Search for ultra-high energy photons and neutrinos at the Pierre Auger Observatory

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1 Search for ultra-high energy photons and neutrinos at the Pierre Auger Observatory Mathieu Tartare 1 on behalf of the Pierre Auger Collaboration 2 1 Laboratoire de Physique Subatomique et de Cosmologie (LPSC) - Grenoble, France UMR UJF/INPG/CNRS 2 Observatorio Pierre Auger, Av. San Martín Norte 304, (5613) Malargüe, Argentina Full author list: html

$If GZK cutoff : photons and neutrinos expected Constraints on production models (top-down models) Neutrinos point directly to sources Limits on EeV photon fraction$ reduce systematic in other analyses The Pierre Auger Observatory Surface Detector (SD) 1600 Cherenkov water tanks with a 1.

reduce systematic in other analyses The Pierre Auger Observatory Surface Detector (SD) 1600 Cherenkov water tanks with a 1.

2 Context The UHECR puzzle Composition? Origin? GZK cutoff or maximum acceleration? If GZK cutoff : photons and neutrinos expected Constraints on production models (top-down models) Neutrinos point directly to sources Limits on EeV photon fraction reduce systematic in other analyses The Pierre Auger Observatory Surface Detector (SD) 1600 Cherenkov water tanks with a 1.5 km spacing covering 3000 km 2 61 tanks in 750 m grid ( infill low energies) 0 % duty cycle Fluorescence Detector (FD) 4 sites + 1 HEAT (low energies) 6 fluorescence telescopes per site Field of view : % duty cycle Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 1

3 Ultra-high energy neutrinos Mathieu Tartare Rencontres de Moriond, 03/12/2013 2

Identifying neutrinos in data Identify neutrino showers from nucleonic showers background Regular nucleonic showers : Interact high in the atmosphere At ground : mainly muons, flat shower front

4 Identifying neutrinos in data Identify neutrino showers from nucleonic showers background Regular nucleonic showers : Interact high in the atmosphere At ground : mainly muons, flat shower front Neutrinos May interact closer to the ground level At ground : EM component, curved shower front Discrimination power enhanced at high zenith-angle Selection criteria : Inclined young (=deep) shower Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 3

5 Identification criteria : Inclined Showers Elongated footprint Apparent speed along major axis L Vertical Shower T ij 0 V c Horizontal Shower V c Earth Skimming Elongated event : L/W 5 Down Going Elongated event : L/W 3 Apparent speed : 0.29 m ns V 0.31 m ns SD(V ) < 0.08 m.ns 1 Apparent speed : V m ns SD(V ) V < 8% Rec. zenith angle θ 75 Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 4

6 Identification criteria : Inclined Showers Elongated footprint Apparent speed along major axis L Vertical Shower T ij 0 V c Horizontal Shower V c Events 3 2 Events 3 2 Events L/ W <V> (m ns -1 ) v (m ns-1 ) Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 4

7 Identification criteria : Young Showers Young/Deep Showers = Broad Signal Signal extented in time Time over Threshold trigger Large Area over Peak value Station trigger Area over Peak ToT station ToT fraction > 0.6 Thr station ToT station ToT fraction < 0.6 Thr station Earth Skimming ToT fraction Down Going Fisher discriminant based on AoP Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 5

Training Data simulation 0 0.2 0.4 0.6 0.

8 Identification criteria : Young Showers Young/Deep Showers = Broad Signal Signal extented in time Time over Threshold trigger Large Area over Peak value Events Training Data simulation ToT stations Events Fisher discriminant value Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 5

9 Exposure Based on detailed dedicated Monte Carlo simulations Earth-skimming (3.5 yr of full Auger) s sr] 2 Exposure [cm Down-going (2 yr of full Auger) Total CC e CCµ CCτ NC x CCτ Mountains ν energy (ev) Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 6

10 Limits to diffuse fluxes After unblinding : 0 candidates survive the cuts Assuming a flux φ(e) = k E 2 k < GeV cm 2 s 1 sr 1 in ev< E < 2 19 ev k < GeV cm 2 s 1 sr 1 in 1 17 ev< E < 1 20 ev -5 Single flavour neutrino limits (90% CL) s -1 sr -1 ] -2 ) [ GeV cm ν Φ(E k = E ν ν limits Auger downward-going Auger Earth-skimming IceCube-40 (333.5 days) Anita-II (28.5 days) Cosmogenic models Ahlers 20 Kotera E ν [ev] Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/ k = N up Emax φ(e)ede E min Search sample : Earth skimming : Jan May Down going : Nov May

11 Limits to point sources Search for point-like sources of UHEν over a broad range of declinations : [north -65, south +55 ] Single flavour neutrino limits (90% CL) s -1 ] -5 Auger downward-going Auger Earth-skimming -2 ) [GeV cm -6 F(E ν = E k PS 2 ν Source declinationδ [deg] Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013 8

12 Ultra-high energy photons Mathieu Tartare Rencontres de Moriond, 03/12/2013 9

13 Identifying UHE photons Fluorescence Detector Deeper development of the air showers. larger X max Surface Detector Smaller signal at a given distance & same energy Fewer triggered stations S b = ( ) 4 Ri S i 00 i smaller S b Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/2013

Identifying UHE photons FD : Deeper X max SD : Smaller S b ) -2 (g cm X max 1200 00 Monte Carlo Simulations photon 18 < log (E /ev) < 18.

14 Identifying UHE photons FD : Deeper X max SD : Smaller S b ) -2 (g cm X max Monte Carlo Simulations photon 18 < log (E /ev) < 18.5 Photon-like events proton log (S ) b Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

15 Photon selection Data selection Reconstruction Level : Good geometry and longitudinal profile Zenith angle < 60 X max within the field of view Quality cuts : Time periods with clouds rejected Active station within 2 km from the shower axis 4 Fisher analysis 3 separate energy intervals (1-3 EeV, 3- EeV, > EeV) Background : proton QGSJET-II-03 Event are tagged as photon candidates for X > X cut Proton background 1% Photon selection efficiency = 50% Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

16 Photon candidates Using hybrid data from Jan to Sep. 20 : 6, 0, 0, 0 and 0 candidates above 1, 2, 3, 5 and EeV Compatible with the expected nuclear background Example of a selected candidate )] -2 de/dx [PeV/(g cm 4 E [EeV] = 1.18 ± 0.09 Xmax [gcm ] = 23 ± log(sb) = 1.16 ± /Ndf= 93.8/ slant depth [g cm ] ) -2 (g cm X max proton simulations ~ 2% of protons are marked as candidates photon-like events selected candidate log (S Dedicated proton simulations : same energy, arrival direction, core position and detector configuration of this selected candidate ) b Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

17 Hybrid exposure Upper Limit to the Integral Photon Flux : Φ 95CL γ = N 95CL γ (E γ > E 0 ) E γ,min sr yr] 3 Nγ 95CL : Number of photon candidates (at 95% C.L.) with energy E γ above the threshold E 0. Nuclear background not subtracted (conservative approach) E γ,min : Minimum hybrid exposure for photons. Time dependent simulations 2 Hybrid Exposure for photons [km Photon candidate level Realistic and time dependent simulations J anuary January September - 20 level Photon candidate log (Energy/eV) (method according to Astrop. Phys. 34, 2011) Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

18 Limits on photon flux sr -1 y -1 ] -2 [km 0 Integral Flux E>E Y Auger Hyb 2011 Auger Hyb 2009 Y upper limits 95% C.L. A TA 2011 Auger SD A SHDM SHDM TD Z-burst GZK Systematic uncertainties Exposure, X max, S b, Energy scale, hadronic interaction model and mass composition assumptions : +20% 64% (E 0 = 1 EeV) +15% 36% (E 0 > 1 EeV) Energy[eV] Upper limit on the integral photon fraction assuming the Auger spectrum : 0.4%, 0.5%, 1.0%, 2.6% and 8.9% at E > 1, 2, 3, 5 and EeV Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

19 Conclusions Neutrino search using surface detector Earth skimming (sensitive to ν τ ) : k < GeV cm 2 s 1 sr 1 in ev< E < 2 19 ev Down going (sensitive to all flavors) : k < GeV cm 2 s 1 sr 1 in 1 17 ev< E < 1 20 ev The surface detector of the Pierre Auger Observatory is sensitive to potential point sources of UHE neutrinos in a broad range in declination. Photon search using hybrid data 6, 0, 0, 0 and 0 candidates above 1, 2, 3, 5 and EeV Upper limit to the integral photon flux : km 2 sr 1 year 1 above 1 EeV km 2 sr 1 year 1 above 2, 3, 5 and EeV Corresponding to photon fractions limit of : 0.4%, 0.5%, 1.0%, 2.6% and 8.9% at E > 1, 2, 3, 5 and EeV Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

20 Perspective & Outlook GZK within reach in the next few years Photon & neutrino limits provide severe constraints on top-down models. Photon limits allow to reduce systematic uncertainties on mass composition, energy spectrum & cross section measurements Earth skimming and Downgoing combination in progress. Directional search for UHE photons in progress Search for UHE photons and neutrinos Mathieu Tartare Rencontres de Moriond, 03/12/

21 Perspective & Outlook GZK within reach in the next few years Photon & neutrino limits provide severe constraints on top-down models. Photon limits allow to reduce systematic uncertainties on mass composition, energy spectrum & cross section measurements Earth skimming and Downgoing combination in progress. Directional search for UHE photons in progress Search for UHE photons and neutrinos a postdoctoral position Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

22 Backup slides Mathieu Tartare Rencontres de Moriond, 03/12/

23 General neutrino search strategy Mathieu Tartare Rencontres de Moriond, 03/12/

24 Limits to point-like sources s -1 ] -5-6 Single flavour neutrino limits (90% CL) Down-going (2yr) Earth-skimming (3.5yr) Fixed energy range 17 ev < E < 20 ev ev < E < 2 19 ev g(e) [GeV cm -2 2 E -7-8 Cen A IceCube-40 (375.5 days) Energy range depends on declination Below 17 ev Source declination [deg] Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

25 Limits to CenA -4 Centaurus A - Single flavour neutrino limits (90% CL) s -1 ] -2-5 Auger Downward-going LUNASKA 2008 ) [GeV cm ν F(E -6-7 IceCube 2011b Auger Earth-skimming Cuoco 2008 = E 2 ν -8 k PS E ν Kachelriess 2009 [ev] Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

26 Point source as seen by Auger 1 Source atδ= -43 o 1 Source atδ= -80 o θ = 75 o θ = 75 o cosθ 0 θ = 90 o cosθ 0 θ = 90 o Time t [sidereal days] Time [sidereal days] Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

27 safe cut on Fisher value such that expected background < 1 event / 20 yearsof Auger data 11 Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

28 Down- going: estimation of background Assume an exponential shape for the tail of background distribution of F extrapolation to find the value of F_cut corresponding to 1 background event in a given time Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

29 Expected number of events Model& reference Earth-skimming Downward-going Cosmogenic(Fermi)[40] BBR(AGNs)[41] Exotic(SH relics)[42] Table 4: Number of expected events for several theoretical models of UHE neutrino production, given the exposure of the surface detector of the Pierre Auger Observatory to Earth-skimming and downward-going neutrinos(table3). Integrated limit The limits indicate the level of the diffuse neutrino flux needed to detect Nup events with a Poisson probability of 90% given the exposure accumulated during the 3.5 years for Earth-skimming (2.0 years for downward-going) of equivalent time of a full SD Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

30 Elongation rate 1200 <X max > (g cm -2 ) Fly s Eye HiRes-MIA HiRes 2004 Yakutsk 2001 Yakutsk 2005 CASA-BLANCA HEGRA-AIROBICC SPASE-VULCAN DICE TUNKA photon proton photon with preshower iron QGSJET 01 QGSJET II SIBYLL E lab (ev) Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

31 Systematics Mathieu Tartare Rencontres de Moriond, 03/12/

32 Photon candidates Hybrid data J an Sep 20 (~ a factor 2 more events compared to previous analysis) 6, 0, 0, 0 and 0 candidates above 1, 2, 3, 5 and EeV compatible with the expected nuclear background E (EeV) Xmax (gcm -2 ) log(sb) 1.18 ± ± 1.16 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.55 ) -2 Xmax (g cm Photon candidates Jan Sept EeV 1.59 EeV 1.25 EeV 1.20 EeV 1.42 EeV 1.13 EeV log (S ) b Mathieu Tartare [tartare@lpsc.in2p3.fr] Rencontres de Moriond, 03/12/

The Pierre Auger Observatory and ultra-high energy neutrinos: upper limits to the diffuse and point source fluxes

id 068 The Pierre Auger Observatory and ultra-high energy neutrinos: upper limits to the diffuse and point source fluxes Yann Guardincerri1 for the Pierre Auger Collaboration 1 Facultad de Ciencias Exactas