Shardha Jogee

Dr. Jogee’s research addresses central questions on the evolution of galaxies as a function of cosmic epoch, mass, and environment. How do galaxies grow their stars, black holes and dark matter halos across cosmic time and vastly different environments? What is the role played by theoretically predicted growth modes, such as violent mergers of galaxies and slower more ‘quiescent’ modes (e.g., gas accretion along cosmological filaments and secular evolution driven by bars)? How do galaxy clusters — some of the largest bound structures in the Universe — XMM-Newton. Her research group has led a large number of highly cited refereed papers on the structure, evolution and assembly history of galaxies within several international science collaborations, which have conducted some of the largest or deepest galaxy surveys to date with NASA's Hubble Space Telescope, Spitzer Space Telescope, Herschel-SPIRE, Chandra XMM-Newton, GALEX, and many ground-based observatories, including McDonald Observatory.

Some key results from Dr. Jogee's research group include: (a) While earlier work suggested a dearth of barred galaxies at earlier times, they were the first to demonstrate that strong stellar bars are common in massive disk galaxies over the last eight billion years, a period long enough for bars to drive significant secular evolution of galaxies (Jogee et al. 2004); (b) They showed that contrary to common lore, only at most 30% of the cosmic star formation rate density can be assigned to visible major mergers over half of the age of the Universe. They also set the first empirical constraints on the minor merger rate of galaxies over that epoch (Jogee et al. 2009); (c) They found that when the Universe was merely a few billion years old, the majority (>60%) of massive galaxies were disk-dominated and over a third were ultra-compact (Weinzirl, Jogee et al. 2011). This result poses serious challenges to current state-of-the-art theoretical models. (d) Using a sample of massive galaxies from SHELA/HETDEX that is an order of magnitude larger than other studies to date, they robustly measure the high-mass end of the stellar mass function of star-forming galaxies at 1.5 < z <3.5 and stress-test theoretical models of galaxy formation. Predictions from IllustrisTNG 300 hydrodynamical simulations agree within a factor of a few with their results, but three semi-analytic models (SAMS) -- SAG, SAGE,GALACTICUS -- with different AGN feedback moddes underestimate the number density of massive galaxies by up to a factor of 1000. This suggests that the physics of galaxy evolution and/or its sub-grid implementations need to be revisited in the SAMS (Sherman Jogee, Florez et al. 2020a, accepted)

Dr. Jogee's research includes: Galaxy Formation and Evolution; Galaxy Mergers; Star Formation and AGN; Galaxy Evolution in Clusters; Secular Evolution, Bulge Assembly and Barred Galaxies.