We use the emission line measurements of 3CR radio sources with redshift 32.8. Conversely LEG cover the whole range of radio power encompassed by this 3CR subsample (30.7 < log L(178) < 35.4) and they are of both FRI and FRII type. The brightest LEG are all FRII. HEG and LEG obey to two (quasi) linear correlations between the optical line and extended radio luminosities, with HEG being brighter than LEG in the [OIII] line by a factor of ~10. HEG and LEG are offset also in a plane that compares the black hole mass and the ionizing nuclear luminosity. However, although HEG are associated with higher nuclear luminosities, we find LEG among the brightest radio sources of the sample and with a clear FRII morphology, indistinguishable from those seen in HEG. This suggests that LEG are not simply objects with a lower level of accretion. We speculate that the differences between LEG and HEG are related to a different mode of accretion: LEG are powered by hot gas, while HEG require the presence of accreting material. The high temperature of the accreting gas in LEG accounts for the lack of cold structures (i.e. molecular torus and Broad Line Region), for the reduced radiative output of the accretion disk, and for the lower gas excitation. [ABRIDGED]

We explore the implications of our optical spectroscopic survey of 3CR radio sources with z < 0.3 for the unified model (UM) for radio-loud AGN, focusing on objects with a “edge-brightened” (FR II) radio morphology. The sample contains 33 high ionization galaxies (HIGs) and 18 broad line objects (BLOs). According to the UM, HIGs, the narrow line sources, are the nuclearly obscured counterparts of BLOs. The fraction of HIGs indicates a covering factor of the circumnuclear matter of 65% that corresponds, adopting a torus geometry, to an opening angle of 50◦ ± 5. No dependence on redshift and luminosity on the torus opening angle emerges. We also consider the implications for a “clumpy” torus. The distributions of total radio luminosity of HIGs and BLOs are not statistically distinguishable, as expected from the UM. Conversely, BLOs have a radio core dominance, R, more than ten times larger with respect to HIGs, as expected in case of Doppler boosting when the jets in BLOs are preferentially oriented closer to the line of sight than in HIGs. Modeling the R distributions leads to an estimate of the jet bulk Lorentz factor of Γ ∼ 3−5. The test of the UM based on the radio source size is not conclusive due to the limited number of objects and because the size distribution is dominated by the intrinsic scatter rather than by projection effects. The [O II] line luminosities in HIGs and BLOs are similar but the [O III] and [O I] lines are higher in BLOs by a factor of ∼2. We ascribe this effect to the presence of a line emitting region located within the walls of the obscuring torus, visible in BLOs but obscured in HIGs, with a density higher than the [O II] critical density. We find evidence that BLOs have broader [O I] and [O III] lines than HIGs of similar [O II] width, as expected in the presence of high density gas in the proximity of the central black hole. In conclusion, the radio and narrow line region (NLR) properties of HIGs and BLOs are consistent with the UM predictions when the partial obscuration of the NLR is taken into account. We also explored the radio properties of 21 3CR low ionization galaxies with a FR II radio morphology at z < 0.3. We find evidence that they cannot be part of the model that unifies HIGs and BLOs, but they are instead intrinsically different source, still reproduced by a randomly oriented population.

There is increasing evidence for the existence of supermassive black holes at the centers of all galaxies, and much work is being devoted to understand the process that lead to their formation, the duty cycle for the active phase of these black holes and the relevant fueling mechanisms. Seyfert galaxies determined by HST high spatial resolution observations of the kinematics of the central regions. The study of the gas kinematics provides a unique tool to probe the gravitational potential of the nuclear regions of Seyfert galaxies down to a limit radius of a few parsecs. This is particularly important to detect and measure the mass associated with any central massive black hole. We have obtained high spatial resolution spectra of a number of Seyfert galaxies, with the STIS G430M and G750M gratings, and we have been able to separate the emission line components associated with different velocity systems. We have derived two-dimensional velocity fields and determined the mass of the central black hole with good precision for each of the galaxies.

The presence of optical synchrotron jets in radio galaxies is relatively rare. Here we show that of the nearest five FR I 3CR radio galaxies showing optical jets, four show evidence for almost circular, presumably face-on, dust disks. This is strong support for the twofold idea that (1) jets emerge close to perpendicular to inner gas disks and (2) optical nonthermal synchrotron emission is seen only when the jet points toward the observer. The implied critical angle to the line of sight is approximately 30°-40°; i.e., if the angle of the jet to the line of sight is less than about 40° we see an optical jet. The corresponding relativistic γ factor is ≈1.5, which is consistent with current observations of jet proper motion that show a range up to γ ~ 6 for M87. The relatively low speeds implied by γ ≈ 1.5 may be due to a global deceleration of the jet as in unified theories or else to stratification within the jet. Unresolved nuclei are common in the optical. Their luminosities are also consistent with the beaming concept when compared to inclination inferred from the dust lanes. The disk sizes are typically several hundred parsecs to kiloparsec size. The galaxy with an optical jet that does not show a face-on disk, M87, instead has more complex radial dust and ionized gas filaments.

We present narrow-band images of sixty-four 3CR radio sources observed in lines of [OII] 3727 Å, [OIII] 5007 Å, and Hα using the WFPC2 camera on-board HST. The images reveal a wide variety of emission lime morphologies, from compact nuclear regions to large-scale emission knots, filaments, and spiral-like structures. Many objects give evidence of ionization cones. In general we find a close correspondence between the emission-line and radio axes; most are aligned within 40 degrees. There is also evidence for a positive correlation between radio luminosity and the spatial extent of the emission-line region. Properties of interesting individual objects are discussed.

We present new HST NICMOS observations of NGC 4945, a starburst galaxy hosting a highly obscured active nucleus that is one of the brightest extragalactic sources at 100 keV. The HST data are complemented with ground based [FeII] line and mid--IR observations. A 100pc-scale starburst ring is detected in Pa alpha, while H_2 traces the walls of a super bubble opened by supernova-driven winds. The conically shaped cavity is particularly prominent in Pa alpha equivalent width and in the Pa alpha/H_2 ratio. Continuum images are heavily affected by dust extinction and the nucleus of the galaxy is located in a highly reddened region with an elongated, disk-like morphology. No manifestation of the active nucleus is found, neither a strong point source nor dilution in CO stellar features, which are expected tracers of AGN activity. Even if no AGN traces are detected in the near-IR, with the currently available data it is still not possible to establish whether the bolometric luminosity of the object is powered by the AGN or by the starburst: we demonstrate that the two scenarios constitute equally viable alternatives. However, the absence of any signature other than in the hard X-rays implies that, in both scenarios, the AGN is non-standard: if it dominates, it must be obscured in all directions, conversely, if the starburst dominates, the AGN must lack UV photons with respect to X-rays. An important conclusion is that powerful AGNs can be hidden even at mid-infrared wavelengths and, therefore, the nature of luminous dusty galaxies cannot be always characterized by long-wavelength data alone but must be complemented with sensitive hard X-ray observations.

We present mid-infrared integrated photometric properties for a sample of 28 early-type galaxies observed with the ISOCAM instrument on board the ISO satellite. The galaxies were observed at 6.75, 9.63 and 15 mum. We found mid-IR luminosities in the range 5 x 10(8) to 2 x 10(10) L-circle dot. The spectral energy distribution (SED) of the galaxies were built using the mid-IR data together with previously published UV, optical and Far-IR data. These SEDs show that the mid-IR emission of early-type galaxies is dominated by dust emission which can be fit by a 450 K black body.

We present results of a CCD optical imaging survey of the dust content in 22 early-type luminous galaxies, selected from the RC3 Catalog. A large fraction (75%) of the observed galaxies show significant amounts of dust. The morphology and size of the dust distribution of the observed galaxies follows very closely that of the ionized gas. For each galaxy, we have used broad band V and R filters imaging to build colour maps and determine the A V and A R extinction maps. We have found typical A V values of 0.026 and A R of 0.023 and have derived values in the range 0.49-0.68. The A V values together with an assumption of the dust grain size and composition enable us to estimate the dust masses. We have studied the correlations between the mass of dust and the Hα , IR and luminosities. Finally, we investigate the possible mechanisms responsible for the dust emission.

We present observations of the M87 jet made with the Faint Object Camera on board the Hubble Space Telescope at five epochs between 1994 and 1998. These observations reveal 10 superluminal features within the first 6'' of the jet, with eight of these having apparent speeds in the range 4c-6c. Two additional features within the first arcsecond of the jet have subluminal speeds of 0.63c and 0.84c. The latter of these, named HST-1 East, appears to emit new superluminal features moving at 6c, which subsequently fade with a half-intensity timescale of ~2 yr. The fastest speeds we observe require a Lorentz factor γ ≥ 6 for the bulk flow and a jet orientation within 19° of the line of sight, in the context of the relativistic jet model. Finding such large γ in an FR I radio source like M87 strongly supports BL Lac/FR I unification models. These large speeds help to mitigate the particle lifetime problem posed by the optical emission, as well as the jet confinement problem.

We present highlights and preliminary results of our HST observing programs on the M 87 jet. We confirm previously known similarities between the radio and optical jets, but also describe a wealth of differences and new structural details. We identify numerous compact optical features, as well as new structures in the shock-like knots A and C. We also find considerable evidence for structure in the jet as a function of distance from the jet axis — evidence is seen for radial structure in the radio / optical spectrum, in the optical / optical spectrum, and in the polarimetry. Our monitoring between 1994 and 1996 shows numerous features with superluminal speeds in the range 4c to 6c, as well as the emergence of new superluminal components and rapid fading of old features.

Repeated imaging observations have been made of NGC 3627 with the Hubble Space Telescope in 1997/98, over an interval of 58 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F8141,V band. The galaxy hosted the prototypical, Branch normal, type la supernova SN 1989B. A total of 83 variables have been found, of which 68 are definite Cepheid variables with periods ranging from 75 days to 3.85 days. The de-reddened distance modulus is determined to be (m - M)(sub 0) = 30.22 +/- 0.12 (internal uncertainty) using a subset of the Cepheid data whose reddening and error parameters are secure. The photometric data of Wells et al. (1994), combined with the Cepheid data for NGC 3627 give MB(max) = -19.36 +/- 0.18 and M(sub V)(max) = -19.34 +/- 0.16 for SN 1989B. Combined with the previous six calibrations in this program, plus two additional calibrations determined by others gives the mean absolute magnitudes at maximum of (M(sub B)) = -19.48 +/- 0.07 for Brunch normal SNe Ia at this interim stage in the calibration program. Using the argument by Wells et al. (1994) that SN 1989B here is virtually identical in decay rate and colors at maximum with SN 198ON in NGC 1316 in the Fornax cluster, and that such identity means nearly identical absolute magnitude, it follows that the difference in the distance modulus of NGC 3627 and NGC 1316 is 1.62 +/- 0.03 mag. Thus the NGC 3627 modulus implies that (m - M)(sub 0) = 31.84 for NGC 1316. The second parameter correlations of M(max) of blue SNe la with decay rate, color at maximum, and Hubble type are re-investigated. The dependence of (M(max)) on decay rate is non-linear, showing a minimum for decay rates between 1.0 less than ADelta(sub m)15 less than 1.6. Magnitudes corrected for decay rate show no dependence on Hubble type, but a dependence on color remains. Correcting both the fiducial sample of 34 SNe la with decay-rate data and the current eight calibrating SNe la for the correlation with decay rate as well as color gives H(sub 0) = 60 +/- 2 (internal) km/s Mpc, in both B and V. The same value to within 4% is obtained if only the SNe la in spirals (without second parameter corrections) are considered. The correlation of SNe la color at maximum with M(max) cannot be due to internal absorption because the slope coefficients in B, V, and I with the change in magnitude are far from or even opposite to the canonical reddening values. The color effect must be intrinsic to the supernova physics. Absorption corrections of distant blue SNe la will lead to incorrect values of H(sub 0). The Cepheid distances used in this series are insensitive to metallicity differences. The zeropoint of the P-L relation is based on an assumed LMC modulus of (m - M)(sub 0) = 18.50. As this may have to be increased by 0(sup m).06 to 0(sup m).08, all distances in this paper will follow and Ho will decrease by 3 - 4%.

Schmidt et al. presented strong evidence (photometry and spectroscopy) that the late time optical emission of SN 1991T in the Virgo spiral NGC 4527 is caused by a light echo. Here, we present photometry with the Wide Field and Planetary Camera 2 and high-resolution imaging polarimetry and photometry with the Faint Object Camera on board the Hubble Space Telescope, which demonstrates that the feature is indeed a light echo of the original supernova. We show that the emission is spatially resolved, complex, and both growing in size and changing in morphology. The echo is slowly fading. Our primary interest is to use the echo for estimating the distance to the host galaxy geometrically (see 1994 work by Sparks). Given that the elapsed time since the supernova exploded is small and that the galaxy is relatively distant, the expected region of maximally polarized emission cannot be fully resolved as yet. However, we do find polarized emission at the center of the echo, and simple models may be used to yield a distance estimate. The models favor smaller distances, with approximate to 15 Mpc being the upper allowable distance, subject to caveats described in the text. The echo is consistent with being caused by a dust cloud of uniform density n similar to 0.9 cm(-3) and extending to approximate to 50 pc in front of the supernova. It is encouraging that even in a case very far from ideal, we can use this type of observation to derive a distance.

We present and discuss optical continuum images made with the Hubble Space Telescope of the radio galaxy 1138-262 at z = 2.2. This object possesses one of the clumpiest optical morphologies of all known high-redshift radio galaxies, consisting of a bright nucleus aligned along the radio axis and a number of smaller components distributed over a region as large as the radio source (130 kpc). The clumps have sizes ranging from 3 to 13 kpc and absolute visual magnitudes between MV = -21.8 and MV = -19.4. On the basis of HST and previous observations, we claim that these clumps are star-forming galaxies that will be accreted by the host galaxy of 1138-262. We compare this radio galaxy with other high-redshift objects and with the predictions of current scenarios of galaxy formation.

We used HST, WFPC-2 observations of 40 3CR radio galaxies that show evidence for the presence of dust in the nuclear regions to investigate the connection between the radio source and the dust. The data cover a redshift range 0 < z < 0.5. A large range of dust morphologies is observed, including disk-like and filamentary structures. We find that there is a connection between the radio source and the dust. There is a strong tendency for the direction of radio source axes and the dust major axes to be perpendicular, and these position angle differences strongly correlate with the morphologies and the linear sizes of the dust features. The radio source has a preference to be perpendicular to the dust major axis when the dust is settled and localized (linear sizes < 2.5 kpc). There is no such a preference when the dust is distributed in a filamentary fashion throughout the radio galaxy.

We have obtained long-slit observations of the circumnuclear region of M87 at three different locations, with a spatial sampling of 0''.028 using the Faint Object Camera f/48 spectrograph on board HST. These data allow us to determine the rotation curve of the inner similar to 1'' of the ionized gas disk in CO rrl lambda 3727 to a distance as close as 0''.07 (similar or equal to 5 pc) to the dynamic center, thereby significantly improving on both the spatial resolution and coverage of previous FOS observations. We have modeled the kinematics of the gas under the assumption of the existence of both a central black hole and an extended central mass distribution, taking into account the effects of the instrumental PSF, the intrinsic luminosity distribution of the line, and the finite size of the slit. We find that the central mass must be concentrated within a sphere whose maximum radius is 0''.05 (similar or equal to 3.5 pc) and show that both the observed rotation curve and line profiles are consistent with a thin disk in Keplerian motion. We conclude that the most likely explanation for the observed motions is the presence of a supermassive black hole and derive a value of M-BH = (3.2 +/- 0.9) x 10(9) M-. for its mass.