New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR.

Monthly notices of the Royal Astronomical Society 459:3 (2016) 3161-3174

Authors:

D Carbone, AJ van der Horst, RAMJ Wijers, JD Swinbank, A Rowlinson, JW Broderick, YN Cendes, AJ Stewart, ME Bell, RP Breton, S Corbel, J Eislöffel, RP Fender, J-M Grießmeier, JWT Hessels, P Jonker, M Kramer, CJ Law, JCA Miller-Jones, M Pietka, LHA Scheers, BW Stappers, J van Leeuwen, R Wijnands, M Wise, P Zarka

Abstract:

We report on the results of a search for radio transients between 115 and 190 MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 min and several months. A total of 151 images were obtained, giving a total survey area of 2275 deg2. We analysed our data using standard LOFAR tools and searched for radio transients using the LOFAR Transients Pipeline. No credible radio transient candidate has been detected; however, we are able to set upper limits on the surface density of radio transient sources at low radio frequencies. We also show that low-frequency radio surveys are more sensitive to steep-spectrum coherent transient sources than GHz radio surveys. We used two new statistical methods to determine the upper limits on the transient surface density. One is free of assumptions on the flux distribution of the sources, while the other assumes a power-law distribution in flux and sets more stringent constraints on the transient surface density. Both of these methods provide better constraints than the approach used in previous works. The best value for the upper limit we can set for the transient surface density, using the method assuming a power-law flux distribution, is 1.3 × 10-3 deg-2 for transients brighter than 0.3 Jy with a time-scale of 15 min, at a frequency of 150 MHz. We also calculated for the first time upper limits for the transient surface density for transients of different time-scales. We find that the results can differ by orders of magnitude from previously reported, simplified estimates.

Evidence for simultaneous jets and disk winds in luminous low-mass X-ray binaries

(2016)

Authors:

Jeroen Homan, Joseph Neilsen, Jessamyn L Allen, Deepto Chakrabarty, Rob Fender, Joel K Fridriksson, Ronald A Remillard, Norbert Schulz

Energy estimation of cosmic rays with the Engineering Radio Array of the Pierre Auger Observatory

Physical Review D American Physical Society (APS) 93:12 (2016) 122005

Authors:

A Aab, P Abreu, M Aglietta, EJ Ahn, I Al Samarai, IFM Albuquerque, I Allekotte, P Allison, A Almela, J Alvarez Castillo, J Alvarez-Muñiz, R Alves Batista, M Ambrosio, A Aminaei, GA Anastasi, L Anchordoqui, S Andringa, C Aramo, F Arqueros, N Arsene, H Asorey, P Assis, J Aublin, G Avila, N Awal, AM Badescu, C Baus, JJ Beatty, KH Becker, JA Bellido, C Berat, ME Bertaina, X Bertou, PL Biermann, P Billoir, SG Blaess, A Blanco, M Blanco, J Blazek, C Bleve, H Blümer, M Boháčová, D Boncioli, C Bonifazi, N Borodai, J Brack, I Brancus, T Bretz, A Bridgeman, P Brogueira, P Buchholz, A Bueno, S Buitink, M Buscemi, KS Caballero-Mora, B Caccianiga, L Caccianiga, M Candusso, L Caramete, R Caruso, A Castellina, G Cataldi, L Cazon, R Cester, AG Chavez, A Chiavassa, JA Chinellato, J Chudoba, M Cilmo, RW Clay, G Cocciolo, R Colalillo, A Coleman, L Collica, MR Coluccia, R Conceição, F Contreras, MJ Cooper, A Cordier, S Coutu, CE Covault, J Cronin, R Dallier, B Daniel, S Dasso, K Daumiller, BR Dawson, RM de Almeida, SJ de Jong, G De Mauro, JRT de Mello Neto, I De Mitri, J de Oliveira, V de Souza, L del Peral, O Deligny, N Dhital, C Di Giulio, A Di Matteo, JC Diaz, ML Díaz Castro, F Diogo, C Dobrigkeit, W Docters, JC D’Olivo, A Dorofeev, Q Dorosti Hasankiadeh, RC dos Anjos, MT Dova, J Ebr, R Engel, M Erdmann, M Erfani, CO Escobar, J Espadanal, A Etchegoyen, H Falcke, K Fang, G Farrar, AC Fauth, N Fazzini, AP Ferguson, B Fick, JM Figueira, A Filevich, A Filipčič, O Fratu, MM Freire, T Fujii, B García, D Garcia-Gamez, D Garcia-Pinto, F Gate, H Gemmeke, A Gherghel-Lascu, PL Ghia, U Giaccari, M Giammarchi, M Giller, D Głas, C Glaser, H Glass, G Golup, M Gómez Berisso, PF Gómez Vitale, N González, B Gookin, J Gordon, A Gorgi, P Gorham, P Gouffon, N Griffith, AF Grillo, TD Grubb, F Guarino, GP Guedes, MR Hampel, P Hansen, D Harari, TA Harrison, S Hartmann, JL Harton, A Haungs, T Hebbeker, D Heck, P Heimann, AE Herve, GC Hill, C Hojvat, N Hollon, E Holt, P Homola, JR Hörandel, P Horvath, M Hrabovský, D Huber, T Huege, A Insolia, PG Isar, I Jandt, S Jansen, C Jarne, JA Johnsen, M Josebachuili, A Kääpä, O Kambeitz, KH Kampert, P Kasper, I Katkov, B Keilhauer, E Kemp, RM Kieckhafer, HO Klages, M Kleifges, J Kleinfeller, R Krause, N Krohm, D Kuempel, G Kukec Mezek, N Kunka, AW Kuotb Awad, D LaHurd, L Latronico, R Lauer, M Lauscher, P Lautridou, S Le Coz, D Lebrun, P Lebrun, MA Leigui de Oliveira, A Letessier-Selvon, I Lhenry-Yvon, K Link, L Lopes, R López, A López Casado, K Louedec, A Lucero, M Malacari, M Mallamaci, J Maller, D Mandat, P Mantsch, AG Mariazzi, V Marin, IC Mariş, G Marsella, D Martello, H Martinez, O Martínez Bravo, D Martraire, JJ Masías Meza, HJ Mathes, S Mathys, J Matthews, JAJ Matthews, G Matthiae, D Maurizio, E Mayotte, PO Mazur, C Medina, G Medina-Tanco, R Meissner, VBB Mello, D Melo, A Menshikov, S Messina, MI Micheletti, L Middendorf, IA Minaya, L Miramonti, B Mitrica, L Molina-Bueno, S Mollerach, F Montanet, C Morello, M Mostafá, CA Moura, MA Muller, G Müller, S Müller, S Navas, P Necesal, L Nellen, A Nelles, J Neuser, PH Nguyen, M Niculescu-Oglinzanu, M Niechciol, L Niemietz, T Niggemann, D Nitz, D Nosek, V Novotny, L Nožka, LA Núñez, L Ochilo, F Oikonomou, A Olinto, N Pacheco, D Pakk Selmi-Dei, M Palatka, J Pallotta, P Papenbreer, G Parente, A Parra, T Paul, M Pech, J Pȩkala, R Pelayo, IM Pepe, L Perrone, E Petermann, C Peters, S Petrera, Y Petrov, J Phuntsok, R Piegaia, T Pierog, P Pieroni, M Pimenta, V Pirronello, M Platino, M Plum, A Porcelli, C Porowski, RR Prado, P Privitera, M Prouza, EJ Quel, S Querchfeld, S Quinn, J Rautenberg, O Ravel, D Ravignani, D Reinert, B Revenu, J Ridky, M Risse, P Ristori, V Rizi, W Rodrigues de Carvalho, J Rodriguez Rojo, MD Rodríguez-Frías, D Rogozin, J Rosado, M Roth, E Roulet, AC Rovero, SJ Saffi, A Saftoiu, H Salazar, A Saleh, F Salesa Greus, G Salina, JD Sanabria Gomez, F Sánchez, P Sanchez-Lucas, E Santos, EM Santos, F Sarazin, B Sarkar, R Sarmento, C Sarmiento-Cano, R Sato, C Scarso, M Schauer, V Scherini, H Schieler, D Schmidt, O Scholten, H Schoorlemmer, P Schovánek, FG Schröder, A Schulz, J Schulz, J Schumacher, SJ Sciutto, A Segreto, M Settimo, A Shadkam, RC Shellard, G Sigl, O Sima, A Śmiałkowski, R Šmída, GR Snow, P Sommers, S Sonntag, J Sorokin, R Squartini, YN Srivastava, D Stanca, S Stanič, J Stapleton, J Stasielak, M Stephan, A Stutz, F Suarez, M Suarez Durán, T Suomijärvi, AD Supanitsky, MS Sutherland, J Swain, Z Szadkowski, OA Taborda, A Tapia, A Tepe, VM Theodoro, C Timmermans, CJ Todero Peixoto, G Toma, L Tomankova, B Tomé, A Tonachini, G Torralba Elipe, D Torres Machado, P Travnicek, M Trini, R Ulrich, M Unger, M Urban, JF Valdés Galicia, I Valiño, L Valore, G van Aar, P van Bodegom, AM van den Berg, S van Velzen, A van Vliet, E Varela, B Vargas Cárdenas, G Varner, R Vasquez, JR Vázquez, RA Vázquez, D Veberič, V Verzi, J Vicha, M Videla, L Villaseñor, B Vlcek, S Vorobiov, H Wahlberg, O Wainberg, D Walz, AA Watson, M Weber, K Weidenhaupt, A Weindl, C Welling, F Werner, A Widom, L Wiencke, H Wilczyński, T Winchen, D Wittkowski, B Wundheiler, S Wykes, L Yang, T Yapici, A Yushkov, E Zas, D Zavrtanik, M Zavrtanik, A Zepeda, B Zimmermann, M Ziolkowski, F Zuccarello

Radio Galaxy Zoo: discovery of a poor cluster through a giant wide-angle tail radio galaxy

(2016)

Authors:

JK Banfield, H Andernach, AD Kapinska, L Rudnick, MJ Hardcastle, G Cotter, S Vaughan, TW Jones, I Heywood, JD Wing, OI Wong, T Matorny, IA Terentev, AR Lopez-Sanchez, RP Norris, N Seymour, SS Shabala, KW Willett

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy.

Physical review letters American Physical Society (APS) 116:24 (2016) ARTN 241101

Authors:

A Aab, P Abreu, M Aglietta, Ej Ahn, I Al Samarai, Ifm Albuquerque, I Allekotte, P Allison, A Almela, J Alvarez Castillo, J Alvarez-Muñiz, R Alves Batista, M Ambrosio, A Aminaei, Ga Anastasi, L Anchordoqui, S Andringa, C Aramo, F Arqueros, N Arsene, H Asorey, P Assis, J Aublin, G Avila, N Awal, Am Badescu, C Baus, Jj Beatty, Kh Becker, Ja Bellido, C Berat, Me Bertaina, X Bertou, Pl Biermann, P Billoir, Sg Blaess, A Blanco, M Blanco, J Blazek, C Bleve, H Blümer, M Boháčová, D Boncioli, C Bonifazi, N Borodai, J Brack, I Brancus, T Bretz, A Bridgeman, P Brogueira

Abstract:

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8±0.7(stat)±6.7(syst)  MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.