0 Submission failed due to error communicating with the submission server. Please retry in a few minutes. If this error persists please contact the help desk at help@stsci.edu Assigned ID: 5337 ----- Attempting Submission 1 (Tue Mar 26 05:05:30 GMT 2024) ----- HST Phase I Proposal 5337 successfully submitted. Receipt: # 5337-1 ----- Attempting Submission 2 (Tue Mar 26 05:13:56 GMT 2024) ----- HST Phase I Proposal 5337 successfully submitted. Receipt: # 5337-2 ----- Attempting Submission 3 (Tue Mar 26 14:48:04 GMT 2024) ----- HST Phase I Proposal 5337 successfully submitted. Receipt: # 5337-3 ----- Attempting Submission 4 (Tue Mar 26 18:52:48 GMT 2024) ----- Metals trace the complex interplay between galaxies and their gaseous surroundings, providing crucial insights into the processes driving galaxy evolution. While the metal content of the diffuse gas has been well-characterized at z<1 using UV spectra and at z>2.4 using optical spectra, a gap remains at 0.9<z<2.2, the peak epoch of star formation and black hole activity known as "Cosmic Noon." This era witnessed the most rapid growth of galaxies and the greatest output of ionizing radiation, metals, and feedback energy, making it a critical benchmark for galaxy evolution models. However, characterizing the diffuse gas at Cosmic Noon requires challenging observations, as the key absorption features fall in both the NUV (HST) and optical (ground-based) bands. Using a metal-unbiased HI-selected sample, we propose the first comprehensive census of metals in the diffuse gas at Cosmic Noon. By combining 30 high-resolution HST/NUV and optical QSO spectra, we will determine the metallicity distribution, estimate the metal budget, and constrain the physical state of gas across a vast range of overdensities for >200-300 absorbers, capturing the diversity of enrichment. State-of-the-art ionization modeling will reveal the multi-phase structure of the gas, providing unequaled tests of galaxy evolution and feedback models. This Legacy program will establish transformative insights into the metal enrichment history of the Universe and the complex interplay between galaxies and their gaseous surroundings during the most active phase of cosmic history. The resulting database will be a treasure trove for future studies, offering a new window into the peak epoch of galaxy assembly. We have carefully assembled a team with diverse expertise in QSO absorption line studies, complex spectral fitting and modeling, Bayesian ionization analysis, and cosmological simulations. Our team members have collectively published dozens of high-impact papers on the IGM and CGM in leading scientific journals, including Science and Nature, over the past decade. PI Lehner and Co-PI Howk have extensive experience leading large-scale studies of the IGM and CGM at both low and high redshifts, as well as investigations of the ISM in nearby galaxies. They have successfully spearheaded efforts to estimate metallicities for hundreds of CGM-like absorbers at z<1 and z>2 through programs such as the COS CGM Compendium and KODIAQ-Z. These projects have resulted in the release of valuable data products to the community through the igmspec database (http://github.com/specdb), CDS/Vizier, and the NASA Keck Observatory Archive (KOA). The proposed research program will be primarily overseen by PI Lehner and Co-PI Howk at the University of Notre Dame. A to-be-determined postdoctoral researcher will most likely lead the majority of the work, with contributions from various team members at different stages of the project. CoI Saloni, a graduate student at Notre Dame, will focus on constraining the cosmic metal budget at z~1-2 as a core component of her doctoral thesis. The Notre Dame team brings unique expertise in MCMC Cloudy ionization modeling and has institutional access to the university's cutting-edge supercomputing facilities, which have been instrumental in the success of the COS CGM Compendium and KODIAQ-Z programs. These resources will be leveraged to enable the complex modeling required for this study. CoI Sameer is a pioneer in developing innovative Bayesian techniques that fully exploit the information content of absorption line profiles to disentangle the properties of multi-phase gas. As part of this program, we will collaborate with CoI Sameer to further refine and test his state-of-the-art cloud-by-cloud analysis code, and he will provide mentorship to the postdoctoral researcher to ensure the optimal application of these powerful tools. CoI Berg is an expert in UV and optical galaxy spectroscopy. She led the BASIC survey that has shown that some of the metal-poor CGM-like absorbers are part of the IGM rather than the direct surrounding of galaxies. She will help CoI O'Meara with the Keck HIRES data reduction and the overall interpretation of the results to put them in a galaxy context. CoI O'Meara, who has led the widely-used KODIAQ data releases featuring over 1,000 science-ready HIRES and ESI spectra, also spearheaded a WFC3/ACS program to study the HI properties of optically-selected systems at z~1-2. His expertise in Keck HIRES data reduction and analysis will be critical for ensuring the timely processing of the remaining HIRES spectra in our sample. He will also use his own discretionary Keck time to complete the observations of the QSOs without yet high-resolution ground-based spectra. CoI Oppenheimer, a leading expert in hydrodynamic simulations of the chemical evolution, IGM, galaxies, and their gas flows, will play a key role in putting our empirical results into the context theoretical models and cosmological simulations. CoI Peroux led the ARA&A review of "The Cosmic Baryon and Metal Cycles" and will help constrain the other possible contributors to the metal budget at Cosmic Noon. Her expertise in the VLT UVES spectra will help expedite their analysis. She is the PI on one of the programs that have observed with VLT/MUSE one of the QSO fields in our sample and will lead a pilot study of the absorber-galaxy connection using this survey and the MUSE observations. CoI Tripp, the PI of the COS Absorption Survey of Baryon Harbors (CASBaH), brings unparalleled expertise in the analysis of COS and STIS data and the physics of highly ionized gas in the IGM and CGM at z<1. His insights will be invaluable for interpreting the origins of the OVI absorbers detected in our survey and placing them in the context of CGM/IGM evolution. Intergalactic Medium and the Circumgalactic Medium Large Scale Structure of the Universe 0 false false true true false false false SUPPORTED