We present 32 epochs of optical (3300−9700 Å) spectrophotometric observations of the nearby quintessential “normal” type Ia supernova (SN Ia) SN 2011fe in the galaxy M101, extending from −15 to +97 d ...with respect to B-band maximum, obtained by the Nearby Supernova Factory collaboration. SN 2011fe is the closest (μ = 29.04) and brightest (Bmax = 9.94 mag) SN Ia observed since the advent of modern large scale programs for the intensive periodic followup of supernovae. Both synthetic light curve measurements and spectral feature analysis attest to the normality of SN 2011fe. There is very little evidence for reddening in its host galaxy. The homogeneous calibration, intensive time sampling, and high signal-to-noise ratio of the data set make it unique. Thus it is ideal for studying the physics of SN Ia explosions in detail, and for furthering the use of SNe Ia as standardizable candles for cosmology. Several such applications are shown, from the creation of a bolometric light curve and measurement of the 56Ni mass, to the simulation ofdetection thresholds for unburned carbon, direct comparisons with other SNe Ia, and existing spectral templates.
A metric space for Type Ia supernova spectra Sasdelli, Michele; Hillebrandt, W; Aldering, G ...
Monthly Notices of the Royal Astronomical Society,
02/2015, Volume:
447, Issue:
2
Journal Article
Peer reviewed
Open access
We develop a new framework for use in exploring Type Ia supernovae (SNe Ia) spectra. Combining principal component analysis (PCA) and partial least square (PLS) analysis we are able to establish ...correlations between the principal components (PCs) and spectroscopic/photometric SNe Ia features. The technique was applied to ∼120 SN and ∼800 spectra from the Nearby Supernova Factory. The ability of PCA to group together SNe Ia with similar spectral features, already explored in previous studies, is greatly enhanced by two important modifications: (1) the initial data matrix is built using derivatives of spectra over the wavelength, which increases the weight of weak lines and discards extinction, and (2) we extract time evolution information through the use of entire spectral sequences concatenated in each line of the input data matrix. These allow us to define a stable PC parameter space which can be used to characterize synthetic SN Ia spectra by means of real SN features. Using PLS, we demonstrate that the information from important previously known spectral indicators (namely the pseudo-equivalent width of Si ii 5972 Å/Si ii 6355 Å and the line velocity of S ii 5640 Å/Si ii 6355 Å) at a given epoch is contained within the PC space and can be determined through a linear combination of the most important PCs. We also show that the PC space encompasses photometric features like B/V magnitudes, B − V colours and salt2 parameters c and x
1. The observed colours and magnitudes, which are heavily affected by extinction, cannot be reconstructed using this technique alone. All the above-mentioned applications allowed us to construct a metric space for comparing synthetic SN Ia spectra with observations.
In a galaxy cluster, galaxies are mostly collisionless particles in recent epochs. They resemble collisionless cold dark matter particles in some way. Therefore, the spatial distributions of dark ...matter and cluster galaxies might be expected to possess similar features in the gravitational potential of a cluster. Here we use the galaxy distribution in cluster Cl 0024+17 to probe for the ringlike dark matter structure recently discovered by means of strong and weak lensing observations. The galaxies are taken from the catalog of Czoske et al., which contains 650 objects with measured redshifts, of which similar to 300 galaxies have redshifts in the range 0.37 < z < 0.41 (and are therefore probable cluster members). We find that, at about the 3 sigma level, the ringlike structure seen in the dark matter measurement is not observed in the projected two-dimensional galaxy distribution.
Context. Aims.We study the image of the transform from scale parameters to Hubble diagrams and present a lower bound on the radius of the universe today a0 and a monotonicity constraint on the Hubble ...diagram. Methods.Our theoretical input is minimal: Einstein's kinematics and maximally symmetric universes. Results.Present supernova data yield $a_0 > 1.2\times 10^{26}$, i.e. $\Omega_{k0} > -1.29$. We attempt to quantify the monotonicity constraint and do not see any indication of non-monotonicity. Conclusions.
A major quest in cosmology is to understand the nature of dark energy. It is now well known that the use of several cosmological probes is required to break the underlying degeneracies on ...cosmological parameters. In this paper, we present a method based on a frequentist approach that combines probes without any prior constraints. As one application, the current supernovae type Ia and cosmic microwave background data are analyzed with an evolving dark energy component, and our results are first compared to other analyses. We emphasize the consequences of implementing the dark energy perturbations for an equation of state that varies with time. We then simulate the expectations of different future projects. The constraints from weak lensing surveys on the measurement of dark energy evolution are combined with the measurements from the cosmic microwave background and type Ia supernovae. We present the impacts for mid-term and long-term surveys and confirm that the combination with weak lensing is very powerful in breaking parameter degeneracies. A second generation of experiments is, however, required to achieve a 0.1 error on the parameters describing the evolution of dark energy.
The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for pair-produced charged Higgs bosons in the framework of Two Higgs Doublet Models (2HDMs). The data of the four experiments ...have been statistically combined. The results are interpreted within the 2HDM for Type I and Type II benchmark scenarios. No statistically significant excess has been observed when compared to the Standard Model background prediction, and the combined LEP data exclude large regions of the model parameter space. Charged Higgs bosons with mass below 80
(Type II scenario) or 72.5
(Type I scenario, for pseudo-scalar masses above 12
) are excluded at the 95 % confidence level.
We confront Einstein-Cartan’s theory with the Hubble diagram. An affirmative answer to the question in the title is compatible with today’s supernovae data.
The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia supernova (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 of SN 2011fe can be used to constrain SN Ia explosion scenarios. We base our discussion on three-dimensional simulations of a delayed detonation in a Chandrasekhar-mass white dwarf and of a violent merger of two white dwarfs (WDs)-realizations of explosion models appropriate for two of the most widely discussed progenitor channels that may give rise to SNe Ia. Although both models have their shortcomings in reproducing details of the early and near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory (SNfactory), the overall match with the observations is reasonable. The level of agreement is slightly better for the merger, in particular around maximum, but a clear preference for one model over the other is still not justified. Observations at late epochs, however, hold promise for discriminating the explosion scenarios in a straightforward way, as a nucleosynthesis effect leads to differences in the super(55)Co production. SN 2011fe lfe is close enough to be followed sufficiently long to study this effect.
Recent preliminary results of searches for Higgs bosons outside the Minimal Supersymetric Standard Model (MSSM) are summarised. These results are based on data from the four LEP experiments: ALEPH, ...DELPHI, L3 and OPAL, at a centre-of-mass energies up to 189 GeV. Some new results from the two Tevatron experiments: CDF and D0, are also presented. Finally, the potential mass reach for exotic Higgs at future accelerators are discussed.
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