Latest results of the Pierre Auger Observatory Isabelle Lhenry-Yvon for the Pierre Auger Collaboration IPN Orsay, Université Paris XI, CNRS/IN2P3 1 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Outline The Pierre Auger Observatory Presentation Methods Update of results , towards the understanding of UHECR’s ? Update of Spectrum : new measurements down to 10 16.5 Update of Anisotropies studies at intermediate and large scale Update of Mass composition studies The Auger Prime Upgrade Summary 2
OPEN Questions about UHECR What is their source ? What is their nature ? How are they accelerated ? How do they propagate ? 3 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
The Pierre Auger Observatory in Argentina 1500 m ARRAY Indirect detection of cosmic ray through their atmospheric showers A giant Observatory 1600 Water Cerenkov Detectors covering 3000 km2 1.5 Km spaced on a hexagonal grid to compensate the Can detect shower up to 90° very low fluw at the 100% duty cycle highest energies. 4 Fluorescence Telescopes with 6 telescopes each Telescope f.o.v. 30 x 30 Isabelle Lhenry-Yvon RICAP-14, Noto , September 30th-October 3rd ~15 % duty cycle 4 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
The Pierre Auger Observatory in Argentina LOW ENERGY EXTENSION (10 17 - 3 10 18 eV) 1500 m ARRAY AMIGA Muon HEAT detector 1600 Water Cerenkov Detectors 1.5 Km spaced on a hexagonal grid Can detect shower up to 90° 100% duty cycle 4 Fluorescence Telescopes with 6 telescopes each Telescope f.o.v. 30 x 30 Isabelle Lhenry-Yvon RICAP-14, Noto , September 30th-October 3rd 750 m ARRAY ~15 % duty cycle 5 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Auger Hybrid concept: more than 2 detectors ! Lateral profile by SD Longitudinal profile by FD S(1000) RMS(X max ) <X max > FD provides : SD provides: • Fluorescence light emitted in proportion to energy • Huge aperture (100% duty cycle) easily calculable deposit: -> Near calorimetric energy measurements • Large angular acceptance (showers up to 80°) • A direct view of shower maximum (composition) • Robust detectors • Precise directions (hybrid method). • Good angular resolution • But duty cycle is only 10-15% Optimisation of Auger's hybrid data - FD calibrates SD energy scale that is used on the large statistic of SD events :minimal use of simulations when possible - Various cross-check (directions, energy thresholds…) The Pierre Auger Observatory associates the widest detection surface (3000 km 2 ) together with the highest precision ever achieved 6 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Reconstruction FD : E cal + E Inv E FD E cal = + E Inv Invisible energy SD : S(1000) : energy estimator Remove angular S 38 dependance with energy To be calibrated dependent CIC with hybrid event FD energy 7 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Calibration of the SD Data Set SD 1500 m SD 1500 m «inclined» θ < 60° E > 10 18.4 eV 60°< θ <80° E > 10 18.6 eV S 38 N 19 E FD =A S B SD 750 m New Data set using new triggers θ < 40° E > 10 17 eV S 35 Data Set : 01/01/2004 -> 31/08/2018 8 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
SPECTRUM 9 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Spectrum SD 1500 Full trigger efficiency θ < 60° 215030 events above 10 18.4 eV Exposure = 60400 km 2 sr yr Unfolding for bin-to-bin migration • New E SD resolution from hybrid data • New function θ > 60° 24309 events above 10 18.6 eV Exposure = 17447 km 2 sr yr Energy resolution : 22 à 10% 10 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Spectrum HYBRID 13655 events above 10 18 eV Energy dependent exposure 1 EeV 265 km2 sr yr 10 EeV 2248 km2 sr yr Energy resolution ≈ 7.4% 11 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Spectrum SD 750 New triggers to lower the threshold since 2014 Exposure = 105.4 km 2 sr yr ~600k events above 10 17 eV restrict angle to 0-40° for full trigger efficiency Resolution from E Sd /E Fd : 10 - 25% 12 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Spectrum Cherenkov From HEAT telescope Energy deposited from a profile constrained geometry fit + invisible energy 69793 events above 10 16.5 eV Exposure from full time dependent simulation 13 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Energy Spectrum Fluxes in good agreement among after normalization. Factors are consistent with the systematic uncertainties 14 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Combined Energy Spectrum • abrupt suppression at the highest energies • ankle • clear observation of the second knee • an indication of a further inflection point at E ~ 10 EeV Origin of the cutoff ?? Propagation ( GZK) or limit at the source ? 15 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
ANISOTROPIES 16 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Anisotropy searches Motivation: Structure in the distribution of arrival directions —> a hint to track the nature and origin of UHECRs Large scale anisotropies : To track the transition from Galactic to Extragalactic —> significant change in the large scale angular distribution of CR • Galactic: diffusion & escape of galactic CRs below EeV energies —> might generate dipole pattern • Extragalactic: Small dipole due to our motion —> Compton-Getting effect, expected below 1% Point sources/ intermediate scale anisotropies: At the largest energies: expect small deflection from the source above GZK if there is a light composition → possibly trace source population 17 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Observation of Dipolar Anisotropy above 8 EeV Flux map above 8 EeV- Equatorial coordinates Amplitude increases with Energy Rayleigh analysis Dipole amplitude GC Consistent with expectations Need very careful analyis taking into account detector effects From scenario of extragalactic sources with a mixed CR compositions Auger-like and a density 10-4 Mpc-3 , Dipole 6.6 % amplitude uniformly or according to 2MRS sampled 125° away from GC Phys. Rev. D 92 (2015) 063014 -> galactic origin strongly disfavored Update of Science 357 (2017) 1266-1270 18 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
CEN A 19 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Correlation with sources candidates Method : build probability maps of the arrival distribution of cosmic rays for a group of candidate sources from catalog taking into account brightness of objects and attenuation due to distance Compare to the observed distribution of events using an appropriate test statistics Update of AJL, 853:L29 (2018) Free parameters: • smearing angle around source ( magnetic deflections) • source fraction ( added to isotropy) Sources used • 𝛅 -emitting AGNs ( 33 2FHL blazars and radio galaxies, including CenA) • Swift-BAT (300 X-ray-selected galaxies) • StarburstGalaxies (32 nearby starburst galaxies) • 2MRS (about 10 4 IR-selected galaxies tracing local matter) Scan in energy 32 EeV ≤ Eth ≤ 80 EeV [1 EeV steps] Test statistic defined as the ratio of likelihoods: TS = 2 Log [ ℒ ( ψ , faniso)/ ℒ (faniso= 0) ] 20 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Correlation with sources candidates Best rejection of pure isotropic hypothesis for Starburst galaxies at E th = 38 EeV f aniso = 11% 𝛊 = 15° 4.5 𝜏 post-trial significance 21 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
MASS COMPOSITION 22 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Observables sensitive to composition ➡ FD Heavy showers develop higher in atmosphere -> lower X max ( ~100g.cm- 2 avrg) ➡ SD Heavy showers contain more muons, arriving ealiers -> smaller rise time (t 1/2 ) in Sd traces SD Observable FD Observables • compare rise time of individual detectors to • Depth of shower maximum : benchmark <X max > • Elongation rate: (d< X max >/dlogE); • σ (X max) • combines the deviation of all detector to assign ( distribution at fixed energy) an observalbe to an event. • calibrate to Xmax with hybrid events 23 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Mass composition over 3 decades in energy- X max moments Above E= 2 EeV both X max moments are becoming compatible to MC predictions for heavier nuclei 24 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
Combined Fit of spectrum and mass distributions Simulate propagation of CR particles with various masses in cosmic photon fields to match spectrum and mass. Different power law and rigidity cut off for cosmic ray injection Aab et al. [Auger Collab.] JCAP (2017) 1704, 038. Lack of statistics at the highest energy for Xmax -> best fit low values for rigidity: provide information on the source environment Precision on the mass measurement will help constrain the models 25 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama
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