Presenter: Saxon Stockton
Authors: Saxon Stockton, Christian Draper
Faculty Advisor: Christian Draper
Institution: Utah Valley University
Star forming regions and AGN are both strongly associated with emission lines. What will we see in a study of emission and absorption lines in galactic spectra and what can that tell us about star formation rates and AGN as we look at greater distances? We use data from the Sloan Digital Sky Survey (SDSS) to observe changes in the number of emission line galaxies, star forming galaxies, and AGN. Using Data Release 16 of the SDSS, we obtained the spectra for close to 800,000 galaxies out to a redshift of about z = 0.6. This gives a sample size large enough to draw conclusions about the time rate of change of galactic properties. We charted the fraction of emission line galaxies and absorption line galaxies using spectral lines in the visible region, created BPT (Baldwin, Philips, and Tellervich) diagrams to represent the relative changes in star forming galaxies and AGN, and calculated the change in average star formation rate with redshift. As we look farther in redshift, the fraction of emission line galaxies decreases, the fraction of absorption line galaxies increases, the average star formation rate increases, and the ratio of star forming galaxies to AGN decreases. We will be using this data to develop new methods to distinguish galaxies that exhibit different kinds of star formation and vetting current theories of galactic evolution.