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Reference : UMR5821-CHRVEL-070
Workplace : GRENOBLE
Date of publication : Wednesday, April 15, 2020
Scientific Responsible name : Corinne Bérat
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Identification of ultra high energy photons for multi-messenger astrophysics purpose with the upgraded Pierre Auger Observatory.
Besides the different wavelengths of traditional astronomy, neutrinos, cosmic rays, very high-energy gamma rays and gravitational waves provide complementary information to study the most energetic objects of the Universe. It is now quite clear that there is much potential in the combined analysis of data from different experiments and multi-messenger astronomy has excellent prospects of making many more significant contributions in the near future. The Pierre Auger Observatory is the present flagship experiment studying ultra-high energy cosmic rays (UHECR), and multi-messenger observations were foreseen from the beginning, with unprecedented sensitivities to ultra-high energy (UHE) photons, neutrinos, and neutrons. The discovery of gravitational waves from the merging of compact objects binary systems by LIGO and Virgo triggered a spectacular series of observations over the full electromagnetic spectrum, and searches for neutrino fluxes with ANTARES, IceCube, and the Pierre Auger Observatory. Auger will continue to search for possible UHE neutrino counterparts to transients, and a promising prospect is to include UHE photons in those follow-up searches. It is a real challenge that could be met thanks to the AugerPrime upgrade project.
Observations of photons or neutrinos in the so far dark Universe beyond 1017 eV would be a major breakthrough by itself. Yet, the non-observation of point sources and diffuse fluxes of photons and neutrinos by Auger allowed the derivation of upper bounds that constrain models very effectively. These bounds have ruled out topdown models predicting that UHECR originating from the decay of supermassive particles, and also allowed to explore astrophysical scenarios. In these, UHE photon may be produced by the hadronic interactions of the UHECR inside or in the vicinity of the astrophysics sources. Being undeflected by the galactic and extragalactic magnetic fields, they would allow pointing back to their sources. They may also result from the disintegration of the neutral pions produced in the interaction of the UHECR with the CMB photons known as the Greisen-Zatsepin-Kuzmin (GZK) process thus helping in understanding the origin of the flux suppression above 50 EeV. Indeed, the results from neutral searches started to constrain GZK-effect as a dominant process for explaining the observed flux suppression.
The PhD student will have to design and study a high quality discriminant analysis based on the universality reconstruction method of air showers, with the new observables obtained thanks to the upgraded Surface Detector. The objective is to develop an efficient search for ultra-high energy photons in the Auger data. The identification process could be embedded in a world-wide multi-messenger analysis of the astrophysical phenomena, and be used in the framework of alert network.
The Grenoble Laboratory of Subatomic Physics and Cosmology (LPSC) (http://lpsc.in2p3.fr) is a joint research unit associating the CNRS-IN2P3, the Grenoble Alpes University (UGA) and the Grenoble INP school. , for an average workforce of around 230 people.
The doctoral student will be welcomed into the AUGER research team, made up of three researchers (2 permanent, 1 CDD. The thesis director is the head of the group, co-supervision will be done by the CDD researcher. ). The Auger group is joining Labex Enigmass, and the doctoral contract is funded by this Labex, in the work package Gravitational waves and multi-messenger science
During the thesis, stays of several days in member countries of the Pierre Auger collaboration will be necessary, in particular in Argentina, at the Pierre Auger Observatory
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