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Past Events

Event Date Summary
Astronomy Colloquium: Johnny Greco Thu. May 9th, 2019
3:00 pm-4:00 pm

Low Surface Brightness Galaxies Redux

Johnny Greco (Ohio State)
Low surface brightness (LSB) galaxies provide a unique testing ground for theoretical predictions of galaxy and star formation, stellar feedback processes, and the distribution and nature of dark matter. However, their defining characteristic—central surface brightnesses that are fainter than the night sky—makes them difficult to detect and study, leading to their underrepresentation in previous optical surveys and biasing our view of the full galaxy population. I will present results from our ongoing search for LSB galaxies with the Hyper Suprime-Cam Survey, a new generation imaging survey using the 8.2-meter Subaru Telescope on Mauna Kea.

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Astronomy Colloquium: Zac Berkowicz Thu. April 18th, 2019
3:00 pm-4:00 pm

Remote Sensing: from galaxies to deep ocean ridges
Zac Berkowitz (Woods Hole Oceanographic Institute)

Often it is too costly, or physically impossible, to take measurements in-situ and one must instead rely on other means to gather the desired information remotely. Such remote sensing techniques are used broadly in Astronomy, after all the telescope is one of the most fundamental remote sensing instruments, but the problem is universal and a host of instruments and practices have been developed and applied to broad ranges of experimental observations. I will describe in some detail the unique challenges and similarities of three remote sensing programs I have participated in: Using FM radio as a radar to probe Ionospheric plasma irregularities (e.g.

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Astronomy Colloquium: Chelsea Spengler Mon. January 14th, 2019
2:15 pm-3:15 pm

Nuclear Star Clusters in Virgo: Scaling relations, stellar populations, and the role of environment
Chelsea Spengler (Pontificia Universidad Católica de Chile)

It is readily accepted that many galaxies are inhabited by dense, compact objects deep in their centers, manifesting as supermassive black holes and/or nuclear star clusters (NSCs). Their widespread presence and apparent similar scaling relations with properties of their hosts implies that these black holes and NSCs are two related flavours of central massive object that play essential roles in their hosts’ evolution. How do these NSCs form? How do they relate to black holes and their host galaxies?

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Astronomy Colloquium: Kelsey Johnson Thu. December 13th, 2018
3:00 pm-4:00 pm

How were the most ancient objects in the universe formed?
Kelsey Johnson (University of Virginia / NRAO)

Ancient remnants from the early universe surround our galaxy.  These relics, known as “globular clusters” have the potential to provide insight into the physical conditions that prevailed during an epoch that cannot be directly observed.  We now know that globular clusters can form during extreme episodes of star formation in the relatively nearby universe, but the actual physical conditions that give rise to globular clusters have vexed both observers and theorists for decades.   I will overview the discovery and follow-up of  pre-natal globular clusters ALMA,

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Astronomy Colloquium: Rachel Bezanson Thu. November 15th, 2018
3:00 pm-4:00 pm

The Surprisingly Complex Lives of Massive Galaxies
Rachel Bezanson (UPittsburgh)

Massive galaxies reside in the densest and most evolved regions of the Universe, yet we are only beginning to understand their formation history. Once thought to be relics of a much earlier epoch, the most massive local galaxies are red and dead ellipticals, with little ongoing star formation or organized rotation. In the last decade, observations of their assumed progenitors have demonstrated that the evolutionary histories of massive galaxies have been far from static. Instead, billions of years ago, massive galaxies were morphologically different: compact,

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Astronomy Colloquium: Matt Walker Thu. October 25th, 2018
3:00 pm-4:00 pm

Dark Matter in the Smallest Galaxies
Matt Walker (Carnegie Mellon U)

The Milky Way’s dwarf-galactic satellites include the nearest, smallest, darkest and most chemically primitive galaxies known.  These properties make them sensitive probes of dark matter physics, if only we can learn their dynamical masses.  I will summarize recent results regarding the amount and spatial distribution of dark matter within these systems.  I will discuss implications for two lines of inquiry regarding the nature of dark matter: 1) tests of the standard ‘cold dark matter’ paradigm, and 2) searches for dark matter annihilation/decay signals.

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Astronomy Colloquium: Guillaume Thomas (Herzberg/NRC) Thu. October 11th, 2018
3:00 pm-4:00 pm

CFIS-u : a blue sky for the stellar halo
Guillaume Thomas (Herzberg/NRC)

The stellar halo of the Milky Way is an incredible source of information, whether about the formation and the evolution of our Galaxy or to trace the Galactic potential in three dimensions. Indeed, the stellar halo is largely populated by the old metal-poor stars originally lying in satellites galaxies or globular clusters that have being disrupted by tidal effects. The spatial distribution of the different populations of the stellar halo allow us to reconstruct the formation history of the Milky Way,

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Astronomy Colloquium: Mousumi Das Thu. September 20th, 2018
3:00 pm-4:00 pm

Dark Matter in Galaxy Disks and its Implications for Star Formation in the Outer Regions of Galaxies
Mousumi Das (Indian Institute of Astrophysics)

It is well known that galaxy disks are embedded in massive dark matter halos which make their disks more stable against global disk instabilities. However, there may also be significant amounts of dark matter in galaxy disks as well, as indicated in the early studies of the vertical motion stars in our Galaxy. The disk dark matter is especially important for late type spiral galaxies that have extended neutral hydrogen (HI) gas disks,

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Astronomy Colloquium: Sally Oey Tue. September 11th, 2018
3:00 pm-4:00 pm

Toward Understanding Feedback from Local Lyman Continuum-Emitting Galaxies
Sally Oey (University of Michigan)

The fate of Lyman continuum (LyC) radiation from massive stars is a problem of fundamental importance to both galaxy evolution and cosmic evolution. What conditions and feedback processes allow these ionizing photons to escape their host galaxies? Only small samples of local LyC emitters are currently known, including a few nearby starburst galaxies and extreme Green Pea galaxies. They generally appear to be very young, intense, and compact starbursts triggered by galaxy mergers, and forming super star clusters. I will present what we’re starting to learn about the mechanical and radiative feedback in these systems,

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Research Talk: Sandeep Kumar Kataria Mon. July 30th, 2018
4:00 pm-5:00 pm

The Impact of Bulges on Bar Formation and Bar Pattern Speed in Disk Galaxies
Sandeep Kumar Kataria (Indian Institute of Astrophysics, Bangalore)

We use N-body simulations of bar formation in an isolated galaxy to study the effect of bulge mass and bulge concentration on bar formation and bar pattern speed. Two sets of models are generated, one that has a dense bulge and high surface density disk and a second model that has a less concentrated bulge and a lighter disk. Our simulations of both the models show that there is an upper cut-off in bulge to disk mass ratio Mb/Md above which bars cannot form;

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