We introduce two radiation-hydrodynamical effects in nuclear/circumnuclear regions of active galaxies. One of which is obscuration of a nucleus by the dusty gas. The dusty gas is supported by the radiation force due to a circumnuclear starburst as well as a nucleus and surrounds the nuclear regions. Since the UV/Optical radiation from the nucleus is absorbed and IR radiation is reproduced by a lot of dust grains, the AGN tends to be identified as type 2. Also, QSOs would be observed as ULIRGs when active star-formation occurs in their host galaxies. The other is photon-trapping effect. Photons, which are generated at the internal parts of the accretion disk, are trapped in the accretion flow and fall to the central black hole if diffusion velocity of the radiation is smaller than accretion velocity of the flow. This would be greatly effective in the case of optically thick ADAF. Then, the QSOs/AGNs are recognized as relatively dim objects although they have very high mass accretion rate.
Studies of Galaxies in the Young Universe with New Generation Telescope
- Pub Date:
- February 2004