Fixed issue with attachment (double abstract page) -491723719 Assigned ID: 4098 ----- Attempting Submission 1 (Tue May 23 13:57:40 GMT 2023) ----- HST Phase I Proposal 4098 successfully submitted. Receipt: # 4098-1 ----- Attempting Submission 2 (Wed May 24 14:34:42 GMT 2023) ----- HST Phase I Proposal 4098 successfully submitted. Receipt: # 4098-2 ----- Attempting Submission 3 (Wed May 24 22:38:28 GMT 2023) ----- A fundamental prediction of cosmological simulations is that dark matter and baryons condense into multi-Mpc filamentary structures, forming the Cosmic Web. At low redshift the Cosmic Web is traced by the distribution of galaxies. However, the photoionized gas outside galaxies, observed as the Lyman-alpha Forest, contains three times as many baryons, and is more widespread. We propose a direct comparison of the locations and properties of Lyman-alpha absorbers in relation to local Cosmic Web filaments. We will do this by (a) creating a catalogue of ~130,000 galaxies in the local universe (cz<10,000 km/s; mostly complete down to ~0.2 L*); (b) creating a catalogue of ~1000 galaxy groups; (c) delineating ~50 local Cosmic Web filaments; (d) identifying all ~150,000 absorption lines in ~700 AGN spectra (in order to remove lines from other intergalactic systems that can seem to be low-redshift Lyman-alpha); (e) using the CAMELS suite of simulations, providing models with a range of AGN feedback strength and various models for the Extragalactic UltraViolet BackGround. Combining these datasets and models, we can compare the detection fraction, column density, and linewidth as function of filament impact parameter. This allows us to (a) for the first time use data to measure the transverse extent and kinematic structure of gas in filaments, as set by the dark matter potential, and (b) determine the origin of the ionization of the Lyman-alpha Forest - comparing our data to the CAMELS simulations allows us to resolve the degeneracy between ionization caused by AGN feedback vs by UV radiation. The PI Dr Bart Wakker has an extensive background in studies of the interstellar and intergalactic medium, having published over 100 papers on these subjects, using data from ground-based radio and optical telescopes, as well as many of the UV space instruments (IUE, FUSE, FOS, GHRS, STIS, COS), being PI on 11 HST observing and 5 HST archival projects, as well as Co-PI or Admin-PI on 8 others. Dr Benjamin Oppenheimer over 100 publications on the analysis of simulations, including studies of metal ions in the IGM, the effects of different processes on the physical properties of the CGM, and, of special relevance to the current proposal, the extraction of data on individual galaxies from the simulation. He is also a collaborator on the CAMEL project, and developed the method to break the EUVB/AGN feedback degeneracy. He has access to the Flatirons Binder system to publicly release simulation data. Dr. Francisco Villaescusa-Navarro is one of the PIs of the CAMELS project, which contains the largest suite of cosmological hydrodynamic simulations to date. He is an expert on cosmology and in his research he combines state-of-the-art deep-learning techniques with numerical simulations to develop accurate theoretical models that allow the extraction of the maximum information from astronomical surveys. Dr David French has studied Lyman alpha absorption lines associated with nearby galaxies. He is also the creator of the new galaxy catalogue based on using all the available data in NED. Dr. Benjamin Rosenwasser is currently a postdoc at Toledo University, having obtained his Ph.D.\ at UW Madison in 2022. He is working on a number of projects analyzing absorption line data, focusing especially on photoionization models and finding galaxies near the QSOs. Dr. Nicolas Lehner is an expert in the reduction, analysis, and interpretation of HST/COS spectra of interstellar, intergalactic, and circumgalactic gas in the Universe at all redshifts. He is the PI of several HST GO and AR programs, including one Large and two Legacy programs that all led to numerous refereed publications and several NASA press releases. Intergalactic Medium and the Circumgalactic Medium 0 Legacy false false true false false false SUPPORTED