Abstract

Contributed Talk - Splinter LIM

Friday, 11 September 2026, 15:00   (MW-2050)

Bridging Scales: Multiphase ISM Modeling for Line Intensity Mapping

Karolina Garcia
NCSA, University of Illinois

Line intensity mapping forecasts to date have relied predominantly on empirical scaling relations or zoom-in simulations, leaving a gap in cosmological-volume, multi-line predictions grounded in first-principles ISM physics. We address this gap with SLICK (the Scalable Line Intensity Computation Kit), a post-processing framework that combines molecular, PDR, and ionized-phase radiative transfer with per-cloud aggregation, applied to state-of-the-art cosmological hydrodynamic simulations. I will introduce a new implementation within SLICK that improves cloud-scale modeling across diverse ISM environments, and discuss the implications for interpreting line observations. I will then describe the strategies that allow us to scale SLICK from its original 25 Mpc/h simulations to volumes as large as TNG300, enabling cosmological forecasts that retain detailed ISM physics. Using this framework, I will present auto- and cross-power spectra for [CII] 158 μm and the CO(1–0) through CO(7–6) ladder across cosmic time, highlighting key differences between first-principles predictions and traditional scaling relations. Finally, I will discuss new applications now within reach, including predictions for the evolution of the ISM, and the impact of AGN on molecular and ionized-phase line emission.