- Cosmology and extragalactic astronomy
Once we have produced science-ready spectra from the raw data, our first principle goal is to derive physical properties from the spectra. I have assembled a team of world-leading specialists in the analysis of galaxy spectra. Our combined expertise will allow us to take full advantage of the unprecedented LEGA-C dataset. The spectra contain information about three physical aspects of the galaxies: 1) kinematics; 2) stellar populations; 3) ionized gas properties. Kinematics: The motions of stars and gas in the potential of the galaxy are traced by the Doppler broadening of stellar absorption lines and nebular emission lines. This velocity dispersion is a key characteristic that plays a central role in tracing the growth of galaxies as it encodes vital information about the structure and mass of the galaxies. Stellar populations: The age and chemical composition of the stellar population is encoded in absorption features arising in stellar atmospheres. In particular, Balmer absorption line strengths are a key age indicator. Absorption features from heavier elements trace the abundance ratios, key in reconstructing the star formation history. Ionized gas properties: Balmer emission lines provide precise measurements of the star formation rate, and nebular emission lines trace the chemical composition of the star-forming material. Both are crucial for understanding the ongoing growth of galaxies through the process of star formation. Combining this spectroscopically derived information with extensive photometric datasets from a multitude of facilities will provide new estimates for stellar masses, star formation rates and extinction parameters with unprecedented accuracy. We will also obtain dynamical masses, linking the measured velocity dispersion with galaxy structural parameters (Sersic index, half-light radius, projected axis ratio, position angle) measured from available HST imaging.