Loading...
Please wait, while we are loading the content...
Similar Documents
H2 line emission in three seyfert nuclei: evidence against uv-excitation
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Geballe, T. R. |
| Copyright Year | 1990 |
| Description | Line emission from vibrationally excited molecular hydrogen has been detected in a considerable number of active galactic nuclei (AGNs), including those generally believed to contain compact and luminous central engines (e.g., Seyfert nuclei) and those in which the luminosity is believed to arise from massive bursts of star formation (starburst nuclei). In most of these AGNs, only the bright 1-0 S(1) line (rest wavelength 2.12 microns) has been searched for and detected to date. Line-emitting H2 can be excited directly either by energetic collisions created by shock waves or by absorption of UV radiation. Each of these excitation mechanisms has been clearly identified in galactic and extragalactic regions. In active galactic nuclei strong sources of UV and (in some case) x rays are present. If the nuclear molecular matter is quiescent (i.e., isolated from the active nucleus and not set into motion by episodes of star formation) the H2 line emission will be dominated by fluorescence, or possibly by thermal emission due to heating by x rays (Krolik, this conference). However, it is expected or indeed observed that a significant fraction of the interstellar medium in and near these nuclei is undergoing rapid motions; either generated by the central engine or by a nuclear starburst, which are capable of producing strong shock phenomena in nearby molecular gas. Thus, a priori it is not obvious which mechanism is responsible for the H2 line emission from the nucleus of an active galaxy. |
| File Size | 211245 |
| Page Count | 2 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19910004872 |
| Archival Resource Key | ark:/13960/t8tb61684 |
| Language | English |
| Publisher Date | 1990-07-01 |
| Access Restriction | Open |
| Subject Keyword | Astrophysics Molecular Gases Hydrogen Luminosity Fluorescence Ultraviolet Absorption Matter Physics Shock Waves Seyfert Galaxies Active Galactic Nuclei X Rays Thermal Emission Star Formation Heating Emission Spectra Collisions Nucleons Excitation Interstellar Matter Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
