Dr Thomas Williams: Publications

A 260 pc resolution ALMA map of HCN(1–0) in the galaxy NGC 4321

Astronomy & Astrophysics EDP Sciences 691 (2024) a121

Authors:

Lukas Neumann, Frank Bigiel, Ashley T Barnes, Molly J Gallagher, Adam Leroy, Antonio Usero, Erik Rosolowsky, Ivana Bešlić, Médéric Boquien, Yixian Cao, Mélanie Chevance, Dario Colombo, Daniel A Dale, Cosima Eibensteiner, Kathryn Grasha, Jonathan D Henshaw, María J Jiménez-Donaire, Sharon Meidt, Shyam H Menon, Eric J Murphy, Hsi-An Pan, Miguel Querejeta, Toshiki Saito, Eva Schinnerer, Sophia K Stuber, Yu-Hsuan Teng, Thomas G Williams

Dynamical resonances in PHANGS galaxies

Astronomy & Astrophysics EDP Sciences 691 (2024) a351

Authors:

Marina Ruiz-García, Miguel Querejeta, Santiago García-Burillo, Eric Emsellem, Sharon E Meidt, Mattia C Sormani, Eva Schinnerer, Thomas G Williams, Zein Bazzi, Dario Colombo, Damian R Gleis, Oleg Y Gnedin, Ralf S Klessen, Adam K Leroy, Patricia Sánchez-Blázquez, Sophia K Stuber

Metallicity calibrations based on auroral lines from PHANGS–MUSE data

Astronomy & Astrophysics EDP Sciences 691 (2024) a173

Authors:

Matilde Brazzini, Francesco Belfiore, Michele Ginolfi, Brent Groves, Kathryn Kreckel, Ryan J Rickards Vaught, Dalya Baron, Frank Bigiel, Guillermo A Blanc, Daniel A Dale, Kathryn Grasha, Eric Habjan, Ralf S Klessen, Jose Eduardo Méndez-Delgado, Karin Sandstrom, Thomas G Williams

PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: Physical drivers of the molecular gas fraction, Rmol

Astronomy & Astrophysics EDP Sciences 691 (2024) a163

Authors:

Cosima Eibensteiner, Jiayi Sun, Frank Bigiel, Adam K Leroy, Eva Schinnerer, Erik Rosolowsky, Sushma Kurapati, DJ Pisano, WJG de Blok, Ashley T Barnes, Mallory Thorp, Dario Colombo, Eric W Koch, I-Da Chiang, Eve C Ostriker, Eric J Murphy, Nikki Zabel, Sebstian Laudage, Filippo M Maccagni, Julia Healy, Srikrishna Sekhar, Dyas Utomo, Jakob den Brok, Yixian Cao, Mélanie Chevance, Daniel A Dale, Christopher M Faesi, Simon CO Glover, Hao He, Sarah Jeffreson, María J Jiménez-Donaire, Ralf Klessen, Justus Neumann, Hsi-An Pan, Debosmita Pathak, Miguel Querejeta, Yu-Hsuan Teng, Antonio Usero, Thomas G Williams

The Local Group L -band Survey: The First Measurements of Localized Cold Neutral Medium Properties in the Low-metallicity Dwarf Galaxy NGC 6822

The Astrophysical Journal American Astronomical Society 974:1 (2024) 93

Authors:

Nickolas M Pingel, Hongxing Chen, Snežana Stanimirović, Eric W Koch, Adam K Leroy, Erik Rosolowsky, Chang-Goo Kim, Julianne J Dalcanton, Fabian Walter, Michael P Busch, Ryan Chown, Jennifer Donovan Meyer, Cosima Eibensteiner, Deidre A Hunter, Sumit K Sarbadhicary, Elizabeth Tarantino, Vicente Villanueva, Thomas G Williams

Abstract:

Measuring the properties of the cold neutral medium (CNM) in low-metallicity galaxies provides insights into heating and cooling mechanisms in early Universe-like environments. We report detections of two localized atomic neutral hydrogen (H i) absorption features in NGC 6822, a low-metallicity (0.2 Z ⊙) dwarf galaxy in the Local Group. These are the first unambiguous CNM detections in a low-metallicity dwarf galaxy outside the Magellanic Clouds. The Local Group L-band Survey (LGLBS) enabled these detections, due to its high spatial (15 pc for H i emission) and spectral (0.4 km s−1) resolution. We introduce LGLBS and describe a custom pipeline for searching for H i absorption at high angular resolution and extracting associated H i emission. A detailed Gaussian decomposition and radiative transfer analysis of the NGC 6822 detections reveals five CNM components, with key properties: a mean spin temperature of 32 ± 6 K, a mean CNM column density of 3.1 × 1020 cm−2, and CNM mass fractions of 0.33 and 0.12 for the two sightlines. Stacking nondetections does not reveal low-level signals below our median optical depth sensitivity of 0.05. One detection intercepts a star-forming region, with the H i absorption profile encompassing the CO (2−1) emission, indicating coincident molecular gas and a depression in high-resolution H i emission. We also analyze a nearby sightline with deep, narrow H i self-absorption dips, where the background warm neutral medium is attenuated by intervening CNM. The association of CNM, CO, and Hα emissions suggests a close link between the colder, denser H i phase and star formation in NGC 6822.

91̽��