We report near-infrared spectroscopy of three Seyfert galaxies. Velocity resolved spectra covering low excitation-potential transitions of [Ar III] 8.991 µm, [S IV] 10.514 µm, and [Ne II] 12.813 µm were obtained using the facility mid-infrared array spectrometer (SpectroCam) of the Palomar Observatory Hale 5-m Telescope, and low-resolution spectra covering [Mg V] 5.608 µm, [Ar II] 6.985 µm, and [Ne VI] 7.642 µm were obtained using the faint-object spectrograph (HIFOGS) of the Kuiper Airborne Observatory (KAO).

We find high contrast [Ar III] and [S IV] in each galaxy, and [Ne II] in NGC 1068 and NGC 4151 (12.8 µm data were not obtained on NGC 5506). The line profiles are well resolved. In NGC 1068 and NGC 4151, they are fit by singlecomponent Gaussians. However, in NGC 5506, evidence for a broad pedestal is seen in the [Ar III] and [S IV] spectra, similar to the broad Paβ component reported by Blanco et al. (1990) and Rix et al. (1990).

IC 5063 (PKS 2048–572) is a nearby (z = 0.0110) early-type galaxy hosting a Seyfert 2 nucleus. In broad-band optical images, it shows a complex dust lane, while the ionized gas extends up to ~ 20 kpc and has an unusual X-shaped structure (Danziger et al. 1981, Colina et al. 1990). A faint, very broad emissionline component has been detected (Bergeron et al. 1983, Colina et al. 1991) together with an off-nuclear broad emission-line region (Wagner & Appenzeller 1989). Broad Hα emission was also detected in polarized light (Inglis et al. 1993). Thus, it is likely that this galaxy has a broad-line region which is obscured from our direct view (while the broad-line radiation is scattered into our line of sight by scatterers outside the obscuring regions). The radio luminosity of IC 5063 is nearly two orders of magnitude larger than typical values for nearby Seyferts (Ulvestad & Wilson 1984), making it one of the strongest radio sources found in Seyfert galaxies (1.3 Jy at 1.4 GHz, i.e., 2 × 1023W Hz−1 for H0 = 50 km s−1 Mpc−1). Its H I content is also very high: Danziger et al. (1981) found 1.0 × 1010M⊙, which gives MHI/LB = 0.4, quite anomalous for this type of object.

Observations in the 1 µm to 1 cm wavelength band give important information on the physical processes occurring in and immediately around active galactic nuclei. Concentrating on recent results on ionic, atomic, and molecular emission lines, we discuss as examples the first ISO results on the nature of ultra-luminous infrared galaxies, and near-infrared and millimeter measurements of the central 100 parsecs of the Seyfert 2 galaxy NGC 1068.

Near-infrared high-resolution imaging and spectroscopic observations of NGC 7469, Mrk 231, IRAS F10214+4724, and Circinus are presented. They indicate the presence of extended star-forming activity in the vicinity of the active nuclei of these galaxies on scales between 10 pc and 1 kpc from the nuclei. The very different distance scales covered by these objects show that the coexistence of AGN and star-formation activity is a common phenomenon. A first-order evolving star-cluster model calculation shows that we are beginning to understand the history and evolution of these circumnuclear star-forming regions.

We discuss 2.5–45 µm spectra of the Circinus galaxy and of Cen A, obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory. The large number of detected ionic fine structure lines, observable also in visually obscured sources, provides strong constraints on the shape of the ionizing spectrum, which is found to exhibit a UV bump peaking at ~ 70 eV in the case of Circinus. Pure rotational emission of molecular hydrogen, directly probing warm molecular gas, can for the first time be detected in external galaxies.

Various AGNs, starburst galaxies, and ultraluminous infrared galaxies (ULIRGs) are observed as part of the ISO-SWS central program of mid-infrared spectroscopy on bright galactic nuclei. Prototypical template sources are scanned over the full spectral range of SWS (2.5–45µm) in order to get a complete census of spectral features in this wavelength domain. As an example we present the spectrum of the Seyfert 2 galaxy Circinus. The application of results from this survey to the study of the nature and evolution of other galaxies can be demonstrated by an analysis of the ultraluminous infrared galaxy Arp 220.

We summarize our experience in observing the circumnuclear regions of AGN with the optical-fiber systems that we have developed for the William Herschel and Nordic Optical Telescopes at La Palma.

The TIGER integral field spectrograph has been used to study nearby and distant active galaxies. We first present new TIGER observations of the Seyfert galaxy NGC 1275. In this very complex object, TIGER allows us to disentangle the contributions of the numerous components. We present the first very promising results on NGC 5252 obtained with the 3-D data-cube deconvolution techniques developed by our team in Lyon.

A statistical analysis of the relationship between the continuum and the narrow emission lines of a sample of Seyfert 2 galaxies strongly suggests the presence of a starburst emitting at all wavelengths from radio to soft X-rays as well as in the narrow lines.

We discuss NIR imaging of the starburst galaxy NGC 1808. The circumnuclear continuum emission shows no morphological change with wavelength and most of it is produced by an evolved bulge population, not by red supergiants or dust. The line emission arises from distinct hot spots. From comparison of Brγ and Hα fluxes, we derive extinction Av = 3–5 toward the hot spots. From modeling of the line and continuum luminosities, we derive a star-formation rate of 0.1–0.6 M⊙ yr–1 and SN rate ~ 0.4–11 × 10–3 yr–1 per hot spot. The age of the burst is 8–17 Myr for the hot spots and ~ 40 Myr for the nucleus. Finally, evidence for and against hidden Seyfert activity in NGC 1808 is discussed.

The Circinus galaxy is a nearby (4 Mpc) spiral that hosts a Seyfert nucleus as deduced by the emission of intense coronal lines (Oliva et al. 1994) and by the prominent ionization cone observed in [O III] images (Marconi et al. 1994).

We present K-band imaging spectroscopy of the nucleus of this galaxy obtained by means of 3D, the MPE imaging spectrometer (Weitzel et al. 1996), and ROGUE, a first-order adaptive-optics system (Thatte et al. 1995), mounted on the 2.2-m ESO telescope. The spectral resolution is 1000 and the average optical seeing was about 0”.6 (= 12 pc at the source).

NGC 1275, the Perseus cluster cD galaxy, is a well-known Seyfert 1 galaxy and also one of the strongest extragalactic radio sources (3C84). Although many studies have been done on the extended optical emission-line region of NGC 1275, which is thought to be associated with the X-ray cooling-flow phenomenon (e.g., Heckman et al. 1989, Ferruit and Pecontal 1994), the excitation mechanism of the emission-line gas and two-dimensional gas kinematics are still unclear. We made tri-dimensional spectroscopy of NGC 1275 in order to reveal two-dimensional kinematics and- the relation between the gas motion and the excitation of the emission lines.

The Kyoto 3-D Spectrograph was commissioned successfully at the 188-cm telescope of the Okayama Astrophysical Observatory in the spring of 1996. This instrument has four distinct modes (Ohtani et al. 1994): (1) narrow-band imager, which is an ordinary focal-reducer camera; (2) Spectro-NebulaGraph (long-slit spectrograph; Kosugi et al. 1995); (3) imaging Fabry-Perot interferometer, using either of two Fabry-Perot etalons from Queensgate Instruments (a tunable filter with R = 300 and another with R = 7000 for velocity-field observations. Broad-band (400–700 nm) coatings are deposited on both etalons. During observations, the etalon temperature is stabilized within 0.5°C); and (4) integral-field spectrograph of the TIGER-type (Bacon et al. 1995). In this mode, the spectra of 7 × 11 objects can be recorded simultaneously, along with 7 × 2 spectra of the sky 4′ away. The spatial resolution is 1″.3 and the field of view is 9″ × 14″.

NGC 7319 is a member of the compact group of galaxies known as Stephan’s Quintet. The systemic velocity 6740 km s−1 gives a distance of 90Mpc (H0= 75 kms−1 Mpc−1) for NGC 7319. This galaxy has a tail and/or ring which suggests interaction with a neighboring pair of galaxies, NGC 7318A and B (e.g., Arp 1973). Durret & Warrin (1990) and Durret (1994) performed optical long-slit spectroscopy and found an extended emission-line region (EELR) in NGC 7319. They detected highly excited gas over along PA = 61° and 10″ along PA – 151°. Apart from these works, there have not been any studies on the velocity field and excitation of the gas in the EELR of NGC 7319. More details were published by Aoki et al. (1996).

We present results of high S/N, high spatial and spectral resolution (0″.65 and 0.8Å FWHM, respectively) spectrophotometry of the NLR of NGC 4151 using the Keck 10-m Telescope. The observations are the first in a series that test unambiguously several specific predictions that are based on earlier modeling of spatially unresolved emissionline spectra. Importantly, we partially resolve the source of most of the emission-line flux. Thus, the observations suitably complement analyses of spatially unresolved NLR spectra.

We present preliminary results about the velocity field of the ionized gas in the central region of NGC 1068, inferred from the [O III] λλ4959, 5007 emission lines. The data, 570 spectra in the inner 23″ × 18″ of this galaxy, were obtained with an optical fiber system which allows 2-D spectroscopy. The velocity field for the ionized gas inferred from the [O III] lines is in good agreement with recent results based on the Hα+[N II] lines.

The cosmological evolution of stellar populations can be studied by observing, e.g,, high-z radio galaxies, and comparing their SEDs to those of local objects. But in such objects, the nuclear activity strongly influences the optical properties; to disentangle the superposition of spatial and spectral effects, complete 3-D data cubes are needed, such as those that can be obtained with the pioneering 3-D instrument TIGER.

The presence of shocked regions in the narrow-line region (NLR) of active galactic nuclei (AGN) is discussed. Their effect on the physical conditions, in addition to photoionization from the central radiation source, is analyzed. We show that composite models, accounting for both shocks and photoionization, provide a consistent picture of the NLR which accounts for the observed emission-line and continuum spectra and is in agreement with the AGN unified model. The study of a particular object, NGC 5252, strengthens these results. It also shows that, besides explaining the observational data, the models make predictions that can be tested by infrared, optical, and X-ray imaging.

Representative results of a search for structures suggestive of shocked gas in the circumnuclear regions of Seyfert galaxies are presented. At issue is whether we can identify regions that appear to be shocked by outflows from the active nucleus. Such regions will be good targets for future spectrophotometric studies to determine what role shocks play in the physics of the AGN/host-galaxy interaction.

The classes of radio-loud AGN known as Gigahertz-peak spectrum (GPS), compact steep spectrum (CSS), and compact symmetric objects (CSO) represent an important sub-class of AGN, constituting, for example, 24% of the Baker, Hunstead, & Brinkmann (1995) sample. Table 1 summarizes some of their key properties.