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49 results on '"D. Pelat"'

1. Metallicity of NGC 5128 Globular Clusters

Author: P., Jablonka, primary, B., Bica, additional, D., Pelat, additional, and D., Alloin, additional
Published: 1995
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2. Exploring the inner parsecs of active galactic nuclei using near-infrared high resolution polarimetric simulations with MontAGN

Author: Daniel Rouan, Lucas Grosset, Jan H. Orkisz, Frédéric Marin, Rene W. Goosmann, D. Pelat, Damien Gratadour, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, [PHYS]Physics [physics], Electron density, Active galactic nucleus, 010308 nuclear & particles physics, Infrared, FOS: Physical sciences, Astronomy and Astrophysics, Torus, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Wavelength, Space and Planetary Science, K band, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Optical depth (astrophysics), Radiative transfer, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract: Aims. In this paper we aim to constrain the properties of dust structures in the central first parsecs of active galactic nuclei (AGN). Our goal is to study the required optical depth and composition of different dusty and ionised structures. Methods. We developed a radiative transfer code called Monte Carlo for Active Galactic Nuclei (MontAGN), which is optimised for polarimetric observations in the infrared. With both this code and STOKES, designed to be relevant from the hard X-ray band to near-infrared wavelengths, we investigate the polarisation emerging from a characteristic model of the AGN environment. For this purpose, we compare predictions of our models with previous infrared observations of NGC 1068, and try to reproduce several key polarisation patterns revealed by polarisation mapping. Results. We constrain the required dust structures and their densities. More precisely, we find that the electron density inside the ionisation cone is about 2.0 × 109 m−3. With structures constituted of spherical grains of constant density, we also highlight that the torus should be thicker than 20 in term of K-band optical depth to block direct light from the centre. It should also have a stratification in density: a less dense outer rim with an optical depth at 2.2 μm typically between 0.8 and 4 for observing the double scattering effect previously proposed. Conclusions. We bring constraints on the dust structures in the inner parsecs of an AGN model supposed to describe NGC 1068. When compared to observations, this leads to an optical depth of at least 20 in the Ks band for the torus of NGC 1068, corresponding to τV ≈ 170, which is within the range of current estimation based on observations. In the future, we will improve our study by including non-uniform dust structures and aligned elongated grains to constrain other possible interpretations of the observations.
Published: 2018
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3. Stellar population synthesis in the presence of diluting components

Author: Catherine Boisson, D. Pelat, J. Frémaux, and M. Joly
Subjects: Luminous infrared galaxy, Physics, Active galactic nucleus, Stellar population, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, Stellar collision, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Stars, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Emission spectrum, Astrophysics::Galaxy Astrophysics
Abstract: Aims. Numerous studies of the host galaxy of Seyfert nuclei are being conducted in the optical/visible range. However, in the case of Seyfert 1, the spectra of the inner galactic core can be dominated by broad emission lines coming from the nucleus that totally flood the underlying galactic spectrum, preventing any study of stellar populations. Methods. Because part of the IR H-band is free of the strongest AGN emission lines, we developed a method that allows the stellar population of the very internal regions of the Seyfert 1 galaxies to be studied in the presence of a diluting continuum. Results. A new inverse method using the flux as observables was developed and deeply tested. The specificity of the method is to take the non stellar parameters (reddening, dust emission, and non-stellar continuum) into account directly in the synthetic distance to be minimised. Conclusions. The method is powerful for deriving the stellar content of the very central part of AGN. However, the results for the stellar population are still tentative, as the incompleteness of the stellar base (lack of supermetallic giant stars) could lead to large uncertainties. New observations of stars in the infrared at high spectral resolution, in particular metal-rich stars, are mandatory to build a complete stellar library that can be used to synthesise the host galaxies of AGN with as much accuracy as possible.
Published: 2007
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4. Introducing the CTA concept

Author: A. Mathieu, R. G. Wagner, K. Panagiotidis, S Rosier Lees, Julien Rousselle, M. Gómez Berisso, Michela Uslenghi, Stephen Maxfield, R. C. Shellard, Ivica Puljak, T. Le Flour, Thomas Schanz, Tobias C. Walther, Juanan Aguilar, Pierre Colin, M. Chikawa, N. Fouque, Mosè Mariotti, G. Fontaine, Merja Tornikoski, V. Diez-Blanco, Enrico Giro, A. Krepps, G. Koss, J. M. Martin, Sergio Billotta, E. de Oña Wilhelmi, Keitaro Takahashi, S. Buson, P. Brook, S. Steiner, M. Dyrda, Joseph Silk, Sera Markoff, P. Lubinski, U. Schwanke, Sauvik Bhattacharyya, J. Ripken, T. Haubold, C. Zurbach, H. Wetteskind, R. Hermel, J. Darling, J. Nicolau-Kukliński, Konstancja Satalecka, M. Videla, Stefan Funk, P. Conconi, S. Bajtlik, Lukasz Stawarz, J. M. Paredes, K. Reitberger, Stefan Wagner, Teresa Mineo, David Kieda, G. Pareschi, Shigeto Kabuki, Makoto Sawada, Antonio Stamerra, Rodolfo Canestrari, N. Baby, G. Crimi, P. Kostka, J. Grube, R. Zanin, I. K. Kominis, L. Mc Comb, R. Sternberger, M. Fesquet, M. Tokarz, David Fink, Daniela Dorner, N. Hamer Heras, A. Moralejo Olaizola, M. de Naurois, Diego F. Torres, Claes Fransson, K. Nishijima, Yutaka Fujita, L. Fresnillo, B. García, R. Kossakowski, A. Masserot, H. von Gunten, Alkiviadis F. Bais, Ciro Bigongiari, A. Saggion, G. Papyan, I. Mrusek, K. Farakos, J. Michałowski, A. Franckowiak, Fernando Martinez, M. Doert, R. Wawrzaszek, Michele Doro, L. Sapozhnikov, Claudia Lavalley, D. Thuermann, A.A. Zdziarski, Cristina Knapic, Karen Byrum, N. Neyroud, Petr Schovanek, W. Domainko, D. Kastana, E. Birsin, Adrian Biland, F. Sánchez, Alexandre Marcowith, M. Errando, R. L. C. Starling, J. Schultze, A. Weinstein, B. B. Singh, Yassir Moudden, Jelena Aleksić, C. L. Naumann, V. Waegebaert, M. Shayduk, U. F. Katz, Gianpiero Tagliaferri, M. Schroedter, A. Vollhardt, O. Reimann, Hideyuki Ohoka, Vincenzo Testa, C. Jablonski, Tsuguya Naito, J. Schäfer, Stavros Maltezos, A. Wierzcholska, P. Wawer, L. Nellen, F. Mirabel, Tatsuo Yoshida, P. H. Carton, Nina Nowak, L. Platos, Riccardo Rando, P. P. Krueger, R. Wischnewski, W. Romaszkan, E. Fede, Martino Marisaldi, Markus Gaug, Richard Willingale, J. H. Buckley, U. De AlmeidaBarres, J. Knapp, Saverio Lombardi, D. della Volpe, A. Herrero, A. Bottani, E. Delagnes, Martin J. Hardcastle, C. Morello, Anna Lipniacka, T. Greenshaw, M. Renaud, Giancarlo Cusumano, Jonathan Biteau, M. Sowiński, J. R. T. de Mello Neto, T. B. Humensky, Michael G. Richer, G. Parks, G. Grasseau, H. Baba, Gino Tosti, Damir Lelas, H. Krawzcynski, David Paneque, M. Barcelo, R. Dickherber, P. Ferrando, Shinji Hara, D. Florin, Hideaki Katagiri, T. Shibata, Fuyuki Tokanai, N. A. McCubbin, J. Gomez-Ortega, D. Nakajima, A. Liolios, P. Laporte, Orjan Dale, A. Sillanpää, Dainis Dravins, Timothée Grégoire, Nu. Komin, A. Mihailidis, L. Sidoli, Shiu-Hang Lee, A. W. Chen, J. M. Illa, A. Kuznetsov, P. Munar-Adrover, D. Dominis Prester, Marcos Daniel Actis, Abraham D. Falcone, L. Journet, D. Hadasch, N. Galante, A. Murphy, C. J. Todero Peixoto, S. Wiesand, A. Aravantinos, A. C. Rovero, J. L. Dournaux, P. Romano, M. Hrabovsky, R. de los Reyes Lopez, M. Ostrowski, J. Pallota, Geza Gyuk, Petar Temnikov, R. Dubois, Jan Ebr, R. Koul, David J. Smith, S. Schwarzburg, P. Manigot, Chad Finley, Tarek M. Hassan, Giuseppe Sottile, Evgeni Ovcharov, P. J. Rajda, F. Krennrich, Peter L. Moore, W. B. Focke, W. Bednarek, Elena Amato, Kazunori Kohri, J. Gamez-Garcia, I. Oya, A. Shibuya, German Hermann, William H. Lee, Dorota Sobczyńska, X. Zhou, C. Balkowski, G. Vallejo, M. Hayashida, M. Bitossi, Loukas Vlahos, H. Lockart, N. Geffroy, L. Tibaldo, Marek Jamrozy, Luke O'c. Drury, Pratik Majumdar, P. Sutcliffe, S. Schlenstedt, M. Palatka, Christophe Champion, H. Ueno, M. Rupiński, P. Giommi, J. Schwarz, G. Pühlhofer, Takashi Saito, W. van Driel, C. van Eldik, Q. Xiong, Yasuo Fukui, A. Donat, A. Ibarra, R. S. Warwick, Michiko Ohishi, A. W. Smith, J.-P. Lenain, Aion Viana, Terry Ashton, Guillaume Dubus, Jacek Niemiec, K. Kodani, Luis Ángel Tejedor, A. Wörnlein, Takanori Yoshikoshi, Masahiro Teshima, W. Gäbele, Ll. Font, Olaf Reimer, J. F. Valdés-Galicia, Lucy Fortson, J. P. Osborne, Mattia Fornasa, Keith Bechtol, Masayuki Tanaka, Shigehiro Nagataki, M. Rataj, M. Ribordy, Emmanuel Moulin, I. de la Calle, K. Winiarski, C. Jeanney, I. Mognet, I. Vegas, C. Juffroy, Yutaka Ohira, A. Jacholkowska, Matthew Wood, A. E. Suárez, J. Bähr, K. M. Schure, J. Maya, M. Dafonseca, J. Tasan, R. Sugawara, M. Bourgeat, A. Mancilla, D. Pelat, Olga Botner, D. Nedbal, G. Depaola, Robert Wagner, T. Okuda, H. Arnaldi, Josep Martí, P. Corona, T. Bonev, D. Yelos, J. Sieiro, V. Scalzotto, Jacco Vink, D. Languignon, Marco Ajello, J. Vandenbrouke, Philipp Mertsch, M. Mordalska, P. Wegner, P. Ziółkowski, P. T. O'Brien, A. Nozato, Robert D. Preece, B. Huber, Matteo Balbo, J.R. Bogart, R. Kankanyan, K. Mori, T. Jogler, Seth Digel, Claudio Vuerli, Hiromitsu Takahashi, Thomas Lohse, K. Saito, A. W. Borgland, Elisa Prandini, Helene Sol, Ryan Heller, M. Bogdan, D. Dumas, M. Stodulski, Y. Awane, Piercarlo Bonifacio, Pedro L. Luque-Escamilla, Judith H. Croston, Fabio Pizzolato, P. M. Chadwick, M. K. Daniel, Riccardo Paoletti, Reiko Orito, Katsuaki Asano, R. Frei, G. Disset, Valerie Connaughton, Juhani Huovelin, Hiroyasu Tajima, S. Vercellone, F. Feinstein, G. Decerprit, Riccardo Smareglia, S. Spyrou, Gustavo E. Romero, J. Shi, J. Carr, N. Girard, Dirk L. Hoffmann, Andreas Zech, Markus Boettcher, Osvaldo Catalano, Akira Okumura, M. Dohmke, C. Föhr, Sabrina Casanova, R. A. Cameron, Jan Conrad, K. Umehara, K. K. Yadav, A. Paizis, John L. Quinn, L. Pogosyan, C. Farnier, William J. Potter, Domenico Impiombato, Tadashi Kifune, Jonathan Granot, Gernot Maier, M. Cieślar, S. Palanque, G.W. Fraser, J. Prast, R. Bose, Heidi Sandaker, G. Lamanna, Dusan Mandat, J.F. Glicenstein, J. Harris, D. Naumann, J. Ziolkowski, Michał Szanecki, C. Delgado, J. Kocot, W. Lustermann, Sabine Elles, J. Schmoll, L. Gérard, M. López, Norita Kawanaka, V. Gika, B. Lieunard, A. Pichel, Martin Pohl, Mariusz Sterzel, S. Vincent, Paolo De Coppi, J. Lande, O. Blanch Bigas, Gianluca Giavitto, Yusuke Konno, Julian Sitarek, M. Panter, P.-O. Petrucci, F. Henault, M. Prouza, Philip Kaaret, Josep Colomé, Luciano Nicastro, German Martinez, L. Gebremedhin, J. M. Yebras, Apostolos Mastichiadis, A. S. Madhavan, Thomas J. Maccarone, K. Berger, R. Buehler, P. Jean, N. Sartore, F. Toussenel, Aris Karastergiou, W. Kluźniak, A. Djannati-Ataï, S. J. Fegan, Louis Antonelli, A. González Muñoz, J. Berdugo, S. S. Upadhya, M. Sidz, F. Mottez, Patrick Vogler, F. Di Pierro, Wystan Benbow, B. Sacco, L. Chiappetti, J. Dumm, R. Firpo Curcoll, David Gascon, V. Boccone, J. Krause, J. P. Avernet, B. Peyaud, B. De Lotto, Ana Babić, T. O. B. Schmidt, I. M. McHardy, T. Schweizer, S. P. Wakely, Daniel Gall, Frank M. Rieger, E. Sant'Ambrogio, M. Kagaya, P. Vincent, R. C. Rannot, Sandro Mereghetti, A. De Angelis, M. Scarcioffolo, R. White, G. H. Sembroski, Takeshi Nakamori, C. Medina, M. A. De Oliveira Leigui, Subir Sarkar, A. Marszałek, Reshmi Mukherjee, K. Nakayama, A. Fiasson, S. Giarrusso, T. Bernardino, J. P. Finley, D. Neise, L. O. Takalo, F. Grañena, Nikola Godinovic, H. Sasaki, P. Zychowski, Francesco Dazzi, B. Courty, A. Basili, Vitaly Neustroev, B. Khélifi, T. Glanzman, M. Trifoglio, Regis Terrier, R. A. Ong, E. M. Santos, M. Minuti, Thomas Bretz, R. Moderski, J. Kushida, S. Royer, Emilio Molinari, Etienne Lyard, J. Houles, Juan Abel Barrio, T. Lerch, S. Rivoire, T. Kishimoto, M. Cailles, M. Casiraghi, Nikolaos Stergioulas, J. Gaweda, S. Koyama, Ingomar Allekotte, E. Ismailova, Elina Giannakaki, S. Schwemmer, Ryo Yamazaki, G. Fasola, Christoph Deil, Jose Luis Contreras, T. Bird, Miguel A. Sánchez-Conde, J. Dick, E. Edy, D. Parsons, R. Pyzioł, R. Mirzoyan, Manjuli R. Sharma, J. Borkowski, Jonathan S. Lapington, Cameron B Rulten, Rino Bandiera, Volker Beckmann, Jun Kakuwa, Dimitris Balis, Kenji Toma, Anna Barnacka, Andrea Santangelo, L. Padilla, Peter Eger, G. Decock, Karol Seweryn, N. Sakaki, Darko Veberič, Andrea Bulgarelli, B. Rudak, M. Pérez, H. Koppel, Felix Spanier, M. I. Martínez, D. Horville, Marco Molinaro, R. Walter, P. Ramon, S. Brau-Nogue, J. Camprecios, K. Kärcher, John H. Seiradakis, S. Criswell, D. J. Leopold, V. J. Guarino, R. Gredig, S. Vorobiov, Viktor Gruev, Gareth Hughes, Daniele Spiga, Quirin Weitzel, N. Håkansson, Susumu Inoue, U. Straumann, Juan Cortina, B. Behera, Jürgen Knödlseder, Daniel Nieto, Tomasz Szepieniec, H. Prokoph, Jerzy Grygorczuk, G. De La Vega, Jim Hinton, E. Chabanne, M. Mahabir, R. Krobot, M. Capalbi, Miroslav Pech, C. Díaz, J. Ludwin, F. Gianotti, Garret Cotter, Claudio Melioli, Hiroaki Yamamoto, C. Veyssiere, Kunihito Ioka, S. Sun, J. M. Parraud, L. Rob, Felix Aharonian, G. Maneva, D. Melkumyan, T. Schwab, J. Kasperek, J. M. Huet, E. Lorenz, S. Tanaka, Y. A. Gallant, S. Couturier, B.W. Favill, J. Boix Gargallo, Andrea Tiengo, Leszek Bogacz, Andreu Sanuy, Christian Fruck, J. Sykes, C. Martens, A. Yoshida, Marek Sikora, E. Racero, G. Rouaix, N. Bhat, A. Salini, A. S. Barber, Mauro Ghigo, Jan Ridky, K. Kosack, Konrad Bernlöhr, C. Tenzer, Alice Allafort, M. Torres, Catherine Boisson, Grzegorz Kowal, M. Karczewski, G. Agnetta, Victor Stamatescu, Anthony H. Gonzalez, S. Rousselle, Giovanni Bonanno, A. Zajczyk, A. Gadola, P. Martin, V. Zitelli, I. Manthos, N. Maragos, A. Dettlaff, F. Profeti, S. Colonges, S. Gunji, S. Cazaux, S. Colafrancesco, M. Paz Arribas, Rika Hagiwara, Darell Engelhaupt, Nestor Mirabal, Johann Cohen-Tanugi, S. Grunewald, Abby M. Green, I. D. Davids, D. Nosek, T. Yamamoto, Gagik Tovmassian, R. Sakonaka, Miguel Alcubierre, C. Baixeras, T. L. Usher, Kazufumi Torii, H. Lüdecke, L. Wiśniewski, B. Kellner-Leidel, P. Demange, F. Gonzalez, B. Moal, V. De Caprio, V. Golev, K. Katarzyński, V. Bugaev, A. Reimer, J. Koziol, G. Pojmanski, Alessandro Carosi, J. Bolmont, A. Nikolaidis, R. J. García López, V. A. Kudryavtsev, C. Stegmann, J.-P. Ernenwein, M. Fiorini, Ivone F. M. Albuquerque, Marco Tavani, P. Korohoda, A. Giuliani, E. Carmona, C. Bauer, Kostas D. Kokkotas, O. Tibolla, G. Deleglise, Pierre Brun, Dinko Dimitrov, I. Jung, R. Steenkamp, Marc Ribó, Kathrin Egberts, P. Reardon, Adriano Ghedina, Stefan Rosén, N. Hidaka, Trygve Buanes, A. Segreto, H. Huan, Juri Poutanen, Ruben Lopez-Coto, S. Cavazzani, Massimiliano Belluso, A. Kretzschmann, F. De Frondat, A. Riviere, J. F. Olive, Tsunefumi Mizuno, Serena Mattiazzo, M. González, D. Fantinel, Matteo Cerruti, S. Vergani, Sabrina Einecke, N. La Palombara, Reinhard Schlickeiser, P. Antoranz, Pol Bordas, D. Paillot, V. de Souza, Yasushi Fukazawa, Phil Evans, Werner Hofmann, Hugh Dickinson, F. Roy, Yvonne Becherini, E. O. Angüner, D. Corti, T. C. Arlen, Francesco Russo, V. R. Chitnis, D. Ross, R. Gabriele, Massimo Persic, E. Fokitis, A. Bonardi, D. Garrido, A. Niedźwiecki, L. Cossio, Hidetoshi Kubo, Y. de Oliveira, F. Mattana, Anna Szostek, M. Compin, S. Blake, F. Lucarelli, Petter Hofverberg, Felix Ryde, M. Gougerot, C. Boutonnet, Dimitrios Emmanoulopoulos, A. Mangano, P. Vallania, Jose Miguel Miranda, A. Manalaysay, M. Raue, A. Bouvier, Shohei Yanagita, Nektarios Vlahakis, Joni Tammi, M. Naumann-Godo, Kohta Murase, E. Fillin-Martino, Jiri Chudoba, K. Hatanaka, A. Lopatin, N. Otte, G. Rojas, Tomonori Totani, K. S. Gothe, J. P. Vialle, D. Kolitzus, K. Warda, Hironori Matsumoto, J. Rico, P. Ringegni, James Chiang, R. McKay, A. Bobkov, Aya Bamba, H. Takami, B. Giebels, O. Grimm, S. Basso, F. Dubois, Victor Zabalza, A. Förster, Pasquale Blasi, Alexandros Papayannis, A. G. Akhperjanian, Eckhard Kendziorra, James A. Anderson, Giuseppe Malaguti, R. Welsing, S. Pita, A. Ozieblo, Heide Costantini, D. Tezier, J.-H. Köhne, M. Tluczykont, Ll. Garrido, Alexander Varón Sandoval, Matthew R. Orr, Dominique Durand, F. Chollet, O. Luz, E. O. Saemann, Jun Kataoka, M. Proyetti, C. Barbier, Jürgen Barnstedt, L. Bouchet, Hiroshi Muraishi, Anton N. Baushev, L. A. Otero, Denis Bastieri, S. Incorvaia, Tihomir Surić, V. La Parola, Nathan Smith, Karl-Heinz Sulanke, F. Bernard, Luca Stringhetti, S. Paiano, S. Federici, Hector Flores, Karl Mannheim, Michael S. Briggs, Giovanna Pedaletti, E. M. de Gouveia Dal Pino, J. D. Smith, G. La Rosa, Alicia López-Oramas, M. Janiak, Gary Drake, G. Talbot, Petr Travnicek, Elisabetta Bissaldi, Mario Meucci, R. Northrop, V. Scapin, Vito Conforti, J. D. Ponz, T. Aghajani, J. J. Jimenez, A. D. Supanitsky, Hernán Asorey, M. Werner, Brian Reville, A. Haupt, C. Skole, Gilles Henri, Daniele Gardiol, V. Vassiliev, R. Platzer, Y. Saito, A. La Barbera, Allan Hallgren, C. Eleftheriadis, S. Cantu, G. Maurin, K. Lacombe, A. Le Padellec, F. Stinzing, T. Hayakawa, A. Cillis, M. Suchenek, I. Monteiro, V. Sahakian, A. Di Paola, Grzegorz Madejski, A. De Luca, Andreas Quirrenbach, P. A. Caraveo, N. A. Webb, Michael Zacharias, J. Vanderwalt, Dario Hrupec, K. Ziȩtara, T. Armstrong, A. Lorca, T. Krähenbühl, A. Etchegoyen, Stefano Covino, C. Kalkuhl, K. Kitamoto, Tomasz Bulik, R. Rohlfs, D. Allan, A. Zhao, Luisa Arrabito, B. S. Acharya, T. Johnson, C. Schultz, G. Vasileiadis, Eleen Shum, Daniel Ferenc, Paola Grandi, Maria Concetta Maccarone, E. Strazzeri, H. Kelly, E. J. Quel, H. Vankov, Ruben Alfaro, I. Telezhinsky, J. Becker Tjus, C. Dufour, F. Köck, Ilana M. Braun, Jamie Holder, Ryoji Enomoto, Luigi Lessio, Michael Punch, Stefano Gabici, I. Puerto-Gimenez, S. Karkar, P. Nayman, M. Grudzińska, E. Aliu, Yoshiyuki Inoue, Elina Lindfors, J. Becerra, Daniel Mazin, Yukikatsu Terada, André Schulz, Teresa Montaruli, G. Bonnoli, S. Renner, Dieter Horns, J. Dyks, V. Pelassa, Mark I. Wilkinson, Ricardo Graciani, I. Troyano, P. Ristori, Thomas Kihm, P. Micolon, S. J. Nolan, Torsten Bringmann, David A. Williams, Joachim Hahn, L. Brunetti, U. Roeser, Wolfgang Rhode, Kanaris Tsinganos, Stefan Ohm, J. L. Panazol, G. Busetto, B. S., Acharya, M., Acti, T., Aghajani, G., Agnetta, J., Aguilar, F., Aharonian, M., Ajello, A., Akhperjanian, M., Alcubierre, J., Aleksic, R., Alfaro, E., Aliu, A. J., Allafort, D., Allan, I., Allekotte, E., Amato, J., Anderson, E. O., Anguener, L. A., Antonelli, P., Antoranz, A., Aravantino, T., Arlen, T., Armstrong, H., Arnaldi, L., Arrabito, K., Asano, T., Ashton, H. G., Asorey, Y., Awane, H., Baba, A., Babic, N., Baby, J., Baehr, A., Bai, C., Baixera, S., Bajtlik, M., Balbo, D., Bali, C., Balkowski, A., Bamba, R., Bandiera, A., Barber, C., Barbier, M., Barcelo, A., Barnacka, J., Barnstedt, U. B., De, J. A., Barrio, A., Basili, S., Basso, D., Bastieri, C., Bauer, A., Baushev, J., Becerra, Y., Becherini, K. C., Bechtol, J. B., Tju, V., Beckmann, W., Bednarek, B., Behera, M., Belluso, W., Benbow, J., Berdugo, K., Berger, F., Bernard, T., Bernardino, K., Bernloehr, N., Bhat, S., Bhattacharyya, C., Bigongiari, A., Biland, S., Billotta, T., Bird, E., Birsin, Bissaldi, Elisabetta, J., Biteau, M., Bitossi, S., Blake, O. B., Biga, P., Blasi, A., Bobkov, V., Boccone, M., Boettcher, L., Bogacz, J., Bogart, M., Bogdan, C., Boisson, J. 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M., Comb, N., Mccubbin, I., Mchardy, R., Mckay, C., Medina, C., Melioli, D., Melkumyan, S., Mereghetti, P., Mertsch, M., Meucci, J., Michalowski, P., Micolon, A., Mihailidi, T., Mineo, M., Minuti, N., Mirabal, F., Mirabel, J. M., Miranda, R., Mirzoyan, T., Mizuno, B., Moal, R., Moderski, I., Mognet, E., Molinari, M., Molinaro, T., Montaruli, I., Monteiro, P., Moore, A. M., Olaizola, M., Mordalska, C., Morello, K., Mori, F., Mottez, Y., Moudden, E., Moulin, I., Mrusek, R., Mukherjee, P., Munar Adrover, H., Muraishi, K., Murase, A., Murphy, S., Nagataki, T., Naito, D., Nakajima, T., Nakamori, K., Nakayama, C., Naumann, D., Naumann, M., Naumann Godo, P., Nayman, D., Nedbal, D., Neise, L., Nellen, V., Neustroev, N., Neyroud, L., Nicastro, J., Nicolau Kuklinski, A., Niedzwiecki, J., Niemiec, D., Nieto, A., Nikolaidi, K., Nishijima, S., Nolan, R., Northrop, D., Nosek, N., Nowak, A., Nozato, P., O'Brien, Y., Ohira, M., Ohishi, S., Ohm, H., Ohoka, T., Okuda, A., Okumura, R. 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F., Torre, M., Torre, G., Tosti, T., Totani, C., Toussenel, G., Tovmassian, P., Travnicek, M., Trifoglio, I., Troyano, K., Tsingano, H., Ueno, K., Umehara, S. S., Upadhya, T., Usher, M., Uslenghi, J. F., Valdes Galicia, P., Vallania, G., Vallejo, W. v., Driel, C. v., Eldik, J., Vandenbrouke, J., Vanderwalt, H., Vankov, G., Vasileiadi, V., Vassiliev, D., Veberic, I., Vega, S., Vercellone, S., Vergani, C., Veyssiere, J. P., Vialle, A., Viana, M., Videla, P., Vincent, S., Vincent, J., Vink, N., Vlahaki, L., Vlaho, P., Vogler, A., Vollhardt, H. . ., P., S., Vorobiov, C., Vuerli, V., Waegebaert, R., Wagner, R. G., Wagner, S., Wagner, S. P., Wakely, R., Walter, T., Walther, K., Warda, R., Warwick, P., Wawer, R., Wawrzaszek, N., Webb, P., Wegner, A., Weinstein, Q., Weitzel, R., Welsing, M., Werner, H., Wetteskind, R., White, A., Wierzcholska, S., Wiesand, M., Wilkinson, D. A., William, R., Willingale, K., Winiarski, R., Wischnewski, L., Wisniewski, M., Wood, A., Woernlein, Q., Xiong, K. K., Yadav, H., Yamamoto, T., Yamamoto, R., Yamazaki, S., Yanagita, J. M., Yebra, D., Yelo, A., Yoshida, T., Yoshida, T., Yoshikoshi, V., Zabalza, M., Zacharia, A., Zajczyk, R., Zanin, A., Zdziarski, A., Zech, A., Zhao, X., Zhou, K., Zietara, J., Ziolkowski, P., Ziolkowski, V., Zitelli, C., Zurbach, P., Zychowski, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), 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), AstroParticule et Cosmologie (APC (UMR_7164)), 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), APC - Astrophysique des Hautes Energies (APC - AHE), 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), Centre de Physique des Particules de Marseille (CPPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CTA, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-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), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Laboratoire d'Annecy de Physique des Particules (LAPP), 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), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), 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), 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), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Next generation Cherenkov telescopes, Ciencias Físicas, 01 natural sciences, 7. Clean energy, TeV GAMMA-RAY ASTRONOMY, Observatory, Air showers, HESS, Cherenkov Telescopes, 010303 astronomy & astrophysics, MISSION, SUPERNOVA REMNANT W44, TELESCOPE, ASTRONOMY, EMISSION, Physics, ta213, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, TeV gamma-ray astronomy, ddc:540, CIENCIAS NATURALES Y EXACTAS, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Air shower, AIR SHOWERS, Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Preparatory phase, ta115, TeV gamma-ray astronomy Air showers Cherenkov Telescopes, 010308 nuclear & particles physics, business.industry, CHERENKOV TELESCOPES, Física, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, ASTROFÍSICA, Cherenkov Telescope Array, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astronomía, Design study, Telecommunications, business
Abstract: The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project., La lista completa de autores puede consultarse en el documento o en la página web de la revista., Facultad de Ingeniería
Published: 2013
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5. Stellar populations in Active Galactic Nuclei III

Author: D. Pelat, Martin Ward, Catherine Boisson, and M. Joly
Subjects: Physics, education.field_of_study, Active galactic nucleus, Stellar population, Star formation, Metallicity, Population, Astronomy, Astronomy and Astrophysics, Astrophysics, Galaxy, medicine.anatomical_structure, Space and Planetary Science, medicine, Emission spectrum, education, Nucleus
Abstract: In this paper we apply the stellar population synthesis method previously described in Boisson et al. (2000) to five more AGN. The analysis of these new data strengthen our previous conclusions: i) homogeneity of the stellar population within a class of nuclear activity regardless of the morphological type of the host galaxy; ii) populations within the nuclear regions of LINERs and Seyfert 2s are different: LINERs have a very old metal-rich population while in the Seyfert 2s a contribution of a weak burst of star formation is observed together with the old high metallicity component; iii) in the circum-nuclar region (200 pc ≤ D ≤ 1 kpc) of all the active galaxies in our sample, except for NGC 2992, we detect an old burst of star formation (0.2−1 Gyr),which is contrary to what is observed in normal galaxies. We note that the broad OIλ8446 A emission line detected in the spectrum of the nucleus of NGC 2992 confirms its classification as a Seyfert 1.
Published: 2004
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6. HST/WFPC2 morphologies and color maps of distant luminous infrared galaxies

Author: Hector Flores, X. Z. Zheng, Francois Hammer, Francois Assemat, D. Pelat, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-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), Physique des Galaxies et Cosmologie, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Pôle instrumental, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Pôle Astronomie du LESIA, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Laboratoire Univers et Théories (LUTH (UMR_8102))
Subjects: Luminous infrared galaxy, Physics, Solar mass, Stellar mass, Pixel, Star formation, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Stars, Space and Planetary Science, Bulge, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract: Using HST/WFPC2 imaging in F606W (or F450W) and F814W filters, we obtained the color maps in observed frame for 36 distant (0.4, Comment: 20 pages, 14 figures, accepted for publication in A&A
Published: 2004
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7. Fundamental limitations of high contrast imaging set by small sample statistics

Author: Bertrand Mennesson, D. Pelat, Markus Kasper, Matthew A. Kenworthy, Julien Milli, Laurent Pueyo, Dimitri Mawet, Anthony Boccaletti, Christian Delacroix, Zahed Wahhaj, Christian Marois, Olivier Absil, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), European Southern Observatory (ESO), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-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), Sibley School of Mechanical and Aerospace Engineering (MAE), Cornell University [New York], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Space Telescope Science Institute (STSci), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), and California Institute of Technology (CALTECH)-NASA
Subjects: [PHYS]Physics [physics], methods: statistical, Small number, techniques: high angular resolution, FOS: Physical sciences, Astronomy and Astrophysics, Small sample, High contrast imaging, symbols.namesake, CLs upper limits, Space and Planetary Science, Gaussian noise, Robustness (computer science), Statistics, symbols, False alarm, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), ComputingMilieux_MISCELLANEOUS, Order of magnitude, Mathematics
Abstract: In this paper, we review the impact of small sample statistics on detection thresholds and corresponding confidence levels (CLs) in high contrast imaging at small angles. When looking close to the star, the number of resolution elements decreases rapidly towards small angles. This reduction of the number of degrees of freedom dramatically affects CLs and false alarm probabilities. Naively using the same ideal hypothesis and methods as for larger separations, which are well understood and commonly assume Gaussian noise, can yield up to one order of magnitude error in contrast estimations at fixed CL. The statistical penalty exponentially increases towards very small inner working angles. Even at 5-10 resolution elements from the star, false alarm probabilities can be significantly higher than expected. Here we present a rigorous statistical analysis which ensures robustness of the CL, but also imposes a substantial limitation on corresponding achievable detection limits (thus contrast) at small angles. This unavoidable fundamental statistical effect has a significant impact on current coronagraphic and future high contrast imagers. Finally, the paper concludes with practical recommendations to account for small number statistics when computing the sensitivity to companions at small angles and when exploiting the results of direct imaging planet surveys., Comment: 12 pages, 10 figures, accepted to ApJ
Published: 2014
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8. Stellar population synthesis with more degrees of freedom than observables

Author: D. Pelat
Subjects: Physics, Overdetermined system, Polyhedron, Classical mechanics, Underdetermined system, Space and Planetary Science, Convex polytope, Degrees of freedom (physics and chemistry), Applied mathematics, Astronomy and Astrophysics, Uniqueness, Base (topology), Vector space
Abstract: In order to derive the stellar population of a galaxy or a star cluster, it is a common practice to fit its spectrum by a combination of spectra extracted from a data base (e.g. a library of stellar spectra). If the data to be fitted are equivalent widths, the combination is a non-linear one and the problem of finding the ‘best’ combination of stars that fits the data becomes complex. It is probably because of this complexity that the mathematical aspects of the problem did not receive a satisfying treatment; the question of the uniqueness of the solution, for example, was left in uncertainty. In this paper we complete the solution of the problem by considering the underdetermined case where there are fewer equivalent widths to fit than stars in the data base (the overdetermined case was treated previously). The underdetermined case is interesting to consider because it leaves space for the addition of supplementary astrophysical constraints. In fact, it is shown in this paper that when a solution exists it is generally not unique. There are infinitely many solutions, all of them contained within a convex polyhedron in the solutions vector space. The vertices of this polyhedron are extremal solutions of the stellar population synthesis. If no exact solution exists, an approximate solution can be found using the method described for the overdetermined case. Also provided is an algorithm able to solve the problem numerically; in particular all the vertices of the polyhedron are found.
Published: 1998
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9. A new method to solve stellar population synthesis problems with the use of a data base

Author: D. Pelat
Subjects: Physics, Stellar population, Space and Planetary Science, Astronomy, Astronomy and Astrophysics, Base (topology)
Published: 1997
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10. Discovery of TeV gamma-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift

Author: H. E.S.S. Collaboration, A. Abramowski, F. Acero, A. G. Akhperjanian, G. Anton, S. Balenderan, A. Balzer, A. Barnacka, Y. Becherini, J. Becker Tjus, B. Behera, K. Bernlöhr, E. Birsin, J. Biteau, A. Bochow, C. Boisson, J. Bolmont, P. Bordas, J. Brucker, F. Brun, P. Brun, T. Bulik, S. Carrigan, S. Casanova, M. Cerruti, P. M. Chadwick, R. C. G. Chaves, A. Cheesebrough, S. Colafrancesco, G. Cologna, J. Conrad, C. Couturier, M. Dalton, M. K. Daniel, I. D. Davids, B. Degrange, C. Deil, P. deWilt, H. J. Dickinson, A. Djannati-Ataï, W. Domainko, L. O’C. Drury, G. Dubus, K. Dutson, J. Dyks, M. Dyrda, K. Egberts, P. Eger, P. Espigat, L. Fallon, C. Farnier, S. Fegan, F. Feinstein, M. V. Fernandes, D. Fernandez, A. Fiasson, G. Fontaine, A. Förster, M. Füßling, M. Gajdus, Y. A. Gallant, T. Garrigoux, H. Gast, B. Giebels, J. F. Glicenstein, B. Glück, D. Göring, M.-H. Grondin, M. Grudzińska, S. Häffner, J. D. Hague, J. Hahn, D. Hampf, J. Harris, S. Heinz, G. Heinzelmann, G. Henri, G. Hermann, A. Hillert, J. A. Hinton, W. Hofmann, P. Hofverberg, M. Holler, D. Horns, A. Jacholkowska, C. Jahn, M. Jamrozy, I. Jung, M. A. Kastendieck, K. Katarzyński, U. Katz, S. Kaufmann, B. Khélifi, S. Klepser, D. Klochkov, W. Kluźniak, T. Kneiske, D. Kolitzus, Nu. Komin, K. Kosack, R. Kossakowski, F. Krayzel, P. P. Krüger, H. Laffon, G. Lamanna, J. Lefaucheur, M. Lemoine-Goumard, J.-P. Lenain, D. Lennarz, T. Lohse, A. Lopatin, C.-C. Lu, V. Marandon, A. Marcowith, J. Masbou, G. Maurin, N. Maxted, M. Mayer, T. J. L. McComb, M. C. Medina, J. Méhault, U. Menzler, R. Moderski, M. Mohamed, E. Moulin, C. L. Naumann, M. Naumann-Godo, M. de Naurois, D. Nedbal, N. Nguyen, J. Niemiec, S. J. Nolan, S. Ohm, E. de Oña Wilhelmi, B. Opitz, M. Ostrowski, I. Oya, M. Panter, R. D. Parsons, M. Paz Arribas, N. W. Pekeur, G. Pelletier, J. Perez, P.-O. Petrucci, B. Peyaud, S. Pita, G. Pühlhofer, M. Punch, A. Quirrenbach, S. Raab, M. Raue, A. Reimer, O. Reimer, M. Renaud, R. de los Reyes, F. Rieger, J. Ripken, L. Rob, S. Rosier-Lees, G. Rowell, B. Rudak, C. B. Rulten, V. Sahakian, D. A. Sanchez, A. Santangelo, R. Schlickeiser, A. Schulz, U. Schwanke, S. Schwarzburg, S. Schwemmer, F. Sheidaei, J. L. Skilton, H. Sol, G. Spengler, Ł. Stawarz, R. Steenkamp, C. Stegmann, F. Stinzing, K. Stycz, I. Sushch, A. Szostek, J.-P. Tavernet, R. Terrier, M. Tluczykont, C. Trichard, K. Valerius, C. van Eldik, G. Vasileiadis, C. Venter, A. Viana, P. Vincent, H. J. Völk, F. Volpe, S. Vorobiov, M. Vorster, S. J. Wagner, M. Ward, R. White, A. Wierzcholska, D. Wouters, M. Zacharias, A. Zajczyk, A. A. Zdziarski, A. Zech, H.-S. Zechlin, D. Pelat, H.E.S.S. Collaboration, 12006653 - Venter, Christo, 11005394 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 12792322 - Vorster, Michael Johannes, 22164405 - Sheidaei, Farzaneh, 23909196 - Casanova, Sabrina, Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), 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), 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), GLAST, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HESS, 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-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), 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), 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), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-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), 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), 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), and Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules)
Subjects: [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], galaxies. [Gamma rays], active [Galaxies], Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, purl.org/becyt/ford/1 [https], Gamma ray galaxies, 0103 physical sciences, gamma rays: galaxies, Radiation mechanisms, Blazar, 010303 astronomy & astrophysics, Physics, Non thermal mechanisms, High Energy Astrophysical Phenomena (astro-ph.HE), non-thermal [Radiation mechanisms], individual: PKS 0447-439 [BL Lacertae objects], 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Gamma ray, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], radiation mechanisms: non-thermal, Light curve, Cherenkov Telescope Array, BL Lacertae objects: individual: PKS 0447-439, Redshift, Astronomía, Extragalactic background light, Space and Planetary Science, galaxies [gamma rays], Active galaxies, BL Lacertae objects, ddc:520, Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], CIENCIAS NATURALES Y EXACTAS, Fermi Gamma-ray Space Telescope
Abstract: Very high-energy gamma-ray emission from PKS 0447-439 was detected with the H.E.S.S. Cherenkov telescope array in December 2009. This blazar is one of the brightest extragalactic objects in the Fermi Bright Source List and has a hard spectrum in the MeV to GeV range. In the TeV range, a photon index of 3.89 +- 0.37 (stat) +- 0.22 (sys) and a flux normalisation at 1 TeV, Phi(1 TeV) = (3.5 +- 1.1 (stat) +- 0.9 (sys)) x 10^{-13} cm^{-2} s^{-1} TeV^{-1}, were found. The detection with H.E.S.S. triggered observations in the X-ray band with the Swift and RXTE telescopes. Simultaneous UV and optical data from Swift UVOT and data from the optical telescopes ATOM and ROTSE are also available. The spectrum and light curve measured with H.E.S.S. are presented and compared to the multi-wavelength data at lower energies. A rapid flare is seen in the Swift XRT and RXTE data, together with a flux variation in the UV band, at a time scale of the order of one day. A firm upper limit of z < 0.59 on the redshift of PKS 0447-439 is derived from the combined Fermi-LAT and H.E.S.S. data, given the assumptions that there is no upturn in the intrinsic spectrum above the Fermi-LAT energy range and that absorption on the Extragalactic Background Light (EBL) is not weaker than the lower limit provided by current models. The spectral energy distribution is well described by a simple one-zone Synchrotron Self-Compton (SSC) scenario, if the redshift of the source is less than z, Comment: 14 pages, 10 figures, accepted for publication in A&A
Published: 2013
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11. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry: IV. Advanced experimental measurements

Author: Daniel Rouan, Olivier Dupuis, D. Pelat, D. Pickel, Fanny Chemla, Mathieu Cohen, Jean-Michel Reess, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Ingénierie, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire Univers et Théories (LUTH (UMR_8102)), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Pôle instrumental, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, business.industry, Attenuation, Context (language use), Deformable mirror, law.invention, Interferometry, Wavelength, Optics, Achromatic lens, law, Astronomical interferometer, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Phase shift module
Abstract: International audience; Context. To characterize their atmospheres in order to find evidences of life, one has to detect directly photons from the exoplanets to measure their spectra. One possible technique is dark fringe interferometry that needs an achromatic pi phase shift in one arm of the interferometer. We have conceived a phase shifter made of two cellular mirrors, in which each cell position and phase shift is specific, so that the behaviour of the nulling with respect to wavelength is flat within a broad range. Aims. We want to validate experimentally two versions of this achromatic phase shifter: a transmissive one in bulk optics and a reflective one using a segmented deformable mirror. What we present in this paper are the last results obtained in the lab. Methods. We built an optical bench in the visible that allows us to test the principle and characterize the performances and the limits of this phase shifter. Results. We tested several transmissive and one reflective phase shifter and obtained, for instance, an attenuation of about 2.10-3 for a white source (from 430 to 830 nm) that proved the achromatic behavior of the phase shifter. The preliminary performances and limitations are analyzed.
Published: 2012
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12. Multifrequency monitoring of the Seyfert 1 galaxy NGC 4593 – I. Isolating the nuclear emission

Author: Ian S. Glass, J. Clavel, D. Pelat, P. Barr, Gail A. Reichert, Bradley M. Peterson, and Maria Santos-Lleo
Subjects: Physics, Space and Planetary Science, Astronomy, Astronomy and Astrophysics, Astrophysics, Galaxy
Published: 1994
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13. Telescopes and Images

Author: D. Pelat, Daniel Rouan, Pierre Léna, François Lebrun, and François Mignard
Subjects: Point spread function, Computer science, media_common.quotation_subject, Astrophysics::Instrumentation and Methods for Astrophysics, law.invention, Primary mirror, Telescope, Cardinal point, law, Computer graphics (images), Optical transfer function, Very-long-baseline interferometry, Angular resolution, Function (engineering), media_common
Abstract: The telescope is so often considered as the astronomical tool par excellence that it would be easy to forget that it is just one of the components of an observing system, and that it would serve no purpose without spectrometers or detectors. The aim of this chapter is to examine the double function of the telescope, as both an energy collector and an image former. These two aspects are so closely connected that, in dealing with the second, we inevitably begin to deal with the first.
Published: 2011
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14. The Signal in Astronomy

Author: François Mignard, Daniel Rouan, François Lebrun, Pierre Léna, and D. Pelat
Subjects: Point spread function, Photon noise, Signal processing, Computer science, Noise reduction, Quantum noise, Astronomy, Spectral density, Instrumentation (computer programming), Signal
Abstract: Astronomy has often developed by pushing instruments to the limits of their capacities. Many discoveries spring from a combination of noise reduction, by careful design of instrumentation, and efficient signal processing.
Published: 2011
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15. The Earth Atmosphere and Space

Author: François Lebrun, François Mignard, Daniel Rouan, D. Pelat, and Pierre Léna
Subjects: Rest (physics), Earth's energy budget, symbols.namesake, Atmosphere of the Moon, Atmosphere of Earth, Secondary atmosphere, Observational astronomy, Computer science, Galileo (satellite navigation), symbols, Astrobiology, Exosphere
Abstract: The Earth’s atmosphere has always acted as a screen between the observer and the rest of the Universe. The pre-Copernicans regarded it as the seat of the volatile elements because of its mobility, separating as it did the sublunar world from the world of the stars. From the time of Galileo, and up until the conquest of space, observations of photons were limited to the narrow window of the visible, and this range was extended only recently by the addition of radio frequencies. Despite the recent development of observation from space, ground-based observation retains considerable advantages in terms of both access and cost. The global strategy of observational astronomy therefore requires an exact knowledge of the properties of the Earth’s atmosphere. With such a knowledge, the potential or the limits of ground-based observation can be defined, and, for each wavelength of the spectrum, the best altitude can be determined and the best sites chosen for new instruments. The choice of site is crucial. Many factors must be taken into account, and we shall describe them here. The Antarctic continent is now accessible for astronomy and will no doubt provide many important opportunities.
Published: 2011
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16. Sky Surveys and Virtual Observatories

Author: François Mignard, D. Pelat, François Lebrun, Pierre Léna, and Daniel Rouan
Subjects: History, Astronomer, Sky, media_common.quotation_subject, Astronomy, Virtual observatory, Object (philosophy), media_common
Abstract: Astronomers have always catalogued the objects they observe and study. In ancient times, the Greek astronomer Hipparchos (between 161 and 127 BC) and the Chinese astronomers Shi Shen and Gan De (in the Warring States period, around 500 BC) built up the first systematic catalogues of the celestial regions accessible from their parts of the world. Tycho Brahe did likewise, followed by surveys of non-stellar objects, such as Messier’s.1 At the end of the nineteenth century, sky surveys marked the beginning of the great modern catalogues. Computers completely transformed this landscape in the last decade of the twentieth century, by vastly increasing the volumes of data that could be stored, while improving accessibility, addressability, and communications through a range of automated systems. In this chapter, we shall consider some of the results of this revolution. In addition to the development of statistical astrophysics and systematic whole sky surveys across all wavelengths, we will also discuss the advent of virtual observatories which bring together all available maps and data about a specific object, to assist in solving whatever astrophysical problem is under investigation.
Published: 2011
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17. Diffraction and Image Formation

Author: Daniel Rouan, François Mignard, Pierre Léna, François Lebrun, and D. Pelat
Subjects: Point spread function, Diffraction, Physics, Image formation, Wavelength, Light intensity, Optics, Geometrical optics, business.industry, business, Electromagnetic radiation, Coherence (physics)
Abstract: In the last chapter, we discussed telescopes as optical devices able to form images in a way that could be explained by geometrical optics, at least to first order in the light intensity distribution. The wave nature of electromagnetic radiation produces diffraction effects that modify this distribution and introduce a fundamental limitation on the angular resolution of telescopes. Since astronomers always want to obtain images containing more and more detail, it is essential to come to grips with these effects, whose amplitude is directly related to the wavelength of the radiation. Using the notion of coherence discussed in Chap. 3 (see Sect. 3.2), we begin by examining the process by which images are formed in the presence of diffraction, and translate the results in terms of spatial frequency filtering.
Published: 2011
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18. Space–Time Reference Frames

Author: Pierre Léna, Daniel Rouan, François Lebrun, François Mignard, and D. Pelat
Subjects: Astronomical Objects, Millisecond, Proper motion, Computer science, Space time, Very-long-baseline interferometry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, International Earth Rotation and Reference Systems Service, Satellite, Reference frame
Abstract: An essential part of astrophysical observation and data analysis consists in measuring the positions of astronomical objects and in dating events. Obtaining the photometric magnitudes of the emitted radiation is not enough. The source must be identified in catalogues or data bases, and the position must be determined to great accuracy, since spatial resolutions of the order of several tenths of a millisecond of arc can now be attained in images, and this trend is certain to continue. Concerning the absolution positioning accuracies of celestial objects, over the past 20 years or so, these have gone from a few hundredths of a second of arc before the Hipparcos satellite was launched to about ten microseconds of arc with the Gaia mission. In terms of sensitivity, detectors can now measure the characteristics of phenomena whose time of variation is less than one millisecond. And further, extremely accurate time scales, taking into account the effects of general relativity, are required for space travel and exploration of specific sites in the Solar System.
Published: 2011
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19. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry III: experimental performances

Author: Fanny Chemla, D. Pelat, Olivier Dupuis, Daniel Rouan, D. Pickel, Mathieu Cohen, Jean-Michel Reess, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Pôle Astronomie du LESIA, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Galaxies, Etoiles, Physique, Instrumentation (GEPI)
Subjects: Physics, business.industry, Bandwidth (signal processing), law.invention, Interferometry, Wavelength, Optics, Achromatic lens, law, Chromatic aberration, Astronomical interferometer, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Spectroscopy, business, Phase shift module
Abstract: International audience; Context. Dark fringe interferometry in the thermal infrared is one way to detect directly a planet orbiting a star, and so to characterize the planet's atmosphere through spectroscopy. This method demands a phase shift of pi1 in one arm of the interferometer. In order to detect various bio-tracers gases, a broad wavelength range (6-18 mum)2-3 is necessary, therefore an achromatic phase shift of pi is required. The achromatic device presented here is a phase shifter made of two cellular mirrors, in which each cell induces a specific phase shift. Aims. We wish to demonstrate that this theoretical concept is experimentally valid. We present in this paper the setup and the very first results. Methods. In a first step, we have consolidated the theoretical ground and in a second step we developed an optical bench in the visible domain to test the concept and measure the performances of this device. Results. The preliminary experimental tests show evidences that such a device is working as expected in terms of nulling and achromatism: in spite of an error on one cell of the prototype, it provides a nulling of 2.10-3 at one wavelength, and this value is close to the expected value. Besides, a nulling of 1.10-2 in a 450 to 750 nm bandwidth: a hint that a perfect device should be achromatic.
Published: 2010
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20. PEGASE, an infrared interferometer to study stellar environments and low mass companions around nearby stars

Author: M. Ollivier, O. Absil, F. Allard, J.-P. Berger, P. Bordé, F. Cassaing, B. Chazelas, A. Chelli, O. Chesneau, V. Coudé du Foresto, D. Defrère, P. Duchon, P. Gabor, J. Gay, E. Herwats, S. Jacquinod, P. Kern, P. Kervella, J.-M. Le Duigou, A. Léger, B. Lopez, F. Malbet, D. Mourard, D. Pelat, G. Perrin, Y. Rabbia, D. Rouan, J.-M. Reiss, G. Rousset, F. Selsis, P. Stee, J. Surdej, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire d'Étude des Phénomènes de Transfert et de l'Instantanéité : Agro-industrie et Bâtiment (LEPTIAB), Université de La Rochelle (ULR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Laboratoire Hippolyte Fizeau (FIZEAU), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Bordelais de Recherche en Informatique (LaBRI), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), Laboratoire Gemini (LG), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des Mécanismes de la recombinaison (LMR), Centre National de la Recherche Scientifique (CNRS), Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), La Rochelle Université (ULR), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cosmic Vision, Infrared, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, 010309 optics, 0103 physical sciences, 010303 astronomy & astrophysics, Low mass objects, Astrophysics::Galaxy Astrophysics, Physics, Spacecraft, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Interferometry, Stars, Space interferometry, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Darwin (spacecraft), Astrophysics::Earth and Planetary Astrophysics, Nulling interferometry, business, Low Mass, Circumstellar habitable zone
Abstract: International audience; PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars (particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals, as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.
Published: 2009
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21. A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. II. Quantifying morphological k-correction in the COSMOS field at 1<z<2: Ks band vs. I band

Author: Jean-Paul Kneib, O. Le Fèvre, D. Rouan, David B. Sanders, Peter Capak, Jeyhan S. Kartaltepe, L. A. M. Tasca, Mara Salvato, Marc Huertas-Company, Anton M. Koekemoer, D. Pelat, Chris J. Willott, H. J. McCracken, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), IAA-C/ Camino Bajo de Huétor, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Spitzer Science Center, California Institute of Technology (SSC), Institute for Astronomy, University of Hawaii, Space Telescope Science Institute (STScI), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), California Institute of Technology, Department of Astronomy (CALTECH), and Physics Department, University of Ottawa
Subjects: Physics, I band, education.field_of_study, Field (physics), Population, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Redshift, K correction, Support vector machine, Space and Planetary Science, education, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We quantify the effects of \emph{morphological k-correction} at $11$ could be underestimating the elliptical population. [abridged], Comment: accepted for publication in A&A, updated with referee comments, 12 pages, 10 figures
Published: 2008
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22. Laboratory characterization of the chessboard achromatic phase shifter

Author: Pierre Riaud, Jean-Michel Reess, Fanny Chemla, D. Pelat, Daniel Rouan, N. Meilard, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Galaxies, Etoiles, Physique, Instrumentation (GEPI)
Subjects: Physics, business.industry, Pascal's triangle, Octave (electronics), Exoplanet, law.invention, Interferometry, Wavelength, symbols.namesake, Optics, Achromatic lens, law, Chromatic aberration, symbols, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Phase shift module
Abstract: International audience; We recently presented a new concept for designing an achromatic phase shifter. An APS is required in nulling interferometry, a technique that aims at directly detecting and characterizing planets around a star in the thermal infrared. Our solution is based on two cellular mirrors (alternatively, transparent plates can be used) where cells have thickness which introduce OPD that are respectively odd and even multiples of half the central wavelength, on the fraction of the wave it reflects. A destructive interference is thus produced on axis for the central wavelength when recombining the two beams. We have shown that if the thicknesses are distributed according to the Pascal triangle, a fair quasi-achromatism is also reached on typically one octave in wavelength, provided there is a suffcient number of cells. The major interest of this solution is that it allows a compact, simple and fully symmetric design, without complex sub-systems to adjust. In this paper, after reminding the basic concept, we first present the theoretical estimations for the expected performances in the two possible regimes of recombination: on axis and multi-axial (Fizeau). We then describe the laboratory setup of the demonstration bench we are developing, as well as the first results obtained.
Published: 2008
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23. L'observation en astrophysique

Author: F. Mignard, F. Lebrun, D. Rouan, D. Pelat, P. Léna, 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), 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), Lebrun, François, 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, and Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)
Subjects: [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Materials science, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 0103 physical sciences, 02 engineering and technology, [PHYS.ASTR.IM] Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 021001 nanoscience & nanotechnology, 0210 nano-technology, 010303 astronomy & astrophysics, 01 natural sciences, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract: ISBN:978-2-86883-877-3
Published: 2008

24. The achromatic chessboard, a new concept of phase shifter for Nulling Interferometry - I. theory

Author: D. Pelat, Daniel Rouan, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Pôle Astronomie du LESIA, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire Univers et Théories (LUTH (UMR_8102)), and Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, business.industry, Plane (geometry), Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Octave (electronics), 01 natural sciences, Collimated light, law.invention, 010309 optics, Interferometry, Wavelength, Optics, Space and Planetary Science, Achromatic lens, law, 0103 physical sciences, Darwin (spacecraft), business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Phase shift module
Abstract: Direct detection of a planet around a star in the mid-IR, requires a nulling interferometer featuring an achromatic phase shift of pi on broad range. A new concept for designing such an achromatic phase shifter is presented here. The major interest of this solution is that it allows a simple design, with essentially one device per beam. The heart of the system consists in two cellular mirrors where each cell has a thickness introducing for the central wavelength, a phase shift of (2k+1)pi or of 2k pi on the fraction of the wave it reflects. Each mirror is put in one of the collimated beams of the interferometer. Because of the odd/even distribution, when recombining the two beams, a destructive interference is produced on axis for the central wavelength . If the distribution of cells thickness follows a rather simple law, based on the Pascal's triangle, then the nulling is also efficient for a wavelength not too far from the central wavelength. For instance, with two mirrors of 64x64 cells, one reaches a nulling of 1.e-6 on more than one complete octave. This could satisfy the specifications of space mission as Darwin. We also show the way to distribute the cells in the plane of the pupil for the optimum isolation of the planet image from the residual. We present the nulling performances of those various configurations., Comment: Accepted in Astronomy and Astrophysics
Published: 2008
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25. A new concept of achromatic phase shifter for nulling interferometry

Author: Fanny Chemla, Marie Ygouf, Daniel Rouan, D. Pelat, Pierre Riaud, Jean-Michel Reess, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Galaxies, Etoiles, Physique, Instrumentation (GEPI)
Subjects: Physics, business.industry, Collimated light, law.invention, Telescope, Interferometry, Wavelength, Optics, Achromatic lens, law, Chromatic aberration, Astronomical interferometer, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Phase shift module
Abstract: International audience; Direct detection and characterization of a planet around a star by nulling interferometry, must be efficient in a large wavelength domain in order to detect simultaneously the infrared bio-tracers CO II, O 3 and H IIO. This condition requires that an achromatic phase shift of pi be implemented, with an accuracy sufficient for achieving a deep nulling at all considered wavelengths. Several solutions have been presented. We present here a new concept for designing such an achromatic phase shifter. It is based on two cellular mirrors (alternatively, transparent plates can be used) where cells have thickness which are respectively odd and even multiples of a quarter of the central wavelength. Each cell introduces then a phase shift of (2k 1)pi or of 2kpi, on the fraction of the wave it reflects. Each mirror is introduced in the collimated beam issued from one or the other telescopes. Because of the odd/even distribution, a destructive interference is obviously produced on axis for the central wavelength when recombining the two beams. The trick to obtain a quasi-achromatisation is to distribute the thickness of the cells, so that the nulling is also efficient for a wavelength not too far from the central wavelength. We show that if the thicknesses are distributed according to the Pascal triangle, a fair quasi-achromatism is reached. This effect is the more efficient that the number of cells is large. For instance, with 256 × 256 cells, where phase shift range is between -6pi and 6pi one shows that the nulling reaches 10 -6 on the wavelength range [0.7lambda 0, 1.3lambda 0] which corresponds roughly to the DARWIN specification. In a second step, we study the optimum way to distribute the cells in the plane of the pupil. The most important criterion is the isolation of the planet image from the residual image of the star. Several efficient configurations are presented. Finally we consider some practical aspects on a device belonging to the real world and on the bench we are developing. The major interest of this solution is that it allows a compact, simple and fully symmetric design, with essentially no ajustable sub-systems ; extension to multi-telescopes interferometers with phase shift other than pi can also be envisioned.
Published: 2007
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26. Generation of potential/surface density pairs in flat disks Power law distributions

Author: D. Pelat, A. Pierens, J.-M. Huré, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
Subjects: Physics, Surface (mathematics), Series (mathematics), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Truncation, Astrophysics (astro-ph), Mathematical analysis, FOS: Physical sciences, Astronomy and Astrophysics, 010103 numerical & computational mathematics, Astrophysics, 16. Peace & justice, 01 natural sciences, Power law, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Rate of convergence, Space and Planetary Science, 0103 physical sciences, 0101 mathematics, Closed-form expression, Multipole expansion, Axial symmetry, 010303 astronomy & astrophysics
Abstract: We report a simple method to generate potential/surface density pairs in flat axially symmetric finite size disks. Potential/surface density pairs consist of a ``homogeneous'' pair (a closed form expression) corresponding to a uniform disk, and a ``residual'' pair. This residual component is converted into an infinite series of integrals over the radial extent of the disk. For a certain class of surface density distributions (like power laws of the radius), this series is fully analytical. The extraction of the homogeneous pair is equivalent to a convergence acceleration technique, in a matematical sense. In the case of power law distributions, the convergence rate of the residual series is shown to be cubic inside the source. As a consequence, very accurate potential values are obtained by low order truncation of the series. At zero order, relative errors on potential values do not exceed a few percent typically, and scale with the order N of truncation as 1/N**3. This method is superior to the classical multipole expansion whose very slow convergence is often critical for most practical applications., Accepted for publication in Astronomy & Astrophysics 7 pages, 8 figures, F90-code available at http://www.obs.u-bordeaux1.fr/radio/JMHure/intro2applawd.html
Published: 2007
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27. Acknowledgments

Author: A. Abbas, P.B. Abraham, Ari Abramson, Jose Adachi, R.J. Adler, N. Agmon, M. Ahmad, S.A. Ahmad, Luis Alvarez-Ruso, Maarten H P Ambaum, R.K. Amiet, L.U. Ancarani, M. Antoine, C.R. Appledorn, D.R. Appleton, Mitsuhiro Arikawa, P. Ashoshauvati, C.L. Axness, E. Badralexe, S.B. Bagchi, L.J. Baker, R. Ball, M.P. Barnett, Florian Baumann, Norman C. Beaulieu, Jerome Benoit, V. Bentley, Laurent Berger, M. van den Berg, N.F. Berk, C.A. Bertulani, J. Betancort-Rijo, P. Bickerstaff, Iwo Bialynicki-Birula, Chris Bidinosti, G.R. Bigg, Ian Bindloss, L. Blanchet, Mike Blaskiewicz, R.D. Blevins, Anders Blom, L.M. Blumberg, R. Blumel, S.E. Bodner, M. Bonsager, George Boros, S. Bosanac, B. Van den Bossche, A. Boström, J.E. Bowcock, T.H. Boyer, K.M. Briggs, D.J. Broadhurst, Chris Van Den Broeck, W.B. Brower, H.N. Browne, Christoph Bruegger, William J. Bruno, Vladimir Bubanja, D.J. Buch, D.J. Bukman, F.M. Burrows, R. Caboz, T. Calloway, F. Calogero, D. Dal Cappello, David Cardon, J.A. Carlson Gallos, B. Carrascal, A.R. Carr, S. Carter, G. Cavalleri, W.H.L. Cawthorne, A. Cecchini, B. Chan, M.A. Chaudhry, Sabino Chavez-Cerda, Julian Cheng, H.W. Chew, D. Chin, Young-seek Chung, S. Ciccariello, N.S. Clarke, R.W. Cleary, A. Clement, P. Cochrane, D.K. Cohoon, L. Cole, Filippo Colomo, J.R.D. Copley, D. Cox, J. Cox, J.W. Criss, A.E. Curzon, D. Dadyburjor, D. Dajaputra, C. Dal Cappello, P. Daly, S. Dasgupta, John Davies, C.L. Davis, A. Degasperis, B.C. Denardo, R.W. Dent, E. Deutsch, D. deVries, P. Dita, P.J. de Doelder, Mischa Dohler, G. Dôome, Shi-Hai Dong, Balazs Dora, M.R. D'Orsogna, Adrian A. Dragulescu, Eduardo Duenez, Tommi J. Dufva, E.B. Dussan, null V, C.A. Ebner, M. van der Ende, Jonathan Engle, G. Eng, E.S. Erck, Jan Erkelens, Olivier Espinosa, G.A. Estévez, K. Evans, G. Evendon, V.I. Fabrikant, L.A. Falkovsky, K. Farahmand, Richard J. Fateman, G. Fedele, A.R. Ferchmin, P. Ferrant, H.E. Fettis, W.B. Fichter, George Fikioris, J.C.S.S. Filho, L. Ford, Nicolao Fornengo, J. France, B. Frank, S. Frasier, Stefan Fredenhagen, A.J. Freeman, A. Frink, Jason M. Gallaspy, J.A.C. Gallas, J.A. Carlson Gallas, G.R. Gamertsfelder, T. Garavaglia, Jaime Zaratiegui Garcia, C.G. Gardner, D. Garfinkle, P.N. Garner, F. Gasser, E. Gath, P. Gatt, D. Gay, M.P. Gelfand, M.R. Geller, Ali I. Genc, Vincent Genot, M.F. George, P. Germain, Ing. Christoph Gierull, S.P. Gill, Federico Girosi, E.A. Gislason, M.I. Glasser, P.A. Glendinning, L.I. Goldfischer, Denis Golosov, I.J. Good, J. Good, L. Gorin, Martin Götz, R. Govindaraj, M. De Grauf, L. Green, Leslie O. Green, R. Greenwell, K.D. Grimsley, Albert Groenenboom, V. Gudmundsson, J. Guillera, K. Gunn, D.L. Gunter, Julio C. Gutiérrez-Vega, Roger Haagmans, H. van Haeringen, B. Hafizi, Bahman Hafizi, T. Hagfors, M.J. Haggerty, Timo Hakulinen, Einar Halvorsen, S.E. Hammel, E. Hansen, Wes Harker, T. Harrett, D.O. Harris, Frank Harris, Mazen D. Hasna, Joel G. Heinrich, Sten Herlitz, Chris Herzog, A. Higuchi, R.E. Hise, Henrik Holm, Helmut Hölzler, N. Holte, R.W. Hopper, P.N. Houle, C.J. Howard, J.H. Hubbell, J.R. Hull, W. Humphries, Jean-Marc Huré, Ben Yu-Kuang Hu, Y. Iksbe, Philip Ingenhoven, L. Iossif, Sean A. Irvine, Óttar Ísberg, Cyril-Daniel Iskander, S.A. Jackson, John David Jackson, Francois Jaclot, B. Jacobs, E.C. James, B. Jancovici, D.J. Jeffrey, H.J. Jensen, Edwin F. Johnson, I.R. Johnson, Steven Johnson, I. Johnstone, Y.P. Joshi, Jae-Hun Jung, Damir Juric, Florian Kaempfer, S. Kanmani, Z. Kapal, Dave Kasper, M. Kaufman, B. Kay, Avinash Khare, Ilki Kim, Youngsun Kim, S. Klama, L. Klingen, C. Knessl, M.J. Knight, Mel Knight, Yannis Kohninos, D. Koks, L.P. Kok, K.S. Kölbig, Y. Komninos, D.D. Konowalow, Z. Kopal, I. Kostyukov, R.A. Krajcik, Vincent Krakoviack, Stefan Kramer, Tobias Kramer, Hermann Krebs, J.W. Krozel, E.D. Krupnikov, Kun-Lin Kuo, E.A. Kuraev, Konstantinos Kyritsis, Velimir Labinac, A.D.J. Lambert, A. Lambert, A. Larraza, K.D. Lee, M. Howard Lee, M.K. Lee, P.A. Lee, Todd Lee, J. Legg, Armando Lemus, S.L. Levie, D. Levi, Michael Lexa, Kuo Kan Liang, B. Linet, M.A. Lisa, Donald Livesay, H. Li, Georg Lohoefer, I.M. Longman, D. Long, Sylvie Lorthois, Y.L. Luke, W. Lukosz, T. Lundgren, E.A. Luraev, R. Lynch, R. Mahurin, R. Mallier, G.A. Mamon, A. Mangiarotti, I. Manning, J. Marmur, A. Martin, Sr. Yuzo Maruyama, David J. Masiello, Richard Marthar, H.A. Mavromatis, M. Mazzoni, K.B. Ma, P. McCullagh, J.H. McDonnell, J.R. McGregor, Kim McInturff, N. McKinney, David McA McKirdy, Rami Mehrem, W.N. Mei, Angelo Melino, José Ricardo Mendes, Andy Mennim, J.P. Meunier, Gerard P. Michon, D.F.R. Mildner, D.L. Miller, Steve Miller, P.C.D. Milly, S.P. Mitra, K. Miura, N. Mohankumar, M. Moll, Victor H. Moll, D. Monowalow, Tony Montagnese, Jim Morehead, J. Morice, W. Mueck, C. Muhlhausen, S. Mukherjee, R.R. Müller, Pablo Parmezani Munhoz, Paul Nanninga, A. Natarajan, Stefan Neumeier, C.T. Nguyen, A.C. Nicol, M.M. Nieto, P. Noerdlinger, A.N. Norris, K.H. Norwich, A.H. Nuttall, Frank O'Brien, R.P. O'Keefief, A. Ojo, P. Olsson, M. Ortner, S. Ostlund, J. Overduin, J. Pachner, John D. Paden, Robert A. Padgug, D. Papadopoulos, F.J. Papp, Man Sik Park, Jong-Do Park, B. Patterson, R.F. Pawula, D.W. Peaceman, D. Pelat, L. Peliti, Y.P. Pellegrini, G.J. Pert, Nicola Pessina, J.B. Peterson, Rickard Petersson, Andrew Plumb, Dror Porat, E.A. Power, E. Predazzi, William S. Price, Paul Radmore, F. Raynal, X.R. Resende, J.M. Riedler, Thomas Richard, E. Ringel, T.M. Roberts, N.I. Robinson, P.A. Robinson, D.M. Rosenblum, R.A. Rosthal, J.R. Roth, Klaus Rottbrand, D. Roy, E. Royer, D. Rudermann, Sanjib Sabhapandit, C.T. Sachradja, J. Sadiku, A. Sadiq, Motohiko Saitoh, Naoki Saito, A. Salim, J.H. Samson, Miguel A. Sanchis-Lozano, J.A. Sanders, M.A.F. Sanjun, P. Sarquiz, Avadh Saxena, Vito Scarola, O. Schärpf, A. Scherzinger, B. Schizer, Martin Schmid, J. Scholes, Mel Schopper, H.J. Schulz, G.J. Sears, Kazuhiko Seki, B. Seshadri, A. Shapiro, Masaki Shigemori, J.S. Sheng, Kenneth Ing Shing, Tomohiro Shirai, S. Shlomo, D. Siegel, Matthew Stapleton, Steven H. Simon, Ashok Kumar Singal, C. Smith, G.C.C. Smith, Stefan Llewellyn Smith, S. Smith, G. Solt, J. Sondow, A. Sørenssen, Marcus Spradlin, Andrzej Staruszkiewicz, Philip C.L. Stephenson, Edgardo Stockmeyer, J.C. Straton, H. Suraweera, N.F. Svaiter, V. Svaiter, R. Szmytkowski, S. Tabachnik, Erik Talvila, G. Tanaka, C. Tanguy, G.K. Tannahill, B.T. Tan, C. Tavard, Gonçalo Tavares, Aba Teleki, Arash Dahi Taleghani, D. Temperley, A.J. Tervoort, Theodoros Theodoulidis, D.J. Thomas, Michael Thorwart, S.T. Thynell, D.C. Torney, R. Tough, B.F. Treadway, Ming Tsai, N. Turkkan, Sandeep Tyagi, J.J. Tyson, S. Uehara, M. Vadacchino, O.T. Valls, D. Vandeth, Andras Vanyolos, D. Veitch, Jose Lopez Vicario, K. Vogel, J.M.M.J. Vogels, Alexis De Vos, Stuart Walsh, Reinhold Wannemacher, S. Wanzura, J. Ward, S.I. Warshaw, R. Weber, Wei Qian, D.H. Werner, E. Wetzel, Robert Whittaker, D.T. Wilton, C. Wiuf, K.T. Wong, J.N. Wright, J.D. Wright, D. Wright, D. Wu, Michel Daoud Yacoub, Yu S. Yakovlev, H.-C. Yang, J.J. Yang, Z.J. Yang, J.J. Wang, Peter Widerin, Chun Kin Au Yeung, Kazuya Yuasa, S.P. Yukon, B. Zhang, Y.C. Zhang, Y. Zhao, and Ralf Zimmer
Published: 2007
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28. Constraining the solutions of an inverse method of stellar population synthesis

Author: M. Joly, D. Pelat, J. Moultaka, and Catherine Boisson
Subjects: Physics, Initial mass function, Stellar population, Star formation, Astrophysics (astro-ph), Inverse, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Stability (probability), Galaxy, Overdetermined system, Space and Planetary Science, Globular cluster, Applied mathematics, Astrophysics::Galaxy Astrophysics
Abstract: In three previous papers (Pelat 1997, 1998 and Moultaka & Pelat 2000), we set out an inverse stellar population synthesis method which uses a database of stellar spectra. Unlike other methods, this one provides a full knowledge of all possible solutions as well as a good estimation of their stability; moreover, it provides the unique approximate solution, when the problem is overdetermined, using a rigorous minimization procedure. In Boisson et al. (2000), this method has been applied to 10 active and 2 normal galaxies. In this paper we analyse the results of the method after constraining the solutions. Adding {\it a priori} physical conditions on the solutions constitutes a good way to regularize the synthesis problem. As an illustration we introduce physical constraints on the relative number of stars taking into account our present knowledge of the initial mass function in galaxies. In order to avoid biases on the solutions due to such constraints, we use constraints involving only inequalities between the number of stars, after dividing the H-R diagram into various groups of stellar masses. We discuss the results for a well-known globular cluster of the galaxy M31 and discuss some of the galaxies studied in Boisson et al. (2000). We find that, given the spectral resolution and the spectral domain, the method is very stable according to such constraints (i.e. the constrained solutions are almost the same as the unconstrained one). However, an additional information can be derived about the evolutionary stage of the last burst of star formation, but the precise age of this particular burst seems to be questionable., Accepted in A&A. 15 pages, 5 figures and 6 tables
Published: 2004
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29. Escape probability methods versus 'exact' transfer for modelling the X-ray spectrum of Active Galactic Nuclei and X-ray binaries

Author: D. Pelat, A.-M. Dumont, S. Collin, Olivier Godet, Frédéric Paletou, and S. Coupé
Subjects: Physics, Photon, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Photoionization, Astrophysics::Cosmology and Extragalactic Astrophysics, Lambda, Space and Planetary Science, Ionization, Radiative transfer, Emission spectrum, Line (formation)
Abstract: In the era of XMM-Newton and Chandra missions, it is crucial to use codes able to compute correctly the line spectrum of X-ray irradiated thick media (Thomson thickness of the order of unity) to build models for the structure and the emission of the central regions of AGN or X-ray binaries. In all photoionized codes except in our code Titan, the line intensities are computed with the "escape probability approximation". In its last version, Titan solves the transfer of a thousand lines and of the continuum with the ``Accelerated Lambda Iteration" method, which is one of the most efficient and most secure for line transfer. We find that for conditions typical of the AGN or X-ray binary emission medium, all escape approximations commonly used lead to an overestimation of the soft X-ray lines which can reach one order of magnitude for intense lines., Comment: 19 pages, 14 figures, accepted in A&A
Published: 2003
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30. H-Band Observation of the Stellar Population in Seyfert Galaxies

Author: M. Joly, C. Boisson, S. Coupé, and D. Pelat
Subjects: Luminous infrared galaxy, Physics, Stellar population, Wavelength range, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, H band, Disc galaxy, Stellar classification, Galaxy, Cosmology, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: A very promising wavelength range not yet fully explored to study the stellar populations in the central part of galaxies is the near IR range where cool star spectrum peaks. The H window is particularly well designed for such a study as the non-stellar contribution (mainly dust) is smaller than in the K window.
Published: 2001
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31. Error analysis for stellar population synthesis as an inverse problem

Author: J. Moultaka and D. Pelat
Subjects: Physics, Astrophysics (astro-ph), Process (computing), Inverse, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Inverse problem, Base (topology), Overdetermined system, Set (abstract data type), Transformation (function), Space and Planetary Science, Physical information, Applied mathematics
Abstract: Stellar population synthesis can be approached as an inverse problem. The physical information is extracted from the observations through an inverse model. The process requires the transformation of the observational errors into model errors. A description is given for the error analysis to obtain objectively the errors in the model. Finding a solution for overdetermined and under-determined case was the purpose of two preceding papers. This new one completes the problem of stellar populations synthesis by means of a data base, by providing practical formul\ae defining the set of acceptable solutions. All solutions within this set are compatible, at a given confidence level, with the observations., Comment: 11 pages, LaTeX, 4 figures, 1 table. M.N.R.A.S.(2000) in press
Published: 2000
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32. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

Author: Jean-Michel Reess, Fanny Chemla, D. Pickel, Daniel Rouan, Mathieu Cohen, D. Pelat, and Olivier Dupuis
Subjects: Physics, business.industry, Astronomy and Astrophysics, 01 natural sciences, law.invention, 010309 optics, Interferometry, Optics, Space and Planetary Science, Achromatic lens, law, 0103 physical sciences, business, 010303 astronomy & astrophysics, Phase shift module
Published: 2013
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33. Stellar population synthesis in AGNs

Author: C. Boisson, D. Pelat, M. Joly, and J. Frémaux
Subjects: Physics, Stellar population, Space and Planetary Science, Young stellar object, Astronomy, Astronomy and Astrophysics, Astrophysics
Published: 2004
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34. Multi-Frequency Monitoring of the Seyfert 1 Galaxy NGC~4593 II: a Small, Compact Nucleus ?

Author: P. Barr, Maria Santos-Lleo, Ian S. Glass, J. Clavel, D. Pelat, Bradley M. Peterson, and Gail A. Reichert
Subjects: Luminous infrared galaxy, Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Velocity dispersion, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral component, medicine.disease_cause, Galaxy, Wavelength, Space and Planetary Science, Ionization, medicine, Emission spectrum, Ultraviolet, Astrophysics::Galaxy Astrophysics
Abstract: We discuss the results of a campaign to monitor spectral variations in the low-luminosity Seyfert~1 galaxy NGC~4593, at X-rays, ultraviolet, optical and near IR frequencies. The observations and data analysis have been described in a companion paper (Santos-Lle\'o et al. 1994; Paper~1). The active nucleus in this galaxy is strongly and rapidly variable in all wavebands, implying that the continuum source is unusually compact. Its energy distribution from 1.2~$\mu$m to 1200~\AA\/ obeys a power-law whose index is significantly steeper than is usual in Seyfert's or QSO's; the ``big bump'' is either absent or shifted to wavelengths shorter than 1200~\AA\/. The variations of the soft-X~ray {\em excess\/} do not correlate with those of the UV or hard X-ray continuum. The far UV and optical fluxes are well correlated, while the correlation between the hard X-rays and 1447 \AA\ continuum is only marginally significant. Moreover, the optical flux cannot lag behind the UV by more than 6 days. These results cannot be accommodated in the framework of the standard geometrically thin accretion disk model. Rather, they suggest that the bulk of the UV and optical flux originates from thermal reprocessing of X-rays irradiating the disk. The soft X-ray excess is probably the only spectral component which originates from viscous dissipation inside the disk and the near infrared is probably emitted by hot dust heated by the UV radiation. Such a model is consistent with NGC~4593 having a relatively small black-hole mass of the order of $2\times10^{6}{\rm M_{\odot}}$ as inferred from the line variability study. The high ionization/excitation emission lines are very broad and strongly variable and their variations correlate with those of the continuum. The low excitation lines are significantly narrower and remain constant within the accuracy of our measurements. These results suggest a stratified BLR, where the degree of ionization and the velocity dispersion of the gas increase toward small radii. The \lya\ line responds to the variations of the continuum with a delay $\leq 4$ days. To a first order approximation, the BLR in NGC~4593 is well modelled with two different zones at distances of $\sim$~15 and 3 lt-ds from the ionizing source respectively., Comment: 36 pages, postscript, compressed. tables included; Figures available upon request. MNRAS in press.
Published: 1995

35. The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

Author: D. Pelat, Daniel Rouan, D. Pickel, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-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), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Pôle Astronomie du LESIA, 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris
Subjects: Physics, business.industry, Astronomy and Astrophysics, Context (language use), Starlight, law.invention, Wavelength, Interferometry, Optics, Space and Planetary Science, Achromatic lens, law, Piston (optics), Darwin (spacecraft), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Phase shift module
Abstract: International audience; Context. Nulling interferometry in the mid-IR using two telescopes (commonly referred to a Bracewell interferometer) is one possible way of directly detecting exoplanets in the habitable zone and their characterisation in terms of possible life signatures. A large wavelength domain is needed to simultaneously detect the infrared spectral features of a set of a bio-tracers. An achromatic phase shift of pi is then required, and we previously presented a new concept for such a function that allows a simple design with only one device per beam. It is based on two cellular mirrors, called the chessboards, where each cell has a thickness that introduces, for any given central wavelength, a phase shift of (2k + 1)pi or of 2kpi on the fraction of the wave it reflects. Aims: We explore a more rigorous way to establish the optimum cell pattern design to attain the best theoretical performances for planet detection over a broad wavelength range. Two possible types of interferometres are now considered: on-axis and multi-axis. Methods: We derived a rather simple iterative scheme for both designs, determining the thickness and XY position of the cells. The method confers to the chessboards a high degree of internal symmetry. Each design can be described as an iterative Bracewell interferometer characterised by an integer order. We demonstrate that their efficiencies increases with the power of that order. Results: The device acts both spatially and versus wavelengths as an optical differential operator on the 3D light distribution. Its power is best understood in the on-axis case since its effect is to push away the stellar light from the centre over a very broad range of wavelengths, leaving space for an out of phase object to appear in the cleaned central region. We explore the theoretical performances for on-axis and multi-axis designs in the parameter space, and we especially compute the rejection factor for starlight and the attenuation factor for planet light and introduce the relative nulling efficiency metric. We show that, even with some realistic piston error added, the performances could meet the Darwin space project specifications for both designs, i.e., cancellation of the starlight by a factor of 105 over a wavelength range of 6-17 mum.
Published: 2010
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36. 3.8. Are the stellar populations in starbursts, LINERs and Seyfert galaxies similar?

Author: M. Serote Roos, Martin Ward, C. Boisson, M. Joly, and D. Pelat
Subjects: Physics, Luminous infrared galaxy, Active galactic nucleus, Stellar population, Radio galaxy, Elliptical galaxy, Astrophysics, Disc, Disc galaxy, Galaxy
Abstract: It is well known that about 10% of galaxies harbour an Active Galactic Nuclei (AGN). A debated question is whether the activity influences the stellar population, or inversely, whether the level of activity is induced by the stellar population. By inspection of AGN spectra of low activity level, it is obvious that starlight contributes to a substantial fraction of the light.
Published: 1998
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37. Steps toward determination of the size and structure of the broad-line region in active galatic nuclei. 8: an intensive HST, IUE, and ground-based study of NGC 5548

Author: K. T. Korista, D. Alloin, P. Barr, J. Clavel, R. D. Cohen, D. M. Crenshaw, I. N. Evans, K. Horne, A. P. Koratkar, G. A. Kriss, J. H. Krolik, M. A. Malkan, S. L. Morris, H. Netzer, P. T. O'Brien, B. M. Peterson, G. A. Reichert, P. M. Rodriguez-Pascual, W. Wamsteker, K. S. J. Anderson, D. J. Axon, E. Benitez, P. Berlind, R. Bertram, J. H., Jr. Blackwell, N. G. Bochkarev, C. Boisson, M. Carini, R. Carrillo, T. E. Carone, F.-Z. Cheng, J. A. Christensen, K. K. Chuvaev, M. Dietrich, J. J. Dokter, V. Doroshenko, D. Dultzin-Hacyan, M. N. England, B. R. Espey, A. V. Filippenko, C. M. Gaskell, M. R. Goad, L. C. Ho, J. P. Huchra, X. J. Jiang, S. Kaspi, W. Kollatschny, A. Laor, J.-P. Luminet, G. M. MacAlpine, J. W. MacKenty, Yu. F. Malkov, D. Maoz, P. G. Martin, T. Matheson, B. McCollum, N. Merkulova, L. Metik, M. Mignoli, H. R. Miller, M. G. Pastoriza, D. Pelat, J. Penfold, M. Perez, G. C. Perola, J. L. Persaud, J. Peters, R. Pitts, R. W. Pogge, I. Pronik, V. I. Pronik, R. L. Ptak, L. Rawley, M. C. Recondo-Gonzalez, J. M. Rodriguez-Espinosa, W. Romanishin, A. C. Sadun, I. Salamanca, M. Santos-Lleo, K. Sekiguchi, S. G. Sergeev, A. I. Shapovalova, J. C. Shields, C. Shrader, J. M. Shull, N. A. Silbermann, M. L. Sitko, D. R. Skillman, H. A. Smith, S. M. Smith, M. A. J. Snijders, L. S. Sparke, G. M. Stirpe, R. E. Stoner, W.-H. Sun, U. Thiele, S. Tokarz, Z. I. Tsvetanov, D. A. Turnshek, S. Veilleux, R. M. Wagner, S. J. Wagner, I. Wanders, T. Wang, W. F. Welsh, R. J. Weymann, R. J. White, B. J. Wilkes, B. J. Wills, C. Winge, H. Wu, and Z. L. Zou
Subjects: Physics, Active galactic nucleus, Faint Object Spectrograph, Astronomy, Astronomy and Astrophysics, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astronomical spectroscopy, Galaxy, Photometry (optics), Space and Planetary Science, Ultraviolet astronomy, Astrophysics::Solar and Stellar Astrophysics, Satellite, Astrophysics::Galaxy Astrophysics
Abstract: We present the data and initial results from a combined Hubble Space Telescope (HST)/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988-1989. IUE spectra were obtained once every 2 days for a period of 74 days beginning on 1993 March 14. During the last 39 days of this campaign, spectroscopic observations were also made with the HST Faint Object Spectrograph (FOS) on a daily basis. Ground-based observations, consisting of 165 optical spectra and 77 photometric observations (both CCD imaging and aperture photometry), are reported for the period 1992 October-1993 September, although many of the data are concentrated around the time of the satellite-based program. These data constitute a fifth year of intensive optical monitoring of this galaxy. In this contribution we describe the acquisition and reduction of all of the satellite and ground-based data obtained in this program. We describe in detail various photometric problems with the FOS and explain how we identified and corrected for various anomalies.
Published: 1995
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38. Metallicity of NGC 5128 Globular Clusters

Author: P. Jablonka, B. Bica, D. Pelat, and D. Alloin
Subjects: Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We have analyzed a selection of globular clusters based on the indications of high metallicity from previous photometric studies.
Published: 1995
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39. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 6: Variability of NGC 3783 from ground-based data

Author: G. M. Stirpe, C. Winge, B. Altieri, D. Alloin, E. L. Aguero, G. C. Anupama, R. Ashley, R. Bertram, J. H. Calderon, R. M. Catchpole, R. L. M. Corradi, E. Covino, H. A. Dottori, M. W. Feast, K. K. Ghosh, R. Gil Hutton, I. S. Glass, E. K. Grebel, L. Jorda, C. Koen, C. D. Laney, M. Maia, F. Marang, Y. D. Mayya, N. Morrell, Y. Nakada, M. G. Pastoriza, A. K. Pati, D. Pelat, B. M. Peterson, T. P. Prabhu, G. Roberts, R. Sagar, I. Salamanca, K. Sekiguchi, T. Storchi-Bergmann, A. Subramaniam, H. Van Winckel, F. van Wyk, M. Villada, R. M. Wagner, P. A. Whitelock, H. Winkler, J. Clavel, M. Dietrich, W. Kollatschny, P. T. O'Brien, G. C. Perola, M. C. Recondo-Gonzalez, P. Rodriguez-Pascual, and M. Santos-Lleo
Subjects: Physics, Active galactic nucleus, 010504 meteorology & atmospheric sciences, Continuum (measurement), Lag, Astronomy and Astrophysics, Astrophysics, Light curve, 01 natural sciences, Galaxy, Space and Planetary Science, Ionization, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: The Seyfert 1 galaxy NGC 3783 was intensely monitored between 1991 December and 1992 August. We present the results from the ground-based observations in the optical and near-IR, which complement the data-set from the IUE, discussed elsewhere. Spectroscopic and photometric data from many observatories were combined in order to obtain well sampled light curves of the continuum and of H-Beta. During the campaign the source varied significantly. The light curves of the optical continuum and of H-Beta are similar to those obtained with the IUE. The near-IR flux did not vary significantly except for an increase at the end of the campaign. The optical continuum and the flux of H-Beta lag the UV continuum by 1 day or less and by 8 days respectively. These results confirm that the continuum variations are simultaneous or have a very small lag across the entire UV-optical range, and that the lines of NGC 3783 respond to ionizing continuum variations with less delay than those of NGC 5548. As in NGC 5548, the lag of H-Beta is greater than those of the high ionization lines.
Published: 1994
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40. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 5: Variability of the ultraviolet continuum and emission lines of NGC 3783

Author: H. R. Miller, C. M. Gaskell, Alexei V. Filippenko, Hagai Netzer, M. A. J. Snijders, Gail A. Reichert, Joseph C. Shields, Aldo Altamore, E. I. Rosenblatt, S. M. Simkin, Kirk T. Korista, M. C. Recondo-Gonzalez, J. H. Blackwell, I. N. Evans, A. C. Sadun, Thaisa Storchi-Bergmann, Miriani Griselda Pastoriza, Chris Shrader, Claudia Winge, R. Stoner, P. M. Gondhalekar, M. A. Malkan, G. M. Stirpe, Tsevi Mazeh, G. C. Perola, Anuradha Koratkar, M. N. England, Tinggui Wang, T. E. Carone, B. McCollum, Bradley M. Peterson, Gerard A. Kriss, J. M. Shull, W. Zheng, Danielle Alloin, M. Santos-Lleo, Roger Ptak, Catherine Boisson, J. Clavel, Demos Kazanas, K. S. J. Anderson, Julian H. Krolik, Noah Brosch, C. Mendes de Oliveira, Richard W. Pogge, W. Wamsteker, D. M. Crenshaw, P. T. O'Brien, Gordon M. MacAlpine, J. M. Rodriguez-Espinoza, W. F. Welsh, M. Dietrich, D. Maoz, B. Altieri, M. R. Goad, Linda S. Sparke, Enrique Pérez, P. M. Rodriquez-Pascual, Wolfram Kollatschny, D. Pelat, Keith Horne, Wei-Hsin Sun, R. J. White, Michael L. Sitko, Reichert, Ga, Rodriguezpascual, Pm, Alloin, D, Clavel, J, Crenshaw, Dm, Kriss, Ga, Krolik, Jh, Malkan, Ma, Netzer, H, Peterson, Bm, Wamsteker, W, Altamore, Aldo, Altieri, B, Anderson, K, Blackwell, Jh, Boisson, C, Brosch, N, Carone, Te, Dietrich, M, England, Mn, Evans, In, Filippenko, Av, Gaskell, Cm, Goad, M, Gondhalekar, Pm, Horne, K, Kazanas, D, Kollatschny, W, Koratkar, Ap, Korista, Kt, Macalpine, Gm, Maoz, D, Mazeh, T, Mccollum, B, Miller, Hr, Deoliveira, Cm, Obrien, Pt, Pastoriza, Mg, Pelat, D, Perez, E, Perola, Gc, Pogge, Rw, Ptak, Rl, Recondogonzalez, Mc, Rodriguezespinosa, J, Rosenblatt, Ei, Sadun, Ac, Santoslleo, M, Shields, Jc, Shrader, Cr, Shull, Jm, Simkin, Sm, Sitko, Ml, Snijders, Maj, Sparke, L, Stirpe, Gm, Stoner, R, Storchibergmann, T, Sun, Wh, Wang, T, Welsh, Wf, White, Rj, Winge, C, and Zheng, W.
Subjects: Physics, Active galactic nucleus, Astronomy, Doubly ionized oxygen, Astronomy and Astrophysics, Astrophysics, Light curve, Galaxy, Wavelength, Amplitude, Space and Planetary Science, Ionization, Emission spectrum
Abstract: We report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of 7 months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or 'dips,' the first lasting is less than or approximately 20 days and the second is less than or approximately 4 days, with additional episodes of relatively rapid flickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became 'harder' when brighter. The variations in the continuum occurred simultaneously at all wavelengths (delta(t) is less than 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N V (which is relatively weak and badly blended with Ly(alpha), the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or 'lag.' As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are considerably shorter than those obtained for NGC 5548, with values of (formally) approximately 0 days for He II + O III), and approximately 4 days for Ly(alpha) and C IV. The data further suggest lags of approximately 4 days for Si IV + O IV) and 8-30 days for Si III + C III). Mg II lagged the 1460 A continuum by approximately 9 days, although this result depends on the method of measuring the line flux and may in fact be due to variability of the underlying Fe II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over timescales of is less than or approximately 2 days, and that the character of the continuum variability may change with time.
Published: 1994
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41. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I - an 8 month campaign of monitoring NGC 5548 with IUE

Author: Wei-Hsin Sun, C. M. Gaskell, G. C. Perola, M. Santos-Lleo, Aldo Altamore, A. P. Koratkar, Jean-Pierre Lasota, M. A. Malkan, Ian S. Glass, D. Pelat, D. J. Hutter, Gerard A. Kriss, Elia M. Leibowitz, Anne L. Kinney, Tsevi Mazeh, P. T. O'Brien, Sara C. Beck, E. J.A. Meurs, J. Clavel, Paolo Giommi, Wei Zheng, Roger Ptak, A. C. Sadun, P. M. Rodríguez-Pascual, Ari Laor, G. M. Stirpe, Kirk T. Korista, R. L. Hackney, Bradley M. Peterson, Julian H. Krolik, T. Baribaud, D. Maoz, Noah Brosch, D. M. Crenshaw, P. Barr, W. Wamsteker, Angeles I. Díaz, G. A. Reichert, E. van Groningen, Wolfram Kollatschny, Peter G. Martin, M. H. Ulrich, G. E. Bromage, Alexei V. Filippenko, Jules P. Halpern, Hagai Netzer, Klaus J. Fricke, E. I. Rosenblatt, R. A. Shaw, Danielle Alloin, Luc Binette, Enrique Pérez, Paul S. Smith, R. Stoner, P. M. Gondhalekar, S. Jörsäter, and A. D. Nair
Subjects: Physics, Satellite observation, Active galactic nucleus, Space and Planetary Science, Reverberation mapping, Astronomy, Astronomy and Astrophysics, Emission spectrum, Astrophysics, Ultraviolet radiation, Astronomical spectroscopy, Galaxy
Abstract: This is an electronic version of an article published in The Astrophysical Journal. Clavel, J. et al. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I. An 8 month campaign of monitoring NGC 5548 with IUE. The Astrophysical Journal 366 (1991): 64-81
Published: 1991
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42. Revisiting the Geometry of the BLR in AKN120: Preliminary Results from UV Data and Line Profile Analysis

Author: D. Alloin, T. Baribaud, C. Boisson, and D. Pelat
Abstract: From continuum and line intensity light-curves in the ultraviolet range, we find that the CIV peak-emission lies at about 2 ± 0.5 light-month from the centre. Line profile variations in the Ha and CIV emission suggest that the BLR is made of two regions with distinct kinematical properties: •a spherically distributed set of clouds, responsible for the broad HIL emission and responding to ionizing flux variations with a time-lag of 2 light-months at most•a disc-like structure from which most of the LIL emission arises, with a slow response to ionizing flux changes: hence larger is size.
Published: 1989
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43. A Detailed Study of the CIV 1550 Line Profile and Adjacent Spectral Features in NGC 4151 from 1978 UP to 1983

Author: C. G. Perola, M. V. Penston, M. A. J. Snijders, J. Clavel, Aldo Altamore, D. Pelat, M. H. Ulrich, A. Boksenberg, A. Elvius, G. E. Bromage, Clavel, J, Altamore, Aldo, Boksenberg, A, Bromage G., E, Elvius, A, Pelat, D, Perola, C, Penston M., V, Snijders M. A., J, and Ulrich, M. H.
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Line (text file), Astrophysics::Galaxy Astrophysics
Abstract: Fitting technics are applied to study the variations of the 1550 line profile and adjacent features in the IUE spectrum of the Seyfert galaxy NGC 4151, from 1978 up to 1983. New important results are found concerning the kinematics and physics of the emission line gas at a few light-days from the continuum source.
Published: 1986

44. Electronographic Study of the Nuclear Region in M 31

Author: D. Alloin, D. Pelat, and A. Bijaoui
Published: 1975
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45. Recent spectral variations in the active nucleus of NGC 1566

Author: D. Alloin, D. Pelat, M. Phillips, and Mark Whittle
Subjects: Physics, Luminous infrared galaxy, Balmer series, Astronomy and Astrophysics, Astrophysics, Disc galaxy, Galactic nuclei, Astronomical spectroscopy, Hubble sequence, symbols.namesake, medicine.anatomical_structure, Space and Planetary Science, symbols, medicine, H-alpha, Nucleus
Published: 1985
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46. A detailed study of the C IV 1550-A line profile and adjacent spectral features in NGC 4151 from 1978 to 1983

Author: D. Pelat, M. H. Ulrich, Aldo Altamore, G. C. Perola, Alec Boksenberg, J. Clavel, M. V. Penston, A. Elvius, M. A. J. Snijders, G. E. Bromage, Clavel, J, Altamore, Aldo, Boksenberg, A, Bromage, Ge, Elvius, A, Pelat, D, Penston, Mv, Perola, Gc, Snijders, Maj, and Ulrich, Mh
Subjects: Physics, Absorption spectroscopy, chemistry.chemical_element, Astronomy and Astrophysics, Gas dynamics, Astrophysics, Lambda, Galactic nuclei, chemistry, Space and Planetary Science, Emission spectrum, Spectrum analysis, Carbon, Line (formation)
Abstract: The 1450 - 1720 Å spectral region of NGC 4151 is analyzed by means of Gaussian decomposition for 69 different epochs, from early 1978 to the end of 1983. The C IV λ1550 emission profile is well represented by a core, whose full width at half-maximum varies between 2600 and 5500 km s-1, and an ultrabroad component (14,600 km s-1). The variations of the ultrabroad feature suggest that it originates in a region whose "radius" is ≡5 lt-day. The analysis of lines from He II, C III], N IV] and O III] indicates the presence of two additional discrete broad line subregions. A study of the velocity dispersions indicates that the motion of the gas is Keplerian and yields a value of (3.7±0.5)×107M_sun; for the central mass. A correlation is found between the wavelength of the ultrabroad C IV λ1550 component and its intensity. It strongly suggests the existence of a decelerated outflow whose velocity is 4000 km s-1 at 5 lt-day from the nucleus.
Published: 1987
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47. Balmer profile variations during the fading of the Seyfert 1 galaxy Fairall 9

Author: D. Pelat, Danielle Alloin, W. Wamsteker, and R. Gilmozzi
Subjects: Physics, Astronomy, Balmer series, Astronomy and Astrophysics, Astrophysics, Light curve, Spectral line, Galaxy, symbols.namesake, Space and Planetary Science, Thick disk, symbols, Fading, Emission spectrum, Line (formation)
Abstract: We present variations of the H..beta.. profile during the fading of the Seyfert 1 nucleus of Fairall 9, between 1981 and 1984. Decays with time scales from 250 days to 1000 days are found for the ultraviolet and optical continua, as well as for the H..beta.. line emission. These cannot be easily interpreted in terms of a change in the accretion rate in a steady state thick disk, while disk instabilities provide time scales of the right order of magnitude.
Published: 1985
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48. Recurrent outbursts in the broad-line region of NGC 1566

Author: Danielle Alloin, D. Pelat, R. A. E. Fosbury, K. Freeman, and M. Phillips
Subjects: Physics, Astronomy, Balmer series, Astronomy and Astrophysics, Astrophysics, Galactic nuclei, Spectral line, Astronomical spectroscopy, symbols.namesake, Accretion disc, Space and Planetary Science, symbols, Spectral energy distribution, H-alpha, Line (formation)
Published: 1986
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49. Study of the close environment of the active nucleus in NGC 1068 by decomposition of forbidden O III and H-beta emission-line profiles

Author: D. Pelat, A. Boksenberg, W. L. W. Sargent, and D. Alloin
Subjects: Physics, Active galactic nucleus, Doubly ionized oxygen, Astronomy and Astrophysics, Astrophysics, Galactic nuclei, Decomposition, Beta decay, medicine.anatomical_structure, Space and Planetary Science, medicine, Emission spectrum, Nucleus, Line (formation)
Published: 1983
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