Multiwavelength Observations of Dwarf-Dwarf Mergers: Fueling Hierarchical Assembly

Event date
Speaker
Sabrina Stierwalt
Affiliation
Occidental College
Location
Online
Event Type

Both cosmological simulations and observations of the ultraviolet luminosity function suggest dwarf galaxies are the dominant population at high redshifts and that the galaxy merger rate per unit volume is dominated by low mass galaxies. However, dwarf-dwarf interactions have not yet been subject to systematic study, even in the nearby universe. I will report on our efforts to do just that: TiNy Titans is the first systematic study of a sample of isolated interacting dwarf galaxies and the mechanisms governing their star formation.

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Interstellar Hydrides and What They Tell Us

Event date
Speaker
David Neufeld
Affiliation
JHU
Location
Online
Event Type

Interstellar hydrides - that is, molecules containing a single heavy element atom with one or more hydrogen atoms - were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially atomic gas along with molecular hydrogen and its associated ions.

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Simulating Protoplanetary Disk Ices

Event date
Speaker
Nicholas Ballering
Affiliation
UVA
Location
Online
Event Type

Ices play a crucial role in planet formation and the delivery of volatiles to terrestrial planets, yet direct observations of ices in protoplanetary disks have, to date, been limited. Upcoming observational facilities—including JWST, large ground-based telescopes, SPHEREx, new SOFIA instrumentation, and future far-IR missions—will greatly enhance our view of disk ices by measuring their infrared spectral features. I will present a suite of models designed to complement these upcoming observations.

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Surprises from the Expansion of the Universe

Event date
Speaker
Adam Riess
Affiliation
JHU/STScI
Location
Online
Event Type

The Hubble constant remains one of the most important parameters in the cosmological model, setting the size and age scales of the Universe. Present uncertainties in the cosmological model including the nature of dark energy, the properties of neutrinos and the scale of departures from flat geometry can be constrained by measurements of the Hubble constant made to higher precision than was possible with the first generations of Hubble Telescope instruments.

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Simulating vs. Observing Molecular Clouds: What’s Hidden in The Dark?

Event date
Speaker
Steffie Walch-Gassner
Affiliation
U. Cologne
Location
Online
Event Type

Molecular gas is mostly traced by CO line emission. In particular 12CO(J=1-0) is bright and hence it is commonly used to estimate the molecular gas content of cold clouds. Yet, the CO molecule does not trace all molecular gas. It is more easily dissociated than molecular hydrogen and hence needs visual extinctions higher than 3 mag in order to survive. This leads to the existence of CO-dark molecular hydrogen. Once formed, the CO line becomes quickly optically thick. As a result, only a narrow range of column densities can actually be traced well with 12CO.

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The Magnetic Milky Way in Three Dimensions

Event date
-
Speaker
Susan Clark
Affiliation
Stanford U
Location
Online
Event Type

Magnetic fields thread our Milky Way Galaxy, influencing interstellar physics from cosmic ray propagation to star formation. The magnetic interstellar medium is also a formidable foreground for experimental cosmology, particularly for the quest to find signatures of inflation in the polarized cosmic microwave background (CMB). Despite its importance across scientific realms, the structure of the Galactic magnetic field is not well understood.

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Carbon Stars and Dust

Event date
Speaker
Gregory Sloan
Affiliation
STScI
Location
Online
Event Type

Carbon stars dominate the observed production of dust in nearby metal-poor dwarf galaxies. To understand the chemical enrichment history and dust budgets of those galaxies, we must understandn the carbon stars. Infrared spectra from the Spitzer Space Telescope have shown that carbon stars form and dredge up enough of their own carbon to produce significant amounts of dust, no matter their initial metallicity.

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Uncovering the IR Bright Portions of Sgr A with SOFIA/FORCAST

Event date
Speaker
Matthew Hankins
Affiliation
Arkansas Tech
Location
Online
Event Type

As part of a cycle 7 SOFIA Legacy Program, we obtained imaging observations of some of the brightest infrared portions of the inner ~200 pc of our Galaxy at 25 and 37 microns. These data have provided new insights into some of the most complex regions within our galaxy, and specifically this talk will focus on the Sgr A region where the observations allow us to examine possible signs of nuclear activity.

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The Far Ultraviolet diffuse background

Event date
Speaker
Shrinivas Kulkani
Affiliation
Caltech
Location
Online
Event Type

Historically, the IGM motivated the search for FUV background which in turn led to a number of experiments and missions. Decades later the focus shifted to FUV as the primary heating and ionizing agent of the atomic phases (warm and cold neutral medium). The current view is that the diffuse FUV emission, at high latitudes, has three components: FUV light from hot stars in the Galactic plane reflected by dust grains (diffuse galactic light or DGL), FUV from other galaxies (extra-galactic background light, EBL) and a component of unknown origin.

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