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Cosmology & Gravitation

This series consists of talks in the areas of Cosmology, Gravitation and Particle Physics.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.
 

 

Mardi oct 30, 2018
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In July 2018 the Planck Collaboration released its final set of cosmology results. I will discuss some of the  interesting new science that remains to be done with the CMB, including some not so often discussed topics such as the kinetic SZ effect and 21cm cross-correlations.

 

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Jeudi oct 25, 2018
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In this third of 3 talks I will discuss the effects of the conformal anomaly in the low energy infrared relevant correction to General Relativity. Among the significant implications of this effective field theory of gravity are the prediction of scalar gravitational wave solutions—a spin-0 breather mode— in addition to the transversely polarized tensor waves of the classical Einstein theory.

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Mercredi oct 24, 2018
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Hyper Suprime-Cam (HSC) is an imaging camera mounted at the Prime Focus of the Subaru 8.2-m telescope operated by the National Astronomical Observatory of Japan on the summit of Maunakea in Hawaii. A consortium of astronomers from Japan, Taiwan and Princeton University is carrying out a three-layer, 300-night, multiband survey from 2014-2019 with this instrument. In this talk, I will focus on the HSC survey Wide Layer, which will cover 1400 square degrees in five broad bands (grizy), to a 5 sigma point-source depth of r~26.

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Jeudi oct 18, 2018
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In the second lecture, I will extend the previous discussion to gravity, and show that the conformal trace anomaly must play a special role in the effective field theory of low energy gravity.

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Mercredi oct 17, 2018
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In this first of two lectures, intended to be a pedagogical introduction, I will review the quantum field theory origin of anomalies starting with the more familiar example of the axial anomaly in QED, emphasizing the infrared effects and the appearance of a two-particle massless state, similar to a Cooper pairing in superconductor, associated with both the axial and conformal anomalies in two and four dimensions.

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Mardi oct 16, 2018
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A key prediction of the Lambda CDM framework of structure formation is that a host halo containing a Milky Way sized disk galaxy should contain hundreds of thousands of sub-dwarf galaxy mass dark matter subhalos. Devoid of stars, these substructures remain undetected. Detecting them will not only corroborate the existence of dark matter but also give crucial information on the particle nature of dark matter and how they cluster at small scale. Cold stellar streams originate when globular clusters are tidally disrupted in the Milky Way potential.

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Mardi oct 09, 2018
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Line Intensity Mapping has emerged as a powerful tool to probe the large-scale structure across redshift, with the potential to shed light on dark energy at low redshift and the cosmic dawn and reionization process at high redshift.  Multiple spectral lines, including the redshifted 21cm, CO, [CII], H-alpha, and Lyman-alpha emissions, are promising tracers in the intensity mapping regime, with several experiments on-going or in the planning.  I will discuss results from current pilot programs, prospects for the upcoming TIME experiment, and the outlook of future space missions such as SPHER

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Mardi sep 25, 2018
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Stars orbiting in the halo of our galaxy, the Milky Way, are a window into the distribution of dark matter. In particular, tidally disrupted star clusters, which produce thin stellar streams, are optimal tracers of matter. Based on a Fisher-information calculation, we expect that the current data on the known Milky Way streams should constrain the radial profile and the shape of the inner halo to a precision of a few percent. In addition, stellar streams retain a detailed record of the matter field on small scales.

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Mardi sep 18, 2018
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In galaxy redshift surveys, the line-of-sight velocity information is encoded in the observed redshift as a Doppler component that radially distorts the galaxy positions. The linear component of such `Redshift-Space Distortions' (RSD) is directly proportional to the growth rate of structure, f(z), and motivates the interest in RSD as a powerful way to constrain gravity. However, the non-linear evolution of the density and velocity fields requires the use of sophisticated theoretical models to extract reliable cosmological information from quasi-linear scales.

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Lundi sep 10, 2018
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Gravitational lensing has long served as a unique probe of the growth of structure, which is sensitive on large scales to the properties of dark energy and gravity.  In particular, lensing is instrumental in forming the statistic E_G, which is constructed to measure the growth rate of structure in a way independent of galaxy clustering bias.  Me

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