| Description |
scientific abstract we propose spectroscopic survey observations and individual line observations using lws, sws, and isophot designed to provide the first complete spectral characterization of agn in the 3-200 micron region. the major goals of the program are to: a) distinguish between non-stellar engine and starburst origins of the luminosity in galactic nuclei (emission line ratios sensitive to density and excitation will identify all of the current classes of nuclear activity, discriminating between thermal and nonthermal models), b) measure the distribution and kinematics of nuclear gas and probe the dynamical geography of the nucleus via line profile shape analysis, c) study the nature and the origin of the coronal line emission region of agn, d) measure heavy element abundances in agn, e) determine accurately how dust obscures the intrinsic agn spectra, f) search for the postulated hidden blr in narrow-line.. agns, g) search for molecules in thick tori (seyfert 2) and outer regions of accretion disks and study their kinematics at high spectral resolution, h) determine the importance of thermal and nonthermal emission for the continua of all classes of agns and the shape of the far infrared continuum turnover, and i) measure the detailed continuum energy distribution of agn, with emphasis on high z qsos for which we will address questions about the formation of heavy elements at very large z, the formation of galaxies and its relation with qsos, the structure and the energetics of host galaxies of qsos. observation summary this program includes observation of roughly 50 agn and qsos. the majority of agn will be spectroscopically surveyed using lws, sws, and isophot grating spectra; distant qsos will use phot22. all of the survey spectra will cover the full wavelength range at the full resolving power afforded by the grating subsystem of each instrument. full sws scans on ngc 1068 and ngc 4151 are omitted to avoid duplication with the sws team guaranteed time proposal infrared spectroscopy of bright galactic nuclei and the connection between starformation and agn.s. similarly, pht spectroscopy on a number of our program objects (i zw 1, mkn 551, and mkn 463) are omitted to avoid duplication with the sws team proposal.) the sws and pht observation times (including sws01, sws02, and sws06 aots) are designed to achieve a signal to noise ratio of twenty to several hundred on the continuum of each object. the lowest signal to noise occurs in sws01 scans shortward of 7 microns. the survey aots utilized are lws01, sws01, and pht40. specific line observations utilize sws02 and sws06. in all cases, sws01 observations will be made in full r mode, and lws01 observations will be nyquist sampled over 45-180 microns. depending on the wavelength range, a signal to noise ratio of twenty to several hundred on the continuum will be obtained for each object. for most of the targets these correspond to 10-sigma detections of emission lines with fluxes of 5.0e-17 watts/meter2 in the most sensitive wavelength regions (around 100um). in the least sensitive detector bands (at the shortest wavelengths), lines of this flux would typically be detected at only the 2-sigma level. higher signal-to-noise ratios will be obtained for the two brightest archetypical agns, the seyfert 1 ngc 4151, and the seyfert 2 ngc 1068, allowing detection of even fainter lines in these two special cases. in addition to these survey observations, high quality line profiles will be obtained on lines listed in table 1a and 1b below. these lines are chosen to included all iso observable ionization states of neon. transitions of several other intermediate mass elements are included to yield abundances and to produce a data set that spans a wide range of transition critical densities to probe agn dynamical structure. all sws02 observations in the program pertain to table 1. observations of mkn 3, i zw 1, ngc 3783, mkn 573, and mkn 463 with sws02 will observe lines listed in table 1b to avoid duplication with the sws team proposal. the remainder of our sws02 and sws06 observations will observe lines listed in table 1a. observations with sws02 or sws06 will also be made on lines listed in table 2 during follow up time only, and where no duplication with the sws team observations exist. observations made with sws06 cover a 2000 km/s spectral baseline centered on the line. we propose to obtain high-resolution fabry-perot scans for the profiles of two emission lines expected to be strong in the seyfert 2 nucleus of ngc 1068: o i 63um and the co (j=57-->56) line at 46um. while this is a top sientific priority, we have listed it as priority 3 because the priority 1 grating scans should sensibly be examined first. both will reveal the presence of high-density, but low-ionization gas--in particular the dense molecular gas that is believed to form a thick obscuring torus surrounding the central engine (eg., krolik and begelman 1988). this dense region is probably too optically thick to emit strong lines at much shorter wavelengths. the trade-of |
