Astronomy Research Talk
Speaker 1: Vedant Chandra
Title: To 100 kpc and Beyond: Tales from the Milky Way's Distant Horizon
Abstract:
The outer halo of the Milky Way (MW) contains a fossil record of our galaxy's assembly history, and traces the global gravitational field of the MW. We have been conducting an all-sky spectroscopic survey of the Galactic outskirts. I will summarize our recent results, from finding coherent structures imprinted by the MW's last major merger, to discovering the long-sought stellar counterpart to the Magellanic Stream. I will then focus on the global dynamical response of the MW to the infalling Large Magellanic Cloud (LMC). Using distant halo stars as a reference, we measure that the inner MW is lurching sharply towards the LMC, suggesting a massive LMC dark matter halo that is > 15% the mass of the MW's.
Speaker 2: Sawant Prasad
Title: Linking Gas, Dust, and Star Formation: Probing the baryonic cycle in early galaxies with the ALPINE survey
Abstract:
The ALMA Large Program ALPINE benefits from the panchromatic observations of z ~ 5 star-forming galaxies providing fundamental information about their gas/dust content, their morphological and kinematical properties and mechanisms influencing their baryonic cycle highlighted in the studies in recent years.
In this work, we make use of chemical evolution models to probe the evolution of gas and dust content within these star-forming galaxies. We attempt to reproduce the observed gas and dust content of these galaxies by considering different dust production mechanisms, including Type I/II supernovae, asymptotic giant branch stars, and dust growth within the interstellar medium.
Our models successfully reproduce the gas and dust content in most of these primordial galaxies, indicating dust production primarily through SNII and gas/dust removal via galactic outflows and moderate inflow of primordial gas. However, a small number of galaxies show a rapid dust build-up in short timescales (~ 20 - 100 Myr). This fast dust production is partially explained by adopting a top-heavy initial mass function, thus favoring the formation of more massive stars and a more rapid dust production. Our results, combined with observations from JWST, will further help us to reconcile observations with models and gain deeper insights into different channels of dust production in the early Universe.