| タイトル | Star trapping and metallicity enrichment in quasars and active galactic nuclei |
| 著者（英） | Wampler, E. J.; Lin, D. N. C.; Artymowicz, Pawel |
| 著者所属（英） | NASA Goddard Space Flight Center; NASA Headquarters |
| 発行日 | 1993-06-01 |
| 言語 | eng |
| 内容記述 | Recent observational evidence suggests that the metallicity in quasars within a wide range of redshifts, in particular in gas flowing out of the nuclear regions, may be approximately redshift-independent and comparable with or larger than solar. It is plausible that the nuclear metallicity can be internally generated and maintained at approximately time-stationary values in quasars. We identify and estimate efficiency of a mechanism for rapid metallicity enrichment of quasar nuclear gas (in general, in active galactic nuclei) based on star-gas interactions and equivalent to an unusual mode of massive star formation. The mechanism involves capture of low-mass stars from the host galaxy's nucleus by the assemblages of clouds or by accretion disks orbiting the central massive objects (e.g., black holes). Trapping of stars within gaseous disks/clouds occurs through resonant density and bending wave excitation, as well as by hydrodynamical drag. The time scale for trapping stars with total mass equal to that of disk fragment/cloud is of order Hubble time and is remarkably model-independent. Our results show that the described mechanism can produce features suggested by observations, for example, the (super) solar gas metallicity in the nucleus. Thus the observed metallicities in high-redshift quasars do not necessarily imply that global star formation and efficient chemical changes have occurred in their host galaxies at very early cosmological epochs. |
| NASA分類 | ASTROPHYSICS |
| レポートNO | 93A37785 |
| 権利 | Copyright |
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