arXiv subjects

Pier Stefano Corasaniti

Publications and source records attributed to Pier Stefano Corasaniti.

24 records · Page 2Linked to original sources

arXiv2006

Model selection as a science driver for dark energy surveys

A key science goal of upcoming dark energy surveys is to seek time evolution of the dark energy. This problem is one of {\em model selection}, where the aim is to differentiate between cosmological models with different numbers of parameters. However, the power of these surveys is traditionally assessed by estimating their ability to constrain parameters, which is a different statistical problem. In this paper we use Bayesian model selection techniques, specifically forecasting of the Bayes factors, to compare the abilities of different proposed surveys in discovering dark energy evolution. We consider six experiments -- supernova luminosity measurements by the Supernova Legacy Survey, SNAP, JEDI, and ALPACA, and baryon acoustic oscillation measurements by WFMOS and JEDI -- and use Bayes factor plots to compare their statistical constraining power. The concept of Bayes factor forecasting has much broader applicability than dark energy surveys.

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arXiv2006

Testing Dark Energy with the Advanced Liquid-Mirror Probe of Asteroids, Cosmology and Astrophysics

The Advanced Liquid-Mirror Probe of Asteroids, Cosmology and Astrophysics (ALPACA) is a proposed 8-meter liquid mirror telescope surveying 1000 square degree of the southern-hemisphere sky. It will be a remarkably simple and inexpensive telescope, that nonetheless will deliver a powerful sample of optical data for studying dark energy. The bulk of the cosmological data consists of nightly, high signal-to-noise, multiband light curves of SN Ia. At the end of the three-years run ALPACA is expected to collect 100,000 SNe Ia up to z~1. This will allow us to reduce present systematic uncertainties affecting the standard-candle relation. The survey will also provide several other datasets such as the detection of baryon acoustic oscillations in the matter power spectrum and shear weak lensing measurements. In this preliminary analysis we forecast constraints on dark energy parameters from SN Ia and baryon acoustic oscillations. The combination of these two datasets will provide competitive constraints on the dark energy parameters under minimal prior assumptions. Further studies are needed to address the accuracy of weak lensing measurements.

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arXiv2005

Super-acceleration as Signature of Dark Sector Interaction

We show that an interaction between dark matter and dark energy generically results in an effective dark energy equation of state of w<-1. This arises because the interaction alters the redshift-dependence of the matter density. An observer who fits the data treating the dark matter as non-interacting will infer an effective dark energy fluid with w<-1. We argue that the model is consistent with all current observations, the tightest constraint coming from estimates of the matter density at different redshifts. Comparing the luminosity and angular-diameter distance relations with LambdaCDM and phantom models, we find that the three models are degenerate within current uncertainties but likely distinguishable by the next generation of dark energy experiments.

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arXiv2005

Tracking Dark Energy with the ISW effect: short and long-term predictions

We present an analysis of the constraining power of future measurements of the Integrated Sachs-Wolfe (ISW) effect on models of the equation of state of dark energy as a function of redshift, w(z). To achieve this, we employ a new parameterization of w, which utilizes the mean value of w(z) ( ) as an explicit parameter. This helps to separate the information contained in the estimation of the distance to the last scattering surface (from the CMB) from the information contained in the ISW effect. We then use Fisher analysis to forecast the expected uncertainties in the measured parameters from future ISW observations for two models of dark energy with very different time evolution properties. For example, we demonstrate that the cross-correlation of Planck CMB data and LSST galaxy catalogs will provide competitive constraints on w(z), compared to a SNAP-like SNe project, for models of dark energy with a rapidly changing equation of state (e.g. 'Kink' models). Our work confirms that, while SNe measurements are more suitable for constraining variations in w(z) at low redshift, the ISW effect can provide important independent constraints on w(z) at high z.

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arXiv2005

Gravitational waves, inflation and the cosmic microwave background: towards testing the slow-roll paradigm

One of the fundamental and yet untested predictions of inflationary models is the generation of a very weak cosmic background of gravitational radiation. We investigate the sensitivity required for a space-based gravitational wave laser interferometer with peak sensitivity at $\sim 1$ Hz to observe such signal as a function of the model parameters and compare it with indirect limits that can be set with data from present and future cosmic microwave background missions. We concentrate on signals predicted by slow-roll single field inflationary models and instrumental configurations such as those proposed for the LISA follow-on mission: Big Bang Observer.

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arXiv2004

Phenomenological aspects of dark energy dominated cosmologies

In this thesis we study some observational consequences of dark energy dominated cosmologies. After reviewing the main characteristics of quintessential models of dark energy, by using the SN Ia data and the position of the CMB peaks we constrain a class of parameterized scalar field potentials. Going beyond constraining specific classes models, we introduce a parameterization of the dark energy equation of state. Such an approach allows us to study in a model independent way the imprint dark energy leaves in the CMB power spectrum. Finally we develop a formalism to model localized CMB anisotropies and compute analytical formulae for the power spectrum and the bispectrum.

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