ISM properties in low-metallicity environments I. mid-infrared spectra of dwarf galaxies

By S. Madden, F. Galliano, A. Jones, M. Sauvage. 2005

160 citations recorded by the source corpus.

We present new ISOCAM mid-infrared spectra of three starbursting nearby dwarf galaxies, NGC1569, IIZw40, NGC1140 and the 30Dor region of the LMC and explore the properties of the ISM in low-metallicity environments, also using additional sources from the literature. We analyse the various components of the ISM probed by the mid-infrared observations and compare them with other Galactic and extragalactic objects. The MIR spectra of the low-metallicity starburst sources are dominated by the [NeIII] and [SIV] lines, as well as a steeply rising dust continuum. PAH bands are generaly faint, both locally and averaged over the full galaxy, in stark contrast to dustier starburst galaxies, where the PAH features are very prominant and even dominate on global scales. The hardness of the modeled interstellar radiation fields for the dwarf galaxies increases as the presence of PAH band emission becomes less pronounced. The [NeIII]/[NeII] ratios averaged over the full galaxy are strikingly high, often >10. Thus, the hard radiation fields are pronounced and pervasive. We find a prominent correlation between the PAHs/VSGs and the [NeIII]/[NeII] ratios for a wide range of objects, including the low metallicity galaxies as well as Galactic HII regions and other metal-rich galaxies. This effect is consistent with the hardness of the interstellar radiation field playing a major role in the destruction of PAHs in the low metallicity ISM. We see a PAHs/VSGs and metallicity correlation, also found by Engelbracht et al. (2005) for a larger survey. Combined effects of metallicity and radiation field seem to be playing important roles in the observed behavior of PAHs in the low metallicity systems.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d4a70c7bad657da2d48b1e8c323203e0bdc25ace

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Citations in the corpus

The applicability of far-infrared fine-structure lines as star formation rate tracers over wide ranges of metallicities and galaxy types (2014, background): “2006; Madden et al. 2006; Draine et al. 2007; Engelbracht et al. 2008; Galliano et al. 2008), while the abundance of very small grains grows drastically relative to the large grain population due to the fragmentation of those large grains through shocks experienced in the turbulent ISM (Jones et…”
Variations of the Mid-IR Aromatic Features inside and among Galaxies (2008, methodology): “There is a general correlation between the PAH-to-continuum intensity ratio and the ISMmetallicity (Madden et al. 2006; Wu et al. 2006; O’Halloran et al. 2006; Smith et al. 2007), and consequently between the IRAC8 m/MIPS24 m broadband ratio and the metallicity (Engelbracht et al. 2005).”
The Calibration of Mid-Infrared Star Formation Rate Indicators (2007, background): “A possible mechanism to reduce the mass fraction of PAH molecules in the low–metallicity galaxies is destruction by the hard radiation field in those galaxies (e.g., Madden et al. 2006; Wu et al. 2006), although these molecules have proven surprisingly robust (Engelbracht et al. 2006).”
THE STATE OF THE GAS AND THE RELATION BETWEEN GAS AND STAR FORMATION AT LOW METALLICITY: THE SMALL MAGELLANIC CLOUD (2011, background): “…2175 Å extinction bump and the mid-infrared aromatic features attributed to polycyclic aromatic hydrocarbons (PAHs; Draine & Li 2001; Li & Draine 2002), are considerably depleted at low metallicities and in particular in the SMC (Madden et al. 2006; Engelbracht et al. 2008; Sandstrom et al. 2010).”
A simple model to interpret the ultraviolet, optical and infrared emission from galaxies (2008, methodology): “…we adopt a fixed template spectrum to describe PAH emission in our model.1 We use the mid-infrared spectrum of the photo-dissociation region in the prototypical Galactic starforming region M17 SW extracted from the ISO/ISOCAM observations of Cesarsky et al. (1996) by Madden et al. (2006).”
The HDUV Survey: A Revised Assessment of the Relationship between UV Slope and Dust Attenuation for High-redshift Galaxies (2017, background): “…and stellar population age (e.g., Normand et al. 1995; Helou et al. 2001; Alonso-Herrero et al. 2004; Engelbracht et al. 2005; Hogg et al. 2005; Madden et al. 2006; Draine et al. 2007; Smith et al. 2007; Galliano et al. 2008; Hunt et al. 2010; Sales et al. 2010; Elbaz et al. 2011; Magdis et…”
CONSTRAINING THE LOW-MASS SLOPE OF THE STAR FORMATION SEQUENCE AT 0.5 < z < 2.5 (2014, background): “…formation and destruction is sensitive to the metallicity of a galaxy; observations show a metallicity dependence of the PAH abundance in galaxies (e.g., Engelbracht et al. 2005; Madden et al. 2006), with a paucity of PAH detection in low metallicity galaxies (Z < 0.1 Z ; e.g., Hunt et al. 2010).”
Probing the dust properties of galaxies up to submillimetre wavelengths. II. Dust-to-gas mass ratio trends with metallicity and the submm excess in dwarf galaxies (2011, background): “Previous studies have shown that the form of the global ISRF is different from normal or dusty galaxies to low-metallicity galaxies (e.g. Madden et al. 2006), an effect attributed to the lower dust attenuation and thus the larger mean free path length of the ionizing photons in low-metallicity ISM…”