A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies

Debosmita Pathak; Adam K. Leroy; Todd A. Thompson; Laura A. Lopez; Francesco Belfiore; Mederic Boquien; Daniel A. Dale; Simon C. O. Glover; Ralf S. Klessen; Eric W. Koch; Erik Rosolowsky; Karin M. Sandstrom; Eva Schinnerer; Rowan Smith; Jiayi Sun; Jessica Sutter; Thomas G. Williams; Frank Bigiel; Yixian Cao; Jeremy Chastenet; Melanie Chevance; Ryan Chown; Eric Emsellem; Christopher M. Faesi; Kirsten L. Larson; Janice C. Lee; Sharon Meidt; Eve C. Ostriker; Lise Ramambason; Sumit K. Sarbadhicary; David A. Thilker

doi:10.3847/1538-3881/ad110d

A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies

Debosmita Pathak^*, Adam K. Leroy, Todd A. Thompson, Laura A. Lopez, Francesco Belfiore, Mederic Boquien, Daniel A. Dale, Simon C. O. Glover, Ralf S. Klessen, Eric W. Koch, Erik Rosolowsky, Karin M. Sandstrom, Eva Schinnerer, Rowan Smith, Jiayi Sun, Jessica Sutter, Thomas G. Williams, Frank Bigiel, Yixian Cao, Jeremy ChastenetMelanie Chevance, Ryan Chown, Eric Emsellem, Christopher M. Faesi, Kirsten L. Larson, Janice C. Lee, Sharon Meidt, Eve C. Ostriker, Lise Ramambason, Sumit K. Sarbadhicary, David A. Thilker

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission with complex substructures that trace dust heated both by massive young stars and the diffuse interstellar radiation field. We present high angular (0."85) and physical resolution (20-80 pc) measurements of the probability distribution function (PDF) of mid-infrared (mid-IR) emission (7.7-21 μm) from 19 nearby star-forming galaxies from the PHANGS-JWST Cycle-1 Treasury. The PDFs of mid-IR emission from the disks of all 19 galaxies consistently show two distinct components: an approximately log-normal distribution at lower intensities and a high-intensity power-law component. These two components only emerge once individual star-forming regions are resolved. Comparing with locations of HII regions identified from VLT/MUSE Hα-mapping, we infer that the power-law component arises from star-forming regions and thus primarily traces dust heated by young stars. In the continuum-dominated 21 μm band, the power-law is more prominent and contains roughly half of the total flux. At 7.7-11.3 μm, the power-law is suppressed by the destruction of small grains (including PAHs) close to HII regions while the log-normal component tracing the dust column in diffuse regions appears more prominent. The width and shape of the log-normal diffuse emission PDFs in galactic disks remain consistent across our sample, implying a log-normal gas column density N(H) ≈ 10²¹cm^-2 shaped by supersonic turbulence with typical (isothermal) turbulent Mach numbers ≈ 5-15. Finally, we describe how the PDFs of galactic disks are assembled from dusty HII regions and diffuse gas, and discuss how the measured PDF parameters correlate with global properties such as star-formation rate and gas surface density.

Original language	English
Article number	39
Number of pages	31
Journal	Astronomical Journal
Volume	167
Issue number	1
Early online date	29 Dec 2023
DOIs	https://doi.org/10.3847/1538-3881/ad110d
Publication status	Published - 1 Jan 2024

Keywords

Interstellar medium
Extragalatic astronomy
Dust physics
H II regions
Infrared astronomy
Stellar feedback

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Copyright © 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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Pathak, D., Leroy, A. K., Thompson, T. A., Lopez, L. A., Belfiore, F., Boquien, M., Dale, D. A., Glover, S. C. O., Klessen, R. S., Koch, E. W., Rosolowsky, E., Sandstrom, K. M., Schinnerer, E., Smith, R., Sun, J., Sutter, J., Williams, T. G., Bigiel, F., Cao, Y., ... Thilker, D. A. (2024). A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies. Astronomical Journal, 167(1), Article 39. https://doi.org/10.3847/1538-3881/ad110d

@article{6f432e714fc648a8b3f1e176c16b5efe,

title = "A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies",

abstract = "High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission with complex substructures that trace dust heated both by massive young stars and the diffuse interstellar radiation field. We present high angular (0.{"}85) and physical resolution (20-80 pc) measurements of the probability distribution function (PDF) of mid-infrared (mid-IR) emission (7.7-21 μm) from 19 nearby star-forming galaxies from the PHANGS-JWST Cycle-1 Treasury. The PDFs of mid-IR emission from the disks of all 19 galaxies consistently show two distinct components: an approximately log-normal distribution at lower intensities and a high-intensity power-law component. These two components only emerge once individual star-forming regions are resolved. Comparing with locations of HII regions identified from VLT/MUSE Hα-mapping, we infer that the power-law component arises from star-forming regions and thus primarily traces dust heated by young stars. In the continuum-dominated 21 μm band, the power-law is more prominent and contains roughly half of the total flux. At 7.7-11.3 μm, the power-law is suppressed by the destruction of small grains (including PAHs) close to HII regions while the log-normal component tracing the dust column in diffuse regions appears more prominent. The width and shape of the log-normal diffuse emission PDFs in galactic disks remain consistent across our sample, implying a log-normal gas column density N(H) ≈ 1021cm-2 shaped by supersonic turbulence with typical (isothermal) turbulent Mach numbers ≈ 5-15. Finally, we describe how the PDFs of galactic disks are assembled from dusty HII regions and diffuse gas, and discuss how the measured PDF parameters correlate with global properties such as star-formation rate and gas surface density. ",

keywords = "Interstellar medium, Extragalatic astronomy, Dust physics, H II regions, Infrared astronomy, Stellar feedback",

author = "Debosmita Pathak and Leroy, {Adam K.} and Thompson, {Todd A.} and Lopez, {Laura A.} and Francesco Belfiore and Mederic Boquien and Dale, {Daniel A.} and Glover, {Simon C. O.} and Klessen, {Ralf S.} and Koch, {Eric W.} and Erik Rosolowsky and Sandstrom, {Karin M.} and Eva Schinnerer and Rowan Smith and Jiayi Sun and Jessica Sutter and Williams, {Thomas G.} and Frank Bigiel and Yixian Cao and Jeremy Chastenet and Melanie Chevance and Ryan Chown and Eric Emsellem and Faesi, {Christopher M.} and Larson, {Kirsten L.} and Lee, {Janice C.} and Sharon Meidt and Ostriker, {Eve C.} and Lise Ramambason and Sarbadhicary, {Sumit K.} and Thilker, {David A.}",

note = "Funding: T.G.W. acknowledges funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (grant agreement No. 694343). F.B. would like to acknowledge funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (grant agreement No.726384/Empire).",

year = "2024",

month = jan,

day = "1",

doi = "10.3847/1538-3881/ad110d",

language = "English",

volume = "167",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "1",

}

Pathak, D, Leroy, AK, Thompson, TA, Lopez, LA, Belfiore, F, Boquien, M, Dale, DA, Glover, SCO, Klessen, RS, Koch, EW, Rosolowsky, E, Sandstrom, KM, Schinnerer, E, Smith, R, Sun, J, Sutter, J, Williams, TG, Bigiel, F, Cao, Y, Chastenet, J, Chevance, M, Chown, R, Emsellem, E, Faesi, CM, Larson, KL, Lee, JC, Meidt, S, Ostriker, EC, Ramambason, L, Sarbadhicary, SK & Thilker, DA 2024, 'A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies', Astronomical Journal, vol. 167, no. 1, 39. https://doi.org/10.3847/1538-3881/ad110d

TY - JOUR

T1 - A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies

AU - Pathak, Debosmita

AU - Leroy, Adam K.

AU - Thompson, Todd A.

AU - Lopez, Laura A.

AU - Belfiore, Francesco

AU - Boquien, Mederic

AU - Dale, Daniel A.

AU - Glover, Simon C. O.

AU - Klessen, Ralf S.

AU - Koch, Eric W.

AU - Rosolowsky, Erik

AU - Sandstrom, Karin M.

AU - Schinnerer, Eva

AU - Smith, Rowan

AU - Sun, Jiayi

AU - Sutter, Jessica

AU - Williams, Thomas G.

AU - Bigiel, Frank

AU - Cao, Yixian

AU - Chastenet, Jeremy

AU - Chevance, Melanie

AU - Chown, Ryan

AU - Emsellem, Eric

AU - Faesi, Christopher M.

AU - Larson, Kirsten L.

AU - Lee, Janice C.

AU - Meidt, Sharon

AU - Ostriker, Eve C.

AU - Ramambason, Lise

AU - Sarbadhicary, Sumit K.

AU - Thilker, David A.

N1 - Funding: T.G.W. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 694343). F.B. would like to acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No.726384/Empire).

PY - 2024/1/1

Y1 - 2024/1/1

N2 - High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission with complex substructures that trace dust heated both by massive young stars and the diffuse interstellar radiation field. We present high angular (0."85) and physical resolution (20-80 pc) measurements of the probability distribution function (PDF) of mid-infrared (mid-IR) emission (7.7-21 μm) from 19 nearby star-forming galaxies from the PHANGS-JWST Cycle-1 Treasury. The PDFs of mid-IR emission from the disks of all 19 galaxies consistently show two distinct components: an approximately log-normal distribution at lower intensities and a high-intensity power-law component. These two components only emerge once individual star-forming regions are resolved. Comparing with locations of HII regions identified from VLT/MUSE Hα-mapping, we infer that the power-law component arises from star-forming regions and thus primarily traces dust heated by young stars. In the continuum-dominated 21 μm band, the power-law is more prominent and contains roughly half of the total flux. At 7.7-11.3 μm, the power-law is suppressed by the destruction of small grains (including PAHs) close to HII regions while the log-normal component tracing the dust column in diffuse regions appears more prominent. The width and shape of the log-normal diffuse emission PDFs in galactic disks remain consistent across our sample, implying a log-normal gas column density N(H) ≈ 1021cm-2 shaped by supersonic turbulence with typical (isothermal) turbulent Mach numbers ≈ 5-15. Finally, we describe how the PDFs of galactic disks are assembled from dusty HII regions and diffuse gas, and discuss how the measured PDF parameters correlate with global properties such as star-formation rate and gas surface density.

AB - High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission with complex substructures that trace dust heated both by massive young stars and the diffuse interstellar radiation field. We present high angular (0."85) and physical resolution (20-80 pc) measurements of the probability distribution function (PDF) of mid-infrared (mid-IR) emission (7.7-21 μm) from 19 nearby star-forming galaxies from the PHANGS-JWST Cycle-1 Treasury. The PDFs of mid-IR emission from the disks of all 19 galaxies consistently show two distinct components: an approximately log-normal distribution at lower intensities and a high-intensity power-law component. These two components only emerge once individual star-forming regions are resolved. Comparing with locations of HII regions identified from VLT/MUSE Hα-mapping, we infer that the power-law component arises from star-forming regions and thus primarily traces dust heated by young stars. In the continuum-dominated 21 μm band, the power-law is more prominent and contains roughly half of the total flux. At 7.7-11.3 μm, the power-law is suppressed by the destruction of small grains (including PAHs) close to HII regions while the log-normal component tracing the dust column in diffuse regions appears more prominent. The width and shape of the log-normal diffuse emission PDFs in galactic disks remain consistent across our sample, implying a log-normal gas column density N(H) ≈ 1021cm-2 shaped by supersonic turbulence with typical (isothermal) turbulent Mach numbers ≈ 5-15. Finally, we describe how the PDFs of galactic disks are assembled from dusty HII regions and diffuse gas, and discuss how the measured PDF parameters correlate with global properties such as star-formation rate and gas surface density.

KW - Interstellar medium

KW - Extragalatic astronomy

KW - Dust physics

KW - H II regions

KW - Infrared astronomy

KW - Stellar feedback

U2 - 10.3847/1538-3881/ad110d

DO - 10.3847/1538-3881/ad110d

M3 - Article

SN - 0004-6256

VL - 167

JO - Astronomical Journal

JF - Astronomical Journal

IS - 1

M1 - 39

ER -

A two-component probability distribution function describes the mid-IR emission from the disks of star-forming galaxies

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