Search for high-energy neutrinos in coincidence with Fast Radio Bursts with the ANTARES neutrino telescope
A. Albert, M. André, M. Anghinolfi, G. Anton, M. Ardid, J.-J. Aubert, J. Aublin, T. Avgitas, B. Baret, J. Barrios-Martí, S. Basa, B. Belhorma, V. Bertin, S. Biagi, R. Bormuth, J. Boumaaza, S. Bourret, M.C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, A. Capone, L. Caramete, J. Carr, S. Celli, M. Chabab, R. Cherkaoui El Moursli, T. Chiarusi, M. Circella, J.A.B. Coelho, A. Coleiro, M. Colomer, R. Coniglione, H. Costantini, P. Coyle, A. Creusot, A. F. Díaz, A. Deschamps, C. Distefano, I. Di Palma, A. Domi, C. Donzaud, D. Dornic, D. Drouhin, T. Eberl, I. El Bojaddaini, N. El Khayati, D. Elsässer, A. Enzenhöfer, A. Ettahiri, F. Fassi, I. Felis, P. Fermani, G. Ferrara, L. Fusco, P. Gay, H. Glotin, T. Grégoire, R. Gracia-Ruiz, K. Graf, S. Hallmann, H. van Haren, A.J. Heijboer, Y. Hello, J.J. Hernández-Rey, J. Hößl, J. Hofestädt, G. Illuminati, C.W. James, M. de Jong, M. Jongen, M. Kadler, O. Kalekin, U. Katz, A. Kouchner, M. Kreter, I. Kreykenbohm, V. Kulikovskiy, C. Lachaud, R. Lahmann, D. Lefèvre, E. Leonora, G. Levi, M. Lotze, S. Loucatos, M. Marcelin, A. Margiotta, A. Marinelli, J.A. Martínez-Mora, R. Mele, K. Melis, P. Migliozzi, A. Moussa, S. Navas, E. Nezri, A. Nuñez, M. Organokov, G.E. Păvălaş, C. Pellegrino, et al. (28 additional authors not shown)
SSearch for high-energy neutrinos in coincidencewith Fast Radio Bursts with the ANTARESneutrino telescope
The ANTARES CollaborationA. Albert , M. André , M. Anghinolfi , G. Anton , M. Ardid , J.-J. Aubert , J. Aublin ,T. Avgitas , B. Baret , J. Barrios-Martí , S. Basa , B. Belhorma , V. Bertin , S. Biagi ,R. Bormuth , , J. Boumaaza , S. Bourret , M.C. Bouwhuis , H. Brânzaş , R. Bruijn , ,J. Brunner , J. Busto , A. Capone , , L. Caramete , J. Carr , S. Celli , , , M. Chabab ,R. Cherkaoui El Moursli , T. Chiarusi , M. Circella , J.A.B. Coelho , A. Coleiro , ,M. Colomer , , R. Coniglione , H. Costantini , P. Coyle , A. Creusot , A. F. Díaz ,A. Deschamps , C. Distefano , I. Di Palma , , A. Domi , , C. Donzaud , , D. Dornic ,D. Drouhin , T. Eberl , I. El Bojaddaini , N. El Khayati , D. Elsässer , A. Enzenhöfer , ,A. Ettahiri , F. Fassi , I. Felis , P. Fermani , , G. Ferrara , L. Fusco , , P. Gay , ,H. Glotin , T. Grégoire , R. Gracia-Ruiz , K. Graf , S. Hallmann , H. van Haren ,A.J. Heijboer , Y. Hello , J.J. Hernández-Rey , J. Hößl , J. Hofestädt , G. Illuminati ,C.W. James , M. de Jong , , M. Jongen , M. Kadler , O. Kalekin , U. Katz , A. Kouchner , ,M. Kreter , I. Kreykenbohm , V. Kulikovskiy , , C. Lachaud , R. Lahmann , D. Lefèvre ,E. Leonora , G. Levi , , M. Lotze , S. Loucatos , , M. Marcelin , A. Margiotta , ,A. Marinelli , , J.A. Martínez-Mora , R. Mele , , K. Melis , , P. Migliozzi , A. Moussa ,S. Navas , E. Nezri , A. Nuñez , , M. Organokov , G.E. Păvălaş , C. Pellegrino , ,P. Piattelli , V. Popa , T. Pradier , L. Quinn , C. Racca , N. Randazzo , G. Riccobene ,A. Sánchez-Losa , M. Saldaña , I. Salvadori , D. F. E. Samtleben , , M. Sanguineti , ,P. Sapienza , F. Schüssler , M. Spurio , , Th. Stolarczyk , M. Taiuti , , Y. Tayalati ,A. Trovato , D. Turpin , B. Vallage , , V. Van Elewyck , , F. Versari , , D. Vivolo , ,J. Wilms , D. Zaborov , J.D. Zornoza and J. Zúñiga Received September 24, 2018; accepted ... Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, 08800 Vilanova i la Geltrú, Barcelona, Spain INFN - Sezione di Genova, Via Dodecaneso 33, 16146 Genova, Italy Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany Institut d’Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC) - Universitat Politècnica de València. C/ Paranimf 1, 46730 Gandia,Spain ∗ E-mail: [email protected] † Now at NAOC, Beijing, China. E-mail: [email protected] a r X i v : . [ a s t r o - ph . H E ] S e p Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France APC, Univ Paris Diderot, CNRS/IN2P3, CEA/Irfu, Obs de Paris, Sorbonne Paris Cité, France IFIC - Instituto de Física Corpuscular (CSIC - Universitat de València) c/ Catedrático José Beltrán, 2 E-46980 Paterna, Valencia, Spain LAM - Laboratoire d’Astrophysique de Marseille, Pôle de l’Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, 13388 Marseille Cedex 13,France National Center for Energy Sciences and Nuclear Techniques, B.P.1382, R. P.10001 Rabat, Morocco INFN - Laboratori Nazionali del Sud (LNS), Via S. Sofia 62, 95123 Catania, Italy Nikhef, Science Park, Amsterdam, The Netherlands Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, The Netherlands University Mohammed V in Rabat, Faculty of Sciences, 4 av. IbnBattouta, B.P. 1014, R.P. 10000 Rabat, Morocco Institute of Space Science, RO-077125 Bucharest, Măgurele, Romania Universiteit van Amsterdam, Instituut voor Hoge-Energie Fysica, Science Park 105, 1098 XG Amsterdam, The Netherlands INFN - Sezione di Roma, P.le Aldo Moro 2, 00185 Roma, Italy Dipartimento di Fisica dell’Università La Sapienza, P.le Aldo Moro 2, 00185 Roma, Italy Gran Sasso Science Institute, Viale Francesco Crispi 7, 00167 L’Aquila, Italy LPHEA, Faculty of Science - Semlali, Cadi Ayyad University, P.O.B. 2390, Marrakech, Morocco. INFN - Sezione di Bologna, Viale Berti-Pichat 6/2, 40127 Bologna, Italy INFN - Sezione di Bari, Via E. Orabona 4, 70126 Bari, Italy Department of Computer Architecture and Technology/CITIC, University of Granada, 18071 Granada, Spain Géoazur, UCA, CNRS, IRD, Observatoire de la Côte d’Azur, Sophia Antipolis, France Dipartimento di Fisica dell’Università, Via Dodecaneso 33, 16146 Genova, Italy Université Paris-Sud, 91405 Orsay Cedex, France University Mohammed I, Laboratory of Physics of Matter and Radiations, B.P.717, Oujda 6000, Morocco Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Fischer Str. 31, 97074 Würzburg, Germany Dipartimento di Fisica e Astronomia dell’Università, Viale Berti Pichat 6/2, 40127 Bologna, Italy Laboratoire de Physique Corpusculaire, Clermont Université, Université Blaise Pascal, CNRS/IN2P3, BP 10448, F-63000 Clermont-Ferrand, France LIS, UMR Université de Toulon, Aix Marseille Université, CNRS, 83041 Toulon, France Royal Netherlands Institute for Sea Research (NIOZ) and Utrecht University, Landsdiep 4, 1797 SZ ’t Horntje (Texel), the Netherlands Institut Universitaire de France, 75005 Paris, France Dr. Remeis-Sternwarte and ECAP, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany Moscow State University, Skobeltsyn Institute of Nuclear Physics, Leninskie gory, 119991 Moscow, Russia Mediterranean Institute of Oceanography (MIO), Aix-Marseille University, 13288, Marseille, Cedex 9, France; Université du Sud Toulon-Var, CNRS-INSU/IRD UM 110, 83957, La Garde Cedex, France INFN - Sezione di Catania, Via S. Sofia 64, 95123 Catania, Italy Direction des Sciences de la Matière - Institut de recherche sur les lois fondamentales de l’Univers - Service de Physique des Particules, CEA Saclay,91191 Gif-sur-Yvette Cedex, France INFN - Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy Dipartimento di Fisica dell’Università, Largo B. Pontecorvo 3, 56127 Pisa, Italy INFN - Sezione di Napoli, Via Cintia 80126 Napoli, Italy Dipartimento di Fisica dell’Università Federico II di Napoli, Via Cintia 80126, Napoli, Italy Dpto. de Física Teórica y del Cosmos & C.A.F.P.E., University of Granada, 18071 Granada, Spain GRPHE - Université de Haute Alsace - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568 - 68008 Colmar, France
Abstract
In the past decade, a new class of bright transient radio sources with millisecond duration has beendiscovered. The origin of these so-called Fast Radio Bursts (FRBs) is still a great mystery despite thegrowing observational efforts made by various multi-wavelength and multi-messenger facilities. So far,many models have been proposed to explain FRBs but neither the progenitors nor the radiative and theparticle acceleration processes at work have been clearly identified. In this paper, the question whethersome hadronic processes may occur in the vicinity of the FRB source is assessed. If so, FRBs maycontribute to the high energy cosmic-ray and neutrino fluxes. A search for these hadronic signatureshas been done using the ANTARES neutrino telescope. The analysis consists in looking for high-energyneutrinos, in the TeV-PeV regime, spatially and temporally coincident with the detected FRBs. Mostof the FRBs discovered in the period 2013-2017 were in the field of view of the ANTARES detector,which is sensitive mostly to events originating from the Southern hemisphere. From this period, 12 FRBshave been selected and no coincident neutrino candidate was observed. Upper limits on the per burstneutrino fluence have been derived using a power law spectrum, dNdE ν ∝ E − γν , for the incoming neutrinoflux, assuming spectral indexes γ = 1.0, 2.0, 2.5. Finally, the neutrino energy has been constrained bycomputing the total energy radiated in neutrinos assuming different distances for the FRBs. Constraintson the neutrino fluence and on the energy released are derived from the associated null results. Key words: acceleration of particles – neutrinos – astroparticle physics – radio continuum: transients– methods: data analysis
Discovered in the last decade (Lorimer et al., 2007), Fast Radio Bursts (FRBs) are characterised by a shortduration (t ∼ a few ms) of intense radio emission ( > · ms) measured so far in the 800 MHz and 1.4GHz bands by various radio telescopes. The astrophysical origin of FRBs is largely unknown. However,their high dispersion measures (DM), due to the scattering of the radio wave propagating through an ionisedcolumn of matter, suggest an extragalactic/cosmological origin (Lorimer & Kramer, 2005; Thornton et al.,2013). 2rom the 34 FRBs already detected and reported in the FRB catalog (Petroff et al., 2016), the observedDM can be used to derive upper limits on their cosmological redshift, z DM ∈ [ .
12 ; 2 . ] . This translatesinto an upper limit on the isotropic radio energy release of E rad ∈ [ ; 10 ] erg. Up to now, theFRB progenitors are thought to originate from a large variety of astrophysical sources (Keane et al., 2016)usually split into two classes: the repeating ones and the single cataclysmic events. Indeed, such a largeamount of energy, released in a millisecond timescale, may favor an FRB origin from violent cataclysmicevents. Those are powered by compact objects where the progenitor does not survive afterwards (singleburst model). Several models have been proposed such as neutron star mergers (Totani, 2013; Wang et al.,2016) possibly associated to short Gamma-Ray Bursts (GRBs) (Zhang, 2014; Palaniswamy et al., 2014;Murase et al., 2017) or supramassive neutron star collapses (Falcke & Rezzolla, 2014; Ravi & Lasky, 2014;Li et al., 2014). Non-destructive flaring models including giant pulses from young and rapidly rotatingneutron stars (Pen & Connor, 2015; Cordes & Wasserman, 2016), magnetar giant flares (Popov & Postnov,2013; Lyubarsky, 2014), hyperflares from soft gamma-repeaters (Popov & Postnov, 2010), a young neutronstar embeded in a wind bubble (Murase et al., 2016) or maybe from the interior of young supernovae(Bietenholz & Bartel, 2017) are however good astrophysical candidates to explain both types of repeatingand non repeating FRBs. More exotic models have also been proposed such as radio burst radiation ofsuperconducting cosmic strings (Cao & Yu, 2018; Ye et al., 2017).Recently, the discovery of the repeating behavior of FRB 121102 (Spitler et al., 2016; Scholz et al.,2016) has brought new insights into the nature of the FRB progenitors. In addition, radio interferometricobservations of FRB 121102 (Marcote et al., 2017; Chatterjee et al., 2017) made possible, for the first time,to unambiguously determine the redshift of the FRB source at z ∼ .
19 (Tendulkar et al., 2017), confirmingthe tremendous amount of radio energy that can be released during an FRB event.Radio observation campaigns have been done to search for other FRB "repeaters" among the known FRBpopulation but without any success (Lorimer et al., 2007; Ravi et al., 2015; Petroff et al., 2015a, 2017).However, the instrumental sensitivities and the short observation time of a few hours may account for thisnull result. Therefore, the question whether FRB 121102 belongs or not to a special class of FRB is stillunder debate.The spatial distribution and the all-sky rate of FRBs, R
FRB , can provide additional constraints on the natureof the FRB progenitors when it is compared to those of known astrophysical sources. The all-sky rateR
FRB ∼ day − has been estimated for radio pulses with F > · ms (Champion et al., 2016). This highevent rate would already rule out a short GRB-dominated population of FRBs since R FRB / R short GRB ∼ assuming that R short GRB = N short GRB N all GRB × R GRB where R all GRB = − in the entire sky and the detectedGRB population is composed of 1/3 of short GRBs according to the CGRO-BATSE observations (Goldsteinet al., 2013). Alternatively, R FRB corresponds to only 10% of the observed CCSNe rate (Thornton et al.,2013). Therefore, the CCSNe reservoir may account for the high event rate of FRBs. For instance, Falcke& Rezzolla (2014) claimed that only 3% of the core collapse supernovae (CCSNe) producing supramassiveneutron stars are needed to explain the FRB rate. The various models proposed are difficult to discriminatebecause of lack of additional information on the broadband FRB spectra. Many multi-wavelength follow-ups have been organised recently (Petroff et al., 2015b, 2017; Scholz et al., 2017; Bhandari et al., 2018;Hardy et al., 2017) but no counterpart (optical/x-rays/gamma-rays/VHE gamma-rays) has been identifiedyet. However, in 2016, DeLaunay et al. (2016) reported the detection of a gamma-ray GRB-like counterpartin association with FRB 131104 but with a small significance (3.2 σ ). For FRB 131104, DeLaunay et al.(2016) determined that the radio to gamma-ray energy output ratio would be E rad / E γ > − assuming thesource is at the redshift inferred by the DM measurement. This may show that a large fraction of the totalenergy radiated during these radio bursting events may be emitted at high energy while being still undetectedor marginally detected. If the radio emission is likely produced by coherent emission of leptons (Katz, 2014,and references therein), hadronic processes may be the source of the most energetic photons in the gamma-ray energy domain. In this case, TeV-PeV neutrinos can be produced by photohadronic interactions. Thesehadronic processes may occur in the energetic outflow released during a cataclysmic FRB event (Falcke& Rezzolla, 2014) or in the vicinity of the FRB progenitor through the interaction of the outflow with thesurrounding environment (Zhang et al., 2003; Li et al., 2014; Murase et al., 2016; Dey et al., 2016).Based on their high rate, R FRB , and under the assumption that a fraction of FRBs are indeed efficientaccelerators of TeV-PeV hadrons, they may contribute significantly to the cosmic diffuse neutrino signaldiscovered by the IceCube Collaboration (Aartsen et al., 2013, 2015a,b,c, 2016). This diffuse astrophysicalneutrino signal is now established with a high significance. The ANTARES neutrino telescope also observesa mild excess over the background of neutrino candidates at high energies (Albert et al. , 2018). Up tonow, no population of astrophysical sources clearly emerge from the background to explain this diffuse flux. see the FRB catalog : http://frbcat.org/ z DM corresponds to the upper limit on the cosmological redshift inferredfrom the DM measured in excess to the Galactic contribution.FRB z DM T RA dec radio telescope(UTC) ( o ) ( o )131104 0.59 18:04:11.20 101.04 -51.28 Parkes140514 0.44 17:14:11.06 338.52 -12.31 Parkes150215 0.55 20:41:41.71 274.36 -4.90 Parkes150418 0.49 04:29:06.66 109.15 -19.01 Parkes150807 0.59 17:53:55.83 340.10 -55.27 Parkes151206 1.385 06:17:52.78 290.36 -4.13 Parkes151230 0.76 16:15:46.53 145.21 -3.45 Parkes160102 2.13 08:28:39.37 339.71 -30.18 Parkes160317 0.70 09:00:36.53 118.45 -29.61 UTMOST160410 0.18 08:33:39.68 130.35 6.08 UTMOST160608 0.37 03:53:01.09 114.17 -40.78 UTMOST170107 0.48 20:05:45.14 170.79 -5.02 ASKAPHowever, recently, the IceCube Collaboration claimed the evidence of a high-energy neutrino signal fromthe blazar TXS 0506+056 (Aartsen et al., 2018a,b) which marks an additional step towards the identificationof the nature of the cosmic accelerators in the Universe. Multi-messenger observations of FRBs are crucialto probe them as cosmic accelerators. So far, neutrino searches from FRBs by the IceCube (Fahey et al.,2017; Aartsen et al., 2018) and the ANTARES (Albert et al. , 2017a) Collaborations yielded a null result.In this paper, a search for neutrinos in coincidence with FRBs detected between 2013 and 2017 using theANTARES neutrino telescope is presented. Located in the Mediterranean Sea, ANTARES is the largesthigh-energy neutrino telescope in the Northern Hemisphere, operating since 2008 (Ageron et al., 2011). Bydesign, the ANTARES detector continuously monitors, with a high duty cycle and good angular resolution,the Southern sky (2 π steradian at any time), where most of the FRBs have been discovered to date. Insection 2, the FRB sample used in the analysis is described as well as the results of the search for a neutrinocounterpart. The constraints on the neutrino fluence and energy emission are given in section 3. Finally, insection 4, the results are discussed with respect to different expectations from FRB hadronic models and theFRB contribution to the diffuse neutrino flux. The conclusions are drawn in section 5. This analysis focuses on the period from Jan. 2013 to Jan. 2017 during which 16 FRBs were detectedby the Parkes telescope, UTMOST and ASKAP. When active, the ANTARES telescope monitors the skyregion with declinations δ < − ◦ with almost 100% duty cycle; for − ◦ < δ < + ◦ the duty cycledecreases gradually because of the requirement that the neutrino candidates are upgoing. The first selectioncriterion is that the FRB position must be within the ANTARES field of view (FoV) within a chosen timewindow ∆ T = [ T − h ; T + h ] where T is the FRB trigger time. Three FRBs did not fulfill this firstselection criterion and were then removed from the sample used in this analysis. In addition, the quality ofthe ANTARES data acquired during the whole day around each FRB detection was verified to avoid anyanomalous behavior of the detector. One more FRB (FRB 150610) was excluded since the detector was notactive due to a power cut that happenned 4 hours before the trigger time. At the end, the final sample iscomposed of 12 FRBs for which ANTARES data were considered. In table 1, the main properties of theFRB sample are summarised and a sky map of the FRB positions superimposed with the ANTARES skyvisibility is shown in figure 1. During the review of this paper, a 17th FRB (FRB 141113) has been reported by Patel et al. (2018). Occuring in 2014, FRB141113was below the ANTARES horizon up to 2 hours after its trigger time. - - - - - -90°180° -180° Figure 1: Skymap in Galactic coordinates showing the positions of the 16 FRBs detected in the period2013-2017. The 12 selected FRBs are shown with the blue dots while the 4 non-selected FRBs are displayedwith the red triangles. The region of the sky observable by ANTARES (on average) is also displayed ingreyscale from 100% of visibility for the darkest area to 0% for the white area when considering upgoingneutrino candidates in the detector.
For each selected FRB, the ANTARES data set is extracted within a time window ∆ T = [ T − h ; T + h ] .This time window is chosen to encompass various delay scenarios between the radio and the neutrino signalswhile keeping the background noise at a low level. Within ∆ T , the event rates are checked to verify thedetector stability. No significant time variability of the counting rates was found which ensures the qualityof the extracted data. The search for a significant neutrino flux is then based on the detection of upgoingneutrino-induced muons coincident with the position of the FRB within ∆ T .To suppress the atmospheric muon background contamination in the neutrino sample, selection cuts areapplied using the quality variables of the track reconstruction algorithm (Adrián-Martínez et al., 2012):the reconstructed zenith angle, θ , the error estimate on the reconstructed direction, β , and the quality fitparameter, Λ . Each selected upgoing (cos θ >
0) event was required to have a direction error β < o . Thefinal selection criteria is based on the quality fit parameter Λ . For ∆ T centered on each FRB time, the optimalvalue, Λ σ , was chosen in such a way that the presence of one neutrino candidate in the time window wouldcorrespond to a positive signal with 3 σ significance (Albert et al. , 2017b). Finally, a search cone of 2 ◦ isset around each FRB position. From radio information, the typical localization errors corresponds to radiiof 10 arcmin. No upgoing events spatially and temporally correlated with the 12 selected FRBs were found. This nullresult is compatible with the background event rate of ANTARES estimated to be ∼ · − event · s − .Since no neutrino signal is detected in coincidence with any of the selected FRBs, constraints on the fluenceof neutrinos that would have been observed by the ANTARES detector are derived. An upper limit on the neutrino fluence is computed on a per burst basis with the following procedure. For agiven neutrino flux, the number of expected events, N ν , depends on the detector effective area, A ef f ( E ν , δ ) (units: cm ). Once the selection parameters ( cos θ, β, Λ σ ) have been defined, as explained in §2.2, theeffective area only depends on the neutrino energy, E ν and the source declination, δ . To compute theeffective area at any declination, dedicated Monte Carlo simulations reproducing the ANTARES data takingconditions at the FRB trigger time, T , have been produced.For a given time-integrated neutrino flux, dNdE ν (units: GeV − cm − ), the number of expected neutrino events5or a source at declination δ is N ν ( δ ) = ∫ E ν A ef f ( E ν , δ ) · dNdE ν · dE ν . (1)Usually, a neutrino power-law dN / dE ν ∝ E − γν is assumed. The neutrino fluence at the detector can thus bedefined as E ν dNdE ν = φ · (cid:18) E ν E (cid:19) − γ + ( in GeV · cm − ) . (2)The normalization factor, φ , has the same units as the neutrino fluence and it corresponds to the expectedneutrino energy fluence at the reference energy, E = 100 TeV. Due to the strong energy-dependence of theeffective area with E ν , the sensitivity of the detector to a given neutrino flux is strongly dependent on thespectral index γ . As the neutrino production mechanisms for FRBs are unknown, three spectral models havebeen tested in this analysis to conservatively cover a large range of possibilities: a hard spectrum with γ =1.0 usually considered in some stages of p γ acceleration processes, an intermediate spectrum with γ = 2.0corresponding to the theoretical index for Fermi acceleration processes and a softer spectrum with γ = 2.5.The latter almost corresponds to the best fit value of the isotropic astrophysical neutrino signal measured byIceCube (Aartsen et al., 2015b).By inverting equation 1, a null neutrino detection can be translated to an upper limit on the normalizationfactor φ of the energy spectrum for the given values of the spectral index γ . Assuming Poisson statistics,the 90% confidence level (C.L.) upper limit, φ , is defined by setting N ν ( δ ) = .
3. No neutrino event wasobserved in a temporal coincidence within T ±
6h for any of the considered FRBs. The values of φ foreach FRB and for the three assumed spectral indexes are reported in table 2.Starting from the upper limit on the normalization factor, the corresponding 90% C.L. upper limits onthe fluence for each FRB has also been computed as: F ν = ∫ E max E min E ν · dNdE ν · dE ν = φ · E γ − ∫ E max E min E − γν · dE ν . (3)The integration is over the range from E min to E max , which corresponds to the energies that define the5 −
95% range of the energy distribution of simulated events passing all the analysis cuts for the correspond-ing spectrum.The upper limits on the neutrino fluence, F ν , for each individual FRB and for the three test spectralindexes are reported in table 2 and shown in figure 2. As shown later in figure 5, compared to a time-integrated neutrino point source analysis (e.g. Albert et al., 2017c), searching for neutrinos from shorttransient events permits to improve the upper limit derived on the neutrino fluence by a factor of ∼ The isotropic neutrino energy, E ν, iso , possibly released during an FRB event is an important physicalproperty of the bursting source. It may give information on the baryonic load within the ejected outflow aswell as the efficiency of the hadronic processes at work in the acceleration site nearby the progenitor source.It can be expressed as: E ν, iso = π D ( z ) + z · F ν (4)where z is the redshift of the source and D ( z ) is the distance traveled by the neutrinos depending on theassumed cosmological model: D ( z ) = cH ∫ z ( + z (cid:48) ) dz (cid:48) (cid:112) Ω m ( + z (cid:48) ) + Ω Λ (5)where c is the velocity of light in vacuum and the cosmological parameters are H = . − Mpc − , Ω m = .
308 and Ω Λ = − Ω m (Ade et al. , 2016). For distances in the range d ∈ [ ( z DM )] , the6able 2: The 90% C.L upper limits on the spectral fluence, φ , evaluated at 100 TeV, and the fluence, F ν , for the three spectral models considered in this analysis ( γ = 1.0, 2.0, 2.5). φ and F ν areexpressed in GeV · cm − . The [5% ; 95%] energy boundaries, E min and E max , used to compute the energyintegrated fluence are also shown in the units of log ( E ν / GeV ) .FRB γ = . γ = . γ = . φ F ν E min E max φ F ν E min E max φ F ν E min E max . · . · . · . · . · . · . · . · . · . · . · . · γ = 1.0 (blue), 2.0 (red), 2.5 (black), for each FRB. The limits are computed in theenergy range [ E min ; E max ] where 5-95% of the neutrino signal is expected.7igure 3: The 90% confidence level upper limits on the neutrino energy released by the FRB sources. Theper burst limits, assuming different neutrino power law spectra, are shown with the dashed blue lines ( γ =1.0) and the black solid lines ( γ = 2.5). These limits are computed in the distance range d ∈ [ ( z DM )] .The red area indicates the region that is already excluded by ANTARES at the 90% C.L. for any consideredhadronic model ( γ = 1.0, 2.0, 2.5). The yellow area is only excluded by the soft spectral models ( γ = 2.0,2.5). The white area, divided in 3 distance scenarios, is still allowed according to the ANTARES sensitivity.90% C.L. upper limits on E ν, iso have been computed and the results are shown in figure 3 for each FRB.The excluded region in the E ν, iso - D ( z ) plane for the hardest considered spectrum ( γ = .
0) and the softestspectrum ( γ = .
5) are also indicated. The constraints on E ν, iso obtained with the power law spectrum γ =2.0 are similar to that obtained with γ = 2.5 as the two corresponding F ν are similar.Since the distance of these FRBs are unknown, three distance scenarios can be assumed: i) the sourcesare galactic or very close to our Galaxy, typically up to the distance to the Magellanic Clouds d ≤
50 kpc,ii) extragalactic but non-cosmological d ∈ [
50 kpc ; 100 Mpc ] or iii) cosmological d ≥
100 Mpc. For thesethree ranges of distance, the upper limits on the neutrino fluence, see figure 3, for a E − . ν model, can beconverted in the source rest frame by E ν, iso ≤ [ ; 10 ] , [ ; 10 ] and [ ; 10 ] erg, respectively. The upper limits on the neutrino energy released by both the individual FRB sources and the whole populationmust be compared to the expectations of some FRB hadronic models.
In the merger scenario, collapsing neutron stars may power an FRB at the merger time and then producea short γ -ray burst few seconds to hundreds of seconds after (Zhang, 2014). In the standard framework ofGRBs, particles are accelerated by internal shocks within the relativistic jetted outflow and photo-hadronicprocesses may give rise to a burst of high-energy neutrinos (Waxman & Bahcall, 1997; Guetta et al., 2004;Murase & Nagataki, 2006; Zhang & Kumar, 2013). The neutrino flux can be roughly scaled to the γ -ray8ux and to the baryonic load in the outflow according to (Zhang & Kumar, 2013) : E ν, iso ≈ f p · ( − ( − < χ p / γ > ) τ p γ ) · E γ, iso (6)with f p the baryonic loading factor assumed to be preferentially in the range f p ∈ [ ] , (cid:104) χ p / γ (cid:105) ∼ τ p γ the optical depth for photohadronicinteractions (Albert et al., 2017d). For short GRBs, the isotropic γ -ray energy released is usually in therange E γ, iso ∈ [ ; 10 ] erg. The short GRB 170817A associated to the binary neutron star merger eventof august 2017 (Abbott et al., 2017a) was subluminous with E γ, iso = . ± . · erg integrated over anobserved duration T = ( ± . ) s (Abbott et al., 2017b). Typically, for a so-called standard short GRB ,the optical depth is ∼ · − . Based on these rough estimates, the neutrino expectations are in the range10 − · E γ, iso (cid:46) E ν, iso (cid:46) . · E γ, iso . As shown in figure 4, the derived limits on the neutrino flux can rule outshort GRB models in a very nearby environment (d < >
100 Mpc. Recent advanced hadronic models imply abroken power law spectrum for the neutrino emission in short GRB events. Also the predictions from thosemodels are weakly constrained by our exclusion regions. For instance, Biehl et al. (2018) have computedthe expected neutrino spectrum from the short GRB GRB170817A using the NeuCosmA model (Hümmeret al. , 2010, 2012) for different configurations of the jetted outflow. Considering the low luminosity jetscenario ( Γ = f p ∈ [ ] ), see figure 2 given by Biehl et al. (2018), the corresponding neutrinofluences integrated over 100 TeV-100 PeV are F ν ∈ [ . · − ; 0 . ] GeV · cm − . At a distance of 40 Mpcand a redshift z = 0.008, this translates into E ν, iso ∈ [ ; 10 ] erg which is still below the ANTARESsensitivity as shown in figure 4. In these two scenarios, the FRB event is produced by a sudden release of energy in the magnetosphere ofthe magnetar either driven by magnetic instabilities or high rotational loss (spin-down power). Protons maybe accelerated into the polar cap regions and interact with the x-ray photon field emitted in the neutron starenvironment to produce high-energy neutrinos and secondary particles (Zhang et al., 2003). In the firstscenario, the extremely strong magnetic field ( B > G) is the source of the x-ray photon field and ofthe particle acceleration. It corresponds to the giant flares from magnetars or the SGR models. The secondscenario is related to some highly magnetised ( B ∼ G) neutron stars which are born with a millisecondtimescale period of rotation making them able to power the particle acceleration and the subsequent high-energy neutrino emission (Dey et al., 2016). In both neutron star scenarios, a very high magnetic field isrequired with at least B > G. For a magnetar, the typical values for the stellar radius and the magneticfield used here are B = G, R =
10 km. The rotational period, P, can vary from hundreds of millisecondsfor a very young neutron star to few seconds for slow rotating magnetars (with P > ν, quiescent ∈ [ ; 10 ] erg s − when the magnetar is in the quiescent state. For agiant flare like the one observed from SGR 1806-20 (Palmer et al., 2005), the luminosity of the x-ray/ γ -raybackground (with E γ = −
30 keV Zhang et al. (2000)) can increase by at least a factor 10 in less than asecond compared to the quiescent periods of the magnetar (Thompson, 2000). This kind of bursting eventmay also produce an FRB. By scaling the typical neutrino luminosity expected from quiescent magnetarsto the SGR bursting events (with typical duration for the main spike t spike ∼ E ν, iso ≤ · L ν, quiescent · t spike ≤ [ ; 10 ] erg.These estimates are also compared, in figure 4, to the ANTARES neutrino upper limits. Magnetar/SGRsources are very likely weak sources of high-energy neutrino according to the models depicted above. Hencethe magnetar flare origin of FRBs can not be significantly constrained on a per burst basis with the neutrinoanalysis presented here. with the following parameters : the Lorentz factor Γ = E γ, iso ≈ erg, the minimum variabilitytime scale of the gamma-ray emission t var = .
01 s, the radius at which the p γ interactions occur R p γ ≈ cm and the redshift z =0.5. E ν, iso − distance plane with the region already excluded by ANTARES for different neutrinomodels (red: γ ≥ γ ≥ f p ∈ [ ] Core collapse supernovae are known to produce a compact object such as a neutron star or a black holesurrounded by the material ejected from the progenitor star during the explosion, the so-called supernovaremnant. Murase & Nagataki (2006); Falcke & Rezzolla (2014); Ravi & Lasky (2014); Li et al. (2014)mention the possibility that cosmic-rays and high energy neutrinos may be produced by the interaction of anenergetic outflow ejected by the newly born compact object with the surrounding pulsar nebula or supernovaremnant at a distance R ∼ − cm. A FRB could be also produced during this interaction or directlyinside the ejected outflow. The resulting neutrino flux may be low since at such distance from the progenitorthe density of the target medium for the photo-hadronic interaction is quite small. In addition, the delaybetween the production of the radio and the neutrino signal is not clear yet.For all the hadronic models listed in this discussion, it seems that detecting a neutrino signal from singleFRB sources may be difficult as most of the FRB hadronic model predictions remain orders of magnitudebelow the ANTARES neutrino detection threshold. However, the expected large number of FRBs overthe entire sky may contribute to a diffuse flux that can be tested by a large scale neutrino telescope. Thispossibility is discussed in the following section. In 2013, the IceCube Collaboration reported the significant detection of a cosmic diffuse neutrino flux(Aartsen et al., 2013). So far, the sources responsible for this cosmic isotropic signal have not been clearlyidentified. Even if the first compelling evidence of a cosmic high-energy neutrino signal from the blazar TXS0506+056 has been claimed by Aartsen et al. (2018a,b), it is still not clear how important is the contributionof the blazars to the neutrino diffuse flux. On the contrary, the GRB contribution to this diffuse flux has10lready been constrained to be less than 1% (Aartsen et al., 2015d). The population of fast radio bursts mayalso contribute significantly since their expected rate is high, R
FRB ∼ day − (Champion et al., 2016).This hypothesis is tested here by computing the 90% C.L. upper limit on the diffuse neutrino flux associatedwith FRBs. As before, the neutrino flux associated with FRB sources is assumed with a power law energydistribution with spectral indexes γ = 1.0, 2.0, 2.5. The derived diffuse upper limits depend on the assumedneutrino spectrum. Hence, E ν Φ ν = π · φ FRB · R FRB N FRB
GeV · cm − · s − · sr − (7)where N FRB are the number of FRBs considered in this analysis and φ FRB is the characteristic neutrinofluence normalised to 100 TeV as defined in equation 2 of the combined neutrino spectrum from the 12FRBs. The neutrino fluence limit has been computed at the 90% confidence level by estimating the averageANTARES effective area over the 12 FRB events for the different spectral models : φ FRB = . · E − γ + ∫ (cid:104) A ef f ( E ν )(cid:105) · E − γν · dE ν GeV · cm − (8)According to the ANTARES upper limit on the individual neutrino fluxes from the 12 selected FRBs (seetable 2) and assuming the last updated estimate on the all-sky FRB rate R FRB ∼ . · day − (Bhandariet al., 2018), one can obtain the upper limits on the quasi diffuse flux normalised to E =
100 TeV, E ν φ < · − GeV · cm − · s − · sr − for E − . , E − . and E − . neutrino spectra respectively.The neutrino diffuse flux observed by the IceCube Collaboration for E ν >
60 TeV is at the level of E ν Φ ∼ − GeV · cm − · s − · sr − normalised to E =
100 TeV and with γ = .
46 (Aartsen et al., 2015a).In the present analysis, the derived upper limit on the diffuse flux for FRBs with γ = . ∼ E ν >
60 TeV is detected every 20 days by IceCube (Aartsen et al., 2015a), itappears that finally less than 1 over ∼ E ν >
60 TeV, depending on the spectral index of the cosmic signaland the low-energy cut-off. These cosmic neutrinos at energies below 60 TeV are hidden in the IceCubedata set in the much larger sample of atmospheric neutrinos. The possibility to observe a temporal andspatial coincidence allows for a significant suppression of this background. In this paper, a selection methodis presented and guarantees the 3 σ significance based on the observation of one coincident event. If theIceCube cosmic neutrino diffuse flux is totally produced by the mechanism that induces FRBs, accountingfor the neutrinos below 60 TeV, the number of neutrinos per FRB can increase by to two orders of magnitude.This means that searches for neutrinos with IceCube or ANTARES in coincidence with hundreds of FRBscould significantly constrain such a scenario. Alternatively, the non detection of a neutrino signal fromFRBs could be also due to non-hadronic production mechanisms in the FRB environment, or to the presenceof a beamed jet of neutrinos.Up to now, very few FRBs have been detected which strongly limits the capability of large neutrinodetectors to constrain the contribution of FRBs to the neutrino diffuse flux. In the near future, many radiofacilities e.g. UTMOST (Caleb et al., 2016, 2017; Bailes et al., 2017), SKA/ASKAP (Johnston et al., 2008;Bannister et al., 2017), CHIME (Bandura et al., 2014; Newburgh et al., 2014; Amiri et al. , 2017), Lofar(van Leeuwen, 2014; Maan & van Leeuwen, 2017) will increase the statistics of FRB detection up to a fewper year to several hundreds per year. In the meantine, bright and very close events may be also detected(by CHIME and ASKAP, for instance) which will also increase the discovery capabilities of the large scaleneutrino detectors for individual point sources. A similar search for a high-energy neutrinos from FRBs has been performed by the IceCube Collaboration(Aartsen et al., 2018). Despite the larger detection volume with respect to the ANTARES telescope, nosignificant signal was found. The IceCube neutrino telescope is mostly sensitive to FRBs occurring in the11 -1 A e ff [ c m ] IceCube: < -42 ° ANT PS: < -45 ° (Albert et al. 2017c)ANT FRB 150807: = -55 ° = 2.0 = 1.0 = 2.5 E [GeV]
Figure 5: The ANTARES and the IceCube effective areas ( A ef f ) as function of the neutrino energy. Thedashed dark green line is the ANTARES A ef f computed as for the standard point source neutrino searchesin ANTARES data at a declination δ < − ◦ (Albert et al., 2017c). The red line illustrates the gain of about30% in the A ef f ( δ = − ◦ ) typically achievable when searching for a transient event, such as the FRBspresented in this paper. The IceCube A ef f computed in the last FRB analysis (Aartsen et al., 2018) in thesame range of Southern declinations is represented with the black line.Northern hemisphere where the derived upper limits on the neutrino fluence for a E − spectrum are abouta factor 20 more stringent than those determined by ANTARES at its maximum sensitivity (obtained forsources located in the Southern sky). However, the IceCube effective area is largely reduced for declination δ < − ◦ with respect to positive declinations. Therefore, in the Southern sky, where, up to now, most ofthe FRBs are detected, the ANTARES telescope is still competitive with IceCube to constrain models thatassume a soft spectral index such as γ = .
5. In the Southern sky, the strongest upper limit on the neutrinofluence given by ANTARES for an FRB is a factor ∼ . E ν (cid:46)
25 TeV for the 2/3 of the Southern sky and in the large portion of the energyrange where 90% of the neutrino signal is expected for γ = .
5. In figure 5, the ANTARES A ef f computedat a declination δ = − ◦ for FRB 150807 is compared to the IceCube A ef f computed for FRB searchesin the declination range δ ∈ [− ◦ ; − ◦ ] (Aartsen et al., 2018) and illustrates the complementary betweenIceCube and ANTARES in terms of sky and energy coverages. Thus, in the Southern hemisphere, usingboth the ANTARES and the IceCube neutrino telescopes to search for transient events with soft spectra, asthe one observed for the neutrino cosmic diffuse flux, maximises the discovery potential.Despite the good performances of IceCube for hard neutrino spectra (high energy part of spectrum) in theSouthern sky, see figure 5, a larger detector than ANTARES located in the Northern hemisphere is requiredto improve the sensitivity of the neutrino telescopes to sources located in the Southern hemisphere. Thenext generation of the large-scale high-energy neutrino detector, KM3NeT/ARCA (Adrián-Martínez et al.,2016), is now under construction in the Mediteranean sea and will be fully operational in the upcomingyears. With KM3NeT/ARCA, an unprecedented sensitivity to the high-energy neutrino flux should beobtained at Southern declinations. In the next few years, combined analysis between the KM3NeT/ARCAand the IceCube detectors will provide the most sensitive and homogeneous coverage of the neutrino skyever reached for energies E ν > with a detection volume of the order of the km Conclusions
Fast radio bursts are candidate sources of efficient particle acceleration as they may release a great amountof energy in a short timescale, similar to the short gamma-ray bursts. The question whether a hadroniccomponent is injected in the energetic outflow has been investigated in this paper by directly searching forhigh energy neutrinos in coincidence with 12 FRBs using ANTARES data in the period 2013-2017. Nosignificant coincident neutrino signal was found. The 90% confidence level upper limits on the neutrinofluence has been derived per burst and for the whole population as well as the neutrino energy released.These limits are not stringent enough to significantly constrain the prediction of some FRB hadronic models,e.g. merger events, magnetar flares, especially if these sources are located at cosmological distances. FRBscould be weak sources of high energy neutrinos, but because of their high rate in the Universe, the signalfrom the whole population may be detectable as a diffuse neutrino flux. So far, the lack of FRB statistics doesnot allow to firmly test this hypothesis since the detection of at least a hundred of FRBs are required to bringsignificant constraints. The upcoming first observations of KM3NeT/ARCA, the next generation of large-scale high-energy neutrino telescope in the Northern hemisphere, will also permit to strongly improve theconstraints on the fluence per burst and the FRB contribution to the cosmic neutrino diffuse flux. Recently,new facilities such as UTMOST, CHIME, SKA/ASKAP, have emerged with high discovery capabilities oftens of FRBs per month (against ∼ − δ (cid:46) + ◦ ). In addition, these radiofacilities may be able to observe bright FRBs at close distance (d <
100 Mpc), which will enhance theprobabilty of a multimessenger detection at high energies for an individual FRB. Finally, more accuratemodels describing the neutrino production associated with FRBs will greatly help to refine the constraintson the neutrino fluence and energy released.
Acknowledgements
The authors acknowledge the financial support of the funding agencies: Centre National de la RechercheScientifique (CNRS), Commissariat à l’énergie atomique et aux énergies alternatives (CEA), CommissionEuropéenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), IdEx programand UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), Labex OCEVU (ANR-11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001-02), RégionÎle-de-France (DIM-ACAV), Région Alsace (contrat CPER), Région Provence-Alpes-Côte d’Azur, Dépar-tement du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium für Bildung und Forschung(BMBF), Germany; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Stichting voor FundamenteelOnderzoek der Materie (FOM), Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), theNetherlands; Council of the President of the Russian Federation for young scientists and leading scientificschools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania; Ministeriode Economía y Competitividad (MINECO): Plan Estatal de Investigación (refs. FPA2015-65150-C3-1-P, -2-P and -3-P, (MINECO/FEDER)), Severo Ochoa Centre of Excellence and MultiDark Consolider(MINECO), and Prometeo and Grisolía programs (Generalitat Valenciana), Spain; Ministry of HigherEducation, Scientific Research and Professional Training, Morocco. We also acknowledge the technicalsupport of Ifremer, AIM and Foselev Marine for the sea operation and the CC-IN2P3 for the computingfacilities.