Cosmic Flows (and other novelties on Large Scales)

Cosmic Flows (and other novelties on Large Scales)

 

 

Wednesday Aug 12, 2015
Speaker(s): 

After the completion of the Planck satellite, the next most important experiments in cosmology will be about mapping the Large Scale Structures of the Universe. In order to continue to make progress in our understanding of the early universe, it is essential to develop a precise understanding of this system. The Effective Filed Theory of Large Scale Structures provides a novel framework to analytically compute the clustering of the Large Scale Structures in the weakly non-linear regime in a consistent and reliable way.

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Wednesday Aug 12, 2015
Speaker(s): 

The spin-flip transition in neutral hydrogen may be used to probe large-scale structure at high redshifts, before the first luminous objects formed. The huge number of modes potentially accessible make this a very promising avenue. I will discuss several key unknowns that could be measured with high-redshift 21cm surveys: primordial non-gaussianity, the primordial small-scale power spectrum, and dark-matter-baryon interactions.

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Wednesday Aug 12, 2015
Speaker(s): 

CHIME will use the 21cm emission line of neutral hydrogen to map large-scale
structure between redshifts of 0.8 and 2.5. By measuring BAO we will place
constraints on the dark energy equation of state as it begins to dominate the
expansion of the Universe, particularly at redshifts poorly probed by current
BAO surveys.

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Wednesday Aug 12, 2015
Speaker(s): 

I will present results from the SDSS-III BOSS-DR11 analysis. In this talk I will focus on the analysis of the power spectrum multipoles, which allows to constrain the growth of structure through redshift-space distortions. Such measurements can be used to test GR and measure the sum of the neutrino masses. Beside RSD we also constrain the geometry of the Universe through the Alcock-Paczynski effect and Baryon Acoustic Oscillations.

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Tuesday Aug 11, 2015
Speaker(s): 

New results on the observational signatures of large-scale flows during reionization, using new simulations and analytical methods, will be presented. A preliminary analysis will be described, indicating that cross-correlation of diffuse radiation with tracers of the large scale matter fluctuations can in principle provide new constraints on the timing and duration of reionization, via peculiar velocities.

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Tuesday Aug 11, 2015
Speaker(s): 

I'll present a series of numerical experiments to test simple analytical predictions for large-scale Lyman-alpha forest bias parameters. Despite relying on second-order SPT, some of the predictions are surprisingly accurate, especially if thermal broadening is not taken into account. I'll also discuss details of using filtered and squared small-scale fields as robust tracers of large-scale structure that might be useful for non-Gaussianity measurements.

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Tuesday Aug 11, 2015
Speaker(s): 

Present day streaming motions of neutrinos relative to dark matter and baryons are several hundred km/s, comparable with their thermal velocity dispersion. This results in a unique dipole anisotropic distortion of the matter-neutrino cross power spectrum, which is observable through the dipole distortion in the cross correlation of different galaxy populations. Such a dipole vanishes if not for this relative velocity and so it is a clean signature for neutrino mass.

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Tuesday Aug 11, 2015
Speaker(s): 

TBA

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Tuesday Aug 11, 2015
Speaker(s): 

The measurement of distance has long been a fundamental challenge in astrophysics. We have developed a method of inferring distances to astrophysical sources using spatial cross-correlations with galaxies of known redshift. These “clustering redshifts” are robust to problems plaguing other distance estimates and require only knowledge of the on-sky position of the sources. We have verified the method with sources with spectroscopic redshifts, demonstrating accuracies exceeding those required for many cosmological probes.

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