Empirical determination of the shape of dust attenuation curves in star-forming galaxies

By V. Wild, S. Charlot, J. Brinchmann, T. Heckman, O. Vince, C. Pacifici, J. Chevallard. 2011

170 citations recorded by the source corpus.

We present a systematic study of the shape of the dust attenuation curve in star-forming galaxies from the far-ultraviolet (far-UV) to the near-infrared (NIR; ∼0.15–2 μm), as a function of specific star formation rate (ψ S) and axial ratio (b/a), for galaxies with and without a significant bulge. Our sample comprises 23 000 (15 000) galaxies with a median redshift of 0.07, with photometric entries in the Sloan Digital Sky Survey (SDSS), UKIRT Infrared Deep Sky SurveyLarge Area Survey and Galaxy Evolution Explorer-All-Sky Imaging Survey catalogues and emission-line measurements from the SDSS spectroscopic survey. We develop a new pairmatching technique to isolate the dust attenuation curves from the stellar continuum emission. The main results are: (i) the slope of the attenuation curve in the optical varies weakly with ψ S, strongly with b/a, and is significantly steeper than the Milky Way extinction law in bulgedominated galaxies; (ii) the NIR slope is constant and matches the slope of the Milky Way extinction law; (iii) the UV has a slope change consistent with a dust bump at 2175 A which is evident in all samples and varies strongly in strength with b/a in the bulge-dominated sample; (iv) there is a strong increase in emission-line-to-continuum dust attenuation (τ V,line/τ V,cont) with both decreasing ψ S and increasing b/a; and (v) radial gradients in dust attenuation increase strongly with increasing ψ S, and the presence of a bulge does not alter the strength of the gradients. These results are consistent with the picture in which young stars are surrounded by dense ‘birth clouds’ with low covering factor which disperse on time-scales of ∼10 7 yr and the diffuse interstellar dust is distributed in a centrally concentrated disc with a smaller scaleheight than the older stars that contribute the majority of the red and NIR light. Within this model, the path-length of diffuse dust, but not of birth-cloud dust, increases with increasing inclination and the apparent optical attenuation curve is steepened by the differential effect of larger dust opacity towards younger stars than towards older stars. Additionally, our findings suggest that: (i) galaxies with higher star formation rates per unit stellar mass have a higher fraction of diffuse dust, which is more centrally concentrated; (ii) the observed strength of the 2175-A dust feature is affected predominantly by global geometry; and (iii) only highly inclined discs are optically thick. We provide new empirically derived attenuation curves for correcting the light from star-forming galaxies for dust attenuation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4d9026e86a84f6efcd0813c41d69e1eb75790b0c

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In Astronomy and Astrophysics

1. P. V. van Dokkum
2. C. Conroy
3. P. Hopkins
4. M. Franx
5. L. Hernquist
6. R. Dav'e
7. D. M. Alexander
8. R. Somerville

Citations in the corpus

• Panchromatic spectral energy distributions of Herschel sources (2013, background): “It is worth to note that, since we are fitting the median photometry of several galaxies, possible variations of the eff ctive attenuation law (e.g. Buat et al. 2012; Reddy et al. 2012, 2006; Wild et al. 2011) are diluted.”
• THE DUST ATTENUATION LAW IN DISTANT GALAXIES: EVIDENCE FOR VARIATION WITH SPECTRAL TYPE (2013, methodology): “They also find weaker UV bump strengths in galaxies with larger specific SFRs (see also Wild et al. 2011).”
• Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs (2018, methodology): “First, as pointed out by Wild et al. (2011) and Chevallard et al. (2013), the underlying assumption of the comparison method is that the attenuation curves do not vary with the dust content, as characterized, for exam- ple, by optical opacity (τV or AV ).”
• GALEX–SDSS–WISE LEGACY CATALOG (GSWLC): STAR FORMATION RATES, STELLAR MASSES, AND DUST ATTENUATIONS OF 700,000 LOW-REDSHIFT GALAXIES (2016, result): “Evidence for a steeper-than-Calzetti curve has been found in other studies as well (Charlot & Fall 2000; Buat et al. 2011; Wild et al. 2011; Hao et al. 2011; Salmon et al. 2015), though not as steep as the one found here and in Conroy et al. More detailed investigation of these results and their…”
• THE FMOS-COSMOS SURVEY OF STAR-FORMING GALAXIES AT z ∼ 1.6. I. Hα-BASED STAR FORMATION RATES AND DUST EXTINCTION (2013, background): “Rather than being dependent on redshift, this factor may be related to specific SFR (see Equations (15) and (16) of Wild et al. 2011).”
• GOODS-Herschel: dust attenuation properties of UV selected high redshift galaxies (2012, result): “Instead, from a careful analysis of pairs of galaxy SEDs, Wild et al. (2011) conclude that the UV slope of the attenuation curve is consistent with the presence of a bump at 2175 Å, a conclusion also reached by Conroy et al. (2010) from an analysis of the GALEX-SDSS colours of galaxies.”
• THE MOSDEF SURVEY: MEASUREMENTS OF BALMER DECREMENTS AND THE DUST ATTENUATION CURVE AT REDSHIFTS z ∼ 1.4–2.6 (2015, background): “…and nearby galaxies have yielded detailed information on the shape of the dust extinction and attenuation curves, respectively, in the local Universe (e.g., Prevot et al. 1984; Cardelli et al. 1989; Pei 1992; Calzetti et al. 1994, 2000; Gordon et al. 2003; Johnson et al. 2007a; Wild et al. 2011).”
• GOODS-HERSCHEL: STAR FORMATION, DUST ATTENUATION, AND THE FIR–RADIO CORRELATION ON THE MAIN SEQUENCE OF STAR-FORMING GALAXIES UP TO z ≃ 4 (2014, background): “The correlation found by Wild et al. (2011) nicely explain our findings and also support our conclusions.”
• First results from the IllustrisTNG simulations: the galaxy colour bimodality (2017, unknown): “We take τ1 = 1.0, τ2 = 0.3 (although see Wild et al. 2011), α1 = α2 = 0.7, tage = 10 Myr, and λ0 = 550 nm.”
• PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z = 0–1 (2013, methodology): “2011, ApJ, 739, 24 Brand, K., Moustakas, J., Armus, L., et al. 2009, ApJ, 693, 340 Bressan, A., Fagotto, F., Bertelli, G., & Chiosi, C. 1993, A&AS, 100, 647 Brinchmann, J., Charlot, S., White, S. D. M., et al. 2004, MNRAS, 351, 1151 Brown, M. J. I., Dey, A., Jannuzi, B. T., et al. 2007, ApJ, 654, 85”
• Ultraviolet emission lines in young low-mass galaxies at z ≃ 2: physical properties and implications for studies at z > 7 (2014, background): “But the extra attenuation faced by the HII regions appears to decrease with increasing sSFR (e.g.,Wild et al. 2011, Price et al. 2013).”
• Deriving Physical Properties from Broadband Photometry with Prospector: Description of the Model and a Demonstration of its Accuracy Using 129 Galaxies in the Local Universe (2016, background): “Previous work suggests that the total optical depth toward nebular emission lines is ∼twice that of the stellar component (Calzetti et al. 1994; Price et al. 2014), though the exact value varies with SFR and galaxy inclination (Wild et al. 2011).”
• A CANDELS–3D-HST SYNERGY: RESOLVED STAR FORMATION PATTERNS AT 0.7 < z < 1.5 (2013, methodology): “…regions is obscured by dust from the birth cloud itself in addition to the column of diffuse material spread throughout the galaxy that also affects the bulk of galaxy light emitted by older stars (see also Charlot & Fall 2000; Wild et al. 2011; Pacifici et al. 2012; Chevallard et al. 2013).”
• CIGALE: a python Code Investigating GALaxy Emission (2018, background): “Numerous studies have focussed on determining attenuation laws in galaxies, finding a remarkable diversity (e.g. Wild et al. 2011; Reddy et al. 2015, 2016; Lo Faro et al. 2017; Buat et al. 2018; Salim et al. 2018, Decleir et al., in prep., and many others).”