Astronomy Colloquia

The Rise and Fall of Galaxies

Speaker: 
Evan Scannapieco (Arizona State University)
Event Date and Time: 
Mon, 2018-03-05 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
The golden age of galaxies has come and gone. From an initial distribution of weak density perturbations, gravity acted bring forth ever-larger structures, overcoming a range of feedback processes to efficiently form stars and galaxies at an exponentially increasing rate. Then just as quickly as it arose, the epoch of efficient galaxy formation faded away, the cosmic star formation rate declining by 90% to its current day value. I will discuss our efforts to understand the processes that shaped this dramatic evolution.

Planet formation and migration in extreme planetary systems

Speaker: 
Henry Ngo (Herzberg Institute of Astrophysics)
Event Date and Time: 
Mon, 2018-03-19 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
Discoveries of exoplanetary systems in the last two decades have revealed the diversity of planetary systems in our Galaxy. Due to their large masses and radii, giant planets are often the first planets discovered with each new planet-finding technique. Two giant planet classes on extreme orbits have raised new challenges for planet formation and migration models: the hot Jupiters found on close-in orbits and the directly imaged giant planets detected on wide orbits.

Deep learning for cosmology: Challenges and opportunities

Speaker: 
Siamak Ravanbakhs (UBC Computer Science)
Event Date and Time: 
Mon, 2018-03-26 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
A primary goal of modern cosmology is to map complex large-scale observations to simple theories. This contrast of scale between theory and data inevitably necessitates a computational approach. This computation may involve a compressive analysis of observational data, massive simulations, active exploration, or a search for rare events. In this talk, I will argue that recent advances in machine learning, and in particular deep learning can significantly impact the current practice in all of these fronts.

Ionization of the warm (magneto)ionized medium

Speaker: 
Alex Hill (Dominion Radio Astrophysical Observatory, UBC Physics & Astronomy)
Event Date and Time: 
Mon, 2018-01-22 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
The ionization of the warm ionized medium has been a puzzle since its discovery in the 1970s. Observations suggest a power requirement that can only be explained with photoionization by O stars in the Galactic disk. I will discuss the success of models invoking supernova-driven turbulence to allow ionizing photons to travel from massive stars in the Galactic midplane to more than a kpc above the disk as part of the multi-phase interstellar medium. I will present Global Magnetoionic Medium Survey (GMIMS) observations obtained with the John A.

Probing the atmospheres of exoplanets and brown dwarfs with near-IR polarimetry

Speaker: 
Rebecca Jensen-Clem (Berkeley)
Event Date and Time: 
Mon, 2018-01-15 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
Our understanding of exoplanet compositions and their implications for planet formation are closely linked to our understanding of the physical processes that govern exoplanet atmospheres. However, the atmospheric models that best fit the observed spectra tend to imply implausibly small radii Such discrepancies may be due to a lack of detail in the models of exoplanet clouds, which generally lack well-motivated cloud grain size distributions, depth variations, and horizontal structures.

Measuring the neutron-star equation of state with GW170817

Speaker: 
Jocelyn Read (California State University Fullerton)
Event Date and Time: 
Mon, 2018-02-05 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
Recent observations of merging neutron stars using gravitational waves, and a coincident gamma-ray burst, recently triggered astronomical observations across the electromagnetic spectrum. These observations are shedding new light on the dynamics of dense matter in neutron-star mergers. The dynamics of the compact binary, and thus its gravitational-wave signature, is primarily determined by the mass and spin of the components. Gravitational-wave observations of compact binaries can therefore measure mass and spin parameters.

Very wide binaries and comoving stars in the Gaia era

Speaker: 
Adrian Price-Whelan (Princeton University)
Event Date and Time: 
Mon, 2018-01-29 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
Conatal and coeval stars are important tracers of kinematics, stellar models, dark matter physics, and star and planet formation processes in the Galaxy: The disruption of these systems is sensitive to the Galactic gravitational field, their spectra can be used to calibrate stellar models at fixed age and chemical abundances, and changes or differences in their surface abundances likely relates to the stability and mass in planetary systems. A strong indicator that a given pair of stars are coeval is that they are co-moving in three dimensions. I'll discuss our group's effort to iden

Magnetism with Big Data Radio Surveys: High-z to the Cosmic Web

Speaker: 
Tessa Vernstrom (Dunlap Institute, University of Toronto)
Event Date and Time: 
Mon, 2018-03-12 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
This exciting time of big data from new telescopes and surveys provides unprecedented opportunities for discovery. Cosmic magnetism is a vigorous and rapidly developing area. This surge of interest has been driven in large part by the prospect of dramatic new views of polarization and Faraday rotation offered by new wide-field technological developments. The combination of new deep extragalactic radio surveys, statistical methods, and data-mining techniques allow us to probe to new depths and examine questions such as: was there a primordial magnetic field and what was its strength?

Get ready for the James Webb Space Telescope

Speaker: 
Chris Willott (Herzberg Institute of Astrophysics)
Event Date and Time: 
Mon, 2017-11-20 15:00 - 16:15
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate

The James Webb Space Telescope (JWST) is currently in its final phase of integration and scheduled for launch in the spring of 2019, with science operations to commence six months later. Equipped with four powerful science instruments, JWST will provide imaging and spectroscopy from 0.6 to 28 microns through numerous observing modes specifically designed to tackle of wide range of scientific investigations, from studying planets and moons of our Solar system, detecting the faintest galaxies in the early universe to probing the thin atmosphere of exoplanets transiting nearby bright stars.

EASTER MONDAY - NO ASTRONOMY COLLOQUIUM

Event Date and Time: 
Mon, 2018-04-02 15:30 - 16:45
Location: 
Hennings 318
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