A5064867579- Gamma-ray bursts and supernovae
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Astronomy and Astrophysical Research
- High-Energy Particle Collisions Research
- Stellar, planetary, and galactic studies
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Nuclear Physics and Applications
- Particle Detector Development and Performance
- Computational Physics and Python Applications
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Black Holes and Theoretical Physics
- Particle Accelerators and Free-Electron Lasers
- Infrared Target Detection Methodologies
- Geological and Geophysical Studies
- Calibration and Measurement Techniques
Université Paris Cité
2014-2023
Laboratoire de Physique Nucléaire et de Hautes Énergies
2014-2023
Institut National de Physique Nucléaire et de Physique des Particules
2014-2023
Sorbonne Université
2014-2023
Centre National de la Recherche Scientifique
2014-2023
Université Paris 8
2002-2014
Australian National University
2014
ARC Centre of Excellence for All-sky Astrophysics
2013-2014
University of Oxford
2007-2008
University of Victoria
2007-2008
We report measurements of the mass density, ΩM, and cosmological-constant energy ΩΛ, universe based on analysis 42 type Ia supernovae discovered by Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 0.83, are fitted jointly with a set from Calán/Tololo Survey, below 0.1, to yield values cosmological parameters. All supernova peak magnitudes standardized using SN light-curve width-luminosity relation. measurement yields joint probability...
We present distance measurements to 71 high redshift type Ia supernovae discovered during the first year of 5-year Supernova Legacy Survey (SNLS). These events were detected and their multi-color light-curves measured using MegaPrime/MegaCam instrument at Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in bands, as part CFHT (CFHTLS). Follow-up spectroscopy was performed VLT, Gemini Keck telescopes confirm nature measure redshift. With this data...
Aims. We present cosmological constraints from a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z< 0.1), all three seasons (0.05 <z< 0.4), years (0.2 1), it totals 740 spectroscopically confirmed supernovae with high-quality light curves.
We report measurements of ΩM, ΩΛ, and w from 11 supernovae (SNe) at z = 0.36-0.86 with high-quality light curves measured using WFPC2 on the Hubble Space Telescope (HST). This is an independent set high-redshift SNe that confirms previous SN evidence for accelerating universe. The available photometry make it possible these alone to provide cosmological parameters comparable in statistical weight results. Combined earlier Supernova Cosmology Project data, new yield a measurement mass density...
We present a new compilation of Type Ia supernovae (SNe Ia), dataset low-redshift nearby-Hubble-flow SNe and analysis procedures to work with these heterogeneous compilations. This ``Union'' 414 SN Ia, which reduces 307 after selection cuts, includes the recent large samples from Supernova Legacy Survey ESSENCE Survey, older datasets, as well recently extended distant observed HST. A single, consistent blind procedure is used for all various subsamples, implemented that consistently weights...
We have developed a technique to systematically discover and study high-redshift supernovae that can be used measure the cosmological parameters. report here results based on initial seven of more than 28 discovered date in supernova search Supernova Cosmology Project. find an observational dispersion peak magnitudes σMB=0.27; this narrows σMB, corr=0.19 after "correcting" using light-curve "width-luminosity" relation found for nearby (z ≤ 0.1) Type Ia from Calán/Tololo survey (Hamuy et...
We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including signal-to-noise Hubble Space Telescope data, and spectra six SNe that were discovered during 2001, are presented. Additionally, for two with z > 1, we present ground-based J-band photometry from Gemini Very Large Telescope. These among most distant which near-IR observations have been obtained. add these together other data sets recently become available in...
We combine high redshift Type Ia supernovae from the first 3 years of Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample 472 SNe (123 low-$z$, 93 SDSS, 242 SNLS, and 14 {\it Hubble Space Telescope}). SN data alone require cosmic acceleration >99.9% confidence, including systematic effects. For dark energy equation state parameter (assumed constant out least $z=1.4$) in flat universe, we find $w =...
We present an empirical model of Type Ia supernovae spectro-photometric evolution with time. The is built using a large data set including light-curves and spectra both nearby distant supernovae, the latter being observed by SNLS collaboration. derive average spectral sequence their main variability components color variation law. allows us to measure distance moduli in range 2500-8000 A calculable uncertainties, those arising from features. Thanks use high-redshift SNe rest-frame UV energy...
We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z 1.1) discovered during the first three years Supernova Legacy Survey (SNLS). These events were detected their multi-colour light curves measured using MegaPrime/MegaCam instrument at Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in bands. Follow-up spectroscopy was performed VLT, Gemini Keck telescopes to confirm nature measure redshifts....
We present observational constraints on the nature of dark energy using Supernova Legacy Survey three-year sample (SNLS3) Guy et al. and Conley use 472 Type Ia supernovae (SNe Ia) in this sample, accounting for recently discovered correlations between SN luminosity host galaxy properties, include effects all identified systematic uncertainties directly cosmological fits. Combining SNLS3 data with full WMAP7 power spectrum, Sloan Digital Sky luminous red a prior Hubble constant H0 from SHOES,...
(Abridged) Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) other data, we show there is an additional dependence global characteristics host galaxies: events same shape colour are, average, 0.08mag (~4.0sigma) brighter in massive galaxies (presumably metal-rich) low specific star-formation rates (sSFR). SNe a sSFR also have smaller slope ("beta") between...
(ABRIDGED) We show that Type Ia supernovae (SNe Ia) are formed within both very young and old stellar populations, with observed rates depend on the mass mean star-formation (SFRs) of their host galaxies. Models where SN rate depends solely galaxy ruled out 99% confidence. Our analysis is based 100 spectroscopically-confirmed SNe Ia, plus 24 photometrically-classified events, all from Supernova Legacy Survey (SNLS) distributed over 0.2
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...
R-band intensity measurements along the light curve of Type Ia supernovae (SNe Ia) discovered by Supernova Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter time-axis width factor w ≡ s(1 + z). The data points then individually aligned time axis, normalized, and K-corrected back rest frame, after which nearly 1300 normalized found lie on well-determined common rest-frame B-band curve, we call "composite curve." same procedure is applied 18 low-redshift...
We present a new method to parameterize Type Ia Supernovae (SN Ia) multi-color light curves. The was developed in order analyze the large number of SN curves measured current high-redshift projects. technique is based on empirically modeling luminosity variations as function phase, wavelength, shape parameter, and color parameter. model trained with sample well nearby then tested an independent set supernovae by building optimal distance estimator combining supernova rest-frame luminosity,...
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...