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Characterization of Dark Energy with Subaru and HST

by Julien Bolmont - 18 October 2018

Title: Characterization of Dark Energy with Subaru and HST

Advisor : Nicolas Regnault

Team : Cosmologie et Énergie Noire ; experiment : Subaru Strategic Program (SSP)

Description :

The question of the nature of Dark Energy is one of the fundamental
puzzles in modern cosmology. It has motivated an ambitious observational program which will culminate in the next decade, with two large ground-based surveys (LSST and DESI) and the launch of two dedicated space telescopes (Euclid and WFIRST). The strategy is to combine complementary cosmological probes to constrain simultaneously the history of cosmic expansion (Hubble diagrams of SNIa and BAO) and the growth rate of structure (cosmic shear correlations, redshift space distorsions).

Measuring the luminosity distance-versus-redshift relation using type Ia supernovae (SNe Ia) is one of the most sensitive probes to the nature of Dark Energy (through the measurement of its equation of state w = p/ρ). Over the last 15 years, large surveys (SNLS, SDSS) have produced high-quality SNIa samples in the redshift range 0.05 < z < 0.8 and published the best constrains on w. Our project is to extend this sample up to a redshift of z ~ 1.5, building on the unrivaled collecting power of the Subaru telescope (8.2-m) and the near-infrared capabilites of the Hubble Space Telescope (HST). Our goal is to obtain a measurement of w with a precision of ~3% and to start constraining potential variations of the Dark Energy equation of state. SNe Ia are a statistically efficient probe, which makes that this program can be achieved with about 1 year of observations (two six month campaigns).

The internship and the thesis are centered on this joint Subaru/HST program. As of today, half of the nominal statistics has been collected. In a first stage, the student will take part in the final search campaign (SN detection and spectroscopic follow-up). He or she will then work on the analysis of the photometric data, in particular: the development of a new generation light curve model, the measurement of the SN distances and the combination of this dataset with its lower redshift counterparts to derive cosmological constraints.

Contact : Nicolas Regnault, 33 (0)1 44 27 41 83

Location : LPNHE, Paris

Possible trips : Tokyo, Berkeley, Baltimore

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