Dust in the Small Magellanic Cloud: Interstellar Polarization and Extinction

Rodrigues, C. V.; Magalhães, A. M.; Coyne, G. V.; Piirola, S. J. V.

doi:10.1086/304434

Cited by 33 publications

(65 citation statements)

References 85 publications

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“…Thanks to this relation the dust-to-gas ratio increases with metallicity, as nicely summarized by Brinchmann et al (2013). Indeed, for the Milky Way it is about three times greater than for the Large Magellanic Cloud and ∼1.5 times greater than for the Small Magellanic Cloud, as a direct consequence of the differences in metallicity between these three galaxies (e.g., Bohlin et al 1978;Fitzpatrick 1986;Rodrigues et al 1997). In this case the galactocentric decrease of the abundance may induce a similar gradient for the dust attenuation.…”

Section: Discussionmentioning

confidence: 81%

Imprints of galaxy evolution on H II regions

Sánchez¹,

Pérez²,

Rosales-Ortega³

et al. 2015

A&A

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Context. H ii regions in galaxies are the sites of star formation, so they are special places for understanding the build-up of stellar mass in the universe. The line ratios of this ionized gas are frequently used to characterize the ionization conditions. In particular, the oxygen abundances are assumed to trace the chemical enrichment of galaxies. Aims. We explore the connections between the ionization conditions and the properties of the overall underlying stellar population (ionizing or not-ionizing) in H ii regions, in order to uncover the actual physical connection between them. Methods. We use the H ii regions catalog from the CALIFA survey, which is the largest in existence with more than 5000 H ii regions, to explore their distribution across the classical [O iii] λ5007/Hβ vs. [N ii] λ6583/Hα diagnostic diagram, and the way it depends on the oxygen abundance, ionization parameter, electron density, and dust attenuation. The location of H ii regions within this diagram is compared with predictions from photoionization models. Finally, we explore the dependence of the location within the diagnostic diagram on the properties of the host galaxies, the galactocentric distances, and the properties of the underlying stellar population.Results. The H ii regions with weaker ionization strengths and more metal-rich are located in the bottom righthand area of the diagram. In contrast, those regions with stronger ionization strengths and more metal poor are located in the upper lefthand end of the diagram. Photoionization models per se do not predict these correlations between the parameters and the line ratios. The H ii regions located in earlier-type galaxies, closer to the center and formed in older and more metal-rich regions of the galaxies are located in the bottom-right area of the diagram. On the other hand, those regions located in late-type galaxies in the outer regions of the disks and formed on younger and more metal-poor regions lie in the top lefthand area of the diagram. The two explored line ratios show strong correlations with the age and metallicity of the underlying stellar population.Conclusions. These results indicate that although H ii regions are short-lived events, they are affected by the total underlying stellar population. One may say that H ii regions keep a memory of the stellar evolution and chemical enrichment that have left an imprint on both the ionizing stellar population and the ionized gas. Key words. galaxies: abundances -galaxies: star formation -galaxies: evolution -galaxies: ISM Appendix A is available in electronic form at http://www.aanda.orgArticle published by EDP Sciences A47, page 1 of 17 A&A 574, A47 (2015)

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Section: Discussionmentioning

confidence: 81%

Imprints of galaxy evolution on H II regions

Sánchez¹,

Pérez²,

Rosales-Ortega³

et al. 2015

A&A

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“…Rodrigues et al (1997) carried out polarization studies of the interstellar dust in the Small Magellanic Cloud (SMC) and concluded that it could harbour smaller dust grains than the Milky Way. They suggest that the SMC may be rich in grains with size smaller than 0.05 µm.…”

Section: Implications For Grainsmentioning

confidence: 99%

Physical conditions in three high-zH₂-bearing DLAs: implications for grain size

Shaw

Rawlins

Srianand

2016

Mon. Not. R. Astron. Soc.

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We present results of our numerical simulation of three H2-bearing damped Lyman α absorbers (DLAs) in the redshift interval ~ 2-3. The systems we have modelled are the DLAs at zabs = 2.3377 towards the quasar LBQS 1232+0815, at zabs = 2.41837 towards SDSS J143912.04+111740.5 and at zabs = 2.6265 towards FBQS J081240.6+320808. We have used the spectral synthesis code CLOUDY to simulate the physical environment of these DLAs, and constrain the density, radiation field, geometry and dust-grain properties of the DLAs selfconsistently based on the observed column densities of various atomic and molecular species such as H I, fine structure lines of C I and the rotational level population of H2. In our models, we explore the effect of grain size distribution on the predicted column densities of different species. Within the allowed uncertainties in the inferred dust-to-gas ratio, both models with standard ISM grains and smaller-sized grains reproduce the observations equally well. Improved constraints on dust-to-gas ratio and line-of-sight extinction are important for probing the grain size distribution in high-z DLAs. We find the H2-bearing clouds to have line-of-sight thickness in the range 1-6 pc, consistent with what has been found using partial coverage or 21-cm observations in some high-z DLAs.

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“…There is evidence that the dust grain size distributions in the SMC and the Milky Way are different (Rodrigues et al 1997;Weingartner & Draine 2001;Gordon et al 2003), and that low metallicity galaxies in general may have an excess of small dust grains relative to the Milky Way. These differences, however, should not affect our measurements of the PAH fraction.…”

Section: Parametermentioning

confidence: 99%

THESPITZERSURVEY OF THE SMALL MAGELLANIC CLOUD (S³MC): INSIGHTS INTO THE LIFE CYCLE OF POLYCYCLIC AROMATIC HYDROCARBONS

Sandström

Bolatto

Draine

et al. 2010

ApJ

128

124

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We present the results of modeling dust spectral energy distributions (SEDs) across the Small Magellanic Cloud (SMC) with the aim of mapping the distribution of polycyclic aromatic hydrocarbons (PAHs) in a low-metallicity environment. Using Spitzer Survey of the SMC (S 3 MC) photometry from 3.6 to 160 µm over the main star-forming regions of the Wing and Bar of the SMC along with spectral mapping observations from 5 to 38 µm from the Spitzer Spectroscopic Survey of the Small Magellanic Cloud (S 4 MC) in selected regions, we model the dust spectral energy distribution and emission spectrum to determine the fraction of dust in PAHs across the SMC. We use the regions of overlaping photometry and spectroscopy to test the reliability of the PAH fraction as determined from SED fits alone. The PAH fraction in the SMC is low compared to the Milky Way and variablewith relatively high fractions (q PAH ∼ 1 − 2%) in molecular clouds and low fractions in the diffuse ISM (average q PAH = 0.6%). We use the map of PAH fraction across the SMC to test a number of ideas regarding the production, destruction and processing of PAHs in the ISM. We find weak or no correlation between the PAH fraction and the distribution of carbon AGB stars, the location of supergiant H I shells and young supernova remnants, and the turbulent Mach number. We find that the PAH fraction is correlated with CO intensity, peaks in the dust surface density and the molecular gas surface density as determined from 160 µm emission. The PAH fraction is high in regions of active star-formation, as predicted by its correlation with molecular gas, but is supressed in H II regions. Because the PAH fraction in the diffuse ISM is generally very low-in accordance with previous work on modeling the integrated SED of the SMC-and the PAH fraction is relatively high in molecular regions, we suggest that PAHs are destroyed in the diffuse ISM of the SMC and/or PAHs are forming in molecular clouds. We discuss the implications of these observations for our understanding of the PAH life cycle, particularly in low-metallicity and/or primordial galaxies.

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Dust in the Small Magellanic Cloud: Interstellar Polarization and Extinction

Cited by 33 publications

References 85 publications

Imprints of galaxy evolution on H II regions

Imprints of galaxy evolution on H II regions

Physical conditions in three high-zH₂-bearing DLAs: implications for grain size

THESPITZERSURVEY OF THE SMALL MAGELLANIC CLOUD (S³MC): INSIGHTS INTO THE LIFE CYCLE OF POLYCYCLIC AROMATIC HYDROCARBONS

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Dust in the Small Magellanic Cloud: Interstellar Polarization and Extinction

Cited by 33 publications

References 85 publications

Imprints of galaxy evolution on H II regions

Imprints of galaxy evolution on H II regions

Physical conditions in three high-zH2-bearing DLAs: implications for grain size

THESPITZERSURVEY OF THE SMALL MAGELLANIC CLOUD (S3MC): INSIGHTS INTO THE LIFE CYCLE OF POLYCYCLIC AROMATIC HYDROCARBONS

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Physical conditions in three high-zH₂-bearing DLAs: implications for grain size

THESPITZERSURVEY OF THE SMALL MAGELLANIC CLOUD (S³MC): INSIGHTS INTO THE LIFE CYCLE OF POLYCYCLIC AROMATIC HYDROCARBONS