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Characterizing the Structure of Diffuse Emission in Hi-GAL Maps

Elia, D. and Strafella, F. and Schneider, N. and Paladini, R. and Vavrek, R. and Maruccia, Y. and Molinari, S. and Noriega-Crespo, A. and Pezzuto, S. and Rygl, K. L. J. and di Giorgio, A. M. and Traficante, A. and Schisano, E. and Calzoletti, L. and Pestalozzi, M. and Liu, S. J. and Natoli, P. and Huang, M. and Martin, P. and Fukui, Y. and Hayakawa, T. (2014) Characterizing the Structure of Diffuse Emission in Hi-GAL Maps. Astrophysical Journal, 788 (1). Art. No. 3. ISSN 0004-637X. doi:10.1088/0004-637X/788/1/3.

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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 the 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Paladini, R.0000-0002-5158-243X
Noriega-Crespo, A.0000-0002-6296-8960
Traficante, A.0000-0003-1665-6402
Additional Information:© 2014 American Astronomical Society. Received 2014 January 17; accepted 2014 April 4; published 2014 May 16. Data processing and map production have been possible thanks to generous support from the Italian Space Agency via contracts I/038/080/0 and I/005/11/0. Data presented in this paper were also analyzed using the Herschel interactive processing environment (HIPE), a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS, and SPIRE consortia. During the preparation of this paper, D. E. lost his father, Elio Elia. D. E. is grateful for the example he set and his inborn and unconditional generosity. Nothing in D. E.’s career, including this paper itself, would have been possible without his father’s steady support in many aspects of his life. This paper is dedicated to his memory. Facility: Herschel (PACS, SPIRE)
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)I/038/080/0
Agenzia Spaziale Italiana (ASI)I/005/11/0
Subject Keywords:infrared: ISM; ISM: clouds; ISM: structure; methods: data analysis; methods: statistical; stars: formation
Issue or Number:1
Record Number:CaltechAUTHORS:20140703-131900338
Persistent URL:
Official Citation:Characterizing the Structure of Diffuse Emission in Hi-GAL Maps D. Elia et al. 2014 ApJ 788 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46819
Deposited By: Ruth Sustaita
Deposited On:03 Jul 2014 20:47
Last Modified:10 Nov 2021 17:29

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