S. Bongard
A5072907481- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Nuclear Physics and Applications
- Astro and Planetary Science
- Calibration and Measurement Techniques
- CCD and CMOS Imaging Sensors
- Atmospheric Ozone and Climate
- Galaxies: Formation, Evolution, Phenomena
- Geological and Geophysical Studies
- Infrared Target Detection Methodologies
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Solid-state spectroscopy and crystallography
- Magnetic confinement fusion research
- Solar and Space Plasma Dynamics
- Spacecraft and Cryogenic Technologies
- Geophysics and Gravity Measurements
Laboratoire de Physique Nucléaire et de Hautes Énergies
2014-2024
Sorbonne Université
2014-2024
Centre National de la Recherche Scientifique
2014-2024
Universitat Politècnica de Catalunya
2024
Université Paris Cité
2013-2023
Institut National de Physique Nucléaire et de Physique des Particules
2013-2023
Lawrence Berkeley National Laboratory
2005-2008
University of Oklahoma
2006-2008
Université Claude Bernard Lyon 1
2002-2008
Institute of Nuclear Physics of Lyon
2005-2008
We present photometric and spectroscopic observations of SN 2007if, an overluminous (MV = −20.4), red (B − V 0.16 at B-band maximum), slow-rising (trise 24 days) type Ia supernova (SN Ia) in a very faint (Mg −14.10) host galaxy. A spectrum 5 days past maximum light is direct match to the super-Chandrasekhar-mass candidate 2003fg, showing Si ii C ∼9000 km s−1. high signal-to-noise co-addition spectral time series reveals no Na i D absorption, suggesting negligible reddening galaxy, late-time...
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...
The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and products which are publicly available through ESO archive Data Release 1 (SSDR1). PESSTO uses New Technology Telescope with EFOSC2 SOFI to provide optical NIR spectroscopy imaging. target supernovae transients brighter than 20.5mag for classification. Science targets then selected follow-up based on...
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 Factory (<i>Snfactory</i>) is an international experiment designed to lay the foundation for next generation of cosmology experiments (such as <i>CFHTLS</i>, <i>w</i>P, <i>SNAP</i> and <i>LSST</i>) which will measure expansion history Universe using Type Ia supernovae. <i>Snfactory</i> discover obtain frequent lightcurve spectrophotometry covering 3200-10000Å roughly 300 supernovae at low-redshift end smooth Hubble flow. quantity, quality, breadth galactic...
We report Nearby Supernova Factory observations of SN 2005gj, the second confirmed case a "hybrid" Type Ia/IIn supernova. Our early-phase photometry 2005gj shows that interaction is much stronger than for prototype, 2002ic. first spectrum hot continuum with broad and narrow H-alpha emission. Later spectra, spanning over 4 months from outburst, show clear Ia features combined H-gamma, H-beta, HeI 5876,7065 in At higher resolution, P Cygni profiles are apparent. Surprisingly, we also observe...
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 examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and properties of their host galaxies using a sample 115 SNe from Nearby Supernova Factory. use galaxy stellar masses specific star formation rates fitted photometry for all hosts, as well gas-phase metallicities subset 69 star-forming (non-active galactic nucleus) to show that SN correlate with each these properties. With data we find new evidence correlation intrinsic color metallicity. When combine our those...
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 introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for four-metre-class Visible and Infrared Survey Astronomy (VISTA) at Paranal. Its key specifications are: large field of view (FoV) 4.2 square degrees high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = λ/Δλ\sim 6500$), 812 transferring light to high-resolution spectrograph \sim 20\,000$). After...
We employ 76 type Ia supernovae with optical spectrophotometry within 2.5 days of B-band maximum light obtained by the Nearby Supernova Factory to derive impact Si and Ca features on intrinsic luminosity determine a dust reddening law. use equivalent width II {\lambda}4131 in place curve stretch account for first-order variability. The resultant empirical spectral law exhibits strong associated {\lambda}6355. After applying correction based H&K we find consistent Cardelli extinction Using...
We present a new atmospheric extinction curve for Mauna Kea spanning 3200--9700 \AA. It is the most comprehensive to date, being based on some 4285 standard star spectra obtained 478 nights spread over period of 7 years by Nearby SuperNova Factory using Integral Field Spectrograph. This mean and its dispersion can be used as an aid in calibrating spectroscopic or imaging data from Kea, estimating calibration uncertainty associated with use curve. Our method decomposing into physical...
We present a new method to standardize type Ia supernova (SN Ia) luminosities 0.13 mag using flux ratios from single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for that correlate with SN luminosity. After developing the and selecting best training sample, verified results on separate validation sample data literature. identified multiple whose correlations luminosity are stronger than those light curve shape...
We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova Factory selected to be spectroscopic analogs candidate super-Chandrasekhar-mass events SN 2003fg 2007if. Their spectra are characterized hot, highly ionized photospheres near maximum light, for which 1991T supplies best phase coverage among available close spectral templates. Like 2007if, these overluminous (−19.5 < MV −20) velocity Si ii λ6355 absorption minimum is consistent with...
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...
We present convincing evidence of unburned carbon at photospheric velocities in new observations 5 Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified examining 346 spectra from 124 before +2.5 d relative to maximum. Detections based on presence relatively strong C II 6580 absorption "notches" multiple each SN, aided automated fitting with SYNAPPS code. Four question otherwise spectroscopically unremarkable, ions and ejection typical Ia, but fifth...
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...
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 present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory (SNfactory). Combining GALEX UV data with optical near infrared photometry, we employ stellar population synthesis techniques to measure SN host galaxy masses, star-formation rates (SFRs), reddening due dust. reinforce key role in deriving accurate estimates SFRs dust extinction. Optical spectra are fitted simultaneously for their continua emission...
In this paper we present a general method for multichannel image restoration based on regularized χ2. We introduce separable regularizations that account the dynamics of model and take advantage continuities in data, leaving only two hyper-parameters to tune. illustrate practical implementation context host galaxy subtraction Nearby SuperNova Factory (SNfactory). show obtained fulfils stringent requirements bias photometricity needed by programme. The reconstruction yields sub-per cent...
We present four spectra of the Type Ia supernova (SN Ia) 2006D extending from -7 to +13 days with respect B-band maximum. The include strongest signature unburned material at photospheric velocities observed in a SN date. earliest spectrum exhibits C II absorption features below 14,000 km/s, including distinctive \lambda 6580 feature. carbon signatures dissipate as approaches peak brightness. In addition discussing implications photospheric-velocity for white dwarf explosion models, we...
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...