Rubin-LSST France, Mai 2021

25 mai 2021, 08:00 → 28 mai 2021, 16:00 Europe/Paris

video-conference

Benjamin Racine (CPPM/IN2P3/CNRS), Céline Combet (LPSC - Grenoble), Marc Moniez (LAL-IN2P3), Olivier Ilbert (LAM)

The next biannual meeting of the Rubin-LSST France community will be held from May 25th to 28th, 2021.

This meeting will be held completely remotely, on zoom, following that link:

https://univ-grenoble-alpes-fr.zoom.us/j/93728143384

It is password-protected and the zoom password will be sent separately to the list of registered participants.

Organisation:

• Talks: Acknowledging that some participants may not understand/speak French, using English is encouraged.
• Discussion/Questions: Participants can raise their hand on Zoom to ask a question. Also, dedicated slack channel #meeting-2021a has been created on the lsst-france workspace. It will provide extra space for questions and discussions.
• Participants: Please turn off your microphone when you are not speaking. The camera is up to you. "Raise your hand" on zoom if you have a question.
• Speakers: have your camera on if possible and upload your slides on the indico prior to your talk.

The agendas of the most recent editions of this meeting can be found online:

• November 2020
• February 2020
• November 2019
• November 2018

mardi 25 mai

Welcome

Président de session: Benjamin Racine (CPPM/IN2P3/CNRS)

General session

Président de session: Benjamin Racine (CPPM/IN2P3/CNRS)

COM_LSST_Mai2021.pdf

1 General news

Orateur: Emmanuel Gangler (LPC)

GeneralNews.pdf

2 Update on camera and commissionning

Orateurs: Claire JURAMY ({CNRS}UMR7585), Pierre Antilogus (LPNHE)

LSST_France_LSST_Status_25_05_2021.pdf

3 New LSST-France members

14:40 Break (wonder.me)

Bienvenue à l'INSU

Président de session: olivier Ilbert (LAM)

4 Preparing the LSB science with LSST / Rubin

The exploration of the Low Surface Brightness Universe currently motivates several surveys across the world, carried out with a number of instruments, and provides observational constrains for numerical simulations. It impacts multiple scientific fields, including the ISM structure, galaxy archeology, galaxy evolution and cosmology, and has generated passionate debates, for instance regarding the very existence, nature and properties of the so called Ultra-Diffuse-Galaxies. Meanwhile the community prepares for the exploitation of next generation surveys, including Euclid and LSST. For that purpose several science working groups have recently been created. I will present their on-going works, goals, and address in particular the synergy between LSST and Euclid, through the DDP framework.

Orateur: Pierre-Alain Duc (Observatoire astronomique de Strasbourg)

LSST-LSB.pdf

5 GRBs and GW multi-messenger science with LSST

The survey speed, large field of view and sensitivity of LSST will revolutionize our knowledge of the transient sky.
I will present how LSST observations can impact the field of GRBs and be fundamental for GW multi-messenger science.
I will focus in particular on the synergy with current and future GW detectors, and with SVOM.

Orateur: Susanna Vergani (CNRS-Observatoire de Paris)

LSSTFranceVergani.pdf

6 Study of the Small Solar System Bodies with LSST

Our work relates to the general framework of improving our understanding of the formation and evolution (including the modern-time circulation of materials) of our Solar System. To address these questions, we focus on the various populations of small bodies of the Solar System [SSSBs] (Near Earth asteroids [NEAs], Asteroids, Centaurs, Trans-Neptunian Objects [TNOs]). Because of their large numbers, the physical, compositional and dynamical characteristics of these populations hold statistically significant clues on their origin and evolution, acting as tracers of the Solar System. Moreover, even if they contain a small fraction of the total mass of the Solar System, these small bodies are to the Solar System the equivalent of the radioactive isotopes to the study of rocks.

An exhaustive study of the various populations of SSSBs resides in the search for their physical, compositional and, for some, mineralogical properties. Connecting the physics to the dynamics of these objects can answer fundamental questions related to cosmogony and our civilisation, such as: how, if at all, did the SSSBs contribute to the emergence of life on Earth ? What were the conditions that allowed the formation of our Solar System ? What was the structure of the planetesimals that made the terrestrial planets? What is the link between organic materials identified in interplanetary space and life on Earth? What is the link between SSSBs and meteoroid streams? How do meteoroids influence the Earth's atmosphere?

The LSST astrometric and photometric harvest, its 10 years duration, and its unprecedented discovery of new and faint objects will provide the most complete view of the Solar System ever achieved, near and far, and huge advances in many of the fields cited above. It will be complete for objects down to sub-kilometre size between the Earth and Jupiter and significantly sample more distant objects with an orbital period longer than 10 years, such as Trojan, Centaurs and TNOs. LSST will also be an exceptional platform to search for peculiar objects such as binary objects, active comets or asteroids, interstellar objects, smaller bodies on their course to collide with the Earth, and find a large sample of candidates for stellar occultations.

Based on previous experience with CHFT programmes and Gaia survey, we will focus on these latter aspects, characterisation of the survey and the detection, dynamical and physical properties determination, population characterisation, testing of formation models, predictions of events...

Orateurs: Prof. Daniel HESTROFFER (IMCCE/Paris observatory, CNRS, univ. PSL), Jean-Marc Petit (CNRS)

LSST-FR-SSO.pdf

mercredi 26 mai

Session: FINK

7 Fink broker enabling time-domain science with LSST

We will present the Fink broker which has been designed to ingest, enrich and filter the VRO LSST public alert stream. Within minutes, it can select promising transients by providing preliminary classifications and combining information from multiple channels (multi-messenger and multi-wavelength surveys and catalogues). It can also communicate these candidates to teams and follow-up facilities. We will present an overview of Fink, its aim to enable different science goals, the technology behind it and its current status.

Orateurs: Dr Anais Möller (CNRS / LPC Clermont), Dr Julien Peloton (CNRS-IJCLab), Dr Emille Ishida (LPC-UCA)

Fink_LSST_France_2021_I.pdf

8 Fink broker: how to use it

We will show the different capabilities of Fink from the user side. The goal is to provide examples on how you can access or filter the data for a science case. This session will include: (i) how to set up filtering in the real time processing in Fink, (ii) how to access the aggregated data through the Science Portal and (iii) how to use the API. We will use our current processing of the ZTF alert stream to manipulate the data and showcase duncdionalitiess both through our web portal and Jupiter notebooks that access our API. We will touch different science cases which can include: multi-messenger/wavelength, solar system, extragalactic and galactic science.

Orateurs: Dr Anais Möller (CNRS / LPC Clermont), Julien Peloton (CNRS-IJCLab), Emille Ishida (LPC-UCA)

Fink_LSST_France_2021_I.pdf

General session: Communication

Président de session: Gaëlle SHIFRIN (Centre de Calcul de l'IN2P3)

COM_LSST_Mai2021.pdf

10:50 Break (wonder.me)

Session: Calibration, Auxtel

Président de session: Sébastien Bongard (LPNHE)

9 StarDICE

Update on the StarDICE project

Orateur: Marc Betoule (LPNHE)

betoule_stardice_lpnhe.pdf

Session: Calibration, Auxtel

Président de session: Sébastien Bongard (LPNHE)

10 Spectroscopie slitless et transmission atmosphérique

Slitless spectroscopy and atmospheric transmission

Orateur: Jérémy Neveu (IJCLab)

jneveu_spectractor.pdf

11 Premières données sur AuxTel avec l’hologramme

Le disperseur holographique développé en France a été installé le 15 février sur le télescope auxiliaire de LSST. Les premières images ont été acquises au Chili lors des prises de données de février et mars. Nous montrerons les spectres issus de ces images et confronterons les premiers résultats avec les performances attendues à partir des mesures du banc de test.

Orateur: marc moniez (LAL-IN2P3)

LSST-France-mai21-moniez.pdf

14:50 Break (wonder.me)

Session: Calibration, Auxtel

Président de session: Sébastien Bongard (LPNHE)

12 Calibration de ZTF: état et prospectives

Orateur: Philippe Rosnet (Université Blaise Pascal - CNRS/IN2P3)

LSST-France_20210526.pdf

jeudi 27 mai

Session: SNe

Président de session: Julian Bautista (CPPM)

13 Peculiar velocities with SN Ia

The growth rate of structures of our Universe depends on expansion history and gravity. It can be used to test the cosmological standard model (LCDM) and as a probe of modified-gravity models.

The evolution of the density and the velocity field of galaxies can be characterised by the fsigma8 parameter. Recent papers (Howlett et al 2017, Graziani et al 2020) suggest that we can use Type Ia Supernovae (SN Ia) as tracer of peculiar velocities of host galaxies. Indeed, peculiar velocities have an effect on the observed flux of SN Ia and this effect has measurable repercutions on the SN Hubble Diagram residuals.

During the talk, I will present our current work on SN Ia simulations on LSST and ZTF surveys :
We use realistic simulated SN Ia lightcurves to estimate our abilities to retrieve peculiar velocities from Hubble diagram, then compute the velocity power spectrum and put constraints on fsigma8.
We also plan to study the impact of several systematics errors on the growth-rate estimates.

Orateur: Bastien Carreres (CPPM)

Présentation_lsst_france_final.pdf

14 Probing local anisotropies using Type Ia Supernovae data

A large variety of cosmological observations has validated the Λ CDM model as the leading one in driving the dynamics of the Universe. This model requires the validity of several assumptions : the Cosmological Principle (homogeneity and isotropy at large scales). Despite numerous successes, the standard model is facing some challenges like the detection of large scale velocity flows.
Type Ia supernovae (SNe Ia) are a cosmological probe allowing to map the Universe at different scales to measure its dynamics. The new data set from the Zwicky Transient Facility (ZTF) at z < 0.1 constitutes a unique sample to investigate potential anisotropies in the nearby Universe. I will present the first investigation about the bulk flow measurement.

Orateur: Melissa Amenouche (Laboratoire de Physique de Clermont)

lsst_france_anisotropies(1).pdf

15 A new generation SALT2-like model

Type Ia Supernova (SN Ia) distance measurements rely on an empirical model of the SN spectrophotometric evolution. This model has two main uses : first, it allows to take into account the effect of SN Ia redshift, by reconstructing the flux emitted in the supernova frame, given the flux measured in the observer frame. Second, it allows one to capture the SN Ia diversity and standardize their luminosities. The model currently in use within the community is called Spectral Adaptive Lightcurve Template 2 (SALT2), developed between 2007 and 2010 (Guy & al., 2007, 2010). My main phD project is to develop a new generation of the model. The first milestone is to re-implement the SALT2-like training code while getting rid of several identified limitations in the current training procedure. In a second phase, I will investigate alternate descriptions of the SN Ia diversity, building on the new high-quality and high statistics training samples available today. In this presentation, I will describe the method we have followed to re-implement a SALT2-like training procedure. I will discuss the differences between the new procedure and the SALT2 historic approach, present the general performances of the code as of today, and outline future plans.

Orateur: Guy Augarde (LPNHE)

lsst_augarde_lpnhe.pdf

16 LSST Deep Drilling program and Supernovae

The Deep Drilling (DD) mini-survey of LSST will be critical for the success of the supernovae science program. This presentation will be a summary of the most recent studies related to this topic.

Orateur: Philippe Gris (LPC)

10:50 Break (wonder.me)

Session: Photo-z

Président de session: Julian Bautista (CPPM)

17 Review on photometric redshift techniques

We will review the most common photometric redshifts techniques, showing their applications to recent surveys.
We will split our presentation in two : the first part focusing on SED-fitting techniques (Olivier Ilbert) and the second part on deep learning (Stephane Arnouts).

Orateurs: olivier Ilbert (LAM), stephane arnouts (LAM)

lsst_ilbert.pdf

LSST_May2021_arnouts.pdf

18 PhotoZ estimation with Gaussian Processes

We introduce a Gaussian processes as a possible method to estimate redshift from photometric fluxes.

Gaussian processes method is intermediate method between physically constrained SED-templates fitting methods and highly flexible unconstrained fitting method.
As for ML, it requires to be trained on a training sample, however because it encapsulates physics constraint on the cosmological Flux-Redshift relation, it needs only a reasonable number of free parameters which may be marginalized.

We have adapted the Delight code to the Vera C. Rubin observatory (in the context of RAIL).
We compare the performances of redshift estimation between the generated mock LSST data and a DC2 photoZ sample (training ad evaluation datasets).
We point out the most important free parameters of the model and discuss how those can be tuned to optimize the performances.

Finally we mention the ease to combine/calibrate LSST survey with other survey having different bands.

Orateur: Dr Sylvie Dagoret-Campagne (IJCLab)

GaussianProcesses_LSSTFrance_27mai2021_dagoret.pdf

Session: Clusters

Président de session: Raphael Gavazzi (IAP CNRS)

19 The WaZP cluster finder on DC2 data + The ClEvaR package

Galaxy clusters are the largest gravitationally bound structures of the universe with significant applications in astrophysics and cosmology. The Wavelet Z Photometric (WaZP) cluster finder is a code developed for cluster detection on photometric surveys that does not rely on red-sequence presence. As such, it can provide a unique perspective to study the red-sequence abundance and evolution on galaxy clusters. The Data Challenge 2 (DC2) is a simulated sky survey, based on an underlying N-body dark matter simulation, that contains extragalactic and star “true” catalogs and simulated images with corresponding observed catalogs. We are running WaZP on DC2 on both the true and observed catalogs. This environment, where the dark matter halos are known, allows us to evaluate the performance of WaZP and its membership assignment, and the impact of observational effects on the detection. We also investigate the astrophysical properties of clusters such as the luminosity function and the red-sequence presence.

We also present Cluster Evaluation Resources (ClEvaR), a software developed for matching and evaluating cluster catalogs. ClEvaR was designed to be easily automated for multiple sets of catalogues and with a modular structure for integration with other DESC software.

Orateur: Michel Aguena (LAPP)

2021_05_27 - LSST France - Michel Aguena-1.pdf

20 Weak Lensing mass estimation of DC2 clusters

We present the estimation of the mass-richness-redshift relation for a selection of RedMapper detected clusters in the DC2 catalogs of DESC using weak gravitational lensing. The weak lensing mass estimation is affected by several systematics including the photometrical estimation of background galaxy redshifts & error on galaxy shape measurements. We investigate the effect of increasing the complexity of the survey from the ideal catalog to the LSST-like survey.

Orateur: Constantin Payerne (LPSC (IN2P3))

Presentation_LSST_France_C_Payerne.pdf

21 Dust extinction and magnification by galaxy clusters

In addition to weak lensing shear, information on the mass profiles of galaxy clusters may be inferred from the magnification of galaxies along the line of sight. However such analysis may also be sensitive to the presence of intra-cluster dust, which will act to reduce the magnitude of galaxies. These effects may be differentiated by the chromatic effects of dust extinction and the different redshift dependence of these two effects. It is important that such effects are understood in order to fully exploit the weak lensing magnification information for future Rubin magnification measurements. Furthermore such measurements may provide interesting results on the composition of the intra-cluster medium and the cosmic dust density. We investigate the impact of dust using HSC weak lensing data and the Redmapper SDSS galaxy cluster catalogue.

Orateur: Calum Murray (LPSC)

LSST France Calum Murray.pdf

14:35 Break (wonder.me)

Session: WL

Président de session: Raphael Gavazzi (IAP CNRS)

22 Forecasting the power of Higher Order Weak Lensing Statistics with automatically differentiable simulations

Weak gravitational lensing is one of the most promising tools of cosmology to constrain models and probe the evolution of dark-matter structures. Yet, the current analysis techniques are only able to exploit the 2-pt statistics of the lensing signal, ignoring a large fraction of the cosmological information contained in the non-Gaussian part of the signal. Exactly how much information is lost, and how it could be exploited is an open question.
In this work, we propose to measure the relative constraining power of various map-based higher order weak lensing statistics in a LSST setting.
Such comparisons are typically very costly as they require a large number of simulations, and become intractable for more than 3 or 4 cosmological parameters. Instead we propose a new methodology based on the TensorFlow framework for automatic differentiation, and more specifically the public FlowPM N-body simulation code. By implementing gravitational lensing ray-tracing in this framework, we are able to simulate lensing lightcones to mimic the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). These simulations being based on differentiable physics, we can take derivatives of the resulting gravitational lensing maps with respect to cosmological parameters, or any systematics included in the simulations. Using these derivatives, we can measure the Fisher information content of various lensing summary statistics on cosmological parameters, and thus help maximize the Information Gain of the LSST Survey.

Orateur: Denise Lanzieri

Forecasting the power of Higher Order Weak Lensing Statistics with automatically differentiable simulations

23 Galaxy parameter estimation with Bayesian Neural Networks

Estimating galaxy shape parameters for weak lensing analysis is a complex task. It usually requires a previous debleding step in order to separate overlapped objects. Following the work we did using Variational AutoEncoders for deblending, we propose a parameter estimation algorithm based on Bayesian neural networks in order to predict posterior distribution of galaxy shapes (and potentially redshifts) from the galaxy images, whether it is blended or not. This is work in progress but I will present the first tests that we have done, applying this algorithm to DC2 images.

Orateur: Bastien Arcelin (APC)

Blending_LSST_France_2021.pdf

24 [Teaser] DES Year 3 : cosmological constraints from galaxy lensing and clustering

The Dark Energy Survey has scanned 5000 square degrees of the southern sky to assemble a catalog of over 100 million galaxy shapes in Year 3 data. We combined it with catalogs of the positions of "lens" galaxies with accurate redshifts to measure three two-point functions : cosmic shear (shape-shape), galaxy-galaxy lensing (shape-position) and clustering (position-position). In this talk, I will summarize the results of this "3x2pt" analysis in terms of cosmological constraints, their robustness to modelling assumptions and systematic effets, and finally their internal consistency across probes, redshifts and scales.

Orateur: Cyrille Doux (University of Pennsylvania)

20210527 LSST France.pdf

vendredi 28 mai

Computing activities around DP0 and DESC

Président de session: Dominique Boutigny (LAPP)

25 Computing activities around DP0 and DESC

Orateur: Dominique Boutigny (LAPP)

Computing activities around DP0 and DESC

10:35 Break (wonder.me)

General session

Président de session: Celine Combet (LPSC - Grenoble)

COM_LSST_Mai2021.pdf

26 Nouvelles du comité EDI

Orateur: Gaëlle SHIFRIN (Centre de Calcul de l'IN2P3)

EDI_RubinLSST_Mai2021b.pdf

27 Could the Vera Rubin Observatory, Euclid, and SKA put string theory under serious pressure ?

We explore the ability of future cosmological surveys to put strong constraints on string theory, through the Swampland program. String theory is sometimes thought to be unfalsifiable due to the incredibly large amount of low energy effective versions that can be derived in this framework. However, it is well known that constructing consistent solutions in a de Sitter background is tremendously difficult. This led to speculative conditions on the possible shape of the potential of the effective dark energy scalar field. This postulate is referred to as the "de-Sitter conjecture" and low-energy effective theories that do not satisfy it are said to live in the Swampland. Future experiments, such as the Vera Rubin Observatory, Euclid or SKA, will set strong constraints on dark energy and we investigated their potential conflict with the Swampland theoretical conditions. In particular, we show that the expected constraints on the equation of states of dark energy might be in severe contradiction with the de Sitter conjecture and could therefore put string theory under real pressure. Our study is carried out for many different quintessence potentials and a very wide range of initial conditions.

Orateur: Aurélien Barrau (LPSC)

swampland_Journee_lsst.pdf

28 Update on the Simons Observatory and CMB-S4 status, and expected synergies with Rubin-LSST

I will give an update of the Simons Observatory and CMB-S4 projects, and emphasize the expected synergies with the Rubin-LSST observations.

Orateur: Josquin Errard (Institut Lagrange Paris (ILP))

slides

29 Closing remarks

Orateur: Emmanuel Gangler (LPC)