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This content will become publicly available on September 30, 2026

Title: Impacts of the Metagalactic Ultraviolet Background on Circumgalactic Medium Absorption Systems
Abstract Among the many different pieces of physics that go into simulations of the circumgalactic medium (CGM), the metagalactic ultraviolet background (UVB) plays a significant role in determining the ionization state of different metal species. However, the UVB is uncertain, with multiple models having been developed by various research groups over the past several decades. In this work, we examine how different UVB models influence the ionic column densities of CGM absorbers. We use these UVB models to infer ion number densities in the Figuring Out Gas and Galaxies In Enzo (FOGGIE) galaxy simulations atz= 2.5 and use the Synthetic Absorption Line Surveyor Application package to identify absorbers. Absorbers are then matched across UVB models based on their line-of-sight position so that their column densities can be compared. From our analysis, we find that changing the UVB model produces significant changes in ionization, specifically at lower gas densities and higher temperatures where photoionization dominates over collisional ionization. We also find that the scatter of column density differences between models tends to increase with increasing ionization energy, with the exception of Hi, which has the highest scatter of all species we examined.  more » « less
Award ID(s):
1908109
PAR ID:
10649354
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
American Astronomical Society
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
991
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
221
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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