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1. Generating Component Designs for an Improved NVH Performance by Using an Artificial Neural Network as an Optimization Metamodel

Author: Timo von Wysocki, Frank Rieger, Dimitrios Ernst Tsokaktsidis, and Frank Gauterin
Subjects: component design, optimization, artificial neural network, morphing, FEM, vibration, Technology, Engineering design, TA174
Abstract: In modern vehicle development, suspension components have to meet many boundary conditions. In noise, vibration, and harshness (NVH) development these are for example eigenfrequencies and frequency response function (FRF) amplitudes. Component geometry parameters, for example kinematic hard points, often affect multiple of these targets in a non intuitive way. In this article, we present a practical approach to find optimized parameters for a component design, which fulfills an FRF target curve. By morphing an initial component finite element model we create training data for an artificial neural network (ANN) which predicts FRFs from geometry parameter input. Then the ANN serves as a metamodel for an evolutionary algorithm optimizer which identifies fitting geometry parameter sets, meeting an FRF target curve. The methodology enables a component design which considers an FRF as a component target. In multiple simulation examples we demonstrate the capability of identifying component designs modifying specific eigenfrequency or amplitude features of the FRFs.
Published: 2021
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2. Theory of Gamma-Ray loud AGNs

Author: Frank Rieger
Published: 2023
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3. Active Galactic Nuclei as potential Sources of Ultra-High Energy Cosmic Rays

Author: Frank Rieger
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), General Physics and Astronomy, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Active Galactic Nuclei (AGNs) and their relativistic jets belong to the most promising class of ultra-high-energy cosmic ray (UHECR) accelerators. This compact review summarises basic experimental findings by recent instruments, and discusses possible interpretations and astrophysical constraints on source energetics. Particular attention is given to potential sites and mechanisms of UHECR acceleration in AGNs, including gap-type particle acceleration close to the black hole, as well as first-order Fermi acceleration at trans-relativistic shocks and stochastic shear particle acceleration in large-scale jets. It is argued that the last two represent the most promising mechanisms given our current understanding, and that nearby FR~I type radio galaxies provide a suitable environment for UHECR acceleration., Compact invited review paper; Universe, Special Issue Black Holes and Relativistic Jets; 30 pages, 18 figures
Published: 2022

4. Sicherheitsanalyse der Nedap-Wahlcomputer.

Author: Constanze Kurz and Frank Rieger
Published: 2009
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5. Searching for VHE gamma-ray emission associated with IceCube neutrino alerts using FACT, H.E.S.S., MAGIC, and VERITAS

Author: Konstancja, Satalecka, Acciari, Victor A., Stefano, Ansoldi, Lucio Angelo Antonelli, Axel Arbet Engels, Manuel, Artero, Katsuaki, Asano, Dominik, Baack, Ana, Babic, Andr('(e))s, Baquero, Ulisses Barres de Almeida, Juan Abel Barrio, Ivana, Batkovi('(c)), Josefa Becerra Gonzalez, Wlodek, Bednarek, Lorenzo, Bellizzi, Elisa, Bernardini, Maria-Isabel, Bernardos, Alessio, Berti, Jürgen, Besenrieder, Wrijupan, Bhattacharyya, Ciro, Bigongiari, Adrian, Biland, Oscar, Blanch, Hendrik, Bökenkamp, Giacomo, Bonnoli, Zeljka, Bosnjak, Giovanni, Busetto, Roberto, Carosi, Giovanni, Ceribella, Matteo, Cerruti, Yating, Chai, Ashot, Chilingarian, Stefan, Cikota, Sidika Merve Colak, Eduardo, Colombo, Jose Luis Contreras, Juan, Cortina, Stefano, Covino, Giacomo D( extquotesingle)Amico, Valerio D( extquotesingle)Elia, Paolo Da Vela, Francesco, Dazzi, Alessandro De Angelis, Barbara De Lotto, Manuel, Delfino, Jordi, Delgado, Carlos Delgado Mendez, Davide, Depaoli, Federico Di Pierro, Leonardo Di Venere, Elia Do Souto Espi(~(n))eira, Dijana Dominis Prester, Alice, Donini, Daniela, Dorner, Michele, Doro, Dominik, Elsaesser, Vandad Fallah Ramazani, Alicia, Fattorini, Maria Victoria Fonseca, Lluis, Font, Christian, Fruck, Satoshi, Fukami, Yasushi, Fukazawa, Garc('(i))a L('(o))pez, Ramon J., Markus, Garczarczyk, Sargis, Gasparyan, Markus, Gaug, Giglietto, Nicola, Francesco, Giordano, Pawel, Gliwny, Nikola, Godinovic, David, Green, Jarred Gershon Green, Daniela, Hadasch, Alexander, Hahn, Lea, Heckmann, Javier, Herrera, John, Hoang, Dario, Hrupec, Moritz, Hütten, Tomohiro, Inada, Kazuma, Ishio, Yuki, Iwamura, Irene Jim('(e))nez Mart('(i))nez, Jenni, Jormanainen, L('(e))a, Jouvin, Marie, Karjalainen, Daniel, Kerszberg, Yukiho, Kobayashi, Hidetoshi, Kubo, Junko, Kushida, Alessandra, Lamastra, Damir, Lelas, Francesco, Leone, Elina, Lindfors, Lena, Linhoff, Saverio, Lombardi, Francesco, Longo, Ruben, Lopez-Coto, Marcos, L('(o))pez-Moya, Alicia, L('(o))pez-Oramas, Loporchio, Serena, Bernardo Machado de Oliveira Fraga, Camilla, Maggio, Pratik, Majumdar, Martin, Makariev, Manuela, Mallamaci, Galina, Maneva, Marina, Manganaro, Karl, Mannheim, Laura, Maraschi, Mos(`(e)), Mariotti, Manel, Martinez, Daniel, Mazin, Stefano, Menchiari, Simone, Mender, Sa( (s))a Mi('(c))anovi('(c)), Davide, Miceli, Tjark, Miener, Jose Miguel Miranda, Razmik, Mirzoyan, Edgar, Molina, Abelardo, Moralejo, Daniel, Morcuende, Victoria, Moreno, Elena, Moretti, Takeshi, Nakamori, Lara, Nava, Vitaly, Neustroev, Cosimo, Nigro, Kari, Nilsson, Kyoshi, Nishijima, Koji, Noda, Seiya, Nozaki, Yoshiki, Ohtani, Tomohiko, Oka, Jorge, Otero-Santos, Simona, Paiano, Michele, Palatiello, David, Paneque, Riccardo, Paoletti, Paredes, Josep M., Lovro, Pavleti('(c)), Pablo, Pe(~(n))il, Massimo, Persic, Marine, Pihet, Pier Giorgio Prada Moroni, Elisa, Prandini, Chaitanya, Priyadarshi, Ivica, Puljak, Wolfgang, Rhode, Marc, Rib('(o)), Javier, Rico, Chiara, Righi, Andrea, Rugliancich, Narek, Sahakyan, Takayuki, Saito, Shunsuke, Sakurai, Francesco Gabriele Saturni, Bernd, Schleicher, Kevin, Schmidt, Thomas, Schweizer, Julian, Sitarek, Iva, ( (S))nidari('(c)), Dorota, Sobczy('(n))ska, Alessia, Spolon, Antonio, Stamerra, Jelena Stri( (s))kovi('(c)), Derek, Strom, Marcel, Strzys, Yusuke, Suda, Tihomir, Suri('(c)), Mitsunari, Takahashi, Ryuji, Takeishi, Fabrizio, Tavecchio, Petar, Temnikov, Tomislav, Terzic, Masahiro, Teshima, Luca, Tosti, Stefano, Truzzi, Antonio, Tutone, Santiago, Ubach, Juliane van Scherpenberg, Gaia, Vanzo, Monica VAZQUEZ ACOSTA, Sofia, Ventura, Vassil, Verguilov, Carlo Francesco Vigorito, Vincenzo, Vitale, Ievgen, Vovk, Martin, Will, Carolin, Wunderlich, Tokonatsu, Yamamoto, Darko, Zari('(c)), Matteo, Balbo, Thomas, Bretz, Jens, Buss, Laura, Eisenberger, Dorothee, Hildebrand, Roman, Iotov, Adelina, Kalenski, Dominik, Neise, Maximilian, Noethe, Aleksander, Paravac, Vitalii, Sliusar, Roland, Walter, Rasha, Abbasi, Markus, Ackermann, Jenni, Adams, Juanan, Aguilar, Ahlers, M., Maryon, Ahrens, Cyril Martin Alispach, Antonio Augusto Alves Junior, Najia Moureen Binte Amin, Rui, An, Karen, Andeen, Tyler, Anderson, Gisela, Anton, Carlos, Arguelles, Yosuke, Ashida, Spencer, Axani, Xinhua, Bai, Aswathi Balagopal, V., Anastasia Maria Barbano, Barwick, S. W., Benjamin, Bastian, Vedant, Basu, Sebastian, Baur, Bay, R. C., Beatty, J. J., Becker, K. -H., Julia Becker Tjus, Chiara, Bellenghi, Segev, Benzvi, Berley, D., Besson, D. Z., Gary, Binder, Daniel, Bindig, Blaufuss, E., Summer, Blot, Matthias, Boddenberg, Federico, Bontempo, Jurgen, Borowka, Boser, S., Olga, Botner, Jakob, Bottcher, Etienne, Bourbeau, Federica, Bradascio, Braun, J., Stephanie, Bron, Jannes, Brostean-Kaiser, Sally-Ann, Browne, Alexander, Burgman, Ryan, Burley, Raffaela, Busse, Michael, Campana, Erin, Carnie-Bronca, Chujie, Chen, Dmitry, Chirkin, Koun, Choi, Bryanlee, Clark, Kenneth, Clark, Lew, Classen, Alan, Coleman, Gabriel, Collin, Conrad, J. M., Paul, Coppin, Pablo, Correa, Cowen, D. F., Cross, R., Christian, Dappen, Pranav, Dave, Catherine DE CLERCQ, James, Delaunay, Hans, Dembinski, Kunal, Deoskar, Sam De Ridder, Abhishek, Desai, Paolo, Desiati, Krijn de Vries, Gwenhaël de Wasseige, Meike De With, Tyce, Deyoung, Sukeerthi, Dharani, Alejandro, Diaz, Juan Carlos Diaz-Velez, Markus, Dittmer, Hrvoje, Dujmovic, Matt, Dunkman, Michael, Duvernois, Emily, Dvorak, Thomas, Ehrhardt, Philipp, Eller, Ralph, Engel, Hannah, Erpenbeck, John, Evans, Evenson, P. A., Kwok Lung Fan, Fazely, A. R., Sebastian, Fiedlschuster, Aaron, Fienberg, Kirill, Filimonov, Chad, Finley, Leander, Fischer, Derek, B Fox, Anna, Franckowiak, Elizabeth, Friedman, Alexander, Fritz, Philipp, Furst, Gaisser, T. K., Jay, Gallagher, Erik, Ganster, Alfonso, Garcia, Simone, Garrappa, Gerhardt, L., Ava, Ghadimi, Christian, Glaser, Theo, Glauch, Thorsten, Glusenkamp, Goldschmidt, A., Javier, Gonzalez, Sreetama, Goswami, Darren, Grant, Timoth('(e))e, Gr('(e))goire, Spencer, Griswold, Mehmet, Gunduz, Christoph, Günther, Christian, Haack, Allan, Hallgren, Halliday, R., Halve, L., Halzen, F., Martin Ha Minh, Kael, Hanson, John, Hardin, Harnisch, Alexander A., Andreas, Haungs, Simon, Hauser, Dustin, Hebecker, Helbing, K., Felix, Henningsen, Hettinger, Emma C., Stephanie, Hickford, Joshua, Hignight, Colton, Hill, Hill, G. C., Kara, Hoffman, Ruth, Hoffmann, Tobias, Hoinka, Benjamin, Hokanson-Fasig, Hoshina, K., Feifei, Huang, Matthias, Huber, Thomas, Huber, Klas, Hultqvist, Mirco, Hunnefeld, Raamis, Hussain, Seongjin, In, Nad(`(e))ge, Iovine, Aya, Ishihara, Matti, Jansson, George, Japaridze, Minjin, Jeong, Ben, Jones, Donghwa, Kang, Woosik, Kang, Xinyue, Kang, Alexander, Kappes, David, Kappesser, Timo, Karg, Martina, Karl, Karle, A., Katz, U., Kauer, M., Moritz, Kellermann, Kelley, J. L., Ali, Kheirandish, Ken( extquotesingle)ichi Kin, Thomas, Kintscher, Joanna, Kiryluk, Spencer, Klein, Ramesh, Koirala, Hermann, Kolanoski, Tomas, Kontrimas, Lutz, Kopke, Claudio, Kopper, Sandro, Kopper, Koskinen, D. J., Paras, Koundal, Michael, Kovacevich, Marek, Kowalski, Tetiana, Kozynets, Emma, Kun, Naoko, Kurahashi, Neha, Lad, Cristina Lagunas Gualda, Justin, Lanfranchi, Michael, J Larson, Frederik Hermann Lauber, Jeffrey, Lazar, Jiwoong, Lee, Kayla, Leonard, Agnieszka, Leszczy('(n))ska, Yijia, Li, Massimiliano, Lincetto, Qinrui, Liu, Maria, Liubarska, Elisa, Lohfink, Cristian Jesus Lozano Mariscal, Lu, Lu, Francesco, Lucarelli, Andrew, Ludwig, William, Luszczak, Yang, Lyu, Wing Yan Ma, James, Madsen, Kendall, Mahn, Yuya, Makino, Sarah, Mancina, Ioana Codrina Maris, Maruyama, Reina H., Mase, K., Thomas, Mcelroy, Frank, Mcnally, James Vincent Mead, Meagher, K., Andres, Medina, Maximilian, Meier, Stephan, Meighen-Berger, Jessie, Micallef, Daniela, Mockler, Teresa, Montaruli, Roger, Moore, Morse, R., Marjon, Moulai, Richard, Naab, Ryo, Nagai, Uwe, Naumann, Jannis, Necker, Le Viet Nguyen, Hans, Niederhausen, Mehr, Nisa, Sarah, Nowicki, Dave, Nygren, Anna Obertacke Pollmann, Marie, Oehler, Olivas, A., Erin O( extquotesingle)Sullivan, Hershal, Pandya, Daria, Pankova, Nahee, Park, Grant, Parker, Ek Narayan Paudel, Larissa, Paul, Carlos Perez de los Heros, Lilly, Peters, Saskia, Philippen, Damian, Pieloth, Sarah, Pieper, Martin, Pittermann, Pizzuto, A., Plum, M., Yuiry, Popovych, Alessio, Porcelli, Maria Prado Rodriguez, Buford Price, P., Brandom, Pries, Gerald, Przybylski, Christoph, Raab, Amirreza, Raissi, Mohamed, Rameez, Rawlins, K., Immacolata Carmen Rea, Abdul, Rehman, Ren('(e)), Reimann, Giovanni, Renzi, Elisa, Resconi, Simeon, Reusch, Mike, Richman, Benedikt, Riedel, Ella, Roberts, Sally, Robertson, Gerrit, Roellinghoff, Martin, Rongen, Carsten, Rott, Tim, Ruhe, Dirk, Ryckbosch, Devyn Rysewyk Cantu, Ibrahim, Safa, Julian, Saffer, Sebastian Sanchez Herrera, Alexander, Sandrock, Joakim, Sandroos, Marcos, Santander, Subir, Sarkar, Sourav, Sarkar, Maximilian Karl Scharf, Merlin, Schaufel, Harald, Schieler, Sebastian, Schindler, Schlunder, P., Torsten, Schmidt, Austin, Schneider, Judith, Schneider, Schröder, Frank G., Lisa Johanna Schumacher, Georg, Schwefer, Steve, Sclafani, Seckel, D., Surujhdeo, Seunarine, Ankur, Sharma, Shefali, Shefali, Manuel, Silva, Barbara, Skrzypek, Ben, Smithers, Robert, Snihur, Jan, Soedingrekso, Dennis, Soldin, Christian, Spannfellner, Glenn, Spiczak, Christian, Spiering, Juliana, Stachurska, Michael, Stamatikos, Stanev, T., Robert, Stein, Joeran, Stettner, Steuer, A., Stezelberger, T., Timo, Sturwald, Thomas, Stuttard, Sullivan, G. W., Taboada, I., Frederik, Tenholt, Samvel, Ter-Antonyan, Tilav, S., Franziska, Tischbein, Kirsten, Tollefson, Christoph, Tönnis, Simona, Toscano, Delia, Tosi, Alexander, Trettin, Maria, Tselengidou, Chunfai, Tung, Andrea, Turcati, Roxanne, Turcotte, Colin, Turley, Jean Pierre Twagirayezu, Bunheng, Ty, Martin Unland Elorrieta, Nora, Valtonen-Mattila, Justin, Vandenbroucke, Nick van Eijndhoven, David, Vannerom, Jakob van Santen, Stef, Verpoest, Matthias, Vraeghe, Walck, C., Timothyblake, Watson, Chris, Weaver, Philip, Weigel, Andreas, Weindl, Matthew, Weiss, Jan, Weldert, Chris, Wendt, Johannes, Werthebach, Mark, Weyrauch, Nathan, Whitehorn, Wiebusch, C. H., Dawn, Williams, Martin, Wolf, Kurt, Woschnagg, Gerrit, Wrede, Johan, Wulff, Xianwu, Xu, Yiqian, Xu, Juan Pablo Yanez, Yoshida, S., Shiqi, Yu, Tianlu, Yuan, Zelong, Zhang, Weidong, Jin, Hassan, Abdalla, Felix, Aharonian, Faical, Ait-Benkhali, Oguzhan, Anguener, Cornelia, Arcaro, Celine, Armand, Tom, Armstrong, Halim, Ashkar, Michael, Backes, Vardan, Baghmanyan, Victor Barbosa Martins, Anna, Barnacka, Monica, Barnard, Rowan, Batzofin, Yvonne, Becherini, David, Berge, Konrad, Bernlöhr, Baiyang, Bi, Markus, Boettcher, Catherine, Boisson, Julien, Bolmont, Mathieu de Bony, Mischa, Breuhaus, Robert, Brose, Francois, Brun, Tomasz, Bulik, Thomas, Bylund, Floriane, Cangemi, Sami, Caroff, Sabrina, Casanova, Jaqueline, Catalano, Pauline, Chambery, Tej Bahadur Chand, Andrew, Chen, Garret, Cotter, Malgorzata, Curlo, Jean Damascene Mbarubucyeye, Isak Delberth Davids, James, Davies, Justine, Devin, Arache, Djannati-Ataï, Anton, Dmytriiev, Axel, Donath, Victor, Doroshenko, Lente, Dreyer, Louis Du Plessis, Connor, Duffy, Kathrin, Egberts, Sabrina, Einecke, Gabriel, Emery, Jean-Pierre, Ernenwein, Steven, Fegan, Kirsty, Feijen, Armand, Fiasson, Gaëtan Fichet de Clairfontaine, Gerard, Fontaine, Lott, Frans, Matthias, Fuessling, Stefan, Funk, Stefano, Gabici, Yves, Gallant, Shahede, Ghafourizade, Gianluca, Giavitto, Luca, Giunti, Dorit, Glawion, Jean-Francois, Glicenstein, Marie-H('(e))l(`(e))ne, Grondin, Sumari, Hattingh, Maria, Haupt, German, Hermann, Jim, Hinton, Werner, Hofmann, Clemens, Hoischen, Tim, Holch, Markus, Holler, Dieter, Horns, Zhiqiu, Huang, David, Huber, Mario, Hörbe, Marek, Jamrozy, Felix, Jankowsky, Vikas, Joshi, Ira, Jung, Eli, Kasai, Krzysztof, Katarzynski, Ul(`(i)), Katz, Dmitry, Khangulyan, Bruno, Khelifi, Stefan, Klepser, Wlodek, Kluzniak, Nukri, Komin, Ruslan, Konno, Karl, Kosack, Dmitriy, Kostunin, Michael, Kreter, Ga( (s))per Kukec Mezek, Anu, Kundu, Giovanni, Lamanna, S('(e))bastien Le Stum, Anne, Lemiere, Marianne, Lemoine-Goumard, Jean-Philippe, Lenain, Fabian, Leuschner, Christelle, Levy, Thomas, Lohse, Anna, Luashvili, Iryna, Lypova, Jonathan, Mackey, Jhilik, Majumdar, Denys, Malyshev, Dmitry, Malyshev, Vincent, Marandon, Paolo, Marchegiani, Alexandre, Marcowith, Arnaud, Mares, Guillem Marti( extquotesingle)i-Devesa, Ramin, Marx, Gilles, Maurin, Pieter, Meintjes, Manuel, Meyer, Alison, Mitchell, Rafal, Moderski, Lars, Mohrmann, Alessandro, Montanari, Chris, Moore, Paul, Morris, Emmanuel, Moulin, Jacques, Muller, Thomas, Murach, Kaori, Nakashima, Mathieu Naurois (de), Amid, Nayerhoda, Hambeleleni, Ndiyavala, Jacek, Niemiec, Angel, Noel, Paul O( extquotesingle)Brien, Laenita Lorraine Oberholzer, Stefan, Ohm, Laura, Olivera-Nieto, Emma Ona-Wilhelmi (de), Michal, Ostrowski, Sebastian, Panny, Michael, Panter, Dan, Parsons, Giada, Peron, Santiago, Pita, Vincent, Poireau, Dmitry, Prokhorov, Heike, Prokoph, Gerd, Puehlhofer, Michael, Punch, Andreas, Quirrenbach, Patrick, Reichherzer, Anita, Reimer, Olaf, Reimer, Quentin, Remy, Matthieu, Renaud, Brian, Reville, Frank, Rieger, Carlo, Romoli, Gavin, Rowell, Bronislaw, Rudak, Hector Rueda Ricarte, Edna Ruiz Velasco, Vardan, Sahakian, Simon, Sailer, Heiko, Salzmann, David, Sanchez, Andrea, Santangelo, Manami, Sasaki, Johannes, Schaefer, Hester, Schutte, Ullrich, Schwanke, Fabian, Schüssler, Mohanraj, Senniappan, Albert, Seyffert, Shapopi, Jimmy N. S., Kleopas, Shiningayamwe, Rachel, Simoni, Atreyee, Sinha, Helene, Sol, Hugh, Spackman, Andreas, Specovius, Samuel Timothy Spencer, Marion, Spir-Jacob, Lukasz, Stawarz, Riaan, Steenkamp, Christian, Stegmann, Simon, Steinmassl, Constantin, Steppa, Lei, Sun, Tadayuki, Takahashi, Takaaki, Tanaka, Thomas, Tavernier, Andrew, Taylor, Regis, Terrier, Hannes, Thiersen, Charles, Thorpe-Morgan, Martin, Tluczykont, Lenka, Tomankova, Michelle, Tsirou, Naomi, Tsuji, Richard, Tuffs, Yasunobu, Uchiyama, Johann van der Walt, Christopher van Eldik, Carlo van Rensburg, Brian van Soelen, George, Vasileiadis, Johannes, Veh, Christo, Venter, Pascal, Vincent, Jacco, Vink, Völk, Heinrich J., Stefan, Wagner, Jason John Watson, Felix, Werner, Richard, White, Alicja, Wierzcholska, Yu Wun Wong, Hend, Yassin, Anke, Yusafzai, Michael, Zacharias, Roberta, Zanin, Davit, Zargaryan, Andrzej, Zdziarski, Andreas, Zech, Sylvia, Zhu, Andreas, Zmija, Samuel, Zouari, Natalia, Zywucka, The FACT Collaboration, The H.E.S.S. Collaboration, The IceCube Collaboration, The MAGIC Collaboration, The VERITAS Collaboration, and Współautorami artykułu są członkowie Magic Collaboration, IceCube Collaboration, FACT Collaboration, H.E.S.S. Collaboration, VERITAS Collaboration w liczbie 808
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Point source, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, IACT, Astrophysics, law.invention, High Energy Physics - Experiment, Telescope, High Energy Physics - Experiment (hep-ex), law, HESS - Abteilung Hinton, ddc:530, High Energy Physics::Experiment, MAGIC (telescope), Neutrino, Blazar, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation
Abstract: The realtime follow-up of neutrino events is a promising approach to search for astrophysical neutrino sources. It has so far provided compelling evidence for a neutrino point source: the flaring gamma-ray blazar TXS 0506+056 observed in coincidence with the high-energy neutrino IceCube-170922A detected by IceCube. The detection of very-high-energy gamma rays (VHE, $\mathrm{E} > 100\,\mathrm{GeV}$) from this source helped establish the coincidence and constrained the modeling of the blazar emission at the time of the IceCube event. The four major imaging atmospheric Cherenkov telescope arrays (IACTs) - FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program of target-of-opportunity observations of neutrino alerts sent by IceCube. This program has two main components. One are the observations of known gamma-ray sources around which a cluster of candidate neutrino events has been identified by IceCube (Gamma-ray Follow-Up, GFU). Second one is the follow-up of single high-energy neutrino candidate events of potential astrophysical origin such as IceCube-170922A. GFU has been recently upgraded by IceCube in collaboration with the IACT groups. We present here recent results from the IACT follow-up programs of IceCube neutrino alerts and a description of the upgraded IceCube GFU system., Presented at the 37th International Cosmic Ray Conference (ICRC 2021). See arXiv:2107.06966 for all IceCube contributions. See arXiv:2108.05257 for all H.E.S.S. contributions
Published: 2022

6. NEDAP-Wahlcomputer - Manipulationsmethoden an Hard- und Software.

Author: Constanze Kurz and Frank Rieger
Published: 2007
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7. Detection of new Extreme BL Lac objects with H.E.S.S. and Swift XRT

Author: Angel Priyana Noel, Hassan Abdalla, Felix Aharonian, Faical Ait-Benkhali, Oguzhan Anguener, Cornelia Arcaro, Celine Armand, Tom Armstrong, Halim Ashkar, Michael Backes, Vardan Baghmanyan, Victor Barbosa Martins, Anna Barnacka, Monica Barnard, Rowan William Batzofin, Yvonne Becherini, David Berge, Konrad Bernloehr, Baiyang Bi, Markus Böttcher, Catherine Boisson, Julien Bolmont, Mathieu Bony (de), Mischa Breuhaus, Robert Brose, Francois Brun, Tomasz Bulik, Thomas Bylund, Floriane Cangemi, Sami Caroff, Sabrina Casanova, Jaqueline Catalano, Pauline Chambery, Tej Bahadur Chand, Andrew Chen, Garret Cotter, Malgorzata Curlo, Hannah Dalgleish, Jean Damascene Mbarubucyeye, Isak Delberth Davids, James Davies, Justine Devin, Arache Djannati-Ataï, Anton Dmytriev, Axel Donath, Victor Doroshenko, Lente Dreyer, Louis Du Plessis, Connor Duffy, Kathrin Egberts, Sabrina Einecke, Jean-Pierre ERNENWEIN, Steven Fegan, Kirsty Feijen, Armand Fiasson, Gaëtan Fichet de Clairfontaine, Gerard Fontaine, Lott Frans, Matthias Fuessling, Stefan Funk, Stefano Gabici, Yves Gallant, Gianluca Giavitto, Luca Giunti, Dorit Glawion, Jean-Francois Glicenstein, Marie-Hélène Grondin, Sumari Hattingh, Maria Haupt, German HERMANN, Jim Hinton, Werner Hofmann, Clemens Hoischen, Tim Holch, Markus Holler, Dieter Horns, Zhi-Qiu Huang, David Huber, Mario Hörbe, Marek Jamrozy, Felix Jankowsky, Vikas Joshi, Ira JUNG, Eli Kasai, Krzysztof Katarzynski, Ulì Katz, Dmitry Khangulyan, Bruno Khelifi, Stefan Klepser, Wlodek Kluzniak, Nukri Komin, Ruslan Konno, Karl Kosack, Dmitriy Kostunin, Michael Kreter, Gašper Kukec Mezek, Anu Kundu, Giovanni Lamanna, Sebastien Le Stum, Anne Lemiere, Marianne Lemoine-Goumard, Jean-Philippe Lenain, Fabian Leuschner, Christelle Levy, Thomas Lohse, Anna Luashvili, Iryna Lypova, Jonathan Mackey, Jhilik Majumdar, Denys Malyshev, Dmitry Malyshev, Vincent Marandon, Paolo Marchegiani, Alexandre Marcowith, Arnaud Mares, Guillem Martí-Devesa, Ramin Marx, Gilles Maurin, Pieter Meintjes, Manuel Meyer, Alison Mitchell, Rafal Moderski, Lars Mohrmann, Alessandro Montanari, Chris Moore, Paul Morris, Emmanuel Moulin, Jacques Muller, Thomas Murach, Kaori Nakashima, Mathieu Naurois (de), Amid Nayerhoda, Hambeleleni Davids, Jacek Niemiec, Paul O'Brien, Laenita Lorraine Oberholzer, Stefan Ohm, Laura Olivera-Nieto, Emma Ona-Wilhelmi (de), Michal Ostrowski, Sebastian Panny, Michael Panter, Dan Parsons, Giada Peron, Santiago Pita, Vincent Poireau, Dmitry A Prokhorov, Heike Prokoph, Gerd PUEHLHOFER, Michael Punch, Andreas Quirrenbach, Patrick Reichherzer, Anita Reimer, Olaf Reimer, Quentin Remy, Matthieu Renaud, Brian Reville, Frank Rieger, Carlo Romoli, Gavin P Rowell, Bronislaw Rudak, Hector Rueda Ricarte, Edna Ruiz Velasco, Vardan Sahakian, Simon Sailer, Heiko Salzmann, David Sanchez, Andrea Santangelo, Manami Sasaki, Johannes Schaefer, Hester Schutte, Ullrich Schwanke, Fabian Schüssler, Mohanraj Senniappan, Albert Seyffert, Jimmy N.S. Shapopi, Kleopas Shiningayamwe, Rachel Simoni, Atreyee Sinha, Helene Sol, Hugh Spackman, Andreas Specovius, Samuel Timothy Spencer, Marion Spir-Jacob, Lukasz Stawarz, Riaan Steenkamp, Christian Stegmann, Simon Steinmassl, Constantin Steppa, Lei Sun, Tadayuki Takahashi, Takaaki Tanaka, Thomas Tavernier, Andrew Taylor, Regis Terrier, Hannes Thiersen, Charles Thorpe-Morgan, Martin Tluczykont, Lenka Tomankova, Michelle Tsirou, Naomi Tsuji, Richard Tuffs, Yasunobu Uchiyama, Johann van der Walt, Christopher van Eldik, Carlo van Rensburg, Brian van Soelen, George Vasileiadis, Johannes Veh, Christo Venter, Pascal Vincent, Jacco Vink, Heinrich J. Völk, Stefan Wagner, Jason John Watson, Felix Werner, Richard White, Alicja Wierzcholska, Yu Wun Wong, Hend Mahmoud Yassin, Anke Yusafzai, Michael Zacharias, Roberta Zanin, Davit Zargaryan, Andrzej Zdziarski, Andreas Zech, Sylvia Zhu, Andreas Zmija, Samuel Zouari, Natalia Żywucka, Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), H.E.S.S., and Fermi-LAT
Subjects: accelerator, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, gamma ray: absorption, VHE, law.invention, blazar, X-ray, particle: acceleration, law, HESS, synchrotron, Radiative transfer, TeV, High Energy Stereoscopic System, 10. No inequality, Absorption (electromagnetic radiation), Blazar, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Range (particle radiation), energy: high, redshift, Redshift, Synchrotron, Particle acceleration, spectral, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Extreme high synchrotron peaked blazars (EHBLs) are amongst the most powerful accelerators found in nature. Usually the synchrotron peak frequency of an EHBL is above $10^{17}\,$Hz, i.e., lies in the range of medium to hard X-rays making them ideal sources to study particle acceleration and radiative processes. EHBL objects are commonly observed at energies beyond several TeV, making them also powerful probes of gamma-ray absorption in the intergalactic medium. During the last decade, several attempts have been made to increase the number of EHBL detected at TeV energies and probe their spectral characteristics. Here we report new detections of EHBLs in the TeV energy regime, each at a redshift of less than 0.2, by the High Energy Stereoscopic System (H.E.S.S.). Also, we report on X-ray observations of these EHBLs candidates with Swift XRT. In conjunction with the very high energy observations, this allows us to probe the radiation mechanisms and the underlying particle acceleration processes., Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021)
Published: 2022
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8. The young massive stellar cluster Westerlund 1 in gamma rays as seen with H.E.S.S

Author: Lars Mohrmann, Hassan Abdalla, Felix Aharonian, Faical Ait-Benkhali, Oguzhan Anguener, Cornelia Arcaro, Celine Armand, Tom Armstrong, Halim Ashkar, Michael Backes, Vardan Baghmanyan, Victor Barbosa Martins, Anna Barnacka, Monica Barnard, Rowan William Batzofin, Yvonne Becherini, David Berge, Konrad Bernloehr, Baiyang Bi, Markus Böttcher, Catherine Boisson, Julien Bolmont, Mathieu Bony (de), Mischa Breuhaus, Robert Brose, Francois Brun, Tomasz Bulik, Thomas Bylund, Floriane Cangemi, Sami Caroff, Sabrina Casanova, Jaqueline Catalano, Pauline Chambery, Tej Bahadur Chand, Andrew Chen, Garret Cotter, Malgorzata Curlo, Hannah Dalgleish, Jean Damascene Mbarubucyeye, Isak Delberth Davids, James Davies, Justine Devin, Arache Djannati-Ataï, Anton Dmytriev, Axel Donath, Victor Doroshenko, Lente Dreyer, Louis Du Plessis, Connor Duffy, Kathrin Egberts, Sabrina Einecke, Jean-Pierre ERNENWEIN, Steven Fegan, Kirsty Feijen, Armand Fiasson, Gaëtan Fichet de Clairfontaine, Gerard Fontaine, Lott Frans, Matthias Fuessling, Stefan Funk, Stefano Gabici, Yves Gallant, Gianluca Giavitto, Luca Giunti, Dorit Glawion, Jean-Francois Glicenstein, Marie-Hélène Grondin, Sumari Hattingh, Maria Haupt, German HERMANN, Jim Hinton, Werner Hofmann, Clemens Hoischen, Tim Holch, Markus Holler, Dieter Horns, Zhi-Qiu Huang, David Huber, Mario Hörbe, Marek Jamrozy, Felix Jankowsky, Vikas Joshi, Ira JUNG, Eli Kasai, Krzysztof Katarzynski, Ulì Katz, Dmitry Khangulyan, Bruno Khelifi, Stefan Klepser, Wlodek Kluzniak, Nukri Komin, Ruslan Konno, Karl Kosack, Dmitriy Kostunin, Michael Kreter, Gašper Kukec Mezek, Anu Kundu, Giovanni Lamanna, Sebastien Le Stum, Anne Lemiere, Marianne Lemoine-Goumard, Jean-Philippe Lenain, Fabian Leuschner, Christelle Levy, Thomas Lohse, Anna Luashvili, Iryna Lypova, Jonathan Mackey, Jhilik Majumdar, Denys Malyshev, Dmitry Malyshev, Vincent Marandon, Paolo Marchegiani, Alexandre Marcowith, Arnaud Mares, Guillem Martí-Devesa, Ramin Marx, Gilles Maurin, Pieter Meintjes, Manuel Meyer, Alison Mitchell, Rafal Moderski, Alessandro Montanari, Chris Moore, Paul Morris, Emmanuel Moulin, Jacques Muller, Thomas Murach, Kaori Nakashima, Mathieu Naurois (de), Amid Nayerhoda, Hambeleleni Davids, Jacek Niemiec, Angel Noel, Paul O'Brien, Laenita Lorraine Oberholzer, Stefan Ohm, Laura Olivera-Nieto, Emma Ona-Wilhelmi (de), Michal Ostrowski, Sebastian Panny, Michael Panter, Dan Parsons, Giada Peron, Santiago Pita, Vincent Poireau, Dmitry A Prokhorov, Heike Prokoph, Gerd PUEHLHOFER, Michael Punch, Andreas Quirrenbach, Romed Rauth, Patrick Reichherzer, Anita Reimer, Olaf Reimer, Quentin Remy, Matthieu Renaud, Brian Reville, Frank Rieger, Carlo Romoli, Gavin P Rowell, Bronislaw Rudak, Hector Rueda Ricarte, Edna Ruiz Velasco, Vardan Sahakian, Simon Sailer, Heiko Salzmann, David Sanchez, Andrea Santangelo, Manami Sasaki, Johannes Schaefer, Hester Schutte, Ullrich Schwanke, Fabian Schüssler, Mohanraj Senniappan, Albert Seyffert, Jimmy N.S. Shapopi, Kleopas Shiningayamwe, Rachel Simoni, Atreyee Sinha, Helene Sol, Hugh Spackman, Andreas Specovius, Samuel Timothy Spencer, Marion Spir-Jacob, Lukasz Stawarz, Riaan Steenkamp, Christian Stegmann, Simon Steinmassl, Constantin Steppa, Lei Sun, Tadayuki Takahashi, Takaaki Tanaka, Thomas Tavernier, Andrew Taylor, Regis Terrier, Hannes Thiersen, Charles Thorpe-Morgan, Martin Tluczykont, Lenka Tomankova, Michelle Tsirou, Naomi Tsuji, Richard Tuffs, Yasunobu Uchiyama, Johann van der Walt, Christopher van Eldik, Carlo van Rensburg, Brian van Soelen, George Vasileiadis, Johannes Veh, Christo Venter, Pascal Vincent, Jacco Vink, Heinrich J. Völk, Stefan Wagner, Jason John Watson, Felix Werner, Richard White, Alicja Wierzcholska, Yu Wun Wong, Hend Mahmoud Yassin, Anke Yusafzai, Michael Zacharias, Roberta Zanin, Davit Zargaryan, Andrzej Zdziarski, Andreas Zech, Sylvia Zhu, Andreas Zmija, Samuel Zouari, Natalia Żywucka, Naurois , Mathieu, Ona-Wilhelmi , Emma, and Bony , Mathieu
Subjects: Physics, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Gamma ray, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Likelihood analysis, Energy spectrum, Cluster (physics), ddc:530, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract: 37th International Cosmic Ray Conference, ICRC 2021, Berlin, online, Germany, 12 Jul 2021 - 23 Jul 2021; Proceedings of Science / International School for Advanced Studies (ICRC2021), 789 (2021). doi:10.22323/1.395.0789, Massive stellar clusters have recently been hypothesised as candidates for the acceleration of hadronic cosmic rays up to PeV energies. Previously, the H.E.S.S. Collaboration has reported about very extended $\gamma$-ray emission around Westerlund 1, a massive young stellar cluster in the Milky Way. In this contribution we present an updated analysis that employs a new analysis technique and is based on a much larger data set, allowing us to constrain better the morphology and the energy spectrum of the emission. The analysis technique used is a three-dimensional likelihood analysis, which is especially well suited for largely extended sources. The origin of the $\gamma$-ray emission will be discussed in light of multi-wavelength observations., Published by SISSA, Trieste
Published: 2021
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9. Einführung einer Obergrenze für Bargeldtransaktionen – Rechtliche Grenzen und die Perspektive der Praxis

Author: Frank Rieger
Abstract: Die Einfuhrung von Obergrenzen fur Bargeldtransaktionen oder gar dessen Abschaffung ist in Deutschland und Europa in der Diskussion. Hintergrund sind Uberlegungen, dass Bargeld gerade im Bereich der organisierten Kriminalitat, der Korruption oder der Terrorismusfinanzierung eingesetzt wird und man sich von einer Einschrankung des Bargeldverkehrs positive Wirkungen auf die Kriminalitatsbekampfung erhofft. So hatte die Europaische Kommission in einer Mitteilung an den Rat und das Europaische Parlament am 2. Februar 2016 einen Aktionsplan fur ein intensiveres Vorgehen gegen die Terrorismusfinanzierung veroffentlicht.
Published: 2018
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10. Digging the Cosmic Infrared Background out of the lobes of a radio galaxy

Author: M. Georganopoulos, R. M. Sambruna, D. Kazanas, A. N. Cillis, C. C. Cheung, E. S. Perlman, K. M. Blundell, D. S. Davis, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Luminous infrared galaxy, Physics, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, X-shaped radio galaxy, Observational cosmology, Cosmic infrared background, Cosmic noise, Astrophysics::Galaxy Astrophysics
Abstract: We describe a new, independent method for breaking the deadlock of measuring the cosmologically very important Cosmic Infrared Background. Our method measures the energy density of the Cosmic Infrared Background at the location of radio galaxies by using Fermi Gamma-ray and multiwavelength observations of their radio lobes. We present an application of our method for the well-studied radio galaxy Fornax A, showing that Fermi observations will provide us with a direct, model independent measurement of the Cosmic Infrared Background. © 2009 American Institute of Physics.
Published: 2016
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11. Visual Acuity Outcomes of Toric Lens Implantation in Patients Undergoing Cataract Surgery at a Residency Training Program

Author: Meryl, Sundy, Dustin, McKnight, Craig, Eck, and Frank, Rieger
Subjects: Aged, 80 and over, Lenses, Intraocular, Male, genetic structures, Science of Medicine, Visual Acuity, Internship and Residency, Cataract Extraction, Middle Aged, eye diseases, Cataract, Treatment Outcome, Humans, Female, sense organs, Aged
Abstract: Ophthalmology residents must become competent in the use of a variety of intraocular lenses (IOLs) and refractive technologies designed to reduce spectacle use after cataract surgery. Our study of visual acuity outcomes with toric IOLs at the Harry S. Truman Memorial Veterans’ Hospital revealed that residents achieved an uncorrected visual acuity of 20/40 or better in 88% of the surgeries they performed, a rate comparable to that reported by other residency programs and by cataract surgeons.
Published: 2016

12. Rapid variability at very high energies in Mrk 501

Author: Chakraborty, N., Cologna, G., Kastendieck, M. A., Frank Rieger, Romoli, C., Wagner, S. J., Jacholkowska, A., and Taylor, A.
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena
Abstract: A major flaring state of the BL Lac object Mrk 501 was observed by the High Energy Stereoscopic System (H.E.S.S.) in June, 2014. Flux levels higher than one Crab unit were recorded and rapid variability at very high energies ($\sim$2-20 TeV) was revealed. The high statistics afforded by the flares allowed us to probe the presence of minutes timescale variability and study its statistical characteristics exclusively at TeV energies owing to the high energy threshold of approximately 2 TeV. Doubling times of a few minutes are estimated for fluxes greater than 2 TeV. Statistical tests on the light curves show interesting temporal structure in the variations including deviations from a normal flux distribution similar to those found in the PKS 2155-304 flare of July 2006, at nearly an order of magnitude higher threshold energy. Rapid variations at such high energies put strong constraints on the physical mechanisms in the blazar jet., Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands
Published: 2015
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13. Constraints on masses and spins of black holes in blazars from fast TeV variability

Author: A. Neronov, D. Semikoz, S. Sibiryakov, Felix A. Aharonian, Werner Hofmann, Frank Rieger, APC - THEORIE, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut für theoretische Physik, Universität Hamburg (UHH)-Universität Hamburg (UHH), European Organization for Nuclear Research (CERN), Felix A. Aharonian, Werner Hofmann, Frank Rieger., Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut für theoretische Physik, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut für theoretische Physik
Subjects: Physics, Supermassive black hole, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], quasars, Astronomy, 020206 networking & telecommunications, Quasar, 02 engineering and technology, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, gamma-rays, 7. Clean energy, black holes, Black hole, Binary black hole, Intermediate-mass black hole, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Stellar black hole, Spin-flip, Blazar
Abstract: International audience; We discuss a "compact source'' model of very high energy (VHE) emission from blazars in which the variability time is determined by the blazar central engine. In this model electron or proton acceleration close to the supermassive black hole is followed by the development of electromagnetic cascade in a radiatively inefficient accretion flow. Assuming such a model for the TeV blazar PKS 2155-304, we show that the variability properties of the TeV ?-ray signal observed during a bright flare from this source, such as the minimal variability time scale and the recurrence period of the sub-flares, constrain the mass and the angular momentum of the supermassive black hole.
Published: 2008
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14. MHD and Radiation Modelling of G21.5-0.9

Author: O. C. De Jager, S. E. S. Ferreira, A. Djannati-Ataï, Felix A. Aharonian, Werner Hofmann, Frank Rieger, Unit for Space Physics, North-West University, South-Africa, Unit for Space Physics, North-West University, APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Felix A. Aharonian, Werner Hofmann, Frank Rieger., Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), North-West University [Potchefstroom] (NWU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)
Subjects: Physics, supernova remnants, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], 010504 meteorology & atmospheric sciences, Field (physics), Astrophysics::High Energy Astrophysical Phenomena, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Field strength, Astrophysics, 01 natural sciences, Pulsar wind nebula, Magnetic field, Pulsar, Far infrared, 0103 physical sciences, pulsars, Magnetohydrodynamics, magnetohydrodynamics, 010303 astronomy & astrophysics, Equipartition theorem, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: International audience; The H.E.S.S. telescopes detected VHE ?-rays from G21.5-0.9, which is most likely the result of IC scattered VHE ?-rays from the central pulsar wind nebula (PWN). The ~1 kyr age constrains the birth period in the range 50 to 55 ms, which also places a tight constraint on the available energetics for IC radiation. The fact that the reverse shock did not yet reach the PWN allows us to model the time dependence of the average PWN magnetic field strength using a MHD approach, where we simulate the evolution of a composite SNR using the birth period and initial spindown power as the starting values for the MHD simulation. The time dependence of the pre-reverse shock average field strength is then used to calculate the current particle spectrum in the PWN. This field evolution then spreads the radiation spectral break between the far infrared and soft X-ray synchrotron frequencies. The present day average field strength is required to be ~25 ?G, which is ~10 times smaller than the equipartition value of ~0.3 mG. This suggests that the magnetic field strength of the PWN of G21.5-0.9 is currenty well below equipartition.
Published: 2008
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15. GMRT radio observations of HESS J1640-465

Author: E. Giacani, G. Castelletti, G. Dubner, B. C. Joshi, P. Rao, R. Terrier, Felix A. Aharonian, Werner Hofmann, Frank Rieger, APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Felix A. Aharonian, Werner Hofmann, Frank Rieger., Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, and Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO)
Subjects: Physics, supernova remnants, Giant Metrewave Radio Telescope, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, radioactive sources, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, High resolution, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar wind nebula, Coincidence, Pulsar, 0103 physical sciences, pulsars, Astrophysics::Solar and Stellar Astrophysics, Gamma-ray burst, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: International audience; New high resolution and high sensitivity radio observations were conducted with the Giant Metrewave Radio Telescope (GMRT) in the direction of the γ-ray source HESS J1640-465, in positional coincidence with the supernova remnant (SNR) G338.3-0.0. The new images, obtained at 235 MHz and at 610 MHz, allow us to confirm that G338.3-0.0 is a typical shell-like remnant. No sign of the existence of a pulsar wind nebula or a radio pulsar is detected in its interior. Whether the high-energy particles are accelerated at the SNR shell or associated with an undetected pulsar, is still an open question.
Published: 2008
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16. High-energy flux evolution of Pulsar Wind Nebulae

Author: F. Mattana, M. Falanga, D. Götz, R. Terrier, P. Esposito, A. Pellizzoni, A. De Luca, V. Marandon, A. Goldwurm, P. Caraveo, Felix A. Aharonian, Werner Hofmann, Frank Rieger, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Istituto di Astrofisica Spaziale e Fisica Cosmica - Milano (IASF-MI), Istituto Nazionale di Astrofisica (INAF), Département d'Electronique, des Détecteurs et d'Informatique pour la Physique (ex SEDI) (DEDIP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, APC - Astrophysique des Hautes Energies (APC - AHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Felix A. Aharonian, Werner Hofmann, Frank Rieger., Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Département d'Electronique, des Détecteurs et d'Informatique (ex SEDI) (DEDI), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, and Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO)
Subjects: X-ray spectra, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Photon, Astrophysics::High Energy Astrophysical Phenomena, Flux, 02 engineering and technology, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral line, Luminosity, Pulsar, 0202 electrical engineering, electronic engineering, information engineering, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, Spin-½, Physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Compton scattering, Astronomy, 020206 networking & telecommunications, nebulae, 13. Climate action, pulsars, 020201 artificial intelligence & image processing, gamma-ray spectra
Abstract: International audience; The very high energy γ-ray spectra of Pulsar Wind Nebulae are interpreted as due to inverse Compton scattering of ultrarelativistic electrons on the ambient photons, whereas their X-ray spectra are due to synchrotron emission. We investigate the relation between the γ- and X-ray emission and the pulsars' spin-down luminosity and characteristic age. We find that the γ-to X-ray flux ratio of the nebulae is inversely proportional to the spin-down luminosity (~Ė-1.9) and to the characteristic age (~τc2.2) of the parent pulsar. We interpret these results as due to the evolution of the electron energy distribution and the nebular dynamics, supporting the idea of so-called relic pulsar wind nebulae. These empirical relations provide a new tool to classify unidentified diffuse γ-ray sources and to estimate the spin-down luminosity and characteristic age for four rotation powered pulsars with no detected pulsation from the X- and γ-ray properties of the associated pulsar wind nebulae.
Published: 2008
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17. A Multiwavelength View of High-Energy Processes in the Galactic Center Region

Author: Andrea Goldwurm, Felix A. Aharonian, Werner Hofmann, Frank Rieger, APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Felix A. Aharonian, Werner Hofmann, Frank Rieger., Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, and Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO)
Subjects: Solar System, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 010502 geochemistry & geophysics, 01 natural sciences, 0103 physical sciences, galaxies, Galactic centre, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, media_common, Physics, Supermassive black hole, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Galactic Center, Astronomy, Quasar, black holes, Galaxy, Sky, Intermediate-mass black hole, Spin-flip
Abstract: International audience; The central 600 parsecs of our Galaxy can be considered a kind of laboratory for modern astrophysics because in the few square degrees of sky covered by this region, several important non-thermal high energy processes take place and can be studied in detail with the new telescopes operating both in on-ground and in space. In addition to the closest supermassive Black Hole to the solar system the region hosts several other compact and diffuse sources of high-energy radiation whose characteristics need to be studied at different wavelengths from radio to TeV gamma-rays in order to understand the physical processes at work. This paper presents a review of the characteristics of the Galactic Center region from a multiwavelength phenomenological point of view, and giving special emphasis to the sources and processes that shed ligth on the high-energy phenomena taking place in the region.
Published: 2008
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18. Bald wird alles anders sein

Author: Deutscher Hochschulverband and Frank Rieger
Published: 2012
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19. PREFACE

Author: Felix Aharonian, Werner Hofmann, Frank Rieger, Felix A. Aharonian, and Frank M. Rieger
Published: 2011
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20. The Comparison of the Swift Gamma-Ray Bursts With and Without Measured Redshifts

Author: David Huja, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Swift, High Energy Astrophysical Phenomena (astro-ph.HE), Swift Gamma-Ray Burst Mission, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, computer, Redshift, computer.programming_language
Abstract: Gamma-ray bursts, detected by the Swift satellite, are separated into two samples: the bursts with and without determined redshifts. These two samples are compared by the standard Student t-test and F-test. We have compared the dispersions and the mean values of the durations, peak fluxes and fluences in order to find any differences among these two samples. No essential differences were found., Comment: Published in the Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, 2008
Published: 2010
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21. A future very-high-energy view of our Galaxy

Author: S. Funk, J. A. Hinton, G. Hermann, S. Digel, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, Population, Astronomy, Flux, FOS: Physical sciences, Quasar, Cosmic ray, Gamma-ray astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Particle acceleration, Astrophysics of Galaxies (astro-ph.GA), education, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The survey of the inner Galaxy with H.E.S.S. was remarkably successful in detecting a wide range of new very-high-energy gamma-ray sources. New TeV gamma-ray emitting source classes were established, although several of the sources remain unidentified, and progress has been made in understanding particle acceleration in astrophysical sources. In this work, we constructed a model of a population of such very-high-energy gamma-ray emitters and normalised the flux and size distribution of this population model to the H.E.S.S.-discovered sources. Extrapolating that population of objects to lower flux levels we investigate what a future array of imaging atmospheric telescopes (IACTs) such as AGIS or CTA might detect in a survey of the Inner Galaxy with an order of magnitude improvement in sensitivity. The sheer number of sources detected together with the improved resolving power will likely result in a huge improvement in our understanding of the populations of galactic gamma-ray sources. A deep survey of the inner Milky Way would also support studies of the interstellar diffuse gamma-ray emission in regions of high cosmic-ray density. In the final section of this paper we investigate the science potential for the Galactic Centre region for studying energy-dependent diffusion with such a future array., Proceeding of "Heidelberg International Symposium on High Energy Gamma-Ray Astronomy", held in Heidelberg, 7-11 July 2008, submitted to AIP Conference Proceedings. 4 pages, 4 figures
Published: 2009

22. Estimates for Very High Energy Gamma Rays from Globular Cluster Pulsars

Author: C. Venter, O. C. De Jager, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, Population, X-ray binary, Gamma ray, FOS: Physical sciences, Context (language use), Astrophysics, Relativistic particle, Pulsar, Millisecond pulsar, Globular cluster, Astrophysics::Solar and Stellar Astrophysics, education, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract: Low-Mass X-ray Binaries (LMXRBs), believed to be the progenitors of recycled millisecond pulsars (MSPs), occur abundantly in globular clusters (GCs). GCs are therefore expected to host large numbers of MSPs. This is also confirmed observationally. The MSPs continuously inject relativistic electrons into the ambient region beyond their light cylinders, and these relativistic particles produce unpulsed radiation via the synchrotron and inverse Compton (IC) processes. It is thus possible, in the context of General Relativistic (GR) frame-dragging MSP models, to predict unpulsed very high energy radiation expected from nearby GCs. We use a period-derivative cleaned sample of MSPs in 47 Tucanae, where the effects of the cluster potential on the individual period derivatives have been removed. Using a Monte Carlo process to include effects of pulsar geometry, we obtain average injection spectra (with relatively small errors) of particles leaving the MSPs. These spectra are next used to predict cumulative synchrotron and IC spectra expected from 47 Tucanae, which is a lower limit, as no reacceleration is assumed. We find that the IC radiation from 47 Tucanae may be visible for H.E.S.S., depending on the nebular field B as well as the number of MSPs N in the GC. Telescopes such as Chandra and Hubble may find it difficult to test the SR component prediction of diffuse radiation if there are many unresolved sources in the field of view. These results may be rescaled for other GCs where less information is available, assuming universal GC MSP characteristics., Comment: 4 pages, 3 figures, Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy; missing references added
Published: 2009
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23. A Comparison of Gamma-ray Burst Subgroups Measured by RHESSI and BATSE

Author: Jakub Řípa, David Huja, René Hudec, Wojtek Hajdas, Claudia Wigger, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Hardness ratio, FOS: Physical sciences, Astrophysics, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena
Abstract: A sample of almost 400 Gamma-ray bursts (GRBs) detected by the RHESSI satellite is studied statistically. We focus on GRB duration and hardness ratio and use the statistical chi^2 test and the F-test to compare the number of GRB subgroups in the RHESSI database with that of the BATSE database. Although some previous articles based on the BATSE catalog claim the existence of an intermediate GRB subgroup, besides long and short, we have not found a statistically significant intermediate subgroup in the RHESSI data., Comment: Published in Proceedings of the 4th International Meeting on High Energy Gamma-Ray Astronomy
Published: 2009
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24. Time-dependent absorption of very high-energy gamma-rays from the Galactic center by pair-production

Author: Attila Abramowski, Dieter Horns, Stefan Gillessen, Joachim Ripken, Christopher van Eldik, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, Dark matter, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Pulsar wind nebula, Stars, Pair production, Astrophysics - High Energy Astrophysical Phenomena, Low Mass, Schwarzschild radius, Astrophysics::Galaxy Astrophysics
Abstract: Very high energy (VHE) gamma-rays have been detected from the direction of the Galactic center. The H.E.S.S. Cherenkov telescopes have located this gamma-ray source with a preliminary position uncertainty of 8.5" per axis (6" statistic + 6" sytematic per axis). Within the uncertainty region several possible counterpart candidates exist: the Super Massive Black Hole Sgr A*, the Pulsar Wind Nebula candidate G359.95-0.04, the Low Mass X-Ray Binary-system J174540.0-290031, the stellar cluster IRS 13, as well as self-annihilating dark matter. It is experimentally very challenging to further improve the positional accuracy in this energy range and therefore, it may not be possible to clearly associate one of the counterpart candidates with the VHE-source. Here, we present a new method to investigate a possible link of the VHE-source with the near environment of Sgr A* (within approximately 1000 Schwarzschild radii). This method uses the time- and energy-dependent effect of absorption of gamma-rays by pair-production (in the following named pair-eclipse) with low-energy photons of stars closely orbiting the SMBH Sgr A*., Comment: 4 pages, 6 figures, Published in Proceedings of the 4th International Meeting on High Energy Gamma-Ray Astronomy (Gamma 08), Heidelberg
Published: 2009
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25. Morphology and hardness ratio exploitation under limited statistics

Author: A.-C. Clapson, M. Dyrda, D. Nekrassov, M. Renaud, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, education.field_of_study, Meson, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Population, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics, Synchrotron, law.invention, Acceleration, Sky, law, Statistics, Spatial ecology, Angular resolution, education, media_common, Lepton
Abstract: Gamma-ray astronomy has produced for several years now sky maps for low photon statistics, non-negligible background and comparatively poor angular resolution. Quantifying the significance of spatial features remains difficult. Besides, spectrum extraction requires regions with large statistics while maps in energy bands allow only qualitative interpretation. The two main competing mechanisms in the VHE domain are the Inverse-Compton emission from accelerated electrons radiating through synchrotron in the X-ray domain and the interactions between accelerated hadrons and the surrounding medium, leading to the production and subsequent decay of Pi0 mesons. The spectrum of the VHE emission from leptons is predicted to steepen with increasing distance from the acceleration zone, owing to synchrotron losses (i.e. cooled population). It would remain approximately constant for hadrons. Ideally, spectro-imaging analysis would have the same spatial scale in the TeV and X-ray domains, to distinguish the local emission mechanisms. More realistically, we investigate here the possibility of improving upon the currently published HESS results by using more sophisticated tools., 4 pages, 6 figures, Proceeding for a poster at the GAMMA08 Heidelberg Symposium
Published: 2008

26. TeV Gamma-ray Astronomy: The Story So Far

Author: Trevor C. Weekes, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Supernova, High energy, Pulsar, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics, Gamma-ray astronomy, Present generation, Cherenkov radiation, Astrophysics::Galaxy Astrophysics
Abstract: A snapshot is presented of the present status of our knowledge of the TeV gamma-ray universe. Emphasis is put on observations made using the imaging atmospheric Cherenkov technique. The capabilities of the present generation of telescopes is listed. Progress has been dramatic and several features have been different from what was anticipated. The catalog of sources includes some 78 objects and these are tabulated as extragalactic sources (24), supernovae remnants (11), pulsar wind nebulae (10), binaries (4), miscellaneous (9), diffuse high energy sources (3) and unidentified sources (20). Some comments are made on the factors influencing the past and future development of the field., Submitted to Proceedings of "4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy 2008"
Published: 2008

27. A radio and near-infrared mini-survey of the MGRO J2019+37 complex

Author: J. M. Paredes, J. Martí, C. H. Ishwara-Chandra, J. R. Sánchez-Sutil, A. J. Muñoz-Arjonilla, V. Zabalza, M. Ribó, P. L. Luque-Escamilla, V. Bosch-Ramon, M. Peracaula, J. Moldón, P. Bordas, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Giant Metrewave Radio Telescope, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Near-infrared spectroscopy, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Field of view, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Square degree, law.invention, Telescope, Observatory, law, Milagro, Angular resolution, Astrophysics::Galaxy Astrophysics
Abstract: MGRO J2019+37 is an unidentified source of very high energy gamma-rays originally reported by the MILAGRO collaboration as the brightest TeV source in the Cygnus region. Despite the poor angular resolution of MILAGRO, this object seems to be most likely an extended source or, alternatively, a superposition of point-like TeV sources. In order to contribute to the understanding of this peculiar object, we have mosaiced it with the Giant Metrewave Radio Telescope (GMRT) in Pune, India, at the 610 MHz frequency covering a field of view of about 6 square degrees down to a typical rms noise of a few tenths of mJy. We also observed the central square degree of this mosaic in the near infrared Ks-band using the 3.5 m telescope and the OMEGA2000 camera at the Calar Alto observatory (Spain). We present here a first account of our observations and results, together with a preliminar cross correlation of the radio and infrared source catalog as well as a correlation with the available X-ray observations of the region., 4 pages, 3 figures, Proceedings of the "4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy" July 7-11, 2008, Heidelberg, Germany
Published: 2008

28. Gamma rays from compact binary system

Author: Josep M. Paredes, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High energy, Neutron star, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Gamma ray, Binary number, FOS: Physical sciences, Binary system, Astrophysics, Cherenkov radiation, Astrophysics::Galaxy Astrophysics
Abstract: Some of the very high energy (VHE) gamma-ray sources detected with the modern generation of Cherenkov telescopes have been identified with previously known X-ray binary systems. These detections demonstrate the richness of non-thermal phenomena in compact galactic objects containing relativistic outflows or winds produced near black holes and neutron stars. Recently, the well-known microquasar Cygnus X-3 seems to be associated with a gamma-ray source detected with AGILE. Here I summarise the main observational results on gamma-ray emission from X-ray binaries, as well as some of the proposed scenarios to explain the production of VHE gamma-rays., 12 pages, 7 figures. Invited talk at the "Fourth Heidelberg International Symposium on High Energy Gamma-Ray Astronomy 2008"
Published: 2008

29. Probing the Galactic cosmic ray flux with submillimeter and gamma ray data

Author: S. Casanova, S. Gabici, F. A. Aharonian, K. Torii, Y. Fukui, T. Onishi, H. Yamamoto, A. Kawamura, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Molecular cloud, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, Cherenkov Telescope Array, Galaxy, law.invention, Telescope, law, Astrophysics::Galaxy Astrophysics, Fermi Gamma-ray Space Telescope
Abstract: The study of Galactic diffuse $\gamma$ radiation combined with the knowledge of the distribution of the molecular hydrogen in the Galaxy offers a unique tool to probe the cosmic ray flux in the Galaxy. A methodology to study the level of the cosmic ray "sea" and to unveil target-accelerator systems in the Galaxy, which makes use of the data from the high resolution survey of the Galactic molecular clouds performed with the NANTEN telescope and of the data from gamma-ray instruments, has been developed. Some predictions concerning the level of the cosmic ray "sea" and the $\gamma$-ray emission close to cosmic ray sources for instruments such as Fermi and Cherenkov Telescope Array are presented., Comment: Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy
Published: 2008

30. The proton microquasar

Author: Gabriela S. Vila, Gustavo E. Romero, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Proton, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Energy density, Synchrotron radiation, FOS: Physical sciences, Emission spectrum, Electron, Astrophysics
Abstract: We present a model for high-energy emission in microquasars where the energy content of the jets is dominated by relativistic protons. We also include a primary leptonic component. Particles are accelerated up to relativistic energies in a compact region located near the base of the jet, where most of the emission is produced. We calculate the production spectrum due to proton and electron synchrotron radiation and photohadronic interactions. The target field for proton-photon collisions is provided by the synchrotron radiation in the acceleration region. In models with a significant leptonic component, strong internal photon-photon absorption can attenuate the emission spectrum at high energies. Depending on the values of the parameters, our model predicts luminosities in the range 10^34-10^37 erg s^-1 up to GeV energies, with a high-energy tail that can extend up to 10^16 eV. In some cases, however, absorption effects can completely suppress the emission above 10 GeV, giving rise to different spectral shapes. These results can be tested in the near future by observations with instruments like GLAST-Fermi, HESS II and MAGIC II., 4 pages, 3 figures, contribution to the "Fourth Heidelberg International Symposium on High-Energy Gamma-Ray Astronomy 2008"
Published: 2008

31. Structured jets and VHE emission of blazars and radiogalaxies

Author: Fabrizio Tavecchio, Gabriele Ghisellini, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Blazar, Phenomenology (particle physics)
Abstract: Recent observations in the TeV band challenge the simplest models developed to describe the overall emission of blazars and radiogalaxies. In particular, the observation of variable TeV emission from M87 and the fast variability shown by PKS 2155-304 challenge the standard framework. We discuss how the existence of a radial structure in the sub-pc scale jet, with faster a component ("spine" or "needles") embedded in a slower layer can explain the basic phenomenology of these sources., 4 pages, 3 figures. To be published in the proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, July 7-11, 2008
Published: 2008

32. Central engines of Gamma Ray Bursts. Magnetic mechanism in the collapsar model

Author: Maxim V. Barkov, Serguei S. Komissarov, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics, Magnetic field, Black hole, Stars, Astrophysical jet, Magnetohydrodynamic drive, Neutrino, Hypernova, Gamma-ray burst
Abstract: In this study we explore the magnetic mechanism of hypernovae and relativistic jets of long duration gamma ray bursts within the collapsar scenario. This is an extension of our earlier work [1]. We track the collapse of massive rotating stars onto a rotating central black hole using axisymmetric general relativistic magnetohydrodynamic code that utilizes a realistic equation of state and takes into account the cooling associated with emission of neutrinos and the energy losses due to dissociation of nuclei. The neutrino heating is not included. We describe solutions with different black hole rotation, mass accretion rate, and strength of progenitor's magnetic field. Some of them exhibits strong explosions driven by Poynting-dominated jets with power up to $12\times10^{51} {erg s}^{-1}$. These jets originate from the black hole and powered via the Blandford-Znajek mechanism. A provisional criterion for explosion is derived. A number of simulation movies can be downloaded from http://www.maths.leeds.ac.uk/~serguei/research/movies/anim.html, 4 pages, 3 figures, GAMMA08 Heidelberg Symposium
Published: 2008

33. The influence of the Alfv\'enic drift on the shape of cosmic ray spectra in SNRs

Author: Vladimir N. Zirakashvili, Vladimir S. Ptuskin, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Acceleration, Astrophysics::High Energy Astrophysical Phenomena, Physics::Space Physics, Gamma ray, Physics::Accelerator Physics, Cosmic ray, Astrophysics, Spectral line, Magnetic field, Shock (mechanics)
Abstract: Cosmic ray acceleration in SNRs in the presence of the Alfv\'enic drift is considered. It is shown that spectra of accelerated particles may be considerably softer in the presence of amplified magnetic fields., Comment: 4 pages, 4 figures, poster talk at 4-th Gamma-ray Symposium (Heidelberg, Germany, 7-11th of July 2008)
Published: 2008

34. Fermi Acceleration at relativistic Shocks

Author: Guy Pelletier, Martin Lemoine, Alexandre Marcowith, Felix A. Aharonian, Werner Hofmann, Frank Rieger, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)
Subjects: Physics, relativistic shocks, Shock (fluid dynamics), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Scattering, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, 020206 networking & telecommunications, Cosmic ray, Fermi acceleration, 02 engineering and technology, Astrophysics, Power law, Magnetic field, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Mean field theory, Quantum electrodynamics, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, High energy astrophysics, Fermi Gamma-ray Space Telescope
Abstract: International audience; After a successful development of theoretical and numerical works on Fermi acceleration at relativistic shocks, some difficulties recently raised with the scattering issue, a crucial aspect of the process. Most pioneering works were developed assuming the scattering off magnetic fluctuations as given. Even in that case, when a mean field is considered, its orientation is mostly perpendicular to the shock normal in the front frame, and this tends to quench the scattering process. Solving this difficulty leads to address the issue of the generation of very intense magnetic fluctuations at short wave lengths. The relativistic motion of the shock front let the cosmic rays to visit upstream during a very short time only, making this generation of magnetic fluctuations very challenging. Anyway there is some hope to solve the problem. Thanks to a recent work by Spitkovsky (2008) \cite{AS}, we know that the process works without any mean field and now we have to investigate up to which intensity the mean field can be amplified for allowing Fermi process with appropriate fast instabilities. In this presentation, the collisionless shock structure in relativistic regime is sketched, the scattering issue is presented, and the instabilities that can provide the expected magnetic field amplification are presented as well. Although there exists observational evidence that particles are accelerated in relativistic flows and are distributed according to a power law suggesting a Fermi process, the drastic conditions for Fermi process to work are not always clearly fulfilled.
Published: 2008

35. A multivariate analysis approach for the Imaging atmospheric Cerenkov Telescopes System H.E.S.S

Author: F. Dubois, G. Lamanna, A. Jacholkowska, Felix A. Aharonian, Werner Hofmann, Frank Rieger, Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and HESS
Subjects: [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], 0202 electrical engineering, electronic engineering, information engineering, 020206 networking & telecommunications, 020201 artificial intelligence & image processing, 02 engineering and technology
Abstract: International audience; We present a multivariate classification approach applied to the analysis of data from the H.E.S.S. Very High Energy (VHE) gamma-ray IACT stereoscopic system. This approach combines three complementary analysis methods already successfully applied in the H.E.S.S. data analysis. The proposed approach, with the combined effective estimator Xeff, is conceived to improve the signal-to-background ratio and therefore particularly relevant to the morphological studies of faint extended sources.
Published: 2008
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36. Abhören und Lokalisieren von Telefonen. Der Stand der Dinge

Author: Frank Rieger
Published: 2008
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37. Upgrading and testing the 3D reconstruction of gamma-ray air showers as observed with an array of Cherenkov telescopes

Author: Melitta Naumann-Godó, Marianne Lemoine-Goumard, Bernard Degrange, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, business.industry, Gamma ray, Image processing, Stereoscopy, Astrophysics, Gamma-ray astronomy, law.invention, Optics, Quality (physics), Pulsar, law, Calibration, business, Cherenkov radiation
Abstract: Stereoscopic arrays of Imaging Cherenkov Telescopes allow to reconstruct gamma‐ray‐induced showers in 3 dimensions. An analysis method based on a simple 3D‐model of electromagnetic showers and implemented in the framework of the H.E.S.S. experiment was recently improved by an additional quality criterion which reduces the background contamination by a factor of about 2 in the case of extended sources, while hardly affecting gamma‐ray selection efficiency. Moreover, the dramatic flares of PKS 2155‐304 in July 2006, which provided H.E.S.S. data with an almost pure gamma‐ray sample, offered the unique opportunity of a precision test of the 3D‐reconstruction method as well as of the H.E.S.S. simulations used in its calibration. An agreement at a few percent level is found between data and simulations for the distributions of all 3D shower parameters.
Published: 2008
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38. Galactic and Extragalactic Magnetic Fields

Author: Rainer Beck, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Spiral galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Galactic Center, FOS: Physical sciences, Field strength, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Magnetic field, Thin disk, Thick disk, Local field, Astrophysics::Galaxy Astrophysics
Abstract: The current state of research of the Galactic magnetic field is reviewed critically. The average (equipartition) strength of the total field derived from radio synchrotron data is 6 +/- 2 muG locally and about 10 +/- 3 muG at 3 kpc Galactic radius. These values agree well with the estimates using the locally measured cosmic-ray energy spectrum and the radial variation of protons derived from gamma-rays. Optical and synchrotron polarization data yield a strength of the local regular field of 4 +/- 1 muG, but this value is an upper limit if the field strength fluctuates within the beam or if anisotropic fields are present. Pulsar rotation measures, on the other hand, give only 1.4 +/- 0.2 muG, a lower limit if fluctuations in regular field strength and thermal electron density are anticorrelated along the pathlength. The local regular field may be part of a 'magnetic arm' between the optical arms. However, the global structure of the regular Galactic field is not yet known. Several large-scale field reversals in the Galaxy were detected from rotation measure data, but a similar phenomenon was not observed in external galaxies. The Galactic field may be young in terms of dynamo action so that reversals from the chaotic seed field are preserved, or a mixture of dynamo modes causes the reversals, or the reversals are signatures of large-scale anisotropic field loops. The Galaxy is surrounded by a thick disk of radio continuum emission of similar extent as in edge-on spiral galaxies. While the local field in the thin disk is of even symmetry with respect to the plane (quadrupole), the global thick-disk field may be of dipole type. The Galactic center region hosts highly regular fields of up to milligauss strength which are oriented perpendicular to the plane., 20 pages with 7 figures, "The Astrophysics of Galactic Cosmic Rays", eds. R. Diehl et al., Space Science Reviews, Kluwer, Dordrecht, in press
Published: 2008
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39. Optimising Parameters for a multi-TeV IACT Cell

Author: J. Denman, G. Rowell, V. Stamatescu, G. Thornton, R. Dunbar, R. Clay, B. Dawson, A. Smith, N. Wild, R. Protheroe, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Flux, IACT, Cosmic ray, Gamma-ray astronomy, law.invention, Telescope, Optics, law, Angular resolution, Sensitivity (control systems), business, Image resolution
Abstract: This report centres on a single cell of 5 telescopes which would be considered a pathfinder component for the full array. The investigation looks at the effects of image triggering conditions, telescope separation, image cleaning, image size and site altitude on the flux sensitivity, angular resolution and background rejection. This report presents preliminary results for individually varying these parameters. This provides the first guide in choosing the optimal configuration, where the emphasis is presently on the 10–100 TeV energy band. Results indicate that an improvement in q‐factor and angular resolution is seen for telescope separation 200 m at E
Published: 2008
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40. Nonthermal Properties of Relativistic Jets in Blazars

Author: Laura Maraschi, Fabrizio Tavecchio, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, Population, Quasar, Electron, Gamma-ray astronomy, Astrophysics, Galaxy, Lorentz factor, symbols.namesake, Astrophysical jet, symbols, Blazar, education
Abstract: We discuss the non thermal properties of blazars in a unification perspective. The different spectral energy distributions (SED) from the IR to X‐ray and GeV and TeV gamma‐rays can be understood on the basis of rather simple radiation mechanisms involving a single population of high energy electrons and occurring in a region with bulk Lorentz factor of order 10. This accounts also for the main correlations observed between optical, X‐ray and gamma‐ray intensities in the best monitored objects. The radio emission from the former region is strongly sel‐fabsorbed. The observed delays of radio flares with respect to optical flares confirm this picture. Fast variability is difficult to account unless extremely high Lorentz factors are invoked, possibly concerning only parts of a structured jet.The overall regularities of the SEDs with the double peaks shifting to higher energies with decreasing jet powers are confirmed by new data. High power jets are associated with optically thick accretion disks providing s...
Published: 2008
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41. High Energy Studies of Pulsar Wind Nebulae

Author: Patrick Slane, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High energy, Pulsar, Electromagnetic spectrum, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Ejecta, Astrophysics::Galaxy Astrophysics
Abstract: The extended nebulae formed as pulsar winds expand into their surroundings provide information about the composition of the winds, the injection history from the host pulsar, and the material into which the nebulae are expanding. Observations from across the electromagnetic spectrum provide constraints on the evolution of the nebulae, the density and composition of the surrounding ejecta, the geometry of the systems, the formation of jets, and the maximum energy of the particles in the nebulae. Here I provide a broad overview of the structure of pulsar wind nebulae, with specific examples that demonstrate our ability to constrain the above parameters. The association of pulsar wind nebulae with extended sources of very high energy gamma-ray emission are investigated, along with constraints on the nature of such high energy emission., Comment: 9 pages, 9 figures. Invited review, to appear in the proceedings of "4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy 2008"
Published: 2008
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42. On the primary energy distribution and the EBL limits from TeV Blazars

Author: A. Meli, T. Kneiske, J. K. Becker, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Particle acceleration, Physics, Spectral index, Extragalactic background light, Astrophysics::High Energy Astrophysical Phenomena, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Electron, Blazar, Spectral line, Charged particle
Abstract: Knowledge of the acceleration of charged particles in astrophysical shock waves and their consequent emission is crucial on testing the astroparticle physical conditions occurring in environments such as Blazars. In the present work, we discuss how the variation of the primary energy spectral index of accelerated electrons, which may occur in mild or extreme relativistic shocks of Blazars, may consequently affect the limits of the extragalactic absorption models. While in the past the electron spectrum was traditionally assumed to follow an E−2 spectrum below the cooling break energy, our and other recent models of diffusive acceleration result in energy spectra with varying spectral indexes such as E−1.0 up to E−2.5, which pose critical physical constraints. In this work, we re‐examine the limit on the extragalactic background light (EBL) set by the H.E.S.S. While the latter assumed that electron spectra cannot be flatter than dN/dE∼E−1.5, here we give a relaxed limit on the EBL by allowing for spectra a...
Published: 2008
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43. Catching blazars in the act! GLAST triggers for TeV observation of blazars

Author: Bagmeet Behera, Stefan J. Wagner, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, biology, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Gamma-ray astronomy, Astrophysics, biology.organism_classification, Spitzer Space Telescope, Egret, Spectral energy distribution, Intergalactic travel, High Energy Physics::Experiment, Blazar, Cherenkov radiation
Abstract: The double humped SED (Spectral Energy Distribution) of blazars, and their flaring phenomena can be explained by various leptonic and hadronic models. However, accurate modeling of the high frequency component and clear identification of the correct emission mechanism would require simultaneous measurements in both the MeV‐GeV band and the TeV band. Due to the differences in the sensitivity and the field of view of the instruments required to do these measurements, it is essential to identify active states of blazars likely to be detected with TeV instruments.Using a reasonable intergalactic attenuation model, various extrapolations of the EGRET spectra, as a proxy for GLAST (Gamma‐ray Large Area Space Telescope) measurements, are made into TeV energies for selecting EGRET blazars expected to be VHE‐bright. Furthermore, estimates of the threshold fluxes at GLAST energies are provided, at which sources are expected to be detectable at TeV energies, with Cherenkov telescopes like HESS, MAGIC or VERITAS.
Published: 2008
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44. Modeling the Delayed Emission in the 2005 Mkn 501 Very-High-Energy Gamma-Ray Flare

Author: Włodek Bednarek, Robert Wagner, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Telescope, Physics, Photon, law, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Quasar, Astrophysics, Blazar, Synchrotron, law.invention, Fermi Gamma-ray Space Telescope, Flare
Abstract: Recently, the MAGIC collaboration reported evidence for a delay in the arrival times of photons of different energies during a γ‐ray flare from the blazar Markarian 501 on 2005 July 9. We describe the observed delayed high‐energy emission by applying a homogeneous synchrotron self‐Compton (SSC) model under the assumption that the blob, containing relativistic electrons, was observed in its acceleration phase. This modified SSC model predicts the appearance of a γ‐ray flare first at lower energies and subsequently at higher energies. Based on the reported time delay, we predict a delay on the order of 1 h if observed between 10 GeV and 100 GeV, which can be tested in the future by simultaneous flare observations using, e.g., the Fermi Gamma‐Ray Telescope and Cerenkov telescopes.
Published: 2008
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45. The Blazar 3C 66A in 2003-2004: hadronic versus leptonic model fits

Author: A. Reimer, M. Joshi, M. Böttcher, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, High energy, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Astronomy, Spectral energy distribution, Quasar, Astrophysics, Blazar, Galaxy, BL Lac object
Abstract: The low‐frequency peaked BL Lac object 3C 66A was the subject of an extensive multi‐wavelength campaign from July 2003 till April 2004, which included quasi‐simultaneous observations at optical, X‐rays and very high energy gamma‐rays. Here we apply the hadronic Synchrotron‐Proton Blazar (SPB) model to the observed spectral energy distribution time‐averaged over a flaring state, and compare the resulting model fits to those obtained from the application of the leptonic Synchrotron‐Self‐Compton (SSC) model. The results are used to identify diagnostic key predictions of the two blazar models for future multi‐wavelength observations.
Published: 2008
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46. A High Altitude Mexican ACT Project, OMEGA

Author: J. R. Sacahui, F. Huidobro, R. Núñez, R. Alfaro, E. Belmont-Moreno, O. Blanch, A. Carramiñana, B. L. Dingus, M. M. González, V. Grabski, A. Menchaca-Rocha, A. Sandoval, M. Schneider, G. Tovmassian, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Altitude, Observatory, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Broad band, Astronomy, HEGRA, Astronomical telescopes, Gamma-ray astronomy, Omega, Cherenkov radiation
Abstract: Two of the former HEGRA atmospheric Cherenkov telescopes are being refurbished at the Universidad Nacional Autonoma de Mexico (UNAM) with the purpose of being installed as the Observatorio MExicano de GAmmas (OMEGA, Mexican Observatory of Gammas). Mexico has developed infrastructure around two astrophysical facilities with excellent atmospheric conditions, San Pedro Martir at 2800 m a. s. 1. and Sierra Negra at 4600 m a.s. 1. The Sierra Negra site has been chosen over San Pedro Martir to host OMEGA in order to test the performance, sensitivity and energy threshold of atmospheric Cherenkov telescopes at high altitude. OMEGA will also be located adjacent to the HAWC TeV gamma‐ray observatory in order to cross calibrate HAWC events and to follow up HAWC candidate sources. The primary scientific objective of OMEGA is to monitor TeV blazars, and OMEGA will work in synergy with the Sierra Negra consortium of observatories to perform broad band multi‐wavelength observations. We will present the OMEGA project in detail and its status.
Published: 2008
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47. A reinvestigation into the diffuse neutrino flux from the inner Galaxy in light of new very high energy γ-ray observations

Author: Andrew Taylor, Stefano Gabici, Richard White, Sabrina Casanova, Felix Aharonian, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, High Energy Physics::Phenomenology, Hadron, Gamma ray, Astronomy, Quasar, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Milagro, High Energy Physics::Experiment, Neutrino, Disc, Astrophysics::Galaxy Astrophysics
Abstract: In light of the recent MILAGRO collaborations publication of the detection of diffuse multi‐TeV emission from a region close to the inner Galaxy, we reinvestigate the diffuse neutrino flux calculation from this region. Conventional determinations of the diffuse neutrino flux following cosmic ray propagation through the Galaxy, tuned to reproduce the locally observed cosmic ray spectrum, give rise to diffuse fluxes that are significantly below the detected diffuse flux. Assuming that this excess is hadronic in origin and is emitted by the entire inner Galactic region, we determine the diffuse neutrino flux expected from a region of the Galactic disk with coordinates −40°
Published: 2008
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48. Non-thermal emissions from outer magnetospheric accelerator of pulsars

Author: J. Takata, H.-K. Chang, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, Pulsar, law, Crab Pulsar, Astrophysics::High Energy Astrophysical Phenomena, Thermal, Gamma ray, Astrophysics, Polarization (waves), Vela, Curvature, Synchrotron, law.invention
Abstract: We study non‐thermal emission process in pulsar magnetospheric accelerator (outer gap). We discuss emission process in optical through γ‐ray bands. We solve the dynamics in the outer gap in the magnetic meridional plane, which includes the rotation and magnetic axes. We calculate the spectrum of the curvature and synchrotron processes. Using a three‐dimensional geometrical model, we compute pulse profile and polarization characteristics. We compare the model results with the observations of the Vela pulsar and the Crab pulsar. We demonstrate that the observed multi‐peak structure of the pulse profile observed by RXTE can be reproduced by the present study with the outward and inward emissions from the outer gap accelerator. The calculated polarization characteristics are in general consistent with the Crab optical data.
Published: 2008
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49. Reconfinement shocks in relativistic AGN jets

Author: Krzysztof Nalewajko, Marek Sikora, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Shock wave, Physics, Conservation law, Lorentz factor, symbols.namesake, Jet (fluid), Shock (fluid dynamics), Thermal radiation, Astrophysics::High Energy Astrophysical Phenomena, symbols, Astrophysics, Kinetic energy, Pressure gradient
Abstract: Stationary knots observed in many AGN jets can be explained in terms of a reconfinement shock that forms when relativistic flow of the jet matter collides with the external medium. The position of these knots can be used, together with information on external pressure profile, to constrain dynamical parameters of the jet. We present a semi‐analytical model for the dynamical structure of reconfinement shocks, taking into account exact conservation laws both across the shock surface and in the zone of the shocked jet matter. We show that, due to the transverse pressure gradient in the shock zone, the position of the reconfinement is larger than predicted by simple models. A portion of kinetic energy is converted at the shock surface to internal energy, with efficiency increasing strongly with both bulk Lorentz factor of the jet matter and the jet half‐opening angle. Our model may be useful as a framework for modeling non‐thermal radiation produced within the stationary features.
Published: 2008
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50. Resonance absorption processes of high-energy gamma-quanta: what kind of new information they can deliver about early Universe?

Author: Anatoly F. Iyudin, Felix A. Aharonian, Werner Hofmann, and Frank Rieger
Subjects: Physics, QSOS, Supermassive black hole, Astrophysics::High Energy Astrophysical Phenomena, Metallicity, media_common.quotation_subject, Astronomy, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Accretion (astrophysics), Galaxy, Redshift, Universe, Astrophysics::Galaxy Astrophysics, media_common
Abstract: Quasars remain one of the most powerful probes of the early Universe, providing measurements and constraints for re‐ionization, early structure formation, and early chemical enrichment epochs [1], [2], [3]. The obscured phase of QSOs evolution, as well as their accretion history, can be best followed by observing QSOs bright in MeV gamma‐rays [4]. By analysing resonant absorption troughs in spectral energy distribution of flaring QSOs one can measure the (baryonic) absorbing column, e.g. baryonic content, and metallicity of the QSO host galaxy [5], while the flare strength will give information on the accretion rate of the QSO powering supermassive black hole. By measuring the baryonic absorbing column for QSOs at different redshifts one can follow the early obscured evolution of AGN, as well as the evolution of the IGM transmission at the end of the cosmic re‐ionization epoch, while absorption by metals constrain the early chemical evolution of the IGM. These possibilities can be explored in the near fut...
Published: 2008
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