The differential magnification of high-redshift ultraluminous infrared galaxies

This proceeding discusses the potential modifications to the mid-infrared spectral energy distribution (SED) of a high-redshift dusty AGN that is graviationally lensed by a foreground galaxy. The mid-infrared colour of a lensed galaxy would typically be bluer than that of the same galaxy in the absence of magnification. This effect would make it more difficult to interpret the very small sample of high-redshift dusty AGN for which broad-band SEDs are known in terms of the viewing angle of an obscuring dust torus, as all are known to be lensed by galaxies.