Dust attenuation in the restframe ultraviolet: constraints from star-forming galaxies at z~1

Conroy, Charlie
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A novel technique is employed for estimating attenuation curves in galaxies where only photometry and spectroscopic redshifts are available. This technique provides a powerful measure of particular extinction features such as the UV bump at 2175\A, which has been observed in environments ranging from the Milky Way to high-redshift star-forming galaxies. Knowledge of the typical strength of the UV bump as a function of environment and redshift is crucial for converting restframe UV flux into star formation rates. The UV bump will impart a unique signature as it moves through various filters due to redshifting; its presence can therefore be disentangled from other stellar population effects. The utility of this technique is demonstrated with a large sample of galaxies drawn from the DEEP2 Galaxy Redshift Survey. The observed B-R color of star-forming galaxies at 0.6<z<1.4 disfavors the presence of a UV bump as strong as observed in the Milky Way, and instead favors restframe UV (1800A<lambda<3000A) attenuation curves similar to the Milky Way without a UV bump or a power-law with index delta=-0.7. Stronger constraints on the strength of the UV bump in galaxies can be achieved if independent constraints on the V-band optical depth are available.
Comment: 6 pages, 3 figures. MNRAS, accepted
Astrophysics - Cosmology and Nongalactic Astrophysics