Very high-energy gamma-ray follow-up program using neutrino triggers from IceCube

Journal of Instrumentation Institute of Physics 11:11 (2016) P11009

Authors:

MG Aartsen, K Abraham, M Ackermann, Subir Sarkar

Abstract:

We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e.g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015.

Marginal evidence for cosmic acceleration from Type Ia supernovae

Scientific Reports Springer Nature 6:1 (2016) 35596

Authors:

JT Nielsen, A Guffanti, Subir Sarkar

Abstract:

The ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

Contributions of the Cherenkov Telescope Array (CTA) to the 6th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma 2016)

(2016)

Authors:

The CTA Consortium, :, A Abchiche, U Abeysekara, Ó Abril, F Acero, BS Acharya, C Adams, G Agnetta, F Aharonian, A Akhperjanian, A Albert, M Alcubierre, J Alfaro, R Alfaro, AJ Allafort, R Aloisio, J-P Amans, E Amato, L Ambrogi, G Ambrosi, M Ambrosio, J Anderson, M Anduze, EO Angüner, E Antolini, LA Antonelli, M Antonucci, V Antonuccio, P Antoranz, C Aramo, A Aravantinos, M Araya, C Arcaro, B Arezki, A Argan, T Armstrong, F Arqueros, L Arrabito, M Arrieta, K Asano, M Ashley, P Aubert, CB Singh, A Babic, M Backes, A Bais, S Bajtlik, C Balazs, M Balbo, D Balis, C Balkowski, O Ballester, J Ballet, A Balzer, A Bamba, R Bandiera, A Barber, C Barbier, M Barcelo, M Barkov, A Barnacka, U Barres de Almeida, JA Barrio, S Basso, D Bastieri, C Bauer, U Becciani, Y Becherini, J Becker Tjus, V Beckmann, W Bednarek, W Benbow, D Benedico Ventura, J Berdugo, D Berge, E Bernardini, MG Bernardini, S Bernhard, K Bernlöhr, B Bertucci, M-A Besel, V Beshley, N Bhatt, P Bhattacharjee, W Bhattacharyya, S Bhattachryya, B Biasuzzi, G Bicknell, C Bigongiari, A Biland, A Bilinsky, W Bilnik, B Biondo, R Bird, T Bird, E Bissaldi, M Bitossi, O Blanch, P Blasi, J Blazek, C Bockermann, C Boehm, L Bogacz, M Bogdan, M Bohacova, C Boisson, J Boix, J Bolmont, G Bonanno, A Bonardi, C Bonavolontà, P Bonifacio, F Bonnarel, G Bonnoli, J Borkowski, R Bose, Z Bosnjak, M Böttcher, J-J Bousquet, C Boutonnet, F Bouyjou, L Bowman, C Braiding, T Brantseg, S Brau-Nogué, J Bregeon, M Briggs, M Brigida, T Bringmann, W Brisken, D Bristow, R Britto, E Brocato, S Bron, P Brook, W Brooks, AM Brown, K Brügge, F Brun, P Brun, P Brun, G Brunetti, L Brunetti, P Bruno, T Buanes, N Bucciantini, G Buchholtz, J Buckley, V Bugaev, R Bühler, A Bulgarelli, T Bulik, M Burton, A Burtovoi, G Busetto, S Buson, J Buss, K Byrum, F Cadoux, J Calvo Tovar, R Cameron, F Canelli, R Canestrari, M Capalbi, M Capasso, G Capobianco, A Caproni, P Caraveo, J Cardenzana, M Cardillo, S Carius, C Carlile, A Carosi, R Carosi, E Carquín, J Carr, M Carroll, J Carter, P-H Carton, J-M Casandjian, S Casanova, S Casanova, E Cascone, M Casiraghi, A Castellina, J Castroviejo Mora, F Catalani, O Catalano, S Catalanotti, D Cauz, S Cavazzani, P Cerchiara, E Chabanne, P Chadwick, T Chaleil, C Champion, A Chatterjee, S Chaty, R Chaves, A Chen, X Chen, X Chen, K Cheng, M Chernyakova, L Chiappetti, M Chikawa, D Chinn, VR Chitnis, N Cho, A Christov, J Chudoba, M Cieślar, MA Ciocci, R Clay, S Colafrancesco, P Colin, J-M Colley, E Colombo, J Colome, S Colonges, V Conforti, V Connaughton, S Connell, J Conrad, JL Contreras, P Coppi, S Corbel, J Coridian, R Cornat, P Corona, D Corti, J Cortina, L Cossio, A Costa, H Costantini, G Cotter, B Courty, S Covino, G Covone, G Crimi, SJ Criswell, R Crocker, J Croston, J Cuadra, P Cumani, G Cusumano, P Da Vela, Ø Dale, F D'Ammando, D Dang, VT Dang, L Dangeon, M Daniel, I Davids, I Davids, B Dawson, F Dazzi, B de Aguiar Costa, A De Angelis, RF de Araujo Cardoso, V De Caprio, R de Cássia dos Anjos, G De Cesare, A De Franco, F De Frondat, EM de Gouveia Dal Pino, I de la Calle, C De Lisio, R de los Reyes Lopez, B De Lotto, A De Luca, JRT de Mello Neto, M de Naurois, E de Oña Wilhelmi, F De Palma, F De Persio, V de Souza, G Decock, J Decock, C Deil, M Del Santo, E Delagnes, G Deleglise, C Delgado, J Delgado, D della Volpe, P Deloye, M Detournay, A Dettlaff, J Devin, T Di Girolamo, C Di Giulio, A Di Paola, F Di Pierro, MA Diaz, C Díaz, C Dib, J Dick, H Dickinson, S Diebold, S Digel, J Dipold, G Disset, A Distefano, A Djannati-Ataï, M Doert, M Dohmke, A Domínguez, N Dominik, J-L Dominique, D Dominis Prester, A Donat, I Donnarumma, D Dorner, M Doro, J-L Dournaux, T Downes, K Doyle, G Drake, S Drappeau, H Drass, D Dravins, L Drury, G Dubus, L Ducci, D Dumas, K Dundas Morå, D Durand, D D'Urso, V Dwarkadas, J Dyks, M Dyrda, J Ebr, E Edy, K Egberts, P Eger, A Egorov, S Einecke, J Eisch, F Eisenkolb, C Eleftheriadis, D Elsaesser, D Elsässer, D Emmanoulopoulos, C Engelbrecht, D Engelhaupt, J-P Ernenwein, P Escarate, S Eschbach, C Espinoza, P Evans, M Fairbairn, D Falceta-Goncalves, A Falcone, V Fallah Ramazani, D Fantinel, K Farakos, C Farnier, E Farrell, G Fasola, Y Favre, E Fede, R Fedora, E Fedorova, S Fegan, D Ferenc, M Fernandez-Alonso, A Fernández-Barral, G Ferrand, O Ferreira, M Fesquet, P Fetfatzis, E Fiandrini, A Fiasson, A Filipčič, M Filipovic, D Fink, C Finley, JP Finley, A Finoguenov, V Fioretti, M Fiorini, H Fleischhack, H Flores, D Florin, C Föhr, E Fokitis, MV Fonseca, L Font, G Fontaine, B Fontes, M Fornasa, M Fornasa, A Förster, P Fortin, L Fortson, N Fouque, A Franckowiak, A Franckowiak, FJ Franco, I Freire Mota Albuquerque, L Freixas Coromina, L Fresnillo, C Fruck, M Fuessling, D Fugazza, Y Fujita, S Fukami, Y Fukazawa, T Fukuda, Y Fukui, S Funk, A Furniss, W Gäbele, S Gabici, A Gadola, D Galindo, DD Gall, Y Gallant, D Galloway, S Gallozzi, JA Galvez, S Gao, A Garcia, B Garcia, R García Gil, R Garcia López, M Garczarczyk, D Gardiol, C Gargano, F Gargano, S Garozzo, F Garrecht, L Garrido, M Garrido-Ruiz, D Gascon, J Gaskins, J Gaudemard, M Gaug, J Gaweda, B Gebhardt, M Gebyehu, N Geffroy, B Genolini, L Gerard, A Ghalumyan, A Ghedina, P Ghislain, P Giammaria, E Giannakaki, F Gianotti, S Giarrusso, G Giavitto, B Giebels, T Gieras, N Giglietto, V Gika, R Gimenes, M Giomi, P Giommi, F Giordano, G Giovannini, P Girardot, E Giro, M Giroletti, J Gironnet, A Giuliani, J-F Glicenstein, R Gnatyk, N Godinovic, P Goldoni, G Gomez, MM Gonzalez, A González, D Gora, KS Gothe, D Gotz, J Goullon, T Grabarczyk, R Graciani, J Graham, P Grandi, J Granot, G Grasseau, R Gredig, AJ Green, AM Green, T Greenshaw, I Grenier, S Griffiths, A Grillo, M-H Grondin, J Grube, M Grudzinska, J Grygorczuk, V Guarino, D Guberman, S Gunji, G Gyuk, D Hadasch, A Hagedorn, L Hagge, J Hahn, H Hakobyan, S Hara, MJ Hardcastle, T Hassan, K Hatanaka, T Haubold, A Haupt, T Hayakawa, M Hayashida, M Heller, R Heller, JC Helo, F Henault, G Henri, G Hermann, R Hermel, J Herrera Llorente, J Herrera Llorente, A Herrero, O Hervet, N Hidaka, J Hinton, W Hirai, K Hirotani, B Hnatyk, J Hoang, D Hoffmann, W Hofmann, T Holch, J Holder, S Hooper, D Horan, J Hörandel, M Hörbe, D Horns, P Horvath, J Hose, J Houles, T Hovatta, M Hrabovsky, D Hrupec, J-M Huet, M Huetten, G Hughes, D Hui, TB Humensky, M Hussein, M Iacovacci, A Ibarra, Y Ikeno, JM Illa, D Impiombato, T Inada, S Incorvaia, L Infante, Y Inome, S Inoue, T Inoue, Y Inoue, F Iocco, K Ioka, M Iori, K Ishio, K Ishio, GL Israel, Y Iwamura, C Jablonski, A Jacholkowska, J Jacquemier, M Jamrozy, P Janecek, M Janiak, D Jankowsky, F Jankowsky, P Jean, I Jegouzo, P Jenke, JJ Jimenez, M Jingo, M Jingo, L Jocou, T Jogler, CA Johnson, M Jones, M Josselin, L Journet, I Jung, P Kaaret, M Kagaya, J Kakuwa, O Kalekin, C Kalkuhl, H Kamon, R Kankanyan, A Karastergiou, K Kärcher, M Karczewski, S Karkar, P Karn, J Kasperek, H Katagiri, J Kataoka, K Katarzyński, S Kato, U Katz, N Kawanaka, L Kaye, D Kazanas, N Kelley-Hoskins, J Kersten, B Khélifi, DB Kieda, T Kihm, S Kimeswenger, S Kisaka, S Kishida, R Kissmann, S Klepser, W Kluźniak, J Knapen, J Knapp, J Knödlseder, B Koch, F Köck, J Kocot, K Kohri, K Kokkotas, K Kokkotas, D Kolitzus, N Komin, I Kominis, A Kong, Y Konno, K Kosack, G Koss, M Kossatz, G Kowal, S Koyama, J Kozioł, M Kraus, J Krause, M Krause, H Krawzcynski, F Krennrich, A Kretzschmann, P Kruger, H Kubo, V Kudryavtsev, G Kukec Mezek, M Kuklis, H Kuroda, J Kushida, A La Barbera, N La Palombara, V La Parola, G La Rosa, H Laffon, R Lahmann, M Lakicevic, K Lalik, G Lamanna, D Landriu, H Landt, RG Lang, J Lapington, P Laporte, J-P Le Fèvre, T Le Flour, P Le Sidaner, S-H Lee, WH Lee, J-P Lees, J Lefaucheur, K Leffhalm, H Leich, MA Leigui de Oliveira, D Lelas, A Lemière, M Lemoine-Goumard, J-P Lenain, R Leonard, R Leoni, L Lessio, G Leto, A Leveque, B Lieunard, M Limon, R Lindemann, E Lindfors, L Linhoff, A Liolios, A Lipniacka, H Lockart, T Lohse, E Łokas, S Lombardi, F Longo, A Lopatin, M Lopez, D Loreggia, T Louge, F Louis, M Louys, F Lucarelli, D Lucchesi, H Lüdecke, T Luigi, PL Luque-Escamilla, E Lyard, MC Maccarone, T Maccarone, TJ Maccarone, E Mach, GM Madejski, A Madonna, F Magniette, A Magniez, M Mahabir, G Maier, P Majumdar, P Majumdar, M Makariev, G Malaguti, G Malaspina, AK Mallot, A Malouf, S Maltezos, D Malyshev, A Mancilla, D Mandat, G Maneva, M Manganaro, S Mangano, P Manigot, N Mankushiyil, K Mannheim, N Maragos, D Marano, P Marchegiani, JA Marcomini, A Marcowith, M Mariotti, M Marisaldi, S Markoff, C Martens, J Martí, J-M Martin, L Martin, P Martin, G Martínez, M Martínez, O Martínez, K Martynyuk-Lototskyy, R Marx, N Masetti, P Massimino, A Mastichiadis, S Mastroianni, M Mastropietro, S Masuda, H Matsumoto, S Matsuoka, N Matthews, S Mattiazzo, G Maurin, N Maxted, N Maxted, J Maya, M Mayer, D Mazin, MN Mazziotta, L Mc Comb, N McCubbin, I McHardy, C Medina, F Mehrez, C Melioli, D Melkumyan, T Melse, S Mereghetti, M Merk, P Mertsch, J-L Meunier, T Meures, M Meyer, JL Meyrelles, A Miccichè, T Michael, J Michałowski, P Mientjes, I Mievre, A Mihailidis, J Miller, T Mineo, M Minuti, N Mirabal, F Mirabel, JM Miranda, R Mirzoyan, A Mitchell, T Mizuno, R Moderski, I Mognet, M Mohammed, R Moharana, L Mohrmann, E Molinari, P Molyneux, E Monmarthe, G Monnier, T Montaruli, C Monte, I Monteiro, D Mooney, P Moore, A Moralejo, C Morello, E Moretti, K Mori, P Morris, A Morselli, F Moscato, D Motohashi, F Mottez, Y Moudden, E Moulin, S Mueller, R Mukherjee, P Munar, M Munari, C Mundell, J Mundet, H Muraishi, K Murase, A Muronga, A Murphy, N Nagar, S Nagataki, T Nagayoshi, BK Nagesh, T Naito, D Nakajima, D Nakajima, T Nakamori, K Nakayama, J Nanni, D Naumann, P Nayman, L Nellen, R Nemmen, A Neronov, N Neyroud, T Nguyen, TT Nguyen, T Nguyen Trung, L Nicastro, J Nicolau-Kukliński, F Niederwanger, A Niedźwiecki, J Niemiec, D Nieto, M Nievas-Rosillo, A Nikolaidis, M Nikołajuk, K Nishijima, K-I Nishikawa, G Nishiyama, K Noda, K Noda, L Nogues, S Nolan, R Northrop, D Nosek, M Nöthe, B Novosyadlyj, L Nozka, F Nunio, L Oakes, P O'Brien, C Ocampo, G Occhipinti, JP Ochoa, A OFaolain de Bhroithe, R Oger, Y Ohira, M Ohishi, S Ohm, H Ohoka, N Okazaki, A Okumura, J-F Olive, D Olszowski, RA Ong, S Ono, M Orienti, R Orito, A Orlati, J Osborne, M Ostrowski, D Ottaway, N Otte, S Öttl, E Ovcharov, I Oya, A Ozieblo, M Padovani, I Pagano, S Paiano, A Paizis, J Palacio, M Palatka, J Pallotta, K Panagiotidis, J-L Panazol, D Paneque, M Panter, MR Panzera, R Paoletti, M Paolillo, A Papayannis, G Papyan, A Paravac, JM Paredes, G Pareschi, N Park, D Parsons, P Paśko, S Pavy, M Pech, A Peck, G Pedaletti, A Pe'er, S Peet, D Pelat, A Pepato, MDC Perez, L Perri, M Perri, M Persic, M Persic, A Petrashyk, P-O Petrucci, O Petruk, B Peyaud, M Pfeifer, G Pfeiffer, G Piano, D Pieloth, E Pierre, F Pinto de Pinho, C Pio García, Y Piret, A Pisarski, S Pita, Ł Platos, R Platzer, S Podkladkin, L Pogosyan, M Pohl, P Poinsignon, A Pollo, A Porcelli, J Porthault, W Potter, S Poulios, J Poutanen, E Prandini, E Prandini, J Prast, K Pressard, G Principe, F Profeti, D Prokhorov, H Prokoph, M Prouza, R Pruchniewicz, G Pruteanu, E Pueschel, G Pühlhofer, I Puljak, M Punch, S Pürckhauer, R Pyzioł, F Queiroz, EJ Quel, J Quinn, A Quirrenbach, I Rafighi, S Rainò, PJ Rajda, M Rameez, R Rando, RC Rannot, M Rataj, T Ravel, S Razzaque, P Reardon, I Reichardt, O Reimann, A Reimer, O Reimer, A Reisenegger, M Renaud, S Renner, T Reposeur, B Reville, A Rezaeian, W Rhode, D Ribeiro, R Ribeiro Prado, M Ribó, G Richards, MG Richer, T Richtler, J Rico, J Ridky, F Rieger, M Riquelme, PR Ristori, S Rivoire, V Rizi, E Roache, J Rodriguez, G Rodriguez Fernandez, JJ Rodríguez Vázquez, G Rojas, P Romano, G Romeo, M Roncadelli, J Rosado, J Rose, S Rosen, S Rosier Lees, D Ross, G Rouaix, J Rousselle, AC Rovero, G Rowell, F Roy, S Royer, A Rubini, B Rudak, A Rugliancich, W Rujopakarn, C Rulten, M Rupiński, F Russo, F Russo, K Rutkowski, O Saavedra, S Sabatini, B Sacco, I Sadeh, EO Saemann, S Safi-Harb, A Saggion, V Sahakian, T Saito, N Sakaki, S Sakurai, A Salamon, M Salega, D Salek, F Salesa Greus, J Salgado, G Salina, L Salinas, A Salini, D Sanchez, M Sanchez-Conde, H Sandaker, A Sandoval, P Sangiorgi, M Sanguillon, H Sano, M Santander, A Santangelo, EM Santos, R Santos-Lima, A Sanuy, L Sapozhnikov, S Sarkar, K Satalecka, K Satalecka, Y Sato, R Savalle, M Sawada, F Sayède, S Schanne, T Schanz, EJ Schioppa, S Schlenstedt, J Schmid, T Schmidt, J Schmoll, M Schneider, H Schoorlemmer, P Schovanek, A Schubert, E-M Schullian, J Schultze, A Schulz, S Schulz, K Schure, F Schussler, T Schwab, U Schwanke, J Schwarz, T Schweizer, S Schwemmer, U Schwendicke, C Schwerdt, E Sciacca, S Scuderi, A Segreto, J-H Seiradakis, GH Sembroski, D Semikoz, O Sergijenko, N Serre, M Servillat, K Seweryn, N Shafi, A Shalchi, M Sharma, M Shayduk, RC Shellard, T Shibata, A Shigenaka, I Shilon, E Shum, L Sidoli, M Sidz, J Sieiro, H Siejkowski, J Silk, A Sillanpää, D Simone, H Simpson, BB Singh, A Sinha, G Sironi, J Sitarek, P Sizun, V Sliusar, V Sliusar, A Smith, D Sobczyńska, H Sol, G Sottile, M Sowiński, F Spanier, G Spengler, R Spiga, R Stadler, O Stahl, A Stamerra, S Stanič, R Starling, D Staszak, Ł Stawarz, R Steenkamp, S Stefanik, C Stegmann, S Steiner, C Stella, M Stephan, N Stergioulas, R Sternberger, M Sterzel, B Stevenson, F Stinzing, M Stodulska, M Stodulski, T Stolarczyk, G Stratta, U Straumann, L Stringhetti, M Strzys, R Stuik, K-H Sulanke, T Suomijärvi, AD Supanitsky, T Suric, I Sushch, P Sutcliffe, J Sykes, M Szanecki, T Szepieniec, P Szwarnog, A Tacchini, K Tachihara, G Tagliaferri, H Tajima, H Takahashi, K Takahashi, M Takahashi, L Takalo, S Takami, J Takata, J Takeda, G Talbot, T Tam, M Tanaka, S Tanaka, T Tanaka, Y Tanaka, C Tanci, S Tanigawa, M Tavani, F Tavecchio, J-P Tavernet, K Tayabaly, A Taylor, LA Tejedor, I Telezhinsky, F Temme, P Temnikov, C Tenzer, Y Terada, JC Terrazas, R Terrier, D Terront, T Terzic, D Tescaro, M Teshima, M Teshima, V Testa, D Tezier, J Thayer, J Thornhill, S Thoudam, D Thuermann, L Tibaldo, A Tiengo, MC Timpanaro, D Tiziani, M Tluczykont, CJ Todero Peixoto, F Tokanai, M Tokarz, K Toma, J Tomastik, Y Tomono, A Tonachini, D Tonev, K Torii, M Tornikoski, DF Torres, M Torres, E Torresi, G Toso, G Tosti, T Totani, N Tothill, F Toussenel, G Tovmassian, T Toyama, P Travnicek, C Trichard, M Trifoglio, I Troyano Pujadas, M Trzeciak, K Tsinganos, S Tsujimoto, T Tsuru, Y Uchiyama, G Umana, Y Umetsu, SS Upadhya, M Uslenghi, V Vagelli, F Vagnetti, J Valdes-Galicia, M Valentino, P Vallania, L Valore, W van Driel, C van Eldik, B van Soelen, J Vandenbroucke, J Vanderwalt, G Vasileiadis, V Vassiliev, JR Vázquez, ML Vázquez Acosta, M Vecchi, A Vega, I Vegas, P Veitch, P Venault, L Venema, C Venter, S Vercellone, S Vergani, K Verma, V Verzi, GP Vettolani, C Veyssiere, A Viana, N Viaux, J Vicha, C Vigorito, P Vincent, S Vincent, J Vink, V Vittorini, N Vlahakis, L Vlahos, H Voelk, V Voisin, A Vollhardt, A Volpicelli, H von Brand, S Vorobiov, I Vovk, M Vrastil, LV Vu, T Vuillaume, R Wagner, R Wagner, SJ Wagner, SP Wakely, T Walstra, R Walter, T Walther, JE Ward, M Ward, K Warda, D Warren, S Wassberg, JJ Watson, P Wawer, R Wawrzaszek, N Webb, P Wegner, O Weiner, A Weinstein, R Wells, F Werner, H Wetteskind, M White, R White, M Więcek, A Wierzcholska, S Wiesand, R Wijers, P Wilcox, N Wild, A Wilhelm, M Wilkinson, M Will, M Will, DA Williams, JT Williams, R Willingale, N Wilson, M Winde, K Winiarski, H Winkler, M Winter, R Wischnewski, E Witt, P Wojcik, D Wolf, M Wood, A Wörnlein, E Wu, T Wu, KK Yadav, H Yamamoto, T Yamamoto, N Yamane, R Yamazaki, S Yanagita, L Yang, D Yelos, A Yoshida, M Yoshida, T Yoshida, S Yoshiike, T Yoshikoshi, P Yu, V Zabalza, D Zaborov, M Zacharias, G Zaharijas, A Zajczyk, L Zampieri, F Zandanel, R Zanmar Sanchez, D Zaric, D Zavrtanik, M Zavrtanik, A Zdziarski, A Zech, H Zechlin, A Zhao, V Zhdanov, A Ziegler, J Ziemann, K Ziętara, A Zink, J Ziółkowski, V Zitelli, A Zoli, J Zorn, P Żychowski

Frames of most uniform Hubble flow

Journal of Cosmology and Astroparticle Physics IOP Publishing 2016:10 (2016) 1-17

Authors:

David Kraljic, Subir Sarkar

Abstract:

It has been observed [1,2] that the locally measured Hubble parameter converges quickest to the background value and the dipole structure of the velocity field is smallest in the reference frame of the Local Group of galaxies. We study the statistical properties of Lorentz boosts with respect to the Cosmic Microwave Background frame which make the Hubble flow look most uniform around a particular observer. We use a very large N-Body simulation to extract the dependence of the boost velocities on the local environment such as underdensities, overdensities, and bulk flows. We find that the observation [1,2] is not unexpected if we are located in an underdensity, which is indeed the case for our position in the universe. The amplitude of the measured boost velocity for our location is consistent with the expectation in the standard cosmology.

Search for sources of High-Energy neutrons with four years of data from the Icetop Detector

Astrophysical Journal Institute of Physics 830:2 (2016) 129-129

Abstract:

IceTop is an air-shower array located on the Antarctic ice sheet at the geographic South Pole. IceTop can detect an astrophysicalflux of neutrons from Galactic sources as an excess of cosmic-ray air showers arriving from the source direction. Neutrons are undeflected by the Galactic magneticfield and can typically travel 10(E/PeV)pc before decay. Two searches are performed using 4 yr of the IceTop data set to look for a statistically significant excess of events with energies above 10 PeV(10^16 eV) arriving within a small solid angle. The all-sky search method covers from−90°to approximately −50°in declination. No significant excess is found. A targeted search is also performed, looking for significant correlation with candidate sources in different target sets. This search uses a higher-energy cut(100 PeV) since most target objects lie beyond 1 kpc. The target sets include pulsars with confirmed TeV energy photon fluxes and high-mass X-ray binaries. No significant correlation is found for any target set. Flux upper limits are determined for both searches, which can constrain Galactic neutron sources and production scenarios.