High Energy Cosmic Rays at the Pierre Auger Observatory after 10 - PowerPoint PPT Presentation

High Energy Cosmic Rays at the Pierre Auger Observatory after 10 years : results and future Isabelle Lhenry-Yvon on behalf of the Pierre Auger Collaboration IPN Orsay, Université Paris XI, CNRS/IN2P3 1 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

The Pierre Auger Collaboration 460 collaborators 110 institutions from 17 countries 2 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Outline The Pierre Auger Observatory Science case and characteristics Results, towards the understanding of UHECR’s Spectrum, Anisotropy Mass composition Hadronic models Summary and future plans Auger Prime 3

Original AUGER Science Case 1. A precise reconstruction of the energy spectrum Is the GZK cutoff observed or challenged? 2. The identification of primaries , even if only statistical : proton, nuclei , or more exotic particles ( gamma, neutrinos ?) - Based on the air shower properties, Knee - Could give constrain to existing hadronic models 3. A systematic study of arrival directions Search for indication of anisotropies UHECR and existence of point sources 4 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

The Pierre Auger Observatory in Argentina Surface detectors SD 1680 Cherenkov stations 1.5 Km spaced on a hexagonal grid Can detect shower up to 90° 100% duty cycle Fluorescence detectors FD 4 building with 6 telescopes each Telescope f.o.v. 30 x 30 ~15 % duty cycle Completed in 2008 Progressive data taking starting in 2004 Aiming at understanding the origin of Ultra High Energy Cosmic Rays, the PAO associates the widest detection surface (3000 km 2 ) together with the highest precision ever achieved 5 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Shower observables 
 Shower Observables recorded dX dX ] m Z dE recorded at Auger c / g [ h 500 t p e e d l fi t n o a l r s E ∝ p 20 l 1000 a ) s n t i Time structure i d 18 n u u t i . b g 16 n r a o ( L 14 l a n m )] 40 g 12 i s c r / o g 10 max ( t / 30 FD c V X e e 8 t P e [ D X d 6 / 20 E d 4 2 10 SD 0 20 40 60 80 100 120 140 160 180 200 Time bins (25 ns) Signal [VEM] Signal [VEM] 4 4 10 10 Lateral distribution 3 3 10 10 S 1000 ∝ E S 1000 2 2 10 10 10 10 1 1 500 500 1000 1000 1500 1500 2000 2000 2500 2500 r [m] 6 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Present status of the Pierre Auger Observatory LOW ENERGY EXTENSION (10 17 - 3 10 18 eV) 1500 m ARRAY HEAT Isabelle ¡Lhenry-­‑Yvon ¡RICAP-­‑14, ¡Noto ¡, ¡September ¡30th-­‑October ¡3rd 750 m ARRAY 7 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Present status of the Pierre Auger Observatory LOW ENERGY EXTENSION (10 17 - 3 10 18 eV) AERA 1500 m ARRAY HEAT Engineering Array of 7 buried muon detectors COMPLETED FEBRUARY 2015 Isabelle ¡Lhenry-­‑Yvon ¡RICAP-­‑14, ¡Noto ¡, ¡September ¡30th-­‑October ¡3rd AMIGA MUON COUNTERS 750 m ARRAY 8 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

The different AUGER data sets SD-750 m ( θ <55°) SD-1500 m ( θ <60°) SD-1500 m (62°< θ <80°) fully efficient: E > 3 x 10 17 eV fully efficient: E > 4 x 10 18 eV fully efficient: E > 3 x 10 18 eV energy estimator: N19 energy estimator: S 35 energy estimator: S 38 HYBRID FD + ≥ 1 SD 1500 station Fully efficient: E ≿ 10 18 eV HEAT + ≥ 1 SD-750 station Fully efficient E ≿ 10 17 eV Energy measurement: E FD 9 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

SPECTRUM 10 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Energy Reconstruction of Auger Events SD vertical ( θ < 60°) SD horizontal al (62 < θ < 80°) Energy estimator S(1000): Energy estimator : N 19 N 19 : relative number of muons at ground w.r.t. the S ignal at 1000 m from lateral pr ofile density of muons of the reference distribution: S(1000) is θ thPolarMap thPolarMap thPolarMap Entries Entries 40000 40000 dependent due to Mean x Mean x 55.6 55.6 Mean y Mean y -33.89 -33.89 RMS x RMS x 1227 1227 RMS y RMS y 823.9 823.9 S(1000) ¡ ¡ attenuation in atmosphere ρ -2 (m ) ) -2 µ ,19 muon number density (m 10 10 1 1 -1 10 -1 10 -> use of Constant Intensity Cut (CIC) -2 10 -2 10 -3 10 -3 4000 10 2000 4000 Conversion 2000 0 y 0 ( m -2000 ) x (m) -2000 S(1000) -> S 38 -4000 -4000 ρ μ, 19 reference profile from parameterization of muon density at ground ( 10 19 eV p QGSJetII-03) ¡ N 19 is not θ dependent ( already included in ρ μ ,19 ) In case of SD 750m array: S(450) S 35 11 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Calibration of AUGER data sets For each SD data , the energy estimator is calibrated with FD energy with hybrid data set Cross correlation of the SD energy E FD = A * S B estimators (S) with the FD energy Detector N ( E>E E Hybrid 1 ~10000 FD+SD SD 1500m 3 ~100000 (0°-60°) SD 1500 m 4 15000 (60°-80°) SD 750m 0.3 6000 (0°-55°) HEAT +SD 0.1 60000 The FD defines all energy scales -> systematic uncertainty ~ 14% 12 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Energy spectrum over 3 decades in energy 4 data sets combined : SD 750 m, FD (hybrid), SD 1500 m (0-60°), SD 1500 m (60-80°) ≈ 200 000 events, ≈ 50000 km2 sr yr exposure, FOV: -90°, +25 in δ 𝛿 1 = 3.29±0.02±0.05 𝛿 2 = 2.6±0.02±0.1 E ankle = (4.8 ± 0.1 ± 0.8) EeV E supp = (42.1 ± 1.7 ± 7.6) EeV ∆ 𝛿 = 3.14±0.02±0.04 13 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

AUGER/Telescope Array spectra Discrepancy can be accommodated within a systematic energy shift , but not at the highest energies Under study by UHECR spectrum WG(TA/Auger) ( I.C Maris, UHECR2014) 14 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

ANISOTROPIES 15 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

The search for anisotropies to track the origin of cosmic rays At small and intermediate scale : For light particles at the largest energies we expect small deviation from magnetic fields ( a few degrees) : - A clear anisotropie would reveal a large fraction of protons in the high energy flux - Possible CR astronomy ?? -> Intrinsic correlations or correlation with close objects from catalogs At large scale : - diffusion & escape of galactic CR below EeV energies can generate dipole pattern C - A change in the large scale anisotropy could sign the galactic/extra galactic transition ( at the ankle ? ) -> Search of dipole on different energy ranges 16 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Search of small/intermediate scale anisotropies in the arrival directions of the most energetic cosmic rays < 80° Blind search for excesses Scan on parameters: compute the obs./exp number of events in each circular window for: o o E th ∈ [40;80]EeV in1 EeV steps, Ψ ∈ [ 1 ; 30 ] ) in 1 o steps Li-Ma significance map in 12° circles; 4 ApJ 804:15 , 2015 largest excess 4.3 σ , Ethresh = 54 EeV, 18° from CenA; Post-trial probability (from simulations ) 69%, All excess found are compatible with isotropy. � � 17 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october � � � � � � � � � � � � � � � � � � � � � � � � � � � ) � 3

Search of small/intermediate scale anisotropies in the arrival directions of the most energetic cosmic rays < 80° Search of correlations with astrophysical structures Gal-Xgal planes, 2MRS galaxies, Swift-BAT AGNs, jetted radio galaxies, CenA; Ψ . Scan over angles, E thresh , luminosity for AGNs and radio galaxies. Largest excess of pairs for Swift AGNs with E thresh = 58 EeV, 18° circles, L > 1044 erg/s, closer than 130 Mpc; post-trial probability 1.3%. ApJ 804:15 , 2015 > Y = � No statistically significant deviation from isotropy = = - 18 - < ´ Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october � 1 - = ´ = y = � ~ = n - ´

19 Dipole Amplitude: 6.5 ± 1.9% Auger/TA : ≈ 17000 Auger events , ≈ 2500 TA events with E>10 EeV , Full sky coverage (93°±24°, -46°±18°) Pointing to (a, d) = Auger data set : ≈ 70000 events with E>4 EeV and ϑ < 80° , 85% sky coverage challenging the original expectations of isotropy at these energies AUGER/TA (p=5x10 -3 ) Indications of large-scale anisotropies of CRs at E > 8-10 EeV Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october Large scale anisotropies 85% sky coverage. Two energy bins: 4-8 EeV and > 8 AUGER : Harmonic analysis in right ascension ≈ 70000 events with E>4 EeV and ϑ < 80° and azimuth (declination-sensitive) in km � 2 yr � 1 sr � 1 M odified Raleigh or East-West analysis on 1500 m and 750 m arrays dataset Spherical harmonic analysis

MASS ¡COMPOSITION 20 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october

Composition from FD longitudinal profile Observables sensitive to composition: Fe shower develop higher in atmosphere -> lower Xmax ( ~100g.cm- 2 avrg) • Depth of shower maximum (<Xmax>); • Elongation rate (d<Xmax>/dlogE); • RMS of Xmax distribution at fixed energy: 21 Isabelle Lhenry-Yvon, TeVPA 2015, Kashiwa , 26-31 october