Bastien Carreres
Postdoctoral Associate at Duke University
Physics Building
Duke University
Durham, NC, USA
After obtaining a master’s degree in Subatomic Physics and Cosmology at Université Grenoble-Alpes I completed my PhD in Astrophisycs and Cosmology at Centre de Physique des Particules de Marseille.
I’m currently working as a Postdoctoral Associate in the Cosmology group of Duke Universty.
My research focuses on understanding the acceleration of the expansion of the Universe and the nature of dark energy. In particular, I use type Ia supernovae in the nearby universe to measure distances and infer the peculiar velocity field. This field is linked to the growth of structures and allows to test the standard model of cosmology and general relativity.
I am involved in the Zwicky Transient Facility (ZTF) and in the Rubin Observatory - Legacy Survey of Space and Time (Rubin-LSST) within the Dark Energy Science Collaboraration (DESC).
Selected Publications
2025
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In this paper, I study the impact of intrinsic scatter of SNe Ia on the measurement of \(f\sigma_8\). This study is done through the simulation of the full low-z LSST SNe Ia sample for different intrinsic scatter models. We found that the most realistic model of intrinsic scatter causes non-Gaussianities in the Hubble diagram residuals, resulting in a bias on \(f\sigma_8\).
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This paper is part of the second data release of ZTF SNe Ia. In this paper, I study the impact of the peculiar velocity (PV) systematics on the Hubble diagram of the ZTF SN Ia DR2 sample. We show that not taking into account the full PV covariance matrix can lead to a slight underestimation of the error on the Hubble constant \(H_0\)and could shift its value by \(∼\) 1 km s\(^-1\).
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This paper presents the FLIP Python library. This library is based on codes developed during my PhD and proposes a more general framework for the constraint of the growth rate of structure. I actively participated in the development of FLIP and in the writing of this paper.
2023
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This paper is the main publication of my thesis. In this paper, I present my work to prepare for the future measurement of the growth rate of structure (\(f\sigma_8\)) from ZTF SN Ia data. I describe my realistic simulation of the ZTF SN Ia sample and, using these simulations, I study the biases and systematics that can affect the measurement of \(f\sigma_8\). I show that using SN Ia data from the full 6 years of the ZTF II sample with a cut at a redshift of \(z < 0.06\)to avoid selection due to magnitude limit, we can expect an unbiased measurement of \(f\sigma_8\)with an error of \(∼19%\).
