[en] Type Ia supernovae (SNe Ia) are powerful cosmological distance indicators. They were key tools for the discovery of the accelerating expansion of the Universe and today they remain the strongest demonstrated technique for measuring the dark-energy equation of state. However, a major issue remains: despite decades of study, their progenitors are as yet undetermined. Notably, we still ignore the influence of the redshift-evolution of stellar properties on the absolute luminosity of the SNe Ia and therefore on the fitted cosmological parameters. Recent studies have highlighted potential biases correlated with the global properties of their host galaxies, large enough to induce systematic errors into cosmological measurements if not properly treated. However, those studies analyse hosts of Type Ia supernovae globally thus neglecting the known stellar and gas property variations across galaxies. In this thesis, I show how integral field spectroscopy data from the Nearby Supernova Factory allow the study of the local environment of the SNe Ia (∼kpc). In the first part of this document, I introduce the physical principals and the scientific context of this work. In a second part, I start by detailing the technical extraction tools developed in order to extract the local host properties. Then, I show how one could measure the star formation activity in the SN vicinity from those data. I focus the analysis on this star formation activity and notably I show how the SNe Ia properties - particularly their standardised Hubble residuals - depend on the local host environment, which corresponds to a significant cosmological bias. I finish this second part by introducing a simple model based on the known evolution of the galactic star formation activity. This model enables me to estimate the potential influence of the aforementioned environmental bias on cosmology. I also show that this model can be tested using public data and a first analyses tend to confirm our hypotheses. Those results have been published in Astronomy and Astrophysics (Rigault et al. 2013). The third and last part of the document introduces new approaches and future work perspectives. In this thesis, I have highlighted significant environmental biases in SNe Ia properties, thanks to the local approach. However, those biases are less an issue for the cosmological analyses using Type Ia supernovae than a new opportunity to improve them as cosmological probes. (author)

[en] When planning a survey for astronomical transients, many factors such as cadence, filter choice, sky coverage, and depth of observations need to be balanced in order to optimize the scientific gain of the survey. Here we present a software package called simsurvey for simulating the supernova lightcurves that are expected based on a survey strategy, which can then be used to determine the potential for discoveries of each strategy in question. The code is set up in a modular fashion that allows easy modification of small details of the survey and enables the user to adapt it to any survey design and transient template that they wish to use in planning their survey. As an example of its utility, we use simsurvey to simulate the lightcurve of several types of supernovae that the recently started Zwicky Transient Facility (ZTF) is expected to find and compare the results to the discoveries made during its early operations. We conclude that ZTF will find thousands of bright supernovae per year, of which about 10 could potentially be found with two days of explosion. Over the course of three years the survey will obtain lightcurves of about 1800 type Ia supernovae with z < 0.1 that can be used as distance indicators in cosmology if they are spectroscopically classified using additional telescopes. In a comparison to detections from the ZTF public survey, we found good agreement with the numbers of detections expected from the simulations.

[en] This publication gathers 51 contributions made by PhD students and session coordinators on traditional topics (astro-particles, cosmology, standard model) and on instrumentation, neutrinos, nuclear physics and hadronics. As far as astro-particles are concerned, the subjects were: Life and work of astro-particles; Alpha Magnetic Spectrometer 02, a particle sensor on the International Space Station; Anisotropy of cosmic radiation between 10 GeV and 100 TeV; H.E.S.S. and the cosmic accelerators called blazars; Ultra-high energy neutrinos at the Pierre Auger Laboratory; Autonomous radio-detection of high-energy cosmic rays with Codalema. The second theme was 'Beyond the standard model': Physics beyond the standard model; Probing the photon helicity: from BABAR to LHCb; The search for a new physics in the t t invariant mass spectrum with the CMS experiment; To connect supersymmetry and dark matter; Fine tuning in the NMSSM according to the results at 1fb"-"1 of the LHC; Search for new physics in events with 4 top quarks in the ATLAS experiment. For cosmology: Cosmological context; Physical properties of type Ia supernovae, the contribution of SNLS and SNFactory experiments; Reconstruction and analysis of the Sungaev-Zel'dovich effect with Planck; Local host galaxy properties of type Ia supernovae from the Nearby SuperNovae Factory; Observational cosmology with the Planck satellite: the re-ionization. For instrumentation: Introduction to instrumentation; ALFA, Absolute Luminosity For Atlas; Development of the mirrors for the second generation gravitational waves detector Advanced Virgo; EASIER, a radio detector at the Pierre Auger Laboratory; Spectral analysis algorithms in on-board gamma spectrometry; For the Standard Model: Introduction to the session; Triggering optimisation on electrons in CMS; The search for the Higgs boson in the process of vector boson fusion production and study of photon trigger with ATLAS at the LHC; Analysis of the Charmless decay B"0 → ρπ in the LHCb experiment; Correction of radiations in the final state in H → ZZ"* → 4I; Towards a measurement of the γ angle of the CKM theory via the B"0 → D"0K"+"0 disintegration with the LHCb detector; Measurement of the photon pair production cross section in the LHC with the ATLAS detector; The search for the Higgs in the 4-electron channel in ATLAS; Search for the Higgs boson in the H → γγ decay channel with the ATLAS detector. For neutrinos: Neutrino physics; The search for the double β disintegration without neutrino emission in the NEMO experiments; Coincident searches between gravitational waves and high-energy neutrinos with the ANTARES and LIGO/Virgo detectors; Use of the NA61-SHINE data to improve the prediction of the neutrino beam at T2K. For hadronic physics: A phenomenological study of helicity amplitudes of high energy exclusive lepto-production of the ρ-meson; Proton antiproton annihilation into heavy leptons at PANDA experiment; Study of the density of particles charged in collisions of heavy ions in the ALICE experiment at the LHC; Photon + heavy-flavor jet production at Tevatron and LHC; Quarkonium production in ultra-relativistic heavy-ion collisions with the ALICE experiment at the LHC; Loop calculations in gage theories. The last theme was nuclear physics and applications: Introduction to the session; Measurement of mass yields of the reaction "2"4"1Am(2n,f) at the Lohengrin spectrometer; Xenon mobility in uranium dioxide; Ga-Ni coating obtained by electrodeposition in chloride environment

[en] We present SNIascore, a deep-learning-based method for spectroscopic classification of thermonuclear supernovae (SNe Ia) based on very low-resolution (R ∼ 100) data. The goal of SNIascore is the fully automated classification of SNe Ia with a very low false-positive rate (FPR) so that human intervention can be greatly reduced in large-scale SN classification efforts, such as that undertaken by the public Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS). We utilize a recurrent neural network architecture with a combination of bidirectional long short-term memory and gated recurrent unit layers. SNIascore achieves a <0.6% FPR while classifying up to 90% of the low-resolution SN Ia spectra obtained by the BTS. SNIascore simultaneously performs binary classification and predicts the redshifts of secure SNe Ia via regression (with a typical uncertainty of <0.005 in the range from z = 0.01 to z = 0.12). For the magnitude-limited ZTF BTS survey (≈70% SNe Ia), deploying SNIascore reduces the amount of spectra in need of human classification or confirmation by ≈60%. Furthermore, SNIascore allows SN Ia classifications to be automatically announced in real time to the public immediately following a finished observation during the night.

[en] Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the material spatial extent is compact and implies an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility survey. We find that at least six out of ten events for which a spectrum was obtained within two days of the estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction (>30% at 95% confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae.