Cosmology Seminar

Cosmology Seminars are held on Mondays at 11 am during Spring 2022, 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 Simon Birrer, Nick Kokron or Risa Wechsler for more information.

Bright (active) Galaxies in Dark Matter halos

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Location

Campus, Varian 355

Speaker
Shadab Alam (University of Edinburgh)

The bright galaxies comes in different colours and show different activities. Some are red, some blue and others have angry supermassive blackholes. These galaxies acts as the doorway to the cosmological universe we live in. Our understanding of inner working of universe and its mysterious dark components of matter and energy depends on the very large scale structure formed by these bright galaxies.

Stellar Property Statistics of Massive Halos: Common Kernel Shapes from Multiple Cosmological Hydrodynamics Simulations

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Location

Campus, Varian 355

Speaker
August (Gus) Evrard (University of Michigan)

In the last decade, the astrophysical processes driving galaxy formation in a cosmological context at kpc scales have been incorporated, largely independently, into multiple codes developed by different simulation teams.

The probability distribution function (PDF) of cosmic density fluctuations: How to measure it? How to model it? What information does it contain?

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Location

Campus, Varian 355

Speaker
Oliver Friedrich (Kavli Institute for Cosmology Cambridge)

In this talk I will lead you through the highlights of a series of papers (Gruen++2018, Friedrich++2018, Friedrich&Uhlemann et al. in prep, Uhlemann&Friedrich et al. in prep) that promote an alternative framework of studying large scale structure data: analysis of the 1-point PDF of density fluctuations. The main difference between the PDF and 2-point correlation functions is readily explained: 2-point functions measure the variance of fluctuations as a function of scale, while the PDF measures all moments of the fluctuations at one scale.

Precision Cosmology with the Cosmic Microwave Background

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Location

Campus, Varian 355

Speaker
Sara Simon (University of Michigan)

The cosmic microwave background (CMB) provides unparalleled views into the early universe and its later evolution. Recent and ongoing experiments have contributed to our understanding of neutrinos, dark energy, and dark matter through measurements of large scale structure imprinted on the CMB and constrained the conditions in the early universe, tightly restricting inflationary and other cosmological models through measurements of CMB polarization.

Statistical Challenges in photometric redshift inference

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Location

Campus, Varian 355

Speaker
Markus Michael Rau (Carnegie Mellon University)

Observations from large area photometric surveys like LSST or DES will constrain cosmology to unprecedented precision. Deep wide-area imaging will provide observations for faint galaxy samples, for which traditional redshift calibration using spectroscopic data is very difficult.

Increased Hubble tension with a new measurement of the Hubble constant using strong lensing

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Location

Campus, Varian 355

Speaker
Anowar Shajib (UCLA)

The recent tension between early- and late-Universe measurements of the Hubble constant highlights the necessity for independent and precise probes such as the time-delay cosmography. The measured time-delays between the lensed images of a background quasar depend on the absolute physical scales in the lens configuration. Thus, they allow measurement of these scales to infer the Hubble constant, H_0.

Searching for supermassive black hole binaries

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Location

Campus, Varian 355

Speaker
Maria Charisi (Caltech)

Supermassive black hole binaries (SMBHBs) are a natural byproduct of galaxy mergers. Yet, they remain undetectable at small separations. A promising method is to identify quasars with periodic variability. I will discuss candidates identified in time-domain surveys, as well as ongoing efforts to confirm their binary nature.

Cosmic Shear in the Year-3 DES data: 2-point and 3-point correlations

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Location

Campus, Varian 355

Speaker
Lucas Secco (University of Pennsylvania)

The cosmology analyzes of the Year-3 (Y3) data from the Dark Energy Survey (DES) is at full speed ahead. Our preliminary weak lensing sample contains 120 million objects over 4200 square degrees of sky and is the largest shape catalog to date. This statistical power comes at a price: the cosmic shear measurements are more sensitive not only to the signal but also to potential systematics.