Search for neutrinos from gammaray bursts with the

Search for neutrinos from gamma-ray bursts with the ANTARES telescope D. Dornic for the ANTARES Collaboration

Neutrinos from GRBs : powerful cosmic particle accelerators producing a highly variable flux of high energy gamma-rays. Under the assumption of hadronic acceleration in jets a copious flux of neutrinos expected Among the possible astrophysical sources, GRBs offer one of the most promising perspectives for the detection of cosmic neutrinos thanks to an almost background free search. D. Dornic – Rencontres de Moriond 2009

Neutrinos from GRBs The Fireball model tells us how GRBs operate, but: - Which processes generate the energetic ultra-relativistic flows? - How is the shock-acceleration realized ? ~ 100 ~ 10 High energy neutrinos expected by photonuclear interactions of the observed gamma-rays with the protons accelerated by the internal shocks (typical energy above ~10 Te. V) D. Dornic – Rencontres de Moriond 2009

GRB search techniques Triggered search Detection in conjunction with accurate timing and positional information provided by an external source Rolling search Searching for high energy or multiplet of neutrino events from the same direction and within a short time window D. Dornic – Rencontres de Moriond 2009

Triggered search method http: //gcn. gsfc. nasa. gov/ ANTARES is a client of the GCN Special DAQ strategy D. Dornic – Rencontres de Moriond 2009

Triggered search method SWIFT, INTEGRAL, Fermi alerts reception ANTARES Continuous data acquisition + GRB data storage during 2 minutes without filtering D. Dornic – Rencontres de Moriond 2009

Triggered search method Response time to satellite triggers Number of satellite triggers October 2006 – December 2008 Fermi Swift (2008 only) Response time (s) D. Dornic – Rencontres de Moriond 2009

Triggered search method number of satellite triggers ANTARES GRB data taking: oct 06 – jan 09 satellite triggers ANTARES data for 324 alerts satellite triggered data taking 29 during line 1 -2 period 120 during line 1 -5 period 57 during line 1 -10 period 118 during line 1 -12 period Blinded data 24 alerts from INTEGRAL 244 alerts from Swift 56 Alerts from Fermi date D. Dornic – Rencontres de Moriond 2009

Triggered search method Advantages: The nature and the location of the source is known Very low background rate Low energy threshold Disadvantages: Dependant on external sources SWIFT (1. 4 sr fov) → only ~1 / 9 GRB is detected (no external trigger for choked GRBs) D. Dornic – Rencontres de Moriond 2009

GRB search techniques Triggered search Detection in conjunction with accurate timing and positional information provided by an external source Rolling search Searching for high energy or multiplet of neutrino events from the same direction and within a short time window D. Dornic – Rencontres de Moriond 2009

Rolling search method Search for “golden” neutrino events on-line Advantages: Large sky coverage ~100 % duty cycle No assumption on the nature of the source Disadvantages: the nature of the source is unknown → need a follow-up program to confirm detection (nature, redshift…) → need a very fast analysis with a good angular resolution D. Dornic – Rencontres de Moriond 2009

Rolling search method Multiplet of neutrino events (burst) 2 bkg events coincidence rate: Application to ANTARES: ΔΩ = 2° x 2° Δt = 10 min D. Dornic – Rencontres de Moriond 2009

Rolling search method Multiplet of neutrino events (burst) 2 bkg events coincidence rate: Application to ANTARES: ΔΩ = 2° x 2° Δt = 10 min Single neutrino event with HE Above ~20 à 50 Te. V, the background rate begins to be negligible Cuts are tuned to give about 1 or 2 alerts per month D. Dornic – Rencontres de Moriond 2009

Rolling search method Performances of the on-line reconstruction Elevation Data : 582 MC : 494 MC : 13 2008 data (173 active days) D. Dornic – Rencontres de Moriond 2009

Rolling search method Performances of the on-line reconstruction Elevation Angular resolution Data : 582 MC : 494 MC : 13 2008 data (173 active days) D. Dornic – Rencontres de Moriond 2009

Rolling search method Collaboration with the TAROT telescope array TAROT: two 25 cm telescopes located at Calern (South France) and La Silla (Chile) - fov 1. 86° x 1. 86° - Magnitude V<17 (10 s) V<19 (100 s) - ~ 10 s repositioning after the alert reception Limit: difficult association with a source in the galactic plane TAROT La Silla D. Dornic – Rencontres de Moriond 2009

Rolling search method Principle Trigger: multiple / HE single Reconstruction “on-line” (<10 ms) Alert message Neutrino telescope ν Telescope TAROT Real time Observation strategy: Real time (T 0) : 6 images of 3 minutes T 0+1 day, +3 days, +9 days and +27 days D. Dornic – Rencontres de Moriond 2009

Rolling search method First “alert” Time: 2009 -01 -16 11: 15: 53 Zenith = 70. 16° azimuth = 61. 89° Representation D. Dornic – Rencontres de Moriond 2009

Summary and perspectives Triggered search method Special data without filtering for ~324 GRB alerts Analysis is ready & data unblinding requested within ANTARES Rolling search method By complementing neutrino telescopes with an optical follow-up, one gains significant sensitivity for transient sources. The system is operational with TAROT since two weeks. We are waiting for alerts. Would be interesting to extend technique to other wavelength (X-ray, radio). D. Dornic – Rencontres de Moriond 2009