Latest results of the Pierre Auger Observatory Isabelle Lhenry-Yvon - - PowerPoint PPT Presentation

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Latest results of the Pierre Auger Observatory Isabelle Lhenry-Yvon - - PowerPoint PPT Presentation

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Latest results of the Pierre Auger Observatory Isabelle Lhenry-Yvon for the Pierre Auger Collaboration IPN Orsay, Universit Paris XI, CNRS/IN2P3 1 Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama Outline The Pierre Auger

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Latest results of the Pierre Auger Observatory

Isabelle Lhenry-Yvon for the Pierre Auger Collaboration

IPN Orsay, Université Paris XI, CNRS/IN2P3

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Outline

The Pierre Auger Observatory Presentation

Methods

Update of results , towards the understanding of UHECR’s ?

Update of Spectrum : new measurements down to 1016.5 Update of Anisotropies studies at intermediate and large scale Update of Mass composition studies

The Auger Prime Upgrade Summary

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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OPEN Questions about UHECR

What is their source ? What is their nature ? How are they accelerated ? How do they propagate ?

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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The Pierre Auger Observatory in Argentina

Isabelle Lhenry-Yvon RICAP-14, Noto , September 30th-October 3rd

1500 m ARRAY 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 ~15 % duty cycle

A giant Observatory covering 3000 km2 to compensate the very low fluw at the highest energies. Indirect detection of cosmic ray through their atmospheric showers

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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The Pierre Auger Observatory in Argentina

Isabelle Lhenry-Yvon RICAP-14, Noto , September 30th-October 3rd

HEAT 750 m ARRAY

LOW ENERGY EXTENSION (1017 - 3 1018 eV)

1500 m ARRAY 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 ~15 % duty cycle

AMIGA Muon detector

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Auger Hybrid concept: more than 2 detectors !

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…)

Longitudinal profile by FD Lateral profile by SD FD provides:

  • Fluorescence light emitted in proportion to energy

deposit: -> Near calorimetric energy measurements

  • A direct view of shower maximum (composition)
  • Precise directions (hybrid method).
  • But duty cycle is only 10-15%

SD provides:

  • Huge aperture (100% duty cycle) easily calculable
  • Large angular acceptance (showers up to 80°)
  • Robust detectors
  • Good angular resolution

S(1000) <Xmax> RMS(Xmax)

The Pierre Auger Observatory associates the widest detection surface (3000 km2) together with the highest precision ever achieved

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Reconstruction

SD: S(1000) : energy estimator

Remove angular dependance with energy dependent CIC

S38

FD : Ecal + EInv

Ecal =

EInv Invisible energy

EFD

To be calibrated with hybrid event FD energy

+

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Calibration of the SD Data Set

SD 1500 m θ < 60° E > 1018.4 eV SD 1500 m «inclined» 60°<θ <80° E > 1018.6 eV SD 750 m S38 N19 S35

New Data set using new triggers

θ < 40° E > 1017 eV

EFD=A SB

Data Set : 01/01/2004 -> 31/08/2018

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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SPECTRUM

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Spectrum

215030 events above 1018.4 eV Exposure = 60400 km2sr yr

θ < 60°

Unfolding for bin-to-bin migration

  • New ESD resolution from hybrid data
  • New function

θ > 60°

24309 events above 1018.6 eV Exposure = 17447 km2sr yr Energy resolution : 22 à 10%

SD 1500 Full trigger efficiency

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Spectrum

13655 events above 1018 eV Energy dependent exposure 1 EeV 265 km2 sr yr 10 EeV 2248 km2 sr yr Energy resolution ≈ 7.4%

HYBRID

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Spectrum

New triggers to lower the threshold since 2014

SD 750

Resolution from ESd/EFd : 10 - 25%

Exposure = 105.4 km2sr yr ~600k events above 1017 eV

restrict angle to 0-40° for full trigger efficiency

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Spectrum

Cherenkov

Exposure from full time dependent simulation Energy deposited from a profile constrained geometry fit + invisible energy

69793 events above 1016.5 eV

From HEAT telescope

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Energy Spectrum

Fluxes in good agreement among after normalization. Factors are consistent with the systematic uncertainties

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

Origin of the cutoff ?? Propagation ( GZK) or limit at the source ?

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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

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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ANISOTROPIES

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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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

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Observation of Dipolar Anisotropy above 8 EeV

Flux map above 8 EeV- Equatorial coordinates Rayleigh analysis

Amplitude increases with Energy Consistent with expectations Dipole 6.6 % amplitude 125° away from GC

  • > galactic origin strongly disfavored

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 , uniformly or according to 2MRS sampled

Dipole amplitude GC

  • Phys. Rev. D 92 (2015) 063014

Update of Science 357 (2017) 1266-1270

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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CEN A

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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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 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 104 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) ]

Update of AJL, 853:L29 (2018)

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Correlation with sources candidates

Best rejection of pure isotropic hypothesis for Starburst galaxies at Eth = 38 EeV faniso= 11% 𝛊= 15° 4.5 𝜏 post-trial significance

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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MASS COMPOSITION

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Observables sensitive to composition

Heavy showers develop higher in atmosphere -> lower Xmax ( ~100g.cm-2 avrg) Heavy showers contain more muons, arriving ealiers -> smaller rise time (t1/2) in Sd traces

  • Depth of shower maximum :

<Xmax >

  • Elongation rate:

(d< Xmax >/dlogE);

  • σ(Xmax)

( distribution at fixed energy)

➡ FD ➡ SD

  • compare rise time of

individual detectors to benchmark

  • combines the deviation
  • f all detector to assign

an observalbe to an event.

SD Observable FD Observables

  • calibrate to Xmax

with hybrid events

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Mass composition over 3 decades in energy- Xmax moments

Above E= 2 EeV both Xmax moments are becoming compatible to MC predictions for heavier nuclei

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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.

  • > best fit low values for rigidity: provide information on the source environment

Precision on the mass measurement will help constrain the models

Lack of statistics at the highest energy for Xmax

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Mass composition from SD

Systematics 11-14 g.cm-2

Rate of change of primary mass not constant with energy, in agreement with results from FD

The relation between Δs and Xmax is calibrated with hybrid events

Update of Phys. Rev D 96, 122003 (2017)

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Cosmogenic photon and neutrino fluxes

Maximum sensitivity around EeV Expected events:

Auger SD is sensitive to earth-skimming 𝞾 neutrinos and to all-flavors up-going neutrinos Red band: 1.4 - 5.9 Gray band: 0.8 - 2.0 Blue band (top): 0.4

photons neutrinos

Tight limit above 20 EeV New limit below 1 EeV TopDown models excluded

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AUGER PRIME

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Hadronic models: Muons deficit in simulated showers

Even the latest simulations fail to reproduce muon densities 38% (53%) increase in <Nμ> at 1 EeV needed for EPOS-LHC (QGSJetII-04)

Inclined data at 1019 eV

New Data with Amiga at 1017.5 eV

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Science case for Auger Prime

✓ Accurate measurement of the shower components to deepen the study of hadronic interactions at UHE ✓ Tune and test shower universality using all measured components ✓ Event by event mass composition ✓ Astronomy for lighter particles ✓ Study the origin of the suppression ✓ provide better estimates of the neutrino and 𝛅 flux, as such establishing the potential of future CR experiments

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Auger Prime

Use complementary of light response of detectors to discrimate muonic and em components from 0 to 80° on 3000km2

SSD RADIO

+

AMIGA

61 Underground Muon detector in coincidence with 750 m array New electronics (faster) small PMT (dynamic range)

+

+

Extend operations to >2025, increasing the statistics

+

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Auger Prime status

✓ 12 fully upgraded stations (Engineering Array) since 2016 with new electronics, higher sampling, large dynamic range ✓ the SSD preproduction array: 80 stations (since March 2019) ✓ 356 SSD stations already deployed

SSD RADIO

✓153 radio stations deployed ( prototype)

AMIGA

✓1 engineering arrray of 7 cells

  • f 30 m2
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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Summary

✓Highest precision measurement of spectrum with interesting features ✓Updated Composition with FD and SD , light composition at ankle and mixed composition at UHE ✓ Anisotropy : dipole at E > 8 EeV and increasing indication of medium-scale anisotropy, E > 39 EeV ✓New UHE Neutrino and gamma-ray limits constraining proton-dominated sources ✓AugerPrime Upgrade is on its way

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Isabelle Lhenry-Yvon, TAUP 2019 , 9-13 of September, Toyama

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Thank you for your attention

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BACKUP SLIDES

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Mass Fraction from Xmax

Method: Fit in different energy bins the Xmax profile from hybrid data with Xmax profile from individual species (averaged shapes from MC) Test of 3 models : EPOS-LHC , QGSJet II-4 and Sibyll 2.3 Example of profile fit for the E-range 1017.8- 1017.9 eV p-Value from maximum-likelihood fit

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Universality

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Correlation with sources candidates

STARBURST GALAXIES SWIFT BAT 2MRS

𝛿-EMITTING AGNs

CenA NGC253 NGC4945

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detail des catalogues

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Observation of Dipolar Anisotropy above 8 EeV in four bins

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Fluctuations in the number of muons

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No Declination dependence in Auger Spectrum

Only a trend for a slightly larger intensity in the South (consistent with dipole expectations)