A search for neutrinos from long-duration GRBs with the ANTARES underwater neutrino telescope arxiv C.W. James for the ANTARES collaboration Thanks to J. Schmid, C. Rivière, and P. Baerwald

Gamma-Ray Bursts (GRBs) GRBs: Intense flashes of gamma rays Duration: 2s (‘long’) Emission from highly-relativistic jet (‘fireball’) Long-duration GRBs: jet from collapse of massive star Neutrinos? Jet shocks + electrons: observed gamma rays Jet shocks also accelerate protons… Protons + photons = neutrinos! Neutrino search: Test link between GRBs and CR Possible point-source candidates C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil Woosley & Bloom, 2006

ANTARES: a reminder Main detection channel: Muons from CC interactions of cosmic neutrinos Main background: muons/neutrinos from cosmic rays C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

GRB sample 296 selected GRBs, Dec Dec total 6.6 hr duration ANTARES visibility (selection based on GCN notices) C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Expected neutrino flux in fireball paradigm Standard treatment: Guetta et al (based on Waxman & Bahcall, 1997) Individual GRB predictions based on observed gamma-flux Analytic treatment: neutrinos from delta-resonance NeuCosmA (Hümmer et al. 2012) Numerical calculation Full photohadronic cross-sections (inc. delta-production) Secondary particles followed Energy-loss before decay Neutrino mixing … C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Comparison of predictions NeuCosmA: Lower integrated flux Greater high-energy component GRB C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil Guetta et al. spectral break energies NeuCosmA Same for Different for

NeuCosmA predictions for all GRBs* Very wide range of flux magnitudes GRB dominates above ~1 PeV TOTAL individual *Thanks to P. Baerwald, W. Winter C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

GRBs: short, localised Can use data as a statistically- independent background estimation Background calculation: Local detector coordinates Detector conditions at time of GRB Assume constant rate over detection region C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil Background estimation: from data

Search principles Event selection: Within observed GRB duration (~1 minute/GRB) Reconstructed direction: within 10 o of GRB direction Quality cuts (exclude down-going muons from cosmic rays) Extended maximum likelihood (signal vs background) on remaining data Search optimisation: Signal from NeuCosmA Background from data Resolution: ~0.3 o -1 o for muons ~10 o for showers GRB C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Estimate using pseudo-experiments background sims per GRB 10 5 source sims per n s per GRB Require 2 signal events from a single GRB for a 5σ detection Discovery potential C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil GRB True expected source flux (events) Probability of detection

Expectations 10 most-promising GRBs: Expected signal: 0.06 events Expected background: 0.05 events C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

90% C.L. on combined neutrino flux from 296 bursts (NeuCosmA, Guetta): All limits compatible with NeuCosmA predictions Results… no coincident events observed All-sky, time-averaged flux Summed flux from 296 GRBs IceCube: Abbasi et al., ANTARES 2007: Adrian-Martinez et al. C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Conclusions ANTARES limit set on neutrinos from long- duration GRBs Neutrinos from GRBs still possible! NeuCosmA: more detailed physical modelling Fireball model predictions below current limits Nearby, powerful GRBs can dominate (better to be lucky than good) Near-future promising: current neutrino telescope limits close to flux predictions C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

References This paper: ICRC ; arxiv Abbasi et al, Nature 484 (2012) 351 Adrian-Martinez et al, JCAP (2013) 006 Aguilar et al, Proc. ICRC v8, p232 Hümmer S., Baerwald P, Winter W., Phys.Rev.Lett. 108 (2012) Guetta et al.,Astropart Phys 20 (2004) 429 NeuCosmA: courtesy P. Baerwald, W. Winter Fermi: Swift: GCN: C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

GRBs: short, localised Can use data as a statistically- independent background estimation Background calculation: Local detector coordinates Detector conditions at time of GRB Assume constant rate over detection region C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil Background estimation: from data Detector response Short-term variation Long-term variation Normalisation to observed variability

PSF for GRB Muons: 0.3 o fitted angular resolution Cascades: >10 o (since improved) Source simulation: point-spread function ~ C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Statistical tests Test-statistic Q: Model discovery potential: Maximise MDP via quality-cut parameter λ C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Backup 1: distribution of test statistic Test statistic for different numbers of signal events n s (0, 1, 2, 3, 4, 5) Mention sigma after trial factor 296 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Test statistics: null hypothesis Number of signal events n s =0 C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

ANTARES as a gamma-ray telescope Tri’s picture here C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil

Limit on strongest GRB in sample 10 4 weaker than predicted gamma-ray flux Sensitive to rare GRB (e.g. 100 times closer) C.W. James for the ANTARES Collaboration, 33rd ICRC, Rio de Janeiro, Brazil Technique: Astraatmadja, T.L., MNRAS 418, 1774