Galaxies are the building blocks of the Universe − astrophysical laboratories which have profoundly informed our knowledge of cosmology and nature. In an unexpected turn of events, studies of stellar motions in the outskirts of galaxies and of the distribution of galaxies in space have shaken the foundations of modern physics and revealed that 96% of the energy composition of the Universe is due to Dark Matter and Dark Energy, a deep and confounding mystery. Black holes − once a bizarre mathematical consequence of Einstein’s relativity theory − are now mainstream astronomy, thanks to studies of the centers of nearby galaxies in which these exotic objects are routinely found. The cycle of creation of chemical elements by a galaxy’s generations of stars provides the basis for our ideas about the origins and prevalence of life itself.

 During its thirteen-plus billion years of life, how did the Universe progress from the homogeneous hot plasma left over after the Big Bang to the apparently empty space punctuated by swirls of stars, gas and cosmic dust we see today? This is the question that galaxy formation theory seeks to answer. Observations of deep and nearby space and cosmological numerical simulations have given us a basic view of how galaxies grow. We now know that galaxies are the luminous knots that tie together the filaments of the cosmic web in which matter is concentrated. However, the same observational and numerical work has raised new critical questions about the formation, structure, and dynamics of galaxies.

Few topics in current physics or astrophysics cut across as broad a swath of fundamental research problems or interest to the general public as much as the study of massive black holes. Massive (more than a million times the mass of the Sun) black holes that lie at the centers of galaxies appear to be ubiquitous, but their origin and growth remain a mystery. The masses of these objects are related to those of the galaxies in which they reside, indicating that they play a fundamental role in the formation and evolution of galaxies.

To study these topics, two main observational approaches are used. The first uses telescopes as “time machines” to peer out to vast distances and directly observe galaxies and black holes across billions of years of cosmic time. The second approach – sometimes called “Galactic Archaelogy” observes the properties of populations of relatively nearby stars that trace the formation history of our Milky Way Galaxy and its nearest neighbors.

Prof. Tim Heckman and his research group study the ways in which the “feedback” provided by the supernovae and stellar winds generated by populations of massive stars, and the galactic winds and radio jets launched by supermassive black holes, have profoundly affected the physical, dynamical, structural, and chemical properties of galaxies across cosmic time.

To that end, they have used data spanning the electromagnetic spectrum from X-rays (Chandra), Ultraviolet (Hubble and FUSE). Optical (Hubble, SDSS, Magellan, Subaru), infrared (Spitzer, JWST), to sub-mm/radio (ALMA, VLA). The main emphasis has been on ultraviolet and optical spectroscopy, especially of medium-sized to very large samples of galaxies and Active Galactic Nuclei. A new program is utilizing optical and near-infrared spectra obtained for several hundred thousand galaxies at intermediate redshifts using the Subaru Prime Focus Spectrograph. The specific goal is to determine how both radio-quiet and radio-loud active galaxies with active nuclei differ from the population of inactive galaxies, to understand how active galaxies are triggered/fueled, and how these processes have evolved over the last 10 billion years.

Prof. Kevin Schalufman is a theoretically-oriented observational astronomer working at the intersection of Galactic astronomy and exoplanets. His most recent work has focused on theoretically identifying and observationally executing tests of planet formation models. Models of planet formation have struggled to explain the diversity of exoplanet architectures observed in the thousands of exoplanet systems discovered by the radial velocity, transit, microlensing, and direct imaging techniques. At the same time, the large number of systems now known permits the identification of weak signals of the planet formation process that were invisible in smaller samples.

Schlaufman is also leading the first all-sky search for the oldest and most chemically primitive stars in the Milky Way, with a special focus on the inner Galaxy. The kinematics and abundances of the elements in these ancient stars are important for studies of both the formation of the Milky Way and the nucleosynthetic yields and explosive deaths of the first generation of stars in the Universe.

Prof. Rosie Wyse has a research focus in the field of galaxy formation and evolution, with emphases on resolved stellar populations and the nature of dark matter.

Prof. Nadia Zakamska and her research group study supermassive black holes in their galactic and cosmological ecosystems across the age of the Universe. Winds launched by processes near supermassive black holes play a key role in galaxy evolution — for example, they are thought to limit the maximal stellar mass of galaxies in the universe — but they have long evaded direct detection. In the last decade, her group has developed multiple novel techniques for probing this multi-phase phenomenon and discovered galaxy-scale quasar-driven winds in a variety of populations using ground-based and space-based telescopes. Some of the most explosive and dramatic galactic winds originate in  the most rapidly accreting supermassive black holes in the universe her group discovered. Furthermore, she is characterizing the population of dual quasars — the precursors to supermassive black hole mergers. Her group has extensive access to James Webb Space Telescope data through multiple accepted and pending programs.

Figure caption: JWST observations reveal clouds of gas in the host galaxy of an extremely powerful quasar in the epoch of peak quasar and galaxy formation activity 10 billion years ago. Detailed investigations of the spectroscopic signatures reveal that quasar-driven galactic winds shock-ionize the gas in the entire host galaxy. (From https://ui.adsabs.harvard.edu/abs/2023ApJ…955…92V/abstract by Vayner, Zakamska et al., from the JWST Early Release Science program ” Q-3D: Imaging Spectroscopy of Quasar Hosts with JWST”, Co-Principal Investigator Nadia Zakamska)