Prompt Searches for Very-high-energy γ-Ray Counterparts to IceCube Astrophysical Neutrino Alerts
The Astrophysical Journal 997:2 (2026)
Authors:
J Abhir, A Biland, K Brand, T Bretz, D Dorner, L Eisenberger, D Elsaesser, P Günther, S Hasan, D Hildebrand, K Mannheim, M Linhoff, F Pfeifle, W Rhode, B Schleicher, V Sliusar, M Vorbrugg, R Walter, F Aharonian, F Ait Benkhali, J Aschersleben, H Ashkar, M Backes, V Barbosa Martins, R Batzofin, Y Becherini, D Berge, M Böttcher, C Boisson, J Bolmont, J Borowska, R Brose, A Brown, F Brun, B Bruno, S Casanova, J Celic, M Cerruti, A Chen, M Chernyakova, J Chibueze, O Chibueze, B Cornejo, G Cotter, G Cozzolongo, J Damascene Mbarubucyeye, J de Assis Scarpin, A Delgado Giles, A Djannati-Ataï, J Djuvsland, A Dmytriiev, K Egberts, K Egg, S Einecke, J-P Ernenwein, C Escañuela Nieves, K Feijen, M Filipovic, G Fontaine, S Funk, S Gabici, JF Glicenstein, P Goswami, G Grolleron, B Hess, JA Hinton, M Holler, M Jamrozy, F Jankowsky, I Jung-Richardt, E Kasai, K Katarzyński, H Katjaita, D Kerszberg, R Khatoon, B Khélifi, W Kluźniak, Nu Komin, R Konno, K Kosack, D Kostunin, G Kukec Mezek, RG Lang, A Lemière, M Lemoine-Goumard, J-P Lenain, A Luashvili, J Mackey, V Marandon, G Martí-Devesa, R Marx, M Mayer, A Mehta, A Mitchell, R Moderski, MO Moghadam, L Mohrmann, E Moulin, M de Naurois, J Niemiec, E de Ona Wilhelmi, S Panny, M Panter, RD Parsons, U Pensec, P Pichard, G Pühlhofer, M Punch, A Quirrenbach, M Regeard, O Reimer, H Ren, F Rieger, G Rowell, B Rudak, K Sabri, V Sahakian, H Salzmann, M Sasaki, J Schäfer, F Schüssler, HM Schutte, M Senniappan, JNS Shapopi, A Sharma, H Sol, S Spencer, Ł Stawarz, R Steenkamp, S Steinmassl, C Steppa, T Takahashi, T Tanaka, AM Taylor, M Tsirou, C van Eldik, M Vecchi, C Venter, J Vink, T Wach, SJ Wagner, A Wierzcholska, M Zacharias, AA Zdziarski, A Zech, N Żywucka, S Abe, J Abhir, A Abhishek, A Aguasca-Cabot, I Agudo, T Aniello, S Ansoldi, LA Antonelli, A Arbet Engels, C Arcaro, M Artero, K Asano, A Babić, C Bakshi, U Barres de Almeida, JA Barrio, L Barrios-Jiménez, I Batković, J Baxter, J Becerra González, W Bednarek, E Bernardini, J Bernete, A Berti, J Besenrieder, C Bigongiari, A Biland, O Blanch, H Bökenkamp, G Bonnoli, Ž Bošnjak, E Bronzini, I Burelli, A Campoy-Ordaz, A Carosi, R Carosi, M Carretero-Castrillo, AJ Castro-Tirado, D Cerasole, G Ceribella, Y Chai, A Chilingarian, A Cifuentes, JL Contreras, J Cortina, S Covino, G D’Amico, P Da Vela, F Dazzi, A De Angelis, B De Lotto, M Delfino, C Delgado Mendez, F Di Pierro, R Di Tria, L Di Venere, A Dinesh, D Dominis Prester, A Donini, D Dorner, M Doro, L Eisenberger, D Elsaesser, J Escudero, L Fariña, A Fattorini, L Foffano, L Font, S Fröse, Y Fukazawa, S Gasparyan, M Gaug, JG Giesbrecht Paiva, N Giglietto, F Giordano, P Gliwny, N Godinović, T Gradetzke, R Grau, D Green, JG Green, P Günther, D Hadasch, A Hahn, T Hassan, L Heckmann, D Hrupec, R Imazawa, D Israyelyan, I Jiménez Martínez, J Jiménez Quiles, J Jormanainen, S Kankkunen, T Kayanoki, D Kerszberg, J Konrad, PM Kouch, H Kubo, J Kushida, M Láinez, A Lamastra, E Lindfors, S Lombardi, F Longo, R López-Coto, M López-Moya, A López-Oramas, S Loporchio, L Lulić, E Lyard, P Majumdar, M Makariev, M Mallamaci, G Maneva, M Manganaro, S Mangano, S Marchesi, M Mariotti, M Martínez, P Maruševec, A Mas-Aguilar, D Mazin, S Menchiari, J Méndez Gallego, D Miceli, JM Miranda, R Mirzoyan, M Molero González, E Molina, HA Mondal, A Moralejo, T Nakamori, C Nanci, V Neustroev, M Nievas Rosillo, C Nigro, L Nikolić, K Nilsson, K Nishijima, K Noda, S Nozaki, A Okumura, J Otero-Santos, S Paiano, D Paneque, JM Paredes, M Peresano, M Persic, M Pihet, F Podobnik, PG Prada Moroni, E Prandini, M Ribó, J Rico, T Saito, S Sakurai, K Satalecka, FG Saturni, K Schmitz, F Schmuckermaier, JL Schubert, A Sciaccaluga, G Silvestri, J Sitarek, V Sliusar, D Sobczynska, A Stamerra, J Strišković, D Strom, M Strzys, Y Suda, H Tajima, M Takahashi, R Takeishi, P Temnikov, K Terauchi, T Terzić, A Tutone, S Ubach, J van Scherpenberg, M Vazquez Acosta, S Ventura, G Verna, I Viale, A Vigliano, CF Vigorito, E Visentin, V Vitale, I Vovk, R Walter, F Wersig, M Will, T Yamamoto, PKH Yeung, S Yoo, A Acharyya, A Archer, P Bangale, JT Bartkoske, W Benbow, JH Buckley, Y Chen, JL Christiansen, AJ Chromey, M Errando, S Feldman, Q Feng, S Filbert, L Fortson, A Furniss, W Hanlon, O Hervet, CE Hinrichs, J Holder, Z Hughes, TB Humensky, W Jin, MN Johnson, P Kaaret, M Kertzman, M Kherlakian, D Kieda, TK Kleiner, N Korzoun, MJ Lang, M Lundy, G Maier, MJ Millard, J Millis, P Moriarty, R Mukherjee, W Ning, RA Ong, A Pandey, M Pohl, J Quinn, PL Rabinowitz, K Ragan, PT Reynolds, D Ribeiro, E Roache, I Sadeh, AC Sadun, L Saha, M Santander, GH Sembroski, R Shang, D Tak, AK Talluri, JV Tucci, J Valverde, VV Vassiliev, DA Williams, SL Wong, S Buson, R Abbasi, M Ackermann, J Adams, SK Agarwalla, JA Aguilar, M Ahlers, JM Alameddine, S Ali, NM Amin, K Andeen, C Argüelles, Y Ashida, S Athanasiadou, SN Axani, R Babu, X Bai, J Baines-Holmes, A Balagopal V., SW Barwick, S Bash, V Basu, R Bay, JJ Beatty, J Becker Tjus, P Behrens, J Beise, C Bellenghi, B Benkel, S BenZvi, D Berley, E Bernardini, DZ Besson, E Blaufuss, L Bloom, S Blot, I Bodo, F Bontempo, JY Book Motzkin, C Boscolo Meneguolo, S Böser, O Botner, J Böttcher, J Braun, B Brinson, Z Brisson-Tsavoussis, RT Burley, D Butterfield, MA Campana, K Carloni, J Carpio, S Chattopadhyay, N Chau, Z Chen, D Chirkin, S Choi, BA Clark, A Coleman, P Coleman, GH Collin, DA Coloma Borja, A Connolly, JM Conrad, DF Cowen, C De Clercq, JJ DeLaunay, D Delgado, T Delmeulle, S Deng, P Desiati, KD de Vries, G de Wasseige, T DeYoung, JC Díaz-Vélez, S DiKerby, T Ding, M Dittmer, A Domi, L Draper, L Dueser, D Durnford, K Dutta, MA DuVernois, T Ehrhardt, L Eidenschink, A Eimer, P Eller, E Ellinger, D Elsässer, R Engel, H Erpenbeck, W Esmail, S Eulig, J Evans, PA Evenson, KL Fan, K Fang, K Farrag, AR Fazely, A Fedynitch, N Feigl, C Finley, L Fischer, D Fox, A Franckowiak, S Fukami, P Fürst, J Gallagher, E Ganster, A Garcia, M Garcia, G Garg, E Genton, L Gerhardt, A Ghadimi, C Glaser, T Glüsenkamp, JG Gonzalez, S Goswami, A Granados, D Grant, SJ Gray, S Griffin, S Griswold, KM Groth, D Guevel, C Günther, P Gutjahr, C Ha, C Haack, A Hallgren, L Halve, F Halzen, L Hamacher, M Ha Minh, M Handt, K Hanson, J Hardin, AA Harnisch, P Hatch, A Haungs, J Häussler, K Helbing, J Hellrung, B Henke, L Hennig, F Henningsen, L Heuermann, R Hewett, N Heyer, S Hickford, A Hidvegi, C Hill, GC Hill, R Hmaid, KD Hoffman, D Hooper, S Hori, K Hoshina, M Hostert, W Hou, M Hrywniak, T Huber, K Hultqvist, K Hymon, A Ishihara, W Iwakiri, M Jacquart, S Jain, O Janik, M Jansson, M Jeong, M Jin, N Kamp, D Kang, W Kang, X Kang, A Kappes, L Kardum, T Karg, M Karl, A Karle, A Katil, M Kauer, JL Kelley, M Khanal, A Khatee Zathul, A Kheirandish, H Kimku, J Kiryluk, C Klein, SR Klein, Y Kobayashi, A Kochocki, R Koirala, H Kolanoski, T Kontrimas, L Köpke, C Kopper, DJ Koskinen, P Koundal, M Kowalski, T Kozynets, A Kravka, N Krieger, J Krishnamoorthi, T Krishnan, K Kruiswijk, E Krupczak, A Kumar, E Kun, N Kurahashi, N Lad, C Lagunas Gualda, L Lallement Arnaud, M Lamoureux, MJ Larson, F Lauber, JP Lazar, K Leonard DeHolton, A Leszczyńska, J Liao, C Lin, YT Liu, M Liubarska, C Love, L Lu, F Lucarelli, W Luszczak, Y Lyu, M Macdonald, J Madsen, E Magnus, Y Makino, E Manao, S Mancina, A Mand, IC Mariş, S Marka, Z Marka, L Marten, I Martinez-Soler, R Maruyama, J Mauro, F Mayhew, F McNally, JV Mead, K Meagher, S Mechbal, A Medina, M Meier, Y Merckx, L Merten, J Mitchell, L Molchany, S Mondal, T Montaruli, RW Moore, Y Morii, A Mosbrugger, M Moulai, D Mousadi, E Moyaux, T Mukherjee, R Naab, M Nakos, U Naumann, J Necker, L Neste, M Neumann, H Niederhausen, MU Nisa, K Noda, A Noell, A Novikov, A Obertacke, V O’Dell, A Olivas, R Orsoe, J Osborn, E O’Sullivan, V Palusova, H Pandya, A Parenti, N Park, V Parrish, EN Paudel, L Paul, C Pérez de los Heros, T Pernice, TC Petersen, J Peterson, M Plum, A Pontén, V Poojyam, Y Popovych, M Prado Rodriguez, B Pries, R Procter-Murphy, GT Przybylski, L Pyras, C Raab, J Rack-Helleis, N Rad, M Ravn, K Rawlins, Z Rechav, A Rehman, I Reistroffer, E Resconi, S Reusch, CD Rho, W Rhode, L Ricca, B Riedel, A Rifaie, EJ Roberts, M Rongen, A Rosted, C Rott, T Ruhe, L Ruohan, D Ryckbosch, J Saffer, D Salazar-Gallegos, P Sampathkumar, A Sandrock, G Sanger-Johnson, M Santander, S Sarkar, J Savelberg, M Scarnera, P Schaile, M Schaufel, H Schieler, S Schindler, L Schlickmann, B Schlüter, F Schlüter, N Schmeisser, T Schmidt, FG Schröder, L Schumacher, S Schwirn, S Sclafani, D Seckel, L Seen, M Seikh, S Seunarine, PA Sevle Myhr, R Shah, S Shefali, N Shimizu, B Skrzypek, R Snihur, J Soedingrekso, A Sègaard, D Soldin, P Soldin, G Sommani, C Spannfellner, GM Spiczak, C Spiering, J Stachurska, M Stamatikos, T Stanev, T Stezelberger, T Stürwald, T Stuttard, GW Sullivan, I Taboada, S Ter-Antonyan, A Terliuk, A Thakuri, M Thiesmeyer, WG Thompson, J Thwaites, S Tilav, K Tollefson, S Toscano, D Tosi, A Trettin, AK Upadhyay, K Upshaw, A Vaidyanathan, N Valtonen-Mattila, J Valverde, J Vandenbroucke, T Van Eeden, N van Eijndhoven, L Van Rootselaar, J van Santen, J Vara, F Varsi, M Venugopal, M Vereecken, S Vergara Carrasco, S Verpoest, D Veske, A Vijai, J Villarreal, C Walck, A Wang, EHS Warrick, C Weaver, P Weigel, A Weindl, J Weldert, AY Wen, C Wendt, J Werthebach, M Weyrauch, N Whitehorn, CH Wiebusch, DR Williams, L Witthaus, M Wolf, G Wrede, XW Xu, JP Yanez, Y Yao, E Yildizci, S Yoshida, R Young, F Yu, S Yu, T Yuan, A Zander Jurowitzki, A Zegarelli, S Zhang, Z Zhang, P Zhelnin, P Zilberman, F D’Ammando
Abstract:
The search for sources of high-energy astrophysical neutrinos can be significantly advanced through a multimessenger approach, which seeks to detect the γ-rays that accompany neutrinos as they are produced at their sources. Multimessenger observations have so far provided the first evidence for a neutrino source, illustrated by the joint detection of the flaring blazar TXS 0506+056 in high-energy (E > 1 GeV) and very-high-energy (VHE; E > 100 GeV) γ-rays in coincidence with the high-energy neutrino IceCube-170922A, identified by IceCube. Imaging atmospheric Cherenkov telescopes (IACTs), namely FACT, H.E.S.S., MAGIC, and VERITAS, continue to conduct extensive neutrino target-of-opportunity follow-up programs. These programs have two components: follow-up observations of single astrophysical neutrino candidate events (such as IceCube-170922A), and observation of known γ-ray sources after the identification of a cluster of neutrino events by IceCube. Here we present a comprehensive analysis of follow-up observations of high-energy neutrino events observed by the four IACTs between 2017 September (after the IceCube-170922A event) and 2021 January. Our study found no associations between γ-ray sources and the observed neutrino events. We provide a detailed overview of each neutrino event and its potential counterparts. Furthermore, a joint analysis of all IACT data is included, yielding combined upper limits on the VHE γ-ray flux.
