Multifractal analysis of the interstellar medium: First application to Hi-GAL observations
| Autor: | Francesco Strafella, Stefano Pezzuto, Nicola Schneider, Sergio Molinari, Davide Elia, S. E. Jaffa, Eugenio Schisano, Patrick Hennebelle, Sami Dib |
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| Přispěvatelé: | Elia, Davide, Strafella, Francesco, Dib, Sami, Schneider, Nicola, Hennebelle, Patrick, Pezzuto, Stefano, Molinari, Sergio, Schisano, Eugenio, Jaffa, Sarah E., I. Physikalisches Institut [Köln], Universität zu Köln, Polytech'Clermont-Ferrand, Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Universität zu Köln = University of Cologne, ANR-16-CE92-0035,GENESIS,GENeration et Evolution des Structures du milieu InterStellaire(2016) |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
statistical [Methods]
Interstellar cloud ISM [Infrared] cloud [ISM] FOS: Physical sciences 01 natural sciences Fractal dimension Measure (mathematics) 0103 physical sciences image processing [Techniques] Statistical physics 010306 general physics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) ComputingMilieux_MISCELLANEOUS Astrophysics::Galaxy Astrophysics formation [Stars] Physics [PHYS]Physics [physics] Fractional Brownian motion Star formation Molecular cloud Astronomy and Astrophysics Multifractal system Astronomy and Astrophysic Astrophysics - Astrophysics of Galaxies Interstellar medium Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) structure [ISM] [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] |
| Zdroj: | Monthly Notices of the Royal Astronomical Society Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2018, 481 (1), pp.509-532. ⟨10.1093/mnras/sty2170⟩ Monthly Notices of the Royal Astronomical Society, 2018, 481 (1), pp.509-532. ⟨10.1093/mnras/sty2170⟩ |
| ISSN: | 0035-8711 1365-2966 |
| DOI: | 10.1093/mnras/sty2170⟩ |
| Popis: | The multifractal geometry remains an under-exploited approach to describe and quantify the large-scale structure of interstellar clouds. In this paper, the typical tools of multifractal analysis are applied to Herschel far-infrared (70-500 $\mu$m) dust continuum maps, which represent an ideal case of study. This dust component is a relatively optically thin tracer at these wavelengths and the size in pixel of the maps is well suitable for this statistical analysis. We investigate the so-called multifractal spectrum and generalised fractal dimension of six Hi-GAL regions in the third Galactic quadrant. We measure systematic variations of the spectrum at increasing wavelength, which generally correspond to an increasing complexity of the image, and we observe peculiar behaviours of the investigated fields, strictly related to the presence of high-emission regions, which in turn are connected to star formation activity. The same analysis is applied to synthetic column density maps, generated from numerical turbulent molecular cloud models and from fractal Brownian motion (fBm), allowing for the confrontation of the observations with models with well controlled physical parameters. This comparison shows that, in terms of multifractal descriptors of the structure, fBm images exhibit a very different, quite unrealistic behaviour when compared with Hi-GAL observations, whereas the numerical simulations appear in some cases (depending on the specific model) more similar to the observations. Finally, the link between mono-fractal parameters (commonly found in the literature) and multifractal indicators is investigated: the former appear to be only partially connected with the latter, with the multifractal analysis offering a more extended and complete characterization of the cloud structure. Comment: Accepted by MNRAS |
| Databáze: | OpenAIRE |
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