An Investigation of Disk Thickness in M51 from Hα, Paα, and Mid-infrared Power Spectra
Journal article, 2025
Power spectra (PS) of high-resolution images of M51 (NGC 5194) taken with the Hubble Space Telescope and the James Webb Space Telescope (JWST) have been examined for evidence of disk thickness in the form of a change in slope between large scales, which map two-dimensional correlated structures, and small scales, which map three-dimensional correlated structures. Such a slope change is observed here in H alpha, and possibly Pa alpha, using average PS of azimuthal intensity scans that avoid bright peaks. The physical scale of the slope change occurs at similar to 120 pc and similar to 170 pc for these two transitions, respectively. A radial dependence in the shape of the H alpha PS also suggests that the length scale drops from similar to 180 pc at 5 kpc, to similar to 90 pc at 2 kpc, to similar to 25 pc in the central similar to kpc. We interpret these lengths as comparable to the thicknesses of the star-forming disk traced by H ii regions. The corresponding emission measure is similar to 100 times larger than what is expected from the diffuse ionized gas. The PS of JWST Mid-IR Instrument images in eight passbands have more gradual changes in slope, making it difficult to determine a specific value of the thickness for this emission.
Author
Daniela Calzetti
University of Massachusetts
Angela Adamo
Stockholm University
Karin Sandstrom
University of California
Daniel Dale
University of Wyoming
Varun Bajaj
Space Telescope Science Institute (STScI)
Martha L. Boyer
Space Telescope Science Institute (STScI)
Ana Duarte-Cabral
Cardiff University
Ryan Chown
Ohio State University
Matteo Correnti
Agenzia Spaziale Italiana
Istituto nazionale di astrofisica (INAF)
Julianne J. Dalcanton
Flatiron Institute
University of Washington
Bruce T. Draine
Princeton University
Brandt Gaches
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
John S. Gallagher III
University of Wisconsin Madison
Kathryn Grasha
Australian National University
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)
Benjamin Gregg
University of Massachusetts
Leslie K. Hunt
Istituto nazionale di astrofisica (INAF)
Kelsey E. Johnson
University of Virginia
Robert Kennicutt Jr
Texas A&M University
University of Arizona
Ralf S. Klessen
Harvard University
Heidelberg University
Harvard-Smithsonian Center for Astrophysics
Adam K. Leroy
Ohio State University
Sean Linden
University of Arizona
Anna F. McLeod
Durham University
Matteo Messa
Istituto nazionale di astrofisica (INAF)
Goran Ostlin
Stockholm University
Mansi Padave
University of California
Julia Roman-Duval
Space Telescope Science Institute (STScI)
J. D. Smith
University of Toledo
Fabian Walter
Max Planck Society
Tony D. Weinbeck
University of Wyoming
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 986 1 13Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.3847/1538-4357/adcee6