The Institute for Physics of the Universe (IPhU, Aix-Marseille University) invites applications for a PhD position in the field of Cosmology.
Twenty years after the discovery of the acceleration of the expansion of the universe by supernova measurements, the supernova probe remains among the most accurate way to measure the parameters of this recent period in the history of our universe dominated by the so-called dark energy. The precision measurements that can be made by the supernova probe will be a crucial element that, in combination with other probes (LSS, faint lenses, CMB, etc.), will allow to establish strong constraints on the nature of dark energy and to explore possible deviations from general relativity. This will be made possible by the exceptional supernova observations that LSST will provide, with a combination of huge statistics and extreme calibration accuracy.
The Vera Rubin Observatory completes construction early 2023 and will be commissioned in 2023. The Large Survey of Space and Time (LSST) will start full speed in early 2024, with its 8.4-meter telescope equipped with a 3.2 billion-pixel camera, the most powerful ever built.
This telescope will take a picture of half the sky every three nights for ten years. This survey will make it possible to measure billions of galaxies with great precision and to follow the variation in time of all the transient objects. Together with many other astrophysical studies, it will be a very powerful machine for determining cosmological parameters using many different probes and, in particular, will place strong constraints on the nature of dark energy. The LSST project aims to discover up to half a million supernovae, many of which can be used to probe cosmology. With an improvement of two orders of magnitude in statistics over the current data set, this will allow precise tests of the parameters of dark energy, new tests of general relativity, and will also impose new constraints on the isotropy of the universe.
In this thesis, we propose to prepare and participate in the first analysis of LSST supernova data with a focus on measuring the growth rate of structures. The preparation will be done by working on the accurate photometric measurement and photometric selection of Type Ia supernovae and their link to the properties of their host galaxy. These two points and the selection effects are among the most important sources of systematic errors and any work to reduce and mitigate these sources of errors will have a significant impact on the final measurement.
The LSST group at CPPM and LAM is already involved in precision photometry work for LSST with direct involvement in the validation of algorithms within the Dark Energy Science Collaboration of Rubin/LSST (DESC) and has proposed a new deep learning method to improve photometric identification of supernovae and photometric redshifts. The PhD student will work within this framework by applying a full analysis pipeline built with these tools, which she/he will help improve, to currently available precursor data such as HSC to validate her/his work, and will then have access to the first LSST images and supernova detections to participate in the first analysis of the LSST supernova dataset.
The cosmology group is also involved in the ZTF, DESI, and Euclid surveys and is collaborating with theorists to study alternative cosmological models, so extensions of the PhD students’ work can be found by combining data with these other surveys and/or testing a new cosmology through these new supernova data measurements.
IPhU is a leading collaborative scientific research and education environment dedicated to the Physics of the Universe and associated technologies: from the infinitely small scales of particle physics, to the infinitely large ones of cosmology, with high-energy astrophysics in between. It brings together and synergizes the theoretical, observational and experimental skills of three laboratories in Marseille, internationally recognized in those fields.
The PhD student will join the Centre de Physique des Particules de Marseille (CPPM) and the Laboratoire d’Astrophysique de Marseille (LAM), which are both part of IPhU. The student will work under the supervision of Dominique Fouchez (CPPM) and Stephane Arnouts (LAM). The position is expected to start on the 1st of October 2022 and will be funded for three years with a net monthly salary of about 1585 euros (gross monthly salary of about 1975 euros).
QUALIFICATIONS/SKILLS/EDUCATION & RESEARCH REQUIREMENTS
The applicants are expected to hold, or are about to obtain, the Master degree in physics/astrophysics. The candidate should have a strong interest in observational cosmology and data analysis. Good practical skills in python will be an important asset. Ability to work in teams and in large collaborations are highly recommended.
APPLICATION DEADLINE: 15 June 2022
STARTING DATE: 01 October 2022
Aix-Marseille Université, CPPM Lab and LAM Lab, Marseille, France
REQUESTED DOCUMENTS OF APPLICATION
- A motivation letter,
- Two reference letters (to be sent directly to email@example.com and firstname.lastname@example.org),
- CV and University grade transcripts (for all degrees)
CONTACT TO APPLY