C. Saunders
A5023135359- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Nuclear Physics and Applications
- Galaxies: Formation, Evolution, Phenomena
- Atmospheric Ozone and Climate
- Cosmology and Gravitation Theories
- Advanced NMR Techniques and Applications
- Solid-state spectroscopy and crystallography
- CCD and CMOS Imaging Sensors
- Inertial Sensor and Navigation
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Non-Invasive Vital Sign Monitoring
- Infrared Target Detection Methodologies
- Advanced Optical Sensing Technologies
Sorbonne Université
2017-2023
Princeton University
2020-2023
University of California, Berkeley
2012-2023
Lawrence Berkeley National Laboratory
2013-2023
Institut d'Astrophysique de Paris
2018-2023
Laboratoire de Physique Nucléaire et de Hautes Énergies
2017-2021
Institut National de Physique Nucléaire et de Physique des Particules
2017-2021
Centre National de la Recherche Scientifique
2017-2021
Université Paris Cité
2017-2020
Previously we used the Nearby Supernova Factory sample to show that Type Ia supernovae (SNe Ia) having locally star-forming environments are dimmer than SNe passive environments. Here use Constitution together with host galaxy data from GALEX independently confirm result. The effect is seen using both SALT2 and MLCS2k2 lightcurve fitting standardization methods, brightness differences of 0.094 ± 0.037 mag for 0.155 0.041 RV = 2.5. When combined our previous measurement 0.025 SALT2. If ratio...
As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization Type Ia supernovae (SNIa) cosmology, we have statistically classified a large sample nearby SNeIa into those located predominantly younger or older environments. This classification is based on specific star formation rate measured within projected distance 1kpc from each SN location (LsSFR). important refinement compared using local directly as it provides normalization relative...
The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations used constrain explosion scenarios. We base our discussion on three-dimensional simulations a delayed detonation Chandrasekhar-mass white dwarf violent merger two dwarfs-realizations models appropriate most...
We present 32 epochs of optical (3300-9700 \AA) spectrophotometric observations the nearby quintessential "normal" type Ia supernova (SN Ia) SN 2011fe in galaxy M101, extending from -15 to +97 d with respect B-band maximum, obtained by Nearby Supernova Factory collaboration. is closest (\mu = 29.04) and brightest (Bmax 9.94 mag) observed since advent modern large scale programs for intensive periodic followup supernovae. Both synthetic light curve measurements spectral feature analysis...
We present a sample of normal Type Ia supernovae (SNe Ia) from the Nearby Supernova Factory data set with spectrophotometry at sufficiently late phases to estimate ejected mass using bolometric light curve. measure 56Ni masses peak luminosity, then compare luminosity in 56Co-decay tail expected rate radioactive energy release ejecta given mass. infer Bayesian context semi-analytic model ejecta, incorporating constraints contemporary numerical models as priors on density structure and...
(Abridged) We study the host galaxy regions in close proximity to Type Ia supernovae (SNe Ia) analyze relations between properties of SN events and environments most similar where their progenitors formed. focus on local H\alpha\ emission as an indicator young environments. The Nearby Supernova Factory has obtained flux-calibrated spectral timeseries for SNe using integral field spectroscopy, allowing simultaneous measurement its immediate vicinity. For 89 we measure tracing ongoing star...
We present an investigation of the optical spectra 264 low-redshift (z < 0.2) Type Ia supernovae (SNe Ia) discovered by Palomar Transient Factory, untargeted transient survey. focus on velocity and pseudo-equivalent width measurements Si II 4130, 5972, 6355 A lines, as well those Ca near-infrared (NIR) triplet, up to +5 days relative SN B-band maximum light. find that a high-velocity component NIR triplet is needed explain spectrum in ~95 per cent SNe observed before -5 days, decreasing ~80...
While recent supernova cosmology research has benefited from improved measurements, current analysis approaches are not statistically optimal and will prove insufficient for future surveys. This paper discusses the limitations of cosmological analyses in treating outliers, selection effects, shape- color-standardization relations, unexplained dispersion, heterogeneous observations. We present a new Bayesian framework, called UNITY (Unified Nonlinear Inference Type-Ia cosmologY), that...
Context. Our Local Group of galaxies appears to be moving relative the cosmic microwave background with source peculiar motion still uncertain. While in past this has been studied mostly using as distance indicators, weight type Ia supernovae (SNe Ia) increased recently continuously improving statistics available low-redshift supernovae. Aims. We measured bulk flow nearby universe ($0.015 < z 0.1$) 117 SNe observed by Nearby Supernova Factory, well Union2 compilation SN data already...
Type Ia supernova cosmology depends on the ability to fit and standardize observations of magnitudes with an empirical model. We present here a series new models Supernova spectral time that capture greater amount diversity than possible are currently customary. These entitled SuperNova Empirical MOdels (\textsc{SNEMO}\footnote{https://snfactory.lbl.gov/snemo}). The constructed using spectrophotometric from $172$ individual supernovae Nearby Factory, comprising more $2000$ spectra. Using...
We present a fully consistent catalog of local and global properties host galaxies 882 Type Ia supernov\ae\ (SNIa) that were selected based on their light-curve properties, spanning the redshift range $0.01 < z 1.\text{}$ This corresponds to preliminary version compilation sample includes Supernova Legacy Survey (SNLS) 5-year data, Sloan Digital Sky (SDSS), low-redshift surveys. measured low- moderate-redshift galaxy photometry in SNLS SDSS images used spectral energy distribution (SED)...
Abstract We present a new empirical Type Ia supernova (SN Ia) model with three chromatic flux variation templates: one phase dependent and two independent. No underlying dust extinction or patterns of intrinsic variability are assumed. Implemented S tan trained using spectrally binned Nearby Supernova Factory spectrophotometry, we examine this model's 2D, phase-independent space motivated basis representations. In both, the first template captures that appears dust-like, while second...
We report the discovery of a redshift 1.71 supernova in GOODS North field. The Hubble Space Telescope (HST) ACS spectrum has almost negligible contamination from host or neighboring galaxies. Although rest frame sampled range is too blue to include any Si ii line, principal component analysis allows us confirm it as Type Ia with 92% confidence. A recent serendipitous archival HST WFC3 grism contributed key element confirmation by giving host-galaxy 1.713 +/- 0.007. In addition being most...
Using three magnified Type Ia supernovae (SNe Ia) detected behind CLASH (Cluster Lensing and Supernovae with Hubble) clusters, we perform a first pilot study to see whether standardizable candles can be used calibrate cluster mass maps created from strong lensing observations. Such calibrations will crucial when next-generation Hubble Space Telescope surveys (e.g. Frontier) provide magnification that will, in turn, form the basis for exploration of high-redshift Universe. We classify SNe...
We present an analysis of 507 spectra 173 stripped-envelope (SE) supernovae (SNe) discovered by the untargeted Palomar Transient Factory (PTF) and intermediate PTF (iPTF) surveys. Our sample contains 55 Type IIb SNe (SNe IIb), 45 Ib Ib), 56 Ic Ic), 17 Ib/c Ib/c). have compared SE SN subtypes via measurements pseudo-equivalent widths (pEWs) velocities He I λλ 5876, 7065 O λ 7774 absorption lines. Consistent with previous work, we find that show higher pEWs in to Ib. The lines are similar...
We introduce a method for identifying "twin" Type Ia supernovae, and using them to improve distance measurements. This novel approach supernova standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). begin with well-measured set of find pairs whose spectra match well across entire optical window, then test whether this leads smaller dispersion in their absolute brightnesses. analysis completed blinded fashion, ensuring...
We present a novel class of models for Type Ia supernova time-evolving spectral energy distributions (SEDs) and absolute magnitudes: they are each modeled as stochastic functions described by Gaussian processes. The values the SED magnitudes defined through well-defined regression prescriptions, so that data directly inform models. As proof concept, we implement model synthetic photometry built from spectrophotometric time series Nearby Supernova Factory. Absolute at peak B brightness...
As a candidate 'super-Chandrasekhar' or 09dc-like Type Ia supernova (SN Ia), SN 2012dn shares many characteristics with other members of this remarkable class objects but lacks their extraordinary luminosity. Here, we present and discuss the most comprehensive optical data set to date, comprised densely sampled series early-time spectra obtained within Nearby Supernova Factory project, plus photometry spectroscopy at VLT about 1 yr after explosion. The light curves, colour spectral time...
Abstract We calibrate spectrophotometric optical spectra of 32 stars commonly used as standard stars, referenced to 14 already on the Hubble Space Telescope–based CALSPEC flux system. Observations and non-CALSPEC were obtained with SuperNova Integral Field Spectrograph over wavelength range 3300–9400 Å calibration for Nearby Supernova Factory cosmology experiment. In total, this analysis 4289 standard-star taken photometric nights. As a modern analysis, all presubmission methodological...
We develop a new framework for use in exploring Type Ia Supernova (SN Ia) spectra. Combining Principal Component Analysis (PCA) and Partial Least Square analysis (PLS) we are able to establish correlations between the Components (PCs) spectroscopic/photometric SNe features. The technique was applied ~120 supernova ~800 spectra from Nearby Factory. ability of PCA group together with similar spectral features, already explored previous studies, is greatly enhanced by two important...
Abstract We present the discovery and measurements of a gravitationally lensed supernova (SN) behind galaxy cluster MOO J1014+0038. Based on multi-band Hubble Space Telescope Very Large (VLT) photometry supernova, VLT spectroscopy host galaxy, we find 97.5% probability that this SN is Ia, 2.5% chance CC SN. Our typing algorithm combines shape color light curve with expected rates each type in galaxy. With redshift 2.2216, highest Ia discovered spectroscopic host-galaxy redshift. A further...
We study the spectral diversity of Type Ia supernovae (SNe Ia) at maximum light using high signal-to-noise spectrophotometry 173 SNe from Nearby Supernova Factory. decompose these spectra into different extrinsic and intrinsic components, we construct a nonlinear parameterization that preserves pairings "twin" Ia. call this "Twins Embedding". Our methodology naturally handles highly variability in spectra, such as changes photosphere expansion velocity, uses full spectrum rather than being...
Correction of Type Ia Supernova brightnesses for extinction by dust has proven to be a vexing problem. Here we study the foreground highly reddened SN 2012cu, which is projected onto lane in galaxy NGC 4772. The analysis based on multi-epoch, spectrophotometric observations spanning 3,300 - 9,200 {\AA}, obtained Nearby Factory. Phase-matched comparison spectroscopically twinned 2012cu and 2011fe across 10 epochs results best-fit color excess (E(B-V), RMS) = (1.00, 0.03) total-to-selective...
Type Ia Supernovae (SNe Ia) are widely used to measure the expansion of Universe. Improving distance measurements SNe is one technique better constrain acceleration and determine its physical nature. This document develops a new spectral energy distribution (SED) model, called SUpernova Generator And Reconstructor (SUGAR), which improves description Ia, consequently could improve measurements. model constructed from properties spectrophotometric data The Nearby Supernova Factory...
The See Change survey was designed to make $z>1$ cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass through weak lensing. This observed twelve galaxy clusters with the Hubble Space Telescope spanning redshift range $z=1.13$ $1.75$, 57 likely transients 27 SNe at $z\sim 0.8-2.3$. As in similar previous surveys (Dawson et al. 2009), this proved be a highly efficient use of HST for SN observations; additionally tested...