Florian Sarron

In February 2024, I started as a postdoctoral researcher at IRIT in the MAMBO team. I work with Pierre Weiss as part of the MicroBlind ANR project.

I study inverse problems in optical microscopy, currently carrying two main projects:

Deep learning for blind deblurring of fluorescence microscopy images.
Neural networks for instance segmentation of individuals cells in images biological sample with partial annotations.

Over the course of my career in Astrophysics (PhD 2018), I have developped a strong interest in inverse problem solving via a Bayesian approach while studying galaxy evolution using large photometric surveys.
This led me to take a position in the MAMBO team to further explore inverse problem solving in high dimensions in a different context.

I still work part-time on my research in Astrophysics. There, I mainly study the evolution of star-formation in galaxies through cosmic time. I am interested in understanding the role played by the environment surrounding galaxies on large scales on their history and their fate. I am still actively invested in several international collaborations (Euclid, XCLASS).

news

Sep 01, 2024	Welcome to my new website. Some things are still under developments, stay tuned.

selected publications

arXiv
EPOCHS Paper X: Environmental effects on Galaxy Formation and Protocluster Galaxy candidates at 4.5
Qiong Li , Christopher J. Conselice, Florian Sarron, and 16 more authors

arXiv e-prints, May 2024

Abs arXiv Bib HTML

In this paper we describe our search for galaxy protocluster candidates at 4.5< z < 10 and explore the environmental and physical properties of their member galaxies identified through JWST wide-field surveys within the CEERS, JADES, and PEARLS NEP-TDF fields. Combining with HST data, we identify 2948 robust z>4.5 candidates within an area of 185.4 arcmin^2. We determine nearest neighbour statistics and galaxy environments. We find that high-z galaxies in overdense environments exhibit higher star formation activity compared to those in underdense regions. Galaxies in dense environments have a slightly increased SFR at a given mass compared with galaxies in the lower density environments. At the high mass end we also find a gradual flattening of the M_⋆-SFR slope. We find that galaxies in high-density regions often have redder UV slopes than those in low-density regions, suggesting more dust extinction, weaker Lyman-alpha emission and / or a higher damped Lyman-alpha absorption. We also find that the mass-size relation remains consistent and statistically similar across all environments. Furthermore, we quantitatively assess the probability of a galaxy belonging to a protocluster candidate. In total, we identified 26 overdensities at z=5-7 and estimate their dark matter halo masses. We find that all protocluster candidates could evolve into clusters with M_\rm halo > 10^14M_⊙ at z = 0, thereby supporting the theoretical and simulation predictions of cluster formation. Notably, this marks an early search for protocluster candidates in JWST wide field based on photometric data, providing valuable candidates to study cosmic structure formation at the early stages.

@article{Li2024, author = {{Li}, Qiong and {Conselice}, Christopher J. and {Sarron}, Florian and {Harvey}, Tom and {Austin}, Duncan and {Adams}, Nathan and {Trussler}, James A.~A. and {Duan}, Qiao and {Ferreira}, Leonardo and {Westcott}, Lewi and {Harris}, Honor and {Dole}, Herv{\'e} and {Grogin}, Norman A. and {Frye}, Brenda and {Koekemoer}, Anton M. and {Robertson}, Clayton and {Windhorst}, Rogier A. and {Polletta}, Maria del Carmen and {Hathi}, Nimish P.}, title = {{EPOCHS Paper X: Environmental effects on Galaxy Formation and Protocluster Galaxy candidates at $4.5<z<10$ from JWST observations}}, journal = {arXiv e-prints}, keywords = {Astrophysics - Astrophysics of Galaxies}, year = {2024}, month = may, eid = {arXiv:2405.17359}, pages = {arXiv:2405.17359}, doi = {10.48550/arXiv.2405.17359}, archiveprefix = {arXiv}, primaryclass = {astro-ph.GA}, adsurl = {https://ui.adsabs.harvard.edu/abs/2024arXiv240517359L}, adsnote = {Provided by the SAO/NASA Astrophysics Data System}, }
MNRAS
DETECTIFz galaxy groups in the REFINE survey - I. Group detection and quenched fraction evolution at z < 2.5

Florian Sarron, and Christopher J. Conselice

Monthly Notices of the Royal Astronomical Society, Sep 2021

Abs arXiv Bib HTML PDF

We use a large K-selected sample of 299 961 galaxies from the REFINE survey, consisting of a combination of data from three of the deepest near-infrared surveys, UKIDSS UDS, COSMOS/UltraVISTA, and CFHTLS-D1/VIDEO, that were homogeneously reduced to obtain photometric redshifts and stellar masses. We detect 2588 candidate galaxy groups up to z = 3.15 at S/N > 1.5. We build a very pure ( 90\rm  per cent) sample of 448 candidate groups up to z = 2.5 and study some of their properties. Cluster detection is done using the DElaunay TEssellation ClusTer IdentiFication with photo-z (DETECTIFz) algorithm that we describe. This new group finder algorithm uses the joint probability distribution functions of redshift and stellar-mass of galaxies to detect groups as stellar-mass overdensities in overlapping redshift slices, where density is traced using Monte Carlo realization of the Delaunay Tessellation Field Estimator. We compute the algorithm selection function using mock galaxy catalogues taken from cosmological N-body simulation lightcones. Based on these simulations, we reach a completeness of ∼\! 80\,\rm per cent for clusters (M_200 > 10^14M_\ensuremath⊙) at a purity of ∼\! 90 \rm per cent at z < 2.5. Using our 403 most massive candidate groups, we constrain the redshift evolution of the group galaxy quenched fraction at 0.12 \ensuremath≤ z < 2.32, for galaxies with 10.25 < log M_\ensuremath⋆/M_\ensuremath⊙ < 11 in 0.5 \texttimes R_200. We find that the quenched fraction in group cores is higher than in the field in the full redshift range considered, the difference growing with decreasing redshift. This indicates either more efficient quenching mechanisms in group cores at lower redshift or pre-processing by cosmic filaments.
@article{Sarron2021, author = {{Sarron}, Florian and {Conselice}, Christopher J.}, title = {{DETECTIFz galaxy groups in the REFINE survey - I. Group detection and quenched fraction evolution at z < 2.5}}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {galaxies: clusters: general, galaxies: evolution, galaxies: groups: general, galaxies: star formation, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics}, year = {2021}, month = sep, volume = {506}, number = {2}, pages = {2136-2155}, doi = {10.1093/mnras/stab1844}, archiveprefix = {arXiv}, primaryclass = {astro-ph.GA}, adsurl = {https://ui.adsabs.harvard.edu/abs/2021MNRAS.506.2136S}, adsnote = {Provided by the SAO/NASA Astrophysics Data System}, }