Polarization Profiles of Scattered Emission Lines. II. Upstream Dust Scattering in the HH 1 Jet

Detailed comparisons are made between observations of scattered light upstream of the head of the HH~1 jet and predictions of simple scattering models. It is shown that, in order to unambiguously determine the velocity of the head of the jet (bow shock) with respect to the upstream dust, existing spectroscopic observations are insufficient and that spectropolarimetric observations of the scattered light are necessary. Such an independent measure of the bow shock velocity is important in order to test ``multiple outflow'' theories of Herbig-Haro jets. It is also shown 2that the scattering dust must have a very forward-throwing scattering phase function (\langle\cos\theta\rangle\msim 0.7) and slight evidence is found for a dust-gas ratio that is higher than average.Comment: 11 pages, uuencoded compressed postscript (including 9 figures), accepted for publication in Ap.J., IAUNAM_contrib.#34

Models relating the radio emission and ionised gas in Seyfert nuclei

Possible models are discussed in which the radio emitting components in Seyfert II nuclei can compress and accelerate the ambient nuclear medium to produce the characteristics of the narrow line region. A first order model, which considers only the expansion of the radio components, is briefly described. However, in many Seyfert nuclei it appears that the linear motion of the radio components is also important. This can result in shock heating of the ambient medium, and if the cooling time is long enough, can lead to a displacement between the radio component and the associated emission lines. This effect may be present in NGC 1068 and NGC 5929 and by considering ram pressure balance and the cooling length it is possible to estimate lobe velocities and ambient densities

HST and Spitzer point source detection and optical extinction in powerful narrow-line radio galaxies

We present the analysis of infrared HST and Spitzer data for a sample of 13 FRII radio galaxies at 0.03<z<0.11 that are classified as narrow-line radio galaxies (NLRG). In the context of the unified schemes for active galactic nuclei (AGN), our direct view of the AGN in NLRG is impeded by a parsec-scale dusty torus structure. Our high resolution infrared observations provide new information about the degree of extinction induced by the torus, and the incidence of obscured AGN in NLRG. We find that the point-like nucleus detection rate increases from 25 per cent at 1.025$\mu$m, to 80 per cent at 2.05$\mu$m, and to 100 per cent at 8.0$\mu$m. This supports the idea that most NLRG host an obscured AGN in their centre. We estimate the extinction from the obscuring structures using X-ray, near-IR and mid-IR data. We find that the optical extinction derived from the 9.7$\mu$m silicate absorption feature is consistently lower than the extinction derived using other techniques. This discrepancy challenges the assumption that all the mid-infrared emission of NLRG is extinguished by a simple screen of dust at larger radii. This disagreement can be explained in terms of either weakening of the silicate absorption feature by (i) thermal mid-IR emission from the narrow-line region, (ii) non-thermal emission from the base of the radio jets, or (iii) by direct warm dust emission that leaks through a clumpy torus without suffering major attenuation.Comment: 18 pages, 7 figures, 8 tables, accepted for publication in MNRA

The morphology of Sersic-Pastoriza galaxies

The authors present the preliminary results of their radio-continuum and neutral hydrogen observations of Sersic-Pastoriza (S-P) galaxies. They show that the central regions contain a population of compact features thought to be young supernova remnants (SNRs) and discuss the overall morphology of the nuclei

High Accuracy Near-infrared Imaging Polarimetry with NICMOS

The findings of a nine orbit calibration plan carried out during HST Cycle 15, to fully determine the NICMOS camera 2 (2.0 micron) polarization calibration to high accuracy, are reported. Recently Ueta et al. and Batcheldor et al. have suggested that NICMOS possesses a residual instrumental polarization at a level of 1.2-1.5%. This would completely inhibit the data reduction in a number of GO programs, and hamper the ability of the instrument to perform high accuracy polarimetry. We obtained polarimetric calibration observations of three polarimetric standards at three spacecraft roll angles separated by ~60deg. Combined with archival data, these observations were used to characterize the residual instrumental polarization in order for NICMOS to reach its full potential of accurate imaging polarimetry at p~1%. Using these data, we place an 0.6% upper limit on the instrumental polarization and calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, are seen to dominate the accuracy of p and theta. However, the updated coefficients do allow imaging polarimetry of targets with p~1.0% at an accuracy of +/-0.6% and +/-15deg. This work enables a new caliber of science with HST.Comment: 13 pages, 9 figures, PASP accepte

High Accuracy Imaging Polarimetry with NICMOS

The ability of NICMOS to perform high accuracy polarimetry is currently hampered by an uncalibrated residual instrumental polarization at a level of 1.2-1.5%. To better quantify and characterize this residual we obtained observations of three polarimetric standard stars at three separate space-craft roll angles. Combined with archival data, these observations were used to characterize the residual instrumental polarization to enable NICMOS to reach its full polarimetric potential. Using these data, we calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, dominate the accuracy of p and theta. However, the new coefficients now enable imaging polarimetry of targets with p~1.0% at an accuracy of +/-0.6% and +/-15 degrees.Comment: 5 pages, 2 figures. Contributed talk, "Astronomical Polarimetry 2008. Science from Small to Large Telescopes" La Malbaie, Quebec, Canada, 200

WFPC2 LRF Imaging of Emission Line Nebulae in 3CR Radio Galaxies

We present HST/WFPC2 Linear Ramp Filter images of high surface brightness emission lines (either [OII], [OIII], or H-alpha+[NII]) in 80 3CR radio sources. We overlay the emission line images on high resolution VLA radio images (eight of which are new reductions of archival data) in order to examine the spatial relationship between the optical and radio emission. We confirm that the radio and optical emission line structures are consistent with weak alignment at low redshift (z < 0.6) except in the Compact Steep Spectrum (CSS) radio galaxies where both the radio source and the emission line nebulae are on galactic scales and strong alignment is seen at all redshifts. There are weak trends for the aligned emission line nebulae to be more luminous, and for the emission line nebula size to increase with redshift and/or radio power. The combination of these results suggests that there is a limited but real capacity for the radio source to influence the properties of the emission line nebulae at these low redshifts (z < 0.6). Our results are consistent with previous suggestions that both mechanical and radiant energy are responsible for generating alignment between the radio source and emission line gas.Comment: 80 pages, 54 figures. Accepted for publication in ApJ

Integral Field Spectroscopy of 23 Spiral Bulges

We have obtained Integral Field Spectroscopy for 23 spiral bulges using INTEGRAL on the William Herschel Telescope and SPIRAL on the Anglo-Australian Telescope. This is the first 2D survey directed solely at the bulges of spiral galaxies. Eleven galaxies of the sample do not have previous measurements of the stellar velocity dispersion (sigma*). These data are designed to complement our Space Telescope Imaging Spectrograph program for estimating black hole masses in the range 10^6-10^8M_sun using gas kinematics from nucleated disks. These observations will serve to derive the stellar dynamical bulge properties using the traditional Mgb and CaII triplets. We use both Cross Correlation and Maximum Penalized Likelihood to determine projected sigma* in these systems and present radial velocity fields, major axis rotation curves, curves of growth and sigma* fields. Using the Cross Correlation to extract the low order 2D stellar dynamics we generally see coherent radial rotation and irregular velocity dispersion fields suggesting that sigma* is a non-trivial parameter to estimate.Comment: 11 pages, 30 figures, accepted for publication in ApJ

An optical spectroscopic survey of the 3CR sample of radio galaxies with z<0.3. III. Completing the sample

We present optical nuclear spectra for nine 3CR radio sources obtained with the Telescopio Nazionale Galileo, that complete our spectroscopic observations of the sample up to redshifts $<$ 0.3. We measure emission line luminosities and ratios, and derive a spectroscopic classification for these sources.Comment: Accepted for publication in A&A. We provide as additional material two tables presenting the main data for the whole sample, combining the results presented here with those of Paper I and Paper I