The broad line region and dust torus structure of the Seyfert 1 WPVS48

Abstract

Optical and near-mid-infrared reverberation mapping data obtained at Universitätssternwarte Bochum in Chile and with the Spitzer Space Telescope allow us to explore the geometry of both the Hα BLR and the dust torus for the nearby Seyfert 1 galaxy WPVS 48. On average, the Hα variations lag the blue AGN continuum by about 18 days, while the dust emission variations lag by 70 days in the J+K and by 90 days in the L+M bands. The IR echoes are sharp, while the Hα echo is smeared. This together favours a bowl shaped toroidal geometry where the dust sublimation radius is defined by a bowl surface, which is virtually aligned with a single iso-delay surface, thus leading to the sharp IR echoes. The BLR clouds, however, are located inside the bowl and spread over a range of iso-delay surfaces, leading to a smeared echo.