Clues to Quasar Broad Line Region Geometry and Kinematics

We present evidence that the high-velocity CIV lambda 1549 emission line gas of radio-loud quasars may originate in a disk-like configuration, in close proximity to the accretion disk often assumed to emit the low-ionization lines. For a sample of 36 radio-loud z~2 quasars we find the 20--30% peak width to show significant inverse correlations with the fractional radio core-flux density, R, the radio axis inclination indicator. Highly inclined systems have broader line wings, consistent with a high-velocity field perpendicular to the radio axis. By contrast, the narrow line-core shows no such relation with R, so the lowest velocity CIV-emitting gas has an inclination independent velocity field. We propose that this low-velocity gas is located at higher disk-altitudes than the high-velocity gas. A planar origin of the high-velocity CIV-emission is consistent with the current results and with an accretion disk-wind emitting the broad lines. A spherical distribution of randomly orbiting broad-line clouds and a polar high-ionization outflow are ruled out.Comment: 5 Latex pages, 1 figure, accepted for publication in ApJ Letter

Radio imaging of core-dominated high redshift quasars

VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed at sight lines close to their (relativistic, $\gamma \approx$ 4-7) jet axes. The usefulness of the radio source orientation indicator R_V, being defined as ratio of radio core and rest frame optical V-band luminosity, is confirmed.Comment: 11 pages, 11 postscript figures, uses aa.cls 4.03 for LaTeX2e To appear in Astronomy and Astrophysic

Star-forming QSO host galaxies

The recent finding of substantial masses of cold molecular gas as well as young stellar populations in the host galaxies of quasars is at odds with results of Hubble Space Telescope imaging studies, since the latter appear to yield mature, quiescent early type hosts. It is demonstrated here that the characterization as `quiescent' is incorrect. Radio and far-infrared properties of both the HST sample and a larger comparison sample of uv-excess selected radio-quiet QSOs are consistent with substantial recent star-formation activity.Comment: Accepted for publication by Astronomy & Astrophysic

Environment of compact extragalactic radio sources

We have studied the interrelation of young AGN with their hosts. The objects of study are the young and powerful GPS and CSS radio sources. Due to their small size, GPS and CSS sources are excellent probes of this relation. Furhthermore, their young age allows us to compare them to the larger, old radio sources and establish a time-line evolution of this relation. Combining imaging and spectroscopy at UV, optical and radio wavelengths we find evidence of strong interaction between the host and the radio source. The presence and expansion of the radio source clearly affects the properties and evolution of the host. Furthermore, the radio source and host significantly affect each other's evolution. We describe our results and how these interactions take place.Comment: 6 pages. To appear in "Highlights of Spanisg astrophysics IV. Proceedings of the VII scientific meeting of the Spanish Astronomical Society". Editors: F. Figueras, J.M. Girart, M.Hernanz, C. Jordi. Springe

Early Growth and Efficient Accretion of Massive Black Holes at High Redshift

Black-hole masses of the highest redshift quasars (4 <~ z <~ 6) are estimated using a previously presented scaling relationship, derived from reverberation mapping of nearby quasars, and compared to quasars at lower redshift. It is shown that the central black holes in luminous z >~ 4 quasars are very massive (>~ 10^9 solar masses). It is argued that the mass estimates of the high-z quasars are not subject to larger uncertainties than those for nearby quasars. Specifically, the large masses are not overestimates and the lack of similarly large black-hole masses in the nearby Universe does not rule out their existence at high-z. However, AGN host galaxies do not typically appear fully formed or evolved at these early epochs. This supports scenarios in which black holes build up mass very fast in a radiatively inefficient (or obscured) phase relative to the stars in their galaxies. Additionally, upper envelopes of black-hole mass of approximately 10^{10} solar masses and bolometric luminosity of ~ 10^{48} erg/s are observed at all redshifts.Comment: 17 pages including 7 figures (5 in color) and 1 table. To appear in ApJ, v600, January 1, 200

1245+676 - a CSO/GPS source being an extreme case of a double-double structure

AGN with the so-called `double-double' radio structure have been interpreted as restarted AGN where the inner structure is a manifestation of a new phase of activity which happened to begin before the outer radio lobes resulting from the previous one had faded completely. The radio galaxy 1245+676 is an extreme example of such a double-double object - its outer structure, measuring 970 h^{-1} kpc, is five orders of magnitude larger than the 9.6 h^{-1} pc inner one. We present a series of VLBI observations of the core of 1245+676 which appears to be a compact symmetric object (CSO). We have detected the motion of the CSO's lobes, measured its velocity, and inferred the kinematic age of that structure.Comment: A contribution to The Third Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources, Kerastari, Greece May 28-31, 2002. Refereed and accepted by Publications of the Astronomical Society of Australia. 4 pages. Final version copyedited by PASA Edito

Enhancing Terminal Deoxynucleotidyl Transferase Activity on Substrates with 3' Terminal Structures for Enzymatic De Novo DNA Synthesis.

Enzymatic oligonucleotide synthesis methods based on the template-independent polymerase terminal deoxynucleotidyl transferase (TdT) promise to enable the de novo synthesis of long oligonucleotides under mild, aqueous conditions. Intermediates with a 3' terminal structure (hairpins) will inevitably arise during synthesis, but TdT has poor activity on these structured substrates, limiting its usefulness for oligonucleotide synthesis. Here, we described two parallel efforts to improve the activity of TdT on hairpins: (1) optimization of the concentrations of the divalent cation cofactors and (2) engineering TdT for enhanced thermostability, enabling reactions at elevated temperatures. By combining both of these improvements, we obtained a ~10-fold increase in the elongation rate of a guanine-cytosine hairpin