Cosmology Seminar

Cosmology Seminars are held at on Mondays at 11 am during the academic year, on the 3rd floor Varian conference room. These are more focused and less didactic than the colloquium, and provide a stage for younger researchers to present their work in more detail.  

Please contact Risa WechslerDaniel GruenJosh Meyers, or Kyle Story for more information.

TBD

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Location

Campus, Varian 355

Speaker
Philip Mansfield (University of Chicago)

Modelling CMB lensing and galaxy surveys cross-correlations for next generation surveys

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Location

Campus, Varian 355

Speaker
Giulio Fabbian (University of Sussex)

The cosmic microwave background (CMB) gravitational lensing and its cross-correlation with large-scale structure tracers will be important cosmological probes in the coming years. Being able to model these observables and reconstruct them from the data with the level of precision required by future experiments will be mandatory in order to exploit them for robust cosmological applications.

Probing cosmology with Type Ia Supernovae: A new perspective

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Location

Campus, Varian 355

Speaker
Zhongxu Zhai (Caltech)

We present a method to reconstruct the probability distribution of the weak lensing magnification of Type Ia supernovae (SNe Ia) from observational data. The method is directly applicable to future data from surveys like WFIRST. With a realistic synthetic catalog, we measure the weak lensing signature and express the observable in terms of the variance of the lensing magnification.

Are We Ready for Precision Cosmology? General Relativistic Effects and Gauge-Invariant Formalism

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Location

Campus, Varian 355

Speaker
Jaiyul Yoo (University of Zürich)

The current and upcoming surveys in cosmology will soon deliver an unprecedented amount of precision measurements, truly opening an era of precision cosmology.  However, this rapid development in experiments and observations demands substantial advances in theoretical modeling to avoid any systematic errors in our interpretation.  The standard theoretical descriptions of galaxy clustering, weak gravitational lensing, and the CMB Boltzmann equations are incomplete an

Cosmological applications of the kSZ effect

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Location

Campus, Varian 355

Speaker
Mathew Madhavacheril (Princeton)

We show how kSZ tomography measures a bispectrum containing a cosmological power spectrum of the velocity field and an astrophysical power spectrum of the electron density. While these are degenerate up to an overall amplitude (the "galaxy optical depth"), scale-dependent effects on large scales are much better constrained by the inclusion of kSZ on top of galaxy clustering while assuming nothing about the optical depth of galaxy clusters.

How to not run cosmological n-body simulations

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Location

Campus, Varian 355

Speaker
Alexander Mead (University of British Columbia)

Extracting cosmological information from current survey data is increasingly reliant on computationally-intensive n-body simulations of large-scale structure. For weak-lensing surveys, the matter distribution is directly measured from simulations on scales where linear perturbation theory fails. For galaxy-clustering surveys, haloes are identified in simulations and then populated with galaxies to provide mock catalogues.

Towards Weak Lensing Cosmology with WFIRST Near-Infrared Detectors

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Location

Campus, Varian 355

Speaker
Ami Choi (The Ohio State University)

The Wide Field Infrared Survey Telescope (WFIRST) is an upcoming NASA observatory that will investigate the origins of cosmic acceleration using weak gravitational lensing.  WFIRST will perform galaxy shape measurements using Teledyne H4RG-10 detectors; thus it is essential to understand inter-pixel non-linear effects like the brighter-fatter effect (BFE) and non-linear inter-pixel capacitance (NL-IPC) that could cause systematic errors in the lensing analysis.  The

A first look at a super massive black hole

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Location

Campus, Varian 355

Speaker
Lia Medeiros (Institute for Advanced Study )

On April 10, 2019, the Event Horizon Telescope (EHT), a very long baseline interferometry experiment, released the first image of a black hole resolved to event horizon scales. I will discuss the image of M87 and aim to convince the audience that a flux depression in the image is necessary to fit the data. I will also discuss the parameters we derived based on the image and model fitting results.

Large-scale intrinsic alignments of dark matter halo orientations with velocity field

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Location

Campus, Varian 355

Speaker
Teppei Okumura (ASIAA)

The kinematic Sunyaev-Zel'dovich effect enables us to directly probe the density-weighted velocity field up to very large cosmic scales. We investigate the effects of intrinsic alignments (IA) of dark-matter halo shapes on cosmic density and velocity fields on such large scales. In literature IA have been detected with the halo density field up to ~ 100 Mpc/h both in simulations and observations.

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