Aspects of noncommutative gauge theories and their commutative equivalents

We discuss some exact Seiberg--Witten-type maps for noncommutative electrodynamics. Their implications for anomalies in different (noncommutative and commutative) descriptions are also analysed.Comment: 3 pages; Invited talk at the 11th Regional Conference on Mathematics and Mathematical Physics, IPM Tehran, May 2004. To appear in the conference proceeding

Covariant Anomalies, Horizons and Hawking Radiation

Hawking radiation is obtained from anomalies resulting from a breaking of diffeomorphism symmetry near the event horizon of a black hole. Such anomalies, manifested as a nonconservation of the energy momentum tensor, occur in two different forms -- covariant and consistent. The crucial role of covariant anomalies near the horizon is revealed since this is the {\it only} input required to obtain the Hawking flux, thereby highlighting the universality of this effect. A brief description to apply this method to obtain thermodynamic entities like entropy or temperature is provided.Comment: 5 pages; This essay was awarded an Honorable Mention in the 2008 Gravity Research Foundation essay competitio