, D. V. Ellis, G. J. Fishman, J. D. Kurfess, and W. H. Tucker.
Observation of Gamma Radiation from the Crab Nebula. apjl, 151:L9, January 1968.
[49] D. Heck, J. Knapp, J. N. Capdevielle, G. Schatz, and T. Thouw. CORSIKA: a Monte Carlo code to simulate extensive air showers. February 1998.
[50] H.E.S.S Collaboration. Calibration of cameras of the H.E.S.S. detector. arXiv:astro-ph/0406658, 2004.
[51] H.E.S.S. collaboration. Very high energy gamma rays from the direction of Sagit-tarius A*. AandA 425 pL13-L17, 2004.
[52] HESS Collaboration. Acceleration of petaelectronvolt protons in the Galactic Cen-tre. nature, 531:476–479, 2016.
[53] Jim Hinton. Ground-based gamma-ray astronomy with cherenkov telescopes. New Journal of Physics, 11(5):055005, 2009.
[54] A. Hoecker, P. Speckmayer, J. Stelzer, J. Therhaag, E. von Toerne, H. Voss, M. Backes, T. Carli, O. Cohen, A. Christov, D. Dannheim, K. Danielowski, S. Henrot-Versille, M. Jachowski, K. Kraszewski, A. Krasznahorkay, Jr., M. Kruk, Y. Mahalalel, R. Ospanov, X. Prudent, A. Robert, D. Schouten, F. Tegenfeldt, A. Voigt, K. Voss, M. Wolter, and A. Zemla. TMVA - Toolkit for Multivariate Data Analysis. ArXiv Physics e-prints, March 2007.
[55] J. H. Horne and S. L. Baliunas. A prescription for period analysis of unevenly sampled time series. apj, 302:757–763, March 1986.
[56] J. Bolmont, P. Corona, P. Gauron, P. Ghislain, C. Goffin, L. Guevara Riveros, J.-F. Huppert, O. Martineau-Huynh, P. Nayman, J.-M. Parraud, J.-P. Tavernet
et. al. The camera of the fifth H.E.S.S. telescope. Part I: System description. arXiv:1310.5877, 2013.
[57] J. Guy. These de doctorat, Universit ¿e Paris VI (2003). 2003.
[58] Y. Jia, E. Shelhamer, J. Donahue, S. Karayev, J. Long, R. Girshick, S. Guadar-rama, and T. Darrell. Caffe: Convolutional Architecture for Fast Feature Embed-ding. ArXiv e-prints, June 2014.
[59] Stephen B. Vardeman John L. Stanford. Statistical Methods for Physical Science. Academic Press (November 22, 1994), 2007.
[60] K Egberts, F Brun, S Casanova, W Hofmann, M De Naurois. Diffuse TeV Gamma Ray Emission in the H.E.S.S. Galactic Plane Survey. arXiv:1308.0161 [astro-ph.HE], 2013.
[61] V. M. Kaspi, R. F. Archibald, V. Bhalerao, F. Dufour, E. V. Gotthelf, H. An, M. Bachetti, A. M. Beloborodov, S. E. Boggs, F. E. Christensen, W. W. Craig, B. W. Grefenstette, C. J. Hailey, F. A. Harrison, J. A. Kennea, C. Kouveliotou, K. K. Madsen, K. Mori, C. B. Markwardt, D. Stern, J. K. Vogel, and W. W. Zhang.
Timing and Flux Evolution of the Galactic Center Magnetar SGR J1745-2900. apj, 786:84, May 2014.
[62] J. A. Kennea, D. N. Burrows, C. Kouveliotou, D. M. Palmer, E. Göğüş, Y. Kaneko, P. A. Evans, N. Degenaar, M. T. Reynolds, J. M. Miller, R. Wijnands, K. Mori, and N. Gehrels. Swift Discovery of a New Soft Gamma Repeater, SGR J1745-29, near Sagittarius A*. apjl, 770:L24, June 2013.
[63] H. A. Krimm, S. T. Holland, R. H. D. Corbet, A. B. Pearlman, P. Romano, J. A.
Kennea, J. S. Bloom, S. D. Barthelmy, W. H. Baumgartner, J. R. Cummings, N. Gehrels, A. Y. Lien, C. B. Markwardt, D. M. Palmer, T. Sakamoto, M. Sta-matikos, and T. N. Ukwatta. The Swift/BAT Hard X-Ray Transient Monitor. apj, 209:14, November 2013.
[64] S. I. Kuznetsov, M. R. Gilfanov, E. M. Churazov, R. A. Sunyaev, A. V. D’Yachkov, N. G. Khavenson, B. S. Novikov, R. S. Kremnev, P. Goldoni, A. Goldwurm, P. Lau-rent, J. Paul, J.-P. Roques, E. Jourdain, L. Bouchet, and G. Vedrenne. Long-term variability of the hard X-ray source GRS 1758-258: GRANAT/SIGMA observa-tions. Astronomy Letters, 25:351–358, June 1999.
[65] S. Liu and F. Melia. New Constraints on the Nature of Radio Emission in Sagit-tarius A*. apj, 561:L77–L80, November 2001.
[66] S. Liu, V. Petrosian, F. Melia, and C. L. Fryer. A Testable Stochastic Acceleration Model for Flares in Sagittarius A*. apj, 648:1020–1025, September 2006.
[66] S. Liu, V. Petrosian, F. Melia, and C. L. Fryer. A Testable Stochastic Acceleration Model for Flares in Sagittarius A*. apj, 648:1020–1025, September 2006.