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Title: Characterizing the structure of diffuse emission in Hi-GAL maps

We present a study of the structure of the Galactic interstellar medium (ISM) through the Δ-variance technique, related to the power spectrum and the fractal properties of infrared/submillimeter maps. Through this method, it is possible to provide quantitative parameters, which are useful for characterizing different morphological and physical conditions, and better constraining the theoretical models. In this respect, the Herschel Infrared Galactic Plane Survey, carried out at five photometric bands from 70 to 500 μm, constitutes a unique database for applying statistical tools to a variety of regions across the Milky Way. In this paper, we derive a robust estimate of the power-law portion of the power spectrum of four contiguous 2° × 2° Hi-GAL tiles located in the third Galactic quadrant (217° ≲ ℓ ≲ 225°, –2° ≲ b ≲ 0°). The low level of confusion along the line of sight, testified by CO observations, makes this region an ideal case. We find very different values for the power spectrum slope from tile to tile but also from wavelength to wavelength (2 ≲ β ≲ 3), with similarities between fields attributable to components located at the same distance. Thanks to comparisons with models of turbulence, an explanation of themore » determined slopes in terms of the fractal geometry is also provided, and possible relations with the underlying physics are investigated. In particular, an anti-correlation between ISM fractal dimension and star formation efficiency is found for the two main distance components observed in these fields. A possible link between the fractal properties of the diffuse emission and the resulting clump mass function is discussed.« less
Authors:
; ; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ; ; ;  [6] ;  [7] ; ;  [8] ;  [9] ;  [10] ;  [11] more »; « less
  1. INAF-IAPS, Via Fosso del Cavaliere 100, I-00133 Roma (Italy)
  2. Dipartimento di Matematica e Fisica E. De Giorgi, Università del Salento, CP 193, I-73100 Lecce (Italy)
  3. Univ. Bordeaux, LAB, CNRS, UMR 5804, 33270, Floirac (France)
  4. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  5. Herschel Science Centre, European Space Astronomy Centre, Villafranca del Castillo, Apartado de Correos 78, E-28080 Madrid (Spain)
  6. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  7. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)
  8. Agenzia Spaziale Italiana Science Data Center, c/o ESRIN, via Galileo Galilei, I-00044 Frascati (Italy)
  9. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
  10. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)
  11. Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
Publication Date:
OSTI Identifier:
22356719
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; CORRELATIONS; DATA ANALYSIS; EFFICIENCY; EMISSION; MAPS; MASS; MILKY WAY; SPECTRA; STARS; TURBULENCE; WAVELENGTHS