we propose to follow up our recent discovery of the 3.4um interstellar absorption feature in the nuclear spectra of several type 2 seyferts, by using iso to search for the feature in higher redshift active galaxies such as narrow line radio galaxies and to probe the 5-9 um region for corresponding absorption features. the absorption almost certainly arises in the dense molecular torus surrounding the active core in type 2 seyfert galaxies. detection of similar ir absorption features in narrow line radio galaxies would be strong evidence in favour of unified models of agn in which both type 2 seyferts and nlrg have an active core partially or wholly hidden behind a thick, dense torus of obscuring material. the 3.4um feature can be remarkably deep in regions with very high columns of dust and probes a different temperature regime from co molecular absorption features. the proposed observations will provide details of the physical structure of the torus, and also improve our understanding of the formation of interstellar grains.
Instrument
SWS06
Temporal Coverage
1996-12-14T11:37:08Z/1996-12-14T15:34:22Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
