Properties of infrared-luminous galaxies, or, how I spent seven summer vacations

Citation

Carico, David Paul (1991) Properties of infrared-luminous galaxies, or, how I spent seven summer vacations. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/XZPT-HV21. https://resolver.caltech.edu/CaltechETD:etd-05162007-161518

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Galaxies selected from the IRAS database having unusually high 60 - 100µm luminosities are studied at wavelengths ranging from ~1 - 1000µm. It is found that these galaxies differ significantly from normal, optically-selected galaxies, not only in their far-infrared luminosities, but in their near-infrared properties as well. A substantial excess emission at near-infrared wavelengths is attributed to emission from hot dust, with temperatures ~500 - 1000 K. Furthermore, this hot dust emission is confined to the central nuclear regions, within characteristic scale sizes ~1 - 3 kpc. This suggests that the bulk of the infrared luminosity, and hence the processes responsible for the extreme activity in infrared-luminous galaxies, is highly localized about galaxy nuclei. High resolution images of a number of these nuclei reveals a high percentage of double-nucleus sources amongst the most luminous galaxies, giving evidence that galaxy-galaxy interactions play a significant role in the generation of high infrared luminosities. The distribution of the mass of, and luminosity from, dust in infrared-luminous galaxies is analyzed as a function of the temperature of the dust. It is found that, in galaxies for which the entire energy distribution is dominated by emission from dust heated to a steady-state, the mass of dust scales with steady-state temperature as [...], where [...] is typically in the range 6 - 6.5. Dust continues to contribute substantially to the total luminosity up to temperatures in excess of 300 K above the temperatures responsible for the peak in the infrared luminosity. At the lowest temperatures, however, it is very difficult to constrain the contribution to the observed emission: For the galaxies studied, the observations are consistent with models in which the amount of very cold dust ranges from essentially non-existent, to the dominant component of the total dust mass.

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