The Hierarchical Dynamical State of Molecular Gas from 3 to 300 pc in NGC 253

Fuente: arXiv
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Main Authors: Oakes, Elias K., Faesi, Christopher M., Rosolowsky, Erik, Leroy, Adam K., Glover, Simon C. O., Hughes, Annie, Meidt, Sharon E., Schinnerer, Eva, Sun, Jiayi, Amiri, Amirnezam, Barnes, Ashley T., Bazzi, Zein, Bešlić, Ivana, Blanc, Guillermo A., Burton, Charlie, Chown, Ryan, Congiu, Enrico, Dale, Daniel A., Dlamini, Simthembile, He, Hao, Koch, Eric W., Liang, Fu-Heng, Pety, Jérôme, Querejeta, Miguel, Sarbadhicary, Sumit K., Stuber, Sophia K., Usero, Antonio, Williams, Thomas G.
Format: Preprint
Published: 2025
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author Oakes, Elias K.
Faesi, Christopher M.
Rosolowsky, Erik
Leroy, Adam K.
Glover, Simon C. O.
Hughes, Annie
Meidt, Sharon E.
Schinnerer, Eva
Sun, Jiayi
Amiri, Amirnezam
Barnes, Ashley T.
Bazzi, Zein
Bešlić, Ivana
Blanc, Guillermo A.
Burton, Charlie
Chown, Ryan
Congiu, Enrico
Dale, Daniel A.
Dlamini, Simthembile
He, Hao
Koch, Eric W.
Liang, Fu-Heng
Pety, Jérôme
Querejeta, Miguel
Sarbadhicary, Sumit K.
Stuber, Sophia K.
Usero, Antonio
Williams, Thomas G.
author_facet Oakes, Elias K.
Faesi, Christopher M.
Rosolowsky, Erik
Leroy, Adam K.
Glover, Simon C. O.
Hughes, Annie
Meidt, Sharon E.
Schinnerer, Eva
Sun, Jiayi
Amiri, Amirnezam
Barnes, Ashley T.
Bazzi, Zein
Bešlić, Ivana
Blanc, Guillermo A.
Burton, Charlie
Chown, Ryan
Congiu, Enrico
Dale, Daniel A.
Dlamini, Simthembile
He, Hao
Koch, Eric W.
Liang, Fu-Heng
Pety, Jérôme
Querejeta, Miguel
Sarbadhicary, Sumit K.
Stuber, Sophia K.
Usero, Antonio
Williams, Thomas G.
contents Understanding how the dynamical state of the interstellar medium (ISM) changes across spatial scales can provide important insights into how the gas is organized and ultimately collapses to form stars. To this end, we present ALMA $^{12}\mathrm{CO}(2-1)$ observations at $7$ pc ($0''.4$) spatial resolution across a $1.4~\mathrm{kpc}\times5.6~\mathrm{kpc}$ ($1'.3\times1'.3$) region located in the disk of the nearby ($D = 3.5$ Mpc), massive, star-forming galaxy NGC 253. We decompose this emission with a hierarchical, multiscale dendrogram algorithm to identify 2463 structures with deconvolved sizes ranging from $\sim3$ to $300$ pc, complete to a limiting mass of $10^4~M_\odot$. By comparing the virial parameter of these structures against physical properties including size, mass, surface density, velocity dispersion, and hierarchical position, we carry out a comprehensive search for a preferred scale at which gravitationally bound structures emerge. Ultimately, we do not identify evidence of an emergent scale for bound objects in our data, nor do we find a significant correlation between the virial parameter and structure sizes. These findings suggest that simple observational estimates of gravitational binding cannot be used to define molecular clouds and emphasize the need for multiscale approaches to characterize the ISM.
format Preprint
id arxiv_https___arxiv_org_abs_2507_03744
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Hierarchical Dynamical State of Molecular Gas from 3 to 300 pc in NGC 253
Oakes, Elias K.
Faesi, Christopher M.
Rosolowsky, Erik
Leroy, Adam K.
Glover, Simon C. O.
Hughes, Annie
Meidt, Sharon E.
Schinnerer, Eva
Sun, Jiayi
Amiri, Amirnezam
Barnes, Ashley T.
Bazzi, Zein
Bešlić, Ivana
Blanc, Guillermo A.
Burton, Charlie
Chown, Ryan
Congiu, Enrico
Dale, Daniel A.
Dlamini, Simthembile
He, Hao
Koch, Eric W.
Liang, Fu-Heng
Pety, Jérôme
Querejeta, Miguel
Sarbadhicary, Sumit K.
Stuber, Sophia K.
Usero, Antonio
Williams, Thomas G.
Astrophysics of Galaxies
Understanding how the dynamical state of the interstellar medium (ISM) changes across spatial scales can provide important insights into how the gas is organized and ultimately collapses to form stars. To this end, we present ALMA $^{12}\mathrm{CO}(2-1)$ observations at $7$ pc ($0''.4$) spatial resolution across a $1.4~\mathrm{kpc}\times5.6~\mathrm{kpc}$ ($1'.3\times1'.3$) region located in the disk of the nearby ($D = 3.5$ Mpc), massive, star-forming galaxy NGC 253. We decompose this emission with a hierarchical, multiscale dendrogram algorithm to identify 2463 structures with deconvolved sizes ranging from $\sim3$ to $300$ pc, complete to a limiting mass of $10^4~M_\odot$. By comparing the virial parameter of these structures against physical properties including size, mass, surface density, velocity dispersion, and hierarchical position, we carry out a comprehensive search for a preferred scale at which gravitationally bound structures emerge. Ultimately, we do not identify evidence of an emergent scale for bound objects in our data, nor do we find a significant correlation between the virial parameter and structure sizes. These findings suggest that simple observational estimates of gravitational binding cannot be used to define molecular clouds and emphasize the need for multiscale approaches to characterize the ISM.
title The Hierarchical Dynamical State of Molecular Gas from 3 to 300 pc in NGC 253
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2507.03744