The following document lists the file abstract/JSHIELDS_NGC4395A.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
We propose observations of IR fine-structure emission lines in the lowest-luminosity known Seyfert 1 nucleus in NGC4395. This object is of unique value for probing the characteristics of active galactic nuclei (AGNs) at low luminosity. Data from this proposal combined with observations scheduled in Guaranteed Time Programmes will provide insights into luminosity-dependent behavior indicative of the structure and energetics of AGNs and quasars. The nucleus of NGC4395 is also of great interest as an unambiguous AGN with luminosity matching that of the Galactic center. Comparison of observations of NGC4395 with those of Sgr A West thus may provide new insight into the degree to which the Milky Way hosts an active nucleus. Observations will be obtained under the current proposal with the SWS. The measured lines will be used to quantify abundances, densities, and ionization conditions in the narrow-line region of this AGN. The present study will help complete a multiwavelength picture of NGC4395's nucleus, when combined with recent and ongoing observations in the radio, optical, UV, and X-ray spectral regions. The IR transitions add information beyond what is available at optical or UV wavelengths, since these lines are generally insensitive to electron temperature, which aids in abundance determinations, and probe regions that may suffer severe extinction at shorter wavelengths. Measurements of the local continuum accompanying observations of the lines can also be used to quantify the amount of dust reprocessing of radiation in this AGN. Wavelength regions appropriate for detection of coronal features will also be observed with the SWS in parallel when strong lines tracing the narrow-line region are unavailable in merged mode. The lines to be studied under this program are difficult or impossible to measure in suborbital observations.