Centers of galaxies are some of the most extreme objects in our universe: hosting starbursts and active supermassive black holes that can launch jets and winds far outside the compact galaxy nucleus. While there are relics of an active past in the center of our own Milky Way, at present it does not exhibit any of this activity. However, the central 300 parsecs of our Galaxy does contain a sizable reservoir of molecular gas that is the fuel for future star formation and black hole accretion. Constraining the physical conditions of this gas is critical for understanding how this reservoir will evolve to influence future activity in the Milky Way’s nucleus. Determining the origin of these conditions is also key to determining whether the same physics that govern gas conditions in this region can help us interpret more distant and active galaxy nuclei. I will present the results of my recent work following the changes in physical properties of this gas as it approaches the black hole; increasing in temperature, density, and turbulence, while largely resisting the onset of star formation. This work provides evidence that the extreme gas conditions in this region are driven largely by infall processes: the journey it takes to reach the central parsecs, rather than the energetic phenomena (supernovae, cosmic rays, massive star winds, UV radiation, and occasional X-ray flaring) encountered at its destination. However, as our Galactic center is relatively inactive, the next challenge is determining the extent to which the understanding gained from a detailed study of this region can be applied to more active systems. I will end by discussing work underway to double my sample size of galaxy nuclei by making parsec-scale observations of the ionized and molecular gas in the center of NGC 253, a nearby galaxy with an order of magnitude more star formation. Comparison of these two galaxy centers will isolate the gas conditions that both govern and are influenced by a nuclear starburst, and allow the definition of local templates for understanding the gas physics in these regions.

Type Ia Supernovae can be divided into three distinct phases. The pre-supernova evolution, the explosion itself and the expansion phase. In this talk, I will first present our findings on the progenitor question (pre-supernova phase), then shortly touch on our understanding of the explosion itself, and finally, present our work on modeling the spectra resulting from the expansion phase. I will close by giving an outlook of the future of spectroscopic modeling and its consequences for our understanding of pre-supernova evolution and explosion physics.

The morphology of a galaxy provides information on the orbits of stars within it. As such, important clues to the formation history of galaxies is revealed by their morphologies, and this information is complimentary, but not identical to, their star formation history and chemical composition as revealed by photometry and spectra.

The Galaxy Zoo project (www.galaxyzoo.org) has provided quantitative visual morphologies for over a million galaxies (including the entire Sloan Digital Sky Surveys, or SDSS Main Galaxy Sample), and has been part of a reinvigoration of interest in the morphologies of galaxies and what they reveal about the evolution of galaxies.
Mapping Nearby Galaxies at Apache Point Observatory (MaNGA, part of SDSS-IV), is well over halfway through its 6 year plan to obtain spatially resolved spectral maps for 10,000 nearby galaxies (all of which have Galaxy Zoo morphologies). MaNGA is now by far the largest sample of resolved spectroscopy in the world, with over 6000 galaxies observed. The most recent data release from MaNGA happened in December 2018.

In this talk I will review these projects, and show results from them which demonstrate why a resolved view of the internal morphology in large samples of galaxies is interesting and how it provides a unique constraint of our understanding of galaxy evolution.