Events

Astronomy Seminar Series

Ludovic Van Waerbeke, University of British Columbia

Let's assume dark matter is a particle. The DM theories currently tested, WIMPs-like, either via direct or indirect detection, cover only a tiny range of the allowed DM parameters space, and have not been particularly successful so far. A new DM candidate, the Axion Quark Nugget (AQN), has been proposed by Zhitnitsky in 2003, partly inspired by the quark nuggets (Witten 1984).

Astronomy Seminar Series

Alice Pisani, Princeton University

Modern surveys allow us to access to high quality measurements on large areas in the sky and span large redshift ranges—thus sampling the galaxy distribution in detail also in the emptier regions, voids. Void cosmology is hence becoming an increasingly active sector of galaxy clustering analysis: by measuring void properties, such as the abundance or the density profiles, it is possible to constrain cosmological parameters.

Astronomy Seminar Series

Nienke van der Marel, University of British Columbia

Successful exoplanet surveys in the last decade have revealed that planets are ubiquitous throughout the Milky Way, and show a large diversity in mass, location and composition. At the same time, new facilities such as the Atacama Large Millimeter/submillimeter Array (ALMA) and optical/infrared facilities including Gemini/GPI and VLT/SPHERE have provided us with sharper images than ever before of protoplanetary disks around young stars, the birth cradles of planets.

Astronomy Seminar Series

Jo Dunkley, Princeton University

There is currently a tension between various measurements of the expansion rate of the universe. I will give a recap of this issue, and talk about how we use the Cosmic Microwave Background, our most distant observation, to infer the local expansion rate of space. I will explain what assumptions we make about the cosmological model in doing so, and how we might modify this model to bring different measurements of the expansion rate better in line.

Astronomy Seminar Series

Arnaud De-Mattia, CEA Saclay

In this talk I will present the clustering analysis of the ELG (Emission Line Galaxy) sample from the eBOSS (extended Baryon Oscillation Spectroscopic Survey) program of the Sloan Digital Sky Survey and review the other clustering analyses of the eBOSS program, dedicated to Luminous Red Galaxies and Quasars. I will discuss theoretical, observational and analysis systematics, how they were estimated and mitigated, focusing on the improvements over the last release of the BOSS program in 2016.

Astronomy Seminar Series

Sharon Morsink

Neutron stars are tiny stars with ultra-strong magnetic and gravitational fields and densities larger than nuclear. Their small size and large average densities allow them to spin at very rapid rates, with surface velocities that are a large fraction of the speed of light.

CANCELLED

Astronomy Seminar Series

Brenda Frye, University of Arizona

Galaxy clusters as astronomical tools generally offer two advantages:  to boost the brightnesses of objects in the background, and to study the dark matter in the lens.  We can now introduce a third use: to unveil properties of the underlying dark matter by the detection of caustic crossing events which can yield magnification factors of 10,000 or more.  We review the approach to detect a new set of massive objects such as galaxy clusters by their rest-frame far-infrared colors (and not by th

Astronomy Seminar Series

Ramesh Narayan, Harvard University

Accretion disks around black holes are the power source behind many luminous and powerful astrophysical systems, for example, X-ray binaries and active galactic nuclei. The well-known thin disk model does a good job of explaining many accreting black hole systems, but the model is limited to sub-Eddington accretion rates. Can a black hole accrete at a super-Eddington rate? If yes, do we observe such systems, and do they have unique observational signatures?

Astronomy Seminar Series

Gwen Eadie, University of Toronto

Astrostatistics is an interdisciplinary field that lives on the boundary between astronomy and statistics. This interdisciplinary field seeks to answer fundamental science questions about the universe while simultaneously inspiring new and improved statistical methods for data analysis. In this talk, I will introduce two areas of my research in astrostatistics. The first covers hierarchical Bayesian analysis in the context of the Milky Way Galaxy, applied to data from the Gaia satellite and others.

Astronomy Seminar Series

Chang-Goo Kim, Princeton University

Developing a theoretical understanding of star formation and galactic-scale winds from first principles is the major hurdle to build a truly predictive galaxy formation theory. Stars are born in the interstellar medium (ISM) as a consequence of the competition between gravity and turbulent, magnetic, and thermal pressure forces.