0 Assigned ID: 862 ----- Attempting Submission 1 (Fri Apr 07 20:47:45 GMT 2017) ----- How do baryons cycle in and out of galaxies, and how does the baryon cycle drive galaxy evolution? Stellar feedback processes and accretion from the intergalactic medium give rise to extended metal-enriched gaseous structures surrounding galaxies: the circumgalactic medium (CGM). Arguably, the CGM is the key component of the baryonic cycle that regulates galaxy evolution and is therefore the most critical component of the cycle to pin down. COS was developed primarily for this purpose and 100s of HST orbits have been dedicated to CGM observations. However, high resolution hydrodynamic simulations show that standard observational analysis methods of absorption lines are fraught with assumptions that are no longer justified. We aim to address this, thereby increasing the intrinsic sceintific value of archived HST/COS spectra. We propose to enhance the legacy of HST/COS by analyzing Eulerian hydrodynamic cosmological simulations incorporating physics based baryon cycle processes. We will (1) undertake absorption line analysis of simulated galaxies that accurately emulates observational data and analysis methods and compare the results to published COS programs, (2) compare the 3D simulations to the absorption line results, (3) assess commonly applied absorption line methods in order to provide insights into the interpretation of HST/COS data, and (4) develop new absorption line analysis methods that better reflect the CGM gas spatial and kinematic distributions. Our goal is to provide deeper insights into current observational techniques for improving our observational knowledge of the baryon cycle from COS spectra. Galaxies and the IGM 0 Regular false true true SUPPORTED