Algebraic Torsion in Contact Manifolds

We extract a nonnegative integer-valued invariant, which we call the "order of algebraic torsion", from the Symplectic Field Theory of a closed contact manifold, and show that its finiteness gives obstructions to the existence of symplectic fillings and exact symplectic cobordisms. A contact manifold has algebraic torsion of order zero if and only if it is algebraically overtwisted (i.e. has trivial contact homology), and any contact 3-manifold with positive Giroux torsion has algebraic torsion of order one (though the converse is not true). We also construct examples for each nonnegative k of contact 3-manifolds that have algebraic torsion of order k but not k - 1, and derive consequences for contact surgeries on such manifolds. The appendix by Michael Hutchings gives an alternative proof of our cobordism obstructions in dimension three using a refinement of the contact invariant in Embedded Contact Homology.Comment: 53 pages, 4 figures, with an appendix by Michael Hutchings; v.3 is a final update to agree with the published paper, and also corrects a minor error that appeared in the published version of the appendi

The evolution of Radio Loud Quasar host galaxies: AO observations at z = 3

We report on ESO--VLT adaptive optics imaging of one radio-loud quasar at z $\sim$ 3. In spite of the large distance of the object we are able to detect its surrounding extended nebulosity the properties of which are consistent with an underlying massive galaxy of M$_K$ $\sim$ --27 and effective radius R$_e$ = 7 kpc. As far as we know this is the clearest detection of a radio loud quasar host at high redshift. The host luminosity is indicative of the existence of massive spheroids even at this early cosmic epoch. The host luminosity is about 1 magnitude fainter than the expected value based on the average trend of the host galaxies of RLQ at lower redshift. The result, which however is based on a single object, suggests that at z $\sim$ 3 there is a deviation from a luminosity--redshift dependence regulated only by passive evolution.Comment: 6 pages, 3 figures, TeX uses elsart.cls, from workshop "QSO Host Galaxies: Evolution and Environment" (Univ. Leiden, Aug. 22-26, 2005

Retrieval cues fail to influence contextualized evaluations.

Initial evaluations generalise to new contexts, whereas counter-attitudinal evaluations are context-specific. Counter-attitudinal information may not change evaluations in new contexts because perceivers fail to retrieve counter-attitudinal cue-evaluation associations from memory outside the counter-attitudinal learning context. The current work examines whether an additional, counter-attitudinal retrieval cue can enhance the generalizability of counter-attitudinal evaluations. In four experiments, participants learned positive information about a target person, Bob, in one context, and then learned negative information about Bob in a different context. While learning the negative information, participants wore a wristband as a retrieval cue for counter-attitudinal Bob-negative associations. Participants then made speeded as well as deliberate evaluations of Bob while wearing or not wearing the wristband. Internal meta-analysis failed to find a reliable effect of the counter-attitudinal retrieval cue on speeded or deliberate evaluations, whereas the context cues influenced speeded and deliberate evaluations. Counter to predictions, counter-attitudinal retrieval cues did not disrupt the generalisation of first-learned evaluations or the context-specificity of second-learned evaluations (Experiments 2-4), but the counter-attitudinal retrieval cue did influence evaluations in the absence of context cues (Experiment 1). The current work provides initial evidence that additional counter-attitudinal retrieval cues fail to disrupt the renewal and generalizability of first-learned evaluations

On the distance of PG 1553+11. A lineless BL Lac object active in the TeV band

Context: The redshift of PG 1553+11, a bright BL Lac object (V~14), is still unknown. It has been recently observed in the TeV band, a fact that offers an upper limit for the redshift z<0.4. Aims: We intend to provide a lower limit for the distance of the object. Methods: We used a chi^2 procedure to constrain the apparent magnitude of the host galaxy in archived HST images. Supposing that the host galaxy is typical of BL Lac objects (M_{R} -22.8), a lower limit to the distance can be obtained from the limit on the apparent magnitude of the host galaxy. Results: Using the 3 sigma limit on the host galaxy magnitude, the redshift is found to be greater or equal to 0.25. Conlusions: The redshift of PG 1553+11 is probably in the range z=0.3-0.4, making this object the most distant extragalactic source so far detected in the TeV energies. We suggest that other bright BL Lac objects of unknown redshift and similar spectroscopic characteristics may be interesting targets for TeV observations.Comment: Accepted for publication in A&A letters, 4 pages, 5 figure

Mapping the Kinematics of the Narrow-Line Region in the Seyfert Galaxy NGC 4151

Using The Hubble Space Telescope's Space Telescope Imaging Spectrograph HST's STIS, observations of the OIII emission from the narrow-line region (NLR) of NGC 4151 were obtained and radial velocities determined. Five orbits of HST time were used to obtain spectra at five parallel slit configurations, at a position angle of 58 degrees, with spatial resolution 0.2 arcseconds across and 0.1 arcseconds along each slit. A spectral resolving power of ~ 9,000 with the G430M grating gave velocity measurements accurate to ~ 34 km/s. A kinematic model was generated to match the radial velocities, for comparison to previous kinematic models of biconical radial outflow developed for low-dispersion spectra at two slit positions. The new high-resolution spectra permit the measurement of accurate velocity dispersions for each radial-velocity component. The full-width at half-maximum (FWHM) reaches a maximum of 1000 km/s near the nucleus, and generally decreases with increasing distance to about 100 km/s in the extended narrow-line region (ENLR), starting at about 6 arcseconds from the nucleus. In addition to the bright emission knots, which generally fit our model, there are faint high velocity clouds which do not fit the biconical outflow pattern of our kinematic model. These faint clouds occur at the turnover points of the outflowing bright clouds. We suggest possible scenarios that could explain these rogue clouds: (1) backflow resulting from shocks and (2) outflow outside of the bicones, although the latter does not explain how the knots are ionized and accelerated. A comparison of our observations with a high-resolution radio map shows that there is no evidence that the kinematics of the NLR clouds are affected by the radio lobes that comprise the inner jet.Comment: 30 pages, 15 figures (some color), accepted for publication in the Astronomical Journal. Downloadable versions of the paper with high resolution figures/images are available here: http://www.chara.gsu.edu/~crenshaw/NGC4151_kinematics.pdf <--PDF Version http://www.chara.gsu.edu/~crenshaw/NGC4151_kinematics.ps <--PS Versio

Spatially resolved spectra of 3C galaxy nuclei

We present and discuss visible-wavelength long-slit spectra of four low redshift 3C galaxies obtained with the STIS instrument on the Hubble Space Telescope. The slit was aligned with near-nuclear jet-like structure seen in HST images of the galaxies, to give unprecedented spatial resolution of the galaxy inner regions. In 3C 135 and 3C 171, the spectra reveal clumpy emission line structures that indicate outward motions of a few hundred km s$^{-1}$ within a centrally illuminated and ionised biconical region. There may also be some low-ionisation high-velocity material associated with 3C 135. In 3C 264 and 3C 78, the jets have blue featureless spectra consistent with their proposed synchrotron origin. There is weak associated line emission in the innermost part of the jets with mild outflow velocity. These jets are bright and highly collimated only within a circumnuclear region of lower galaxy luminosity, which is not dusty. We discuss the origins of these central regions and their connection with relativistic jets.Comment: 15 pages incl Tables, 12 diagrams, To appear in A

Probing the Kinematics of the Narrow-Line Region in Seyfert Galaxies with Slitless Spectroscopy: Observational Results

We present slitless spectra of 10 Seyfert galaxies observed with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The spectra cover the [OIII] 4959, 5007 emission lines at a spectral resolving power of ~9000 and a spatial resolution of 0.1". We compare the slitless spectra with previous HST narrow-band images to determine the velocity shifts and dispersions of the bright emission-line knots in the narrow-line regions (NLRs) of these Seyferts. Many knots are spatially resolved with sizes of tenths of arcsecs, corresponding to tens of pcs, and yet they appear to move coherently with radial velocities between zero and +/- 1200 km/s with respect to the systemic velocities of their hostgalaxies. The knots also show a broad range in velocity dispersion, ranging from ~30 km/s (the velocity resolution) to ~1000 km/s FWHM. Most of the Seyfert galaxies in this sample show an organized flow pattern, with radial velocities near zero at the nucleus (defined by the optical continuum peak) and increasing to maximum blueshifts and redshifts within ~1'' of the nucleus, followed by a decline to the systemic velocity. The emission-line knots also follow a general trend of decreasing velocity dispersion with increasing distance. In the Seyfert 2 galaxies, the presence of blueshifts and redshifts on either side of the nucleus indicates that rotation alone cannot explain the observed radial velocities, and that radial outflow plays an important role. Each of the Seyfert galaxies in this sample (with the exception of Mrk 3) shows a bright, compact (FWHM < 0.5") [O III] knot at the position of its optical nucleus. These nuclear emission-line knots have radial-velocity centroids near zero, but they typically have the highest velocity dispersions.Comment: 28 pages, 5 figures (on 9 pages), accepted for A