FLASH Talks: Matthew Murphy (Steward Observatory) & Weizhe Liu (Steward Observatory)
Friday, 14 October 2022 1 p.m. — 2 p.m. MST
NOIRLab Headquarters | 950 North Cherry Ave., Tucson, AZ 85719
Matthew Murphy, Steward Observatory
Where’s the Weather on WASP-43 b? Investigating an Exoplanet's Climate
Though the global atmospheres of hot Jupiters have been extensively studied using phase curve observations, the level of time variability in these data is not well constrained. Upcoming JWST observations will use infrared phase curves to learn about exoplanet atmospheres and climates in unprecedented detail. However, we have little idea how atmospheric variability will affect these phase curves as very few planets have received repeated phase curve observations in the same band. Single phase curves cannot probe how a planet’s weather or climate may change the atmosphere, forcing the community to assume the derived properties of the atmosphere do not change in time. In this talk, I will present the results of an observational investigation of time variability in a planetary phase curve, including three repeated Spitzer/IRAC 4.5-micron phase curves of the hot Jupiter WASP-43b. Our observations place an upper limit on variation in WASP-43b's phase curve over time. By comparing our observations to general circulation models, we glean insight into the complex cloud properties of WASP-43b’s atmosphere, including how much the cloud thickness changes over time. I will discuss what these results mean for WASP-43b, for the interpretation of other past Spitzer phase curves, and how JWST can further our understanding of atmospheric variability.
Weizhe Liu, Steward Observatory
AGN feedback in Dwarf Galaxies
Feedback processes likely play a vital role in the evolution of dwarf galaxies, given their shallow potential well. While stellar processes have long been considered the primary source of feedback, it is still debated whether such stellar feedback is effective enough to reproduce the properties of dwarf galaxies we see today. Given the increasing number of AGN detected in dwarf galaxies, it is crucial to also evaluate the impact of AGN feedback in dwarf galaxies. In this talk, I will present our exploration of AGN feedback in dwarf galaxies, by observing the fast outflows in a sample of nearby dwarf galaxies with AGN through optical integral field spectroscopy and far-ultraviolet spectroscopy. These outflows are faster than those observed in star-forming galaxies with similar star formation rates. They are mainly photoionized by the AGN, and a portion of them may escape the galaxies. They are primarily AGN-driven and may have an impact on their host galaxies similar to those taking place in the more luminous AGN with more massive hosts.