| Abstract : | Analyzing a large representative sample of local galaxies (16908), we find that the shape of the dust attenuation curve, i.e., the normalized slope of the curve in ultraviolet and optical wavelengths, is intimately tied to both the dominant structure of the galaxy and its star formation activity. However, no such connection is seen for either the total stellar mass or the inclination of the galaxy. The attenuation curve for star-forming galaxies as compared to the passive ones is nearly twice as shallow. Similar findings are reflected in terms of the structure where the curve is twice as steep for spheroid dominated compared to disc dominated galaxies. The steepness of the curve for spheroids and passive galaxies is driven by minimal attenuation of optical emission compared to the emission in UV wavelengths, underlining the lack of dusty birth-clouds that are integral to complex star-dust geometry. Also, within a particular class, i.e., that of star-forming, passive, discs or spheroids, the slope values are constrained to a narrow range depicting no variation with total dust mass. All evidence indicates that the presence or lack of complex star-dust geometry is the main determinant of galaxy's attenuation properties. |
