The dust attenuation for a sample of ∼10000 local (z 0.1) star forming galaxies is constrained as a function of their physical properties. We utilize aperture-matched multi-wavelength data available from the Galaxy Evolution Explorer (GALEX ) and the Sloan Digital Sky Survey (SDSS) to ensure that regions of comparable size in each galaxy are being analyzed. We follow the method of Calzetti et al. (1994) and characterize the dust attenuation through the UV power-law index, β, and the dust optical depth, which is quantified using the difference in Balmer emission line optical depth, τ l B = τ Hβ − τ Hα . The observed linear relationship between β and τ l B is similar to the local starburst relation, but the large scatter (σ int = 0.44) suggests there is significant variation in the local Universe. We derive a selective attenuation curve over the range 1250Å < λ < 8320Å and find that a single attenuation curve is effective for characterizing the majority of galaxies in our sample. This curve has a slightly lower selective attenuation in the UV compared to previously determined curves. We do not see evidence to suggest that a 2175Å feature is significant in the average attenuation curve. Significant positive correlations are seen between the amount of UV and optical reddening and galaxy metallicity, mass, star formation rate (SFR), and SFR surface density. This provides a potential tool for gauging attenuation where the stellar population is unresolved, such as at high-z.

We provide a coherent, uniform measurement of the evolution of the logarithmic star formation rate (SFR) -stellar mass (M * ) relation, called the main sequence of star-forming galaxies (MS), for starforming and all galaxies out to z ∼ 5. We measure the MS using mean stacks of 3 GHz radio continuum images to derive average SFRs for ∼ 200,000 mass-selected galaxies at z > 0.3 in the COSMOS field. We describe the MS relation adopting a new model that incorporates a linear relation at low stellar mass (log(M * /M )<10) and a flattening at high stellar mass that becomes more prominent at low redshift (z < 1.5). We find that the SFR density peaks at 1.5 < z < 2 and at each epoch there is a characteristic stellar mass (M * = 1−4×10 10 M ) that contributes the most to the overall SFR density. This characteristic mass increases with redshift, at least to z ∼ 2.5. We find no significant evidence for variations in the MS relation for galaxies in different environments traced by the galaxy number density at 0.3 < z < 3, nor for galaxies in X-ray groups at z ∼ 0.75. We confirm that massive bulgedominated galaxies have lower SFRs than disk-dominated galaxies at a fixed stellar mass at z < 1.2. As a consequence, the increase in bulge-dominated galaxies in the local star-forming population leads to a flattening of the MS at high stellar masses. This indicates that "mass-quenching" is linked with changes in the morphological composition of galaxies at a fixed stellar mass.

We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color vs. redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4,000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision (σ ∆z/(1+zspec) 0.04), high accuracy (i.e., minimal offset biases; median(∆z/(1 + z spec )) 0.02), and low catastrophic failure rates (η ≃ 4%) over all redshifts. Interestingly, we find that a weak 2175Å absorption feature in the attenuation curve models is required to remove a subtle systematic z phot offset (z phot − z spec ≃ −0.03) that occurs when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric datasets. Finally, we emphasize that MAGPHYS+photo-z is not intended to replace existing photo-z codes, but rather offer flexibility to robustly interpret physical properties when spectroscopic redshifts are unavailable. The MAGPHYS+photo-z code is publicly available online.

We derive a UV-optical stellar dust attenuation curve of galaxies at z=1.4-2.6 as a function of gas-phase metallicity. We use a sample of 218 star-forming galaxies, excluding those with very young or heavily obscured star formation, from the MOSFIRE Deep Evolution Field survey with Hα, Hβ, and [N II]λ 6585 spectroscopic measurements. We constrain the shape of the attenuation curve by comparing the average flux densities of galaxies sorted into bins of dust obscuration using Balmer decrements, i.e., Hα-to-Hβ luminosities. The average attenuation curve for the high-metallicity sample ( ( )) has a shallow slope, identical to that of the Calzetti local starburst curve, and a significant UV 2175 Å extinction bump that is ∼0.5×the strength of the Milky Way bump. On the other hand, the average attenuation curve of the lowmetallicity sample ( ( ) + ~-12 log O H 8.2 8.5) has a steeper slope similar to that of the SMC curve, only consistent with the Calzetti slope at the 3σ level. The UV bump is not detected in the low-metallicity curve, indicating the relative lack of the small dust grains causing the bump at low metallicities. Furthermore, we find that on average the nebular reddening (E(B − V )) is a factor of 2 times larger than that of the stellar continuum for galaxies with low metallicities, while the nebular and stellar reddening are similar for galaxies with higher metallicities. The latter is likely due to a high surface density of dusty clouds embedding the star-forming regions but also reddening the continuum in the high-metallicity galaxies.Unified Astronomy Thesaurus concepts: Galaxy evolution (594); Interstellar dust extinction (837); High-redshift galaxies (734); Galaxy abundances (574); Chemical abundances (224); Galaxy properties (615); Galaxies (573); Interstellar dust (836); Interstellar abundances (832)

We introduce the Stony Brook / SMARTS Atlas of (mostly) Southern Novae. This atlas contains both spectra and photometry obtained since 2003. The data archived in this atlas will facilitate systematic studies of the nova phenomenon and correlative studies with other comprehensive data sets. It will also enable detailed investigations of individual objects. In making the data public we hope to engender more interest on the part of the community in the physics of novae. The atlas is on-line at