Past Colloquia
The quest of measuring star-formation histories to elucidate the first galaxies
Zoom
Sandro Tacchella, Ulsan National Institute of Science and Technology
September 15, 2021
11:00 am - 12:00 pm
The last great unknown of the cosmic history is when, why and how the first galaxies formed after the Big Bang. These galaxies played an important role in re-ionizing the universe and are also an important tracer of early structure formation. I will present new results on…
Studying star formation from the stratosphere
Zoom
Laura Fissel, Queen's University
April 14, 2021
2:00 pm - 3:00 pm
An important mystery in astrophysics is why the conversion of interstellar gas into stars is such an inefficient process. We typically observe of order 1% the star formation rate expected from a free-fall gravitational collapse of molecular gas clouds. This low efficiency is likely due to regulation from a combination of turbulent gas motions,…
Expanding the gravitational-wave spectrum
Zoom
Sarah Burke-Spolaor, University of West Virginia
April 07, 2021
2:00pm - 3:00pm
We are seeking both electromagnetic and gravitational waves from binary supermassive black holes, the biggest, discrete binary systems in the Universe. When galaxies merge, these giant binaries can form. During their inspiral and coalescence phases, they will produce intense gravitational radiation, which we expect to…
Advancing the Astronomical Inclusion Revolution
Zoom
Dara Norman, NOIRLab
March 31, 2021
2:00 pm - 3:00 pm
The field of Astronomy and Astrophysics has seen major changes in the last couple of decades. There have been discoveries that have evolved our understanding of the Universe. The development of new methods and gathering of datasets have expanded topical areas of the field in…
Shaping the future of weak-lensing cosmology with the Roman Space Telescope
Zoom
Dr. Jenna Freudenburg, DADDAA
March 24, 2021
2:00 pm - 3:00 pm
In the past decade, our understanding of the standard model of cosmology has been shaped by constraints on Lambda-CDM from so-called Stage III surveys, such as the Dark Energy Survey. In the 2020s, a wealth of new data from Stage IV surveys – including the…
The End of all Worlds
Zoom
Boris Gaensicke, University of Warwick
March 17, 2021
2:00 pm - 3:00 pm
Many of the known planets – in the solar system Mars and beyond – will survive the post main-sequence evolution of their host stars into white dwarfs. Later interactions scatter asteroids, moons, and possibly entire planets deep into the gravitational potential of the white dwarf,…
A New Era of Interferometry with GRAVITY
Zoom
Frank Eisenhauer, Max Planck Institute
March 10, 2021
11:00 am - 12:00 pm
The GRAVITY instrument has enabled major steps forward in infrared interferometry, by phase-referenced imaging at milli-arcsecond resolution, with a sensitivity increase by factor thousands, 30-100 micro-arcsecond astrometry, and few micro-arcsecond differential spectro-astrometry. We give an overview of the technology behind GRAVITY and highlight the game-changing…
Cosmology with Gravitational Lens Time Delays
Zoom
Sherry Suyu, Max Planck Institute
March 03, 2021
12:00 pm - 1:00 pm
Strong gravitational lenses with measured time delays between the multiple images can be used to determine the Hubble constant (H0) that sets the expansion rate of the Universe. An independent determination of H0 is important to ascertain the possible need of new physics beyond the…
Colloquia with Dr. Daniel Gilman and Dr. Almog Yalinewich
Zoom
Daniel Gilman, DADDAA; Almog Yalinewich, CITA
February 24, 2021
2:00 pm - 3:00 pm
Investigating the nature of dark matter with strong gravitational lensing by Daniel Gilman Strong gravitational lensing by galaxies provides a powerful, direct, and elegant method to infer the properties of dark matter structure below 10^8 solar masses, where halos are almost completely devoid of stars and…
Interpreting the ALMA continuum images of protoplanetary disks
Zoom
Kees Dullemond, University of Heidelberg
February 17, 2021
2:00 pm - 3:00 pm
In recent years a large number of high-resolution ALMA images of protoplanetary disks were published. It is striking how cleanly structured these disks appear to be: they feature nearly perfect rings of dust, with every now and then an elliptic blob, and sometimes m=2 “grand…