Title: Search and Monitoring of Double-Peaked Broad Lines in LINER's (T. Storchi-Bergmann) Brief program summary and its significance: GOALS OF THE PROJECT: (1) Look for faint broad double-peaked emission in low-activity nuclei; (2) monitor the successful cases, as well as those already known, through spectroscopic observations obtained once or twice a month when the target is up in the night sky. SIGNIFICANCE: In order to account for the large number of quasars observed at high redshifts, it is believed that supermassibe black holes (SBH) may be present in the nuclei of most luminous galaxies, but only become active when an accretion event happens. Theory predicts that such events occur via the formation of an accretion disk or ring, whose more direct observational signatures are emission-line profiles with a characteristic double-peaked structure. These profiles have indeed been observed in several radio-loud objects with LINER type narrow-line spectra (Eracleous & Halpern 1994). We (Storchi-Bergmann, Baldwin & Wilson 1993) have discovered a similar profile in the Balmer lines of the radio-quiet and low-activity LINER nucleus of the spiral galaxy NGC~1097, after the careful subtraction of the stellar population contribution. Bower et al. (1996), using the Hubble Space Telescope found a similar H alpha profile in the low-activity LINER nucleus of M81. These findings seem to confirm that SBH are present in the nucleus of luminous galaxies, several of which present faint LINER- like emission lines, but it is necessary to make a complete survey of such objects to try to find more of them. Once found, it is also necessary to monitor the double-peaked profiles (e.g. Storchi-Bergmann et al. 1995;1997), as only its variation may put constraints on the emitting structure. (A double-peaked line is not only produced by an accretion disk or ring, but also by a nuclear double jet, for example.) PROPOSED OBSERVATIONS High signal-to-noise ratio (S/N) long-slit optical spectra of the nuclear region of nearby LINERs. High S/N is necessary also outside the nucleus, from where a stellar population spectrum will be extracted. This spectrum will be used to subtract the stellar population contribution to the nuclear spectrum and isolate the faint emission. Required minimum field of view (arcmin): 1 arcmin Required psf (FWHM, profile details): smallest possible, so that a very narrow slit can be used to minimize the effect of the stellar population on the nuclear spectrum. Signal/noise required per resolution element: 50-100 Typical exposure time for this S/N & lunar phase: 30 minutes to 1 hour. Any lunar phase Anticipated photometric dynamic range required: 500-1000 What additional photometric calibrations are required? Flux calibration via standard stars, wavelength calibration and daytime flatfielding. If IR, is tip/tilt feasible (consider isoplanatic patch)? Anticipated number of separate pointings to complete program: One per galaxy (sample has approximately 100 galaxies). For the monitoring (sample of two plus the new found), one per galaxy every 15 or 30 days. Can this program execute in a queue? This method is particularly efficient for monitoring the already known nuclei with double-peaked lines, at a frequency of once or twice a month. Anticipated post-focus instrumentation requirements (filters, gratings, etc.): order sorting filters and gratings for spectrograph Required instruments (spectral R, filters, wavelength range): R1000-5000, wavelenght range 3200-7000 A. How soon might you need to revisit this target with another instrument? It would be desirable to have the possibility of obtaining a quick image previously to the spectroscopic observations for the complicated cases, like double or heavily obscured nuclei. Why can't this program execute on the Blanco 4m? Needs higher angular resolution (better image quality), in order to isolate the faint nuclear emission. References (for non-mainstream applications): Eracleous, M. & Halpern, J. 1994, ApJS 90,1. Storchi-Bergmann, T. Baldwin, J. A. & Wilson, A. S. 1993, ApJ 410, L11. Storchi-Bergmann et al. 1995, ApJ 443, 617. Storchi-Bergmann et al. 1997, ApJ, submitted. -------------------------------------------------------------------------- Title: IR imaging of the nuclei of nearby active galaxies (T. Storchi-Bergmann) Brief program summary and its significance: GOAL: Investigate the structure of the circumnuclear region of nearby AGN's (active galactic nuclei) via IR imaging, taking advantage of the reduced extinction at these wavelenghts. SIGNIFICANCE: Unified models of AGN are successful in explaining a number of observed properties of these nuclei, like the anisotropic morphology of the high excitation gas in Seyfert 2 galaxies. These models predict the existence of a dusty molecular torus around the active nucleus, which collimates the radiation and obscures the nucleus in Seyfert 2 galaxies, due to the relatively high inclination of the torus in these galaxies. Nevertheless, there are still very few clear signatures of the tori. The main difficulties in their observation are the high extinction present in the nuclear region of active galaxies (and mostly in the Seyfert 2 galaxies ) and the relatively small size of the tori (few pc's to tens of pc's). OBSERVATIONS: Due to the high obscuration in AGN's, the best spectral region to observe them is the IR. Due to the small size of the tori, very good image quality, and spatial resolution of 0.1-0.2 arcsec are required. The proposed observations are narrow-band images in the molecular H_2(2.12um) line and adjacent continua; and broad-band J, H ,K and L' images which can be used to construct color maps. Required minimum field of view (arcmin): 1 arcmin Required psf (FWHM, profile details): smallest possible; 0.1" FWHM at the closests AGN's correspond to 2-10 pc, which would permit to resolve small structures such as tori. Signal/noise required per resolution element: 10-30 Typical exposure time for this S/N & lunar phase: few minutes for continuum images and 1-2hr for narrow-band images. Any lunar phase. Anticipated photometric dynamic range required: 1000-10000. It would be desirable to observe also Seyfert 1 galaxies, in which the tori would be face on, and, in order to avoid as much as possible saturarion of the nucleus, a large dynamic range is necessary. What additional photometric calibrations are required? Flux calibration via a couple of standard stars and proper flatfielding. If IR, is tip/tilt feasible (consider isoplanatic patch)? yes Anticipated number of separate pointings to complete program: Sample comprises 10-20 galaxies, for which images will be obtained in 6 filters, on- and off-source. Can this program execute in a queue? yes Anticipated post-focus instrumentation requirements (filters, gratings, etc.): broad-band J, H, K and L' filters, narrow-band redshifted H_2 filters and in adjacent continuum. Required instruments (spectral R, filters, wavelength range): IR imager How soon might you need to revisit this target with another instrument? A follow-up project will be IR spectroscopy for the investigation of the gaseous kinematics and excitation. It would be desirable to have the capability of alternate IR image and IR long-slit spectroscopy during the same night. Why can't this program execute on the Blanco 4m? Needs higher angular resolution (better image quality) to resolve small structures. References (for non-mainstream applications):