Beyond the dust: JWST reveals extinction and ice content in local (U)LIRGs
Abstract
We investigate the spatially resolved extinction and ice column densities in four nearby interacting (U)LIRGs using JWST/NIRSpec integral field spectroscopy (R∼2700; 0.97--5.14 μm). This wide range encompasses numerous (>25) H recombination and H2 ro-vibrational emission lines, as well as the prominent H2O (∼3.02 μm) and CO2 (∼4.26 μm) ice absorption features. We develop three methods to derive phase-specific extinction for ionized (AKHII) and hot molecular gas (AKH2), and H2O and CO2 ice column densities (NH2O and NCO2), exploiting H and H2 emission lines and ice absorption features. Nuclear regions (0.2" radius) exhibit higher extinction and ice column densities than extended regions, with median AKHII and AKH2 of 1.25 and 0.75 in the nuclei, compared to 0.61 and 0.50 in the extended regions. The ionized gas is more extincted than the hot molecular gas, with AKHII≈1.5 AKH2, while H2O ice column densities are comparable between phases. In some nuclei, continuum-derived NH2O reaches ∼1018.81 cm−2, likely due to compact obscured components. These results suggest that ionized gas originates in more deeply embedded regions, whereas water ice envelopes both gas phases, with additional ice-rich material around the most obscured nuclei. The median NCO2/NH2O abundance ratio is ∼0.10, a factor of 2--3 below typical Galactic values.
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BibTeX
@misc{speranza2026beyond,
title = {{Beyond the dust: JWST reveals extinction and ice content in local (U)LIRGs}},
author = {G. Speranza and M. Pereira-Santaella and I. García-Bernete and E. González-Alfonso and S. Arribas and I. Lamperti and M. Perna and A. Alonso-Herrero and L. Hermosa Muñoz and D. Rigopoulou and N. Thatte},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24069},
eprint = {2610.24069},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24069},
}
RIS
TY - UNPB
TI - Beyond the dust: JWST reveals extinction and ice content in local (U)LIRGs
AU - G. Speranza
AU - M. Pereira-Santaella
AU - I. García-Bernete
AU - E. González-Alfonso
AU - S. Arribas
AU - I. Lamperti
AU - M. Perna
AU - A. Alonso-Herrero
AU - L. Hermosa Muñoz
AU - D. Rigopoulou
AU - N. Thatte
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.24069
UR - https://arxiv.org/abs/2610.24069
AB - We investigate the spatially resolved extinction and ice column densities in four nearby interacting (U)LIRGs using JWST/NIRSpec integral field spectroscopy (R∼2700; 0.97--5.14 μm). This wide range encompasses numerous (>25) H recombination and H_2 ro-vibrational emission lines, as well as the prominent H_2O (∼3.02 μm) and CO_2 (∼4.26 μm) ice absorption features. We develop three methods to derive phase-specific extinction for ionized (A_K^HII) and hot molecular gas (A_K^H_2), and H_2O and CO_2 ice column densities (N_H_2O and N_CO_2), exploiting H and H_2 emission lines and ice absorption features. Nuclear regions (0.2" radius) exhibit higher extinction and ice column densities than extended regions, with median A_K^HII and A_K^H_2 of 1.25 and 0.75 in the nuclei, compared to 0.61 and 0.50 in the extended regions. The ionized gas is more extincted than the hot molecular gas, with A_K^HII≈1.5 A_K^H_2, while H_2O ice column densities are comparable between phases. In some nuclei, continuum-derived N_H_2O reaches ∼10^18.81 cm^−2, likely due to compact obscured components. These results suggest that ionized gas originates in more deeply embedded regions, whereas water ice envelopes both gas phases, with additional ice-rich material around the most obscured nuclei. The median N_CO_2/N_H_2O abundance ratio is ∼0.10, a factor of 2--3 below typical Galactic values.
ER -