We generally think that the universe was built up to the current state that we see it today --- groups and clusters of galaxies, where the galaxies represent denser regions gas and stars --- through a gradual process of "hierarchical structure formation", where seeds of galaxies started out small, gradually merged with more and more galaxies, and got bigger. Throughout this process, super-massive black holes formed and gradually grew (again, through merger with other supermassive black holes during galaxy mergers) in the centers of galaxies. Sometimes these super-massive black holes can have gas around them, turning them into an "active galactic nucleus;" this refers to a black hole that has highly luminous material around it and shooting out from it. During a galaxy merger, gas and stars are kicked around and exchanged between the two galaxies until the merger settles to form a relaxed, combined galaxy. These mergers and interactions between galactic gas and active galactic nuclei appear to have had a big role in shaping the dynamics, contents, and structures of galaxies. Our group at WVU studies gas in galaxies and merging systems, primarily in the form of Hydrogen. We also have members that study emissions from active galactic nuclei and binary supermassive black holes to understand the role they play in galactic formation and evolution.
Balser, Dana S., Wenger, Trey V., Anderson, L. D., Armentrout, W. P., Bania, T. M., Dawson, J. R., and Dickey, John M., 2021, Discovery of a New Population of Galactic H II Regions with Ionized Gas Velocity Gradients, The Astrophysical Journal, 921.
Witt, Caitlin A., Charisi, Maria, Taylor, Stephen R., and Burke-Spolaor, Sarah, 2021, Quasars with Periodic Variability: Capabilities and Limitations of Bayesian Searches for Supermassive Black Hole Binaries in Time-Domain Surveys, arXiv e-prints.
Bhandari, Shivani, Heintz, Kasper E., Aggarwal, Kshitij, Marnoch, Lachlan, Day, Cherie K., Sydnor, Jessica, Burke-Spolaor, Sarah, Law, Casey J., Prochaska, J. Xavier, Tejos, Nicolas, Bannister, Keith W., Butler, Bryan J., Deller, Adam T., Ekers, R. D., Flynn, Chris, Fong, Wen-fai, James, Clancy W., Lazio, T. Joseph W., Luo, Rui, Mahony, Elizabeth K., Ryder, Stuart D., Sadler, Elaine M., Shannon, Ryan M., Han, JinLin, Lee, Kejia, and Zhang, Bing, 2021, Characterizing the FRB host galaxy population and its connection to transients in the local and extragalactic Universe, arXiv e-prints.
Dokara, R., Brunthaler, A., Menten, K. M., Dzib, S. A., Reich, W., Cotton, W. D., Anderson, L. D., Chen, C. -H. R., Gong, Y., Medina, S. -N. X., Ortiz-León, G. N., Rugel, M., Urquhart, J. S., Wyrowski, F., Yang, A. Y., Beuther, H., Billington, S. J., Csengeri, T., Carrasco-González, C., and Roy, N., 2021, A global view on star formation: The GLOSTAR Galactic plane survey. II. Supernova remnants in the first quadrant of the Milky Way, Astronomy and Astrophysics, 651.
Langer, W. D., Pineda, J. L., Goldsmith, P. F., Chambers, E. T., Riquelme, D., Anderson, L. D., Luisi, M., Justen, M., and Buchbender, C., 2021, The dense warm ionized medium in the inner Galaxy, Astronomy and Astrophysics, 651.