1. Examination of a High Redshift Quasar and its Host Galaxy - Ross, Nathaniel R.
We have measured the spectral energy distribution (SED) of the host galaxy of the z_s=1.7 gravitationally lensed quasar SDSS J1004+4112 from 0.44-8.0 micron (0.16-3.0 micron in the rest frame). The large angular extent of the lensed images and their separation from the central galaxy of this cluster lens allows the images to be resolved even with the Spitzer Space Telescope. Based on the SED, the host galaxy is a mixture of relatively old and intermediate age stars with an inferred stellar mass of log (M_star/M_sun)=11.09+/-0.28 and a star formation rate of log(Mdot/M_sun yr^-1)=1.18+/-0.26. Given the estimated black hole mass of M_BH~ 10^8.6 M_sun...

2. Cosmology with Quasar Absorption Lines - Crighton, Neil, Physics, Faculty of Science, UNSW
In this thesis we make a new measurement of the primordial deuterium abundance, and analyse five other systems selected as possible D/H candidates. We also undertake an investigation of systematic errors in a system where an existing deuterium measurement has been made. We measure the number of hydrogen components and their velocity distributions in a moderate and high redshift sample of Lyman limit systems in one Angstrom resolution spectra. We present a new measurement of the deuterium-to-hydrogen ratio, D/H, at z=3.2560 in a newly-discovered low metallicity absorption system towards the quasar PG1937-1009. We attempt to account for any systematic effects...

3. Analysis of quasar images : the luminosity function of AGN host galaxies - Kuhlbrodt, Björn

4. Quasar--Quasar Correlation Function in the Palomar Transit Grism Survey
Quasar-quasar correlation function is measured in four strips of the Palomar Transit Grism Survey (Schneider, Schmidt, & Gunn 1994), covering an effective area of 50 square degrees at high Galactic latitude. The quasar sample contains 232 objects with well-defined line-flux and equivalent-width selection criteria. It spans the redshift range of 0:7 ! z ! 4:7 and the magnitude range of 16 ! r 4 ! 22. Two estimators are used to measure the covariance function of quasars, ¸ qq = DD=RR Gamma 1 and ¸ qq = (DD Gamma 2DR + RR)=RR. Comparison samples are constructed by scrambling of redshifts and angular coordinates, and by randomly placing quasars within...

5. A Polarization Study of Quasar 4C71.07.
Introduction The study of the magnetic fields in the jets of quasars has shown a trend for the field to align well with the jet direction on arc second scales [1]. However, polarization VLBI, probing the parsec scale jet, shows a substantial range in the difference between the structural and inferred magnetic field directions. At 6 cm this range is as large as 30 - 40 degrees in some quasars [2,3] with quasar 4C71.07 showing one of the largest misalignments. Quasar 4C71.07 (FR II, z = 2.16, 1 mas corresponds to 4pc assuming H 0 = 100kms Gamma1 Mpc Gamma1 ; q 0 = 0:5) has been observed over a wide range...

6. Investigações das periodicidades do quasar 3C 273 pelas transformadas de Fourier e Wavelet de suas curvas de luz em radio - Márcia Auta dos Santos
O estudo da periodicidade das curvas de luz de quasares em comprimentos de onda rádio, é importante para se entender a natureza física dos mesmos, tendo como um dos objetivos acompreensão da origem e o funcionamento dos jatos relativísticos presentes nestes objetos extragaláticos. Desta forma, o trabalho visa apresentar um método para determinar a possível periodicidade do quasar 3C 273. Este objeto tem sido observado regularmente em 4,8, 8,0, 14,5, 22,0 e 43,0 GHz nos Rádio Observatório do Itapetinga (Brasil) e Michigan (EUA). Este trabalho faz parte de um projeto de colaboração internacional entre estes dois centros de pesquisa.

7. Quasar-galaxy associations revisited - Benítez, Narciso; Sanz Estévez, José Luis; Martínez-González, Enrique
9 pages, 6 figures.-- MNRAS accepted.

8. A Spectacular Post-Starburst Quasar - M. S. Brotherton,Wil Van Breugel,S. A. Stanford,R. J. Smith,B. J. Boyle,Lance Miller,T. Shanks,M. Croom
We report the discovery of a spectacular "post-starburst quasar" UN J1025Gamma0040 (B = 19; z = 0:634). The optical spectrum is a chimera, displaying the broad Mg II 2800 emission line and strong blue continuum characteristic of quasars, but is dominated in the red by a large Balmer jump and prominent high-order Balmer absorption lines indicative of a substantial young stellar population at similar redshift. Stellar synthesis population models show that the stellar component is consistent with a 400 Myr old instantaneous starburst with a mass of !10 11 M fi . A deep, K s -band image taken in 0:5 00 seeing shows a point source surrounded by asymmetric extended...

9. A Study of Quasar Clustering at - Andrew W. Stephens,Donald P. Schneider,Maarten Schmidt,James E. Gunn,David H. Weinberg
The quest for structure indicators at earlier and earlier times in the evolution of the universe has led to the search for objects with ever higher redshifts. The Palomar Transit Grism Survey has produced a large sample of high redshift quasars (z ? 2:7), allowing statistical analysis of correlation between quasar positions. In this study, clustering is identified through comparison with 100 000 Monte Carlo generated, randomly populated volumes, which are identical to the observed region in spatial coordinates, redshift distribution, and number of quasars. Three pairs have been observed with comoving separations of 11.34, 12.97, and 24.13 h Gamma1 50 Mpc (assuming q ffi = 0:5), smaller separations...

10. A Study of Quasar Clustering at - Andrew W. Stephens,Donald P. Schneider,Maarten Schmidt,James E. Gunn,David H. Weinberg
The quest for structure indicators at earlier and earlier times in the evolution of the universe has led to the search for objects with ever higher redshifts. The Palomar Transit Grism Survey has produced a large sample of high redshift quasars (z ? 2:7), allowing statistical analysis of correlation between quasar positions. In this study, clustering is identified through comparison with 100 000 Monte Carlo generated, randomly populated volumes, which are identical to the observed region in spatial coordinates, redshift distribution, and number of quasars. Three pairs have been observed with comoving separations of 11.34, 12.97, and 24.13 h Gamma1 50 Mpc (assuming q ffi = 0:5), smaller separations...

11. Deriving the Quasar Luminosity Function from Accretion Disk Instabilities - Aneta Siemiginowska,Martin Elvis
We have derived the quasar luminosity function assuming that the quasar activity is driven by a thermal-viscous unstable accretion disk around a supermassive black hole. The instabilities produce large amplitude, long-term variability of a single source. We take a light curve of a single source and calculate the luminosity function, from the function of time it spends at each luminosity. Convolving this with an assumed mass distribution we fit well the observed optical luminosity function of quasars at four redshifts. As a result we obtain the evolution of the mass distribution between redshifts 2.5 and 0.5. The main conclusions are following: 1) The quasar long-term variability due to...

12. Quasar Populations in a Cosmological Constant Dominated Flat Universe - Sangeeta Malhotra,Edwin L. Turner
Most physical properties derived for quasars, as single entities or as a population, depend upon the cosmology assumed. In this paper, we calculate the quasar luminosity function and some related quantities for a flat universe dominated by a cosmological constant ( = 0:9;Omega = 0:1) and compare them with those deduced for a flat universe with zero cosmological constant ( = 0;Omega = 1). We use the AAT quasar survey data (Boyle et al. 1990) as input in both cases. The data are fit well by a pure luminosity evolution model for both the cosmologies, but with different evolutionary parameters. From the luminosity function, we predict (extrapolate) a greater number of quasars at...

13. The Very Extended Ionized Nebula Around The Quasar Mr2251-178 - P. L. Shopbell,S. Veilleux
We report the results of deep Hff imaging of the ionized gas surrounding the low-redshift (z = 0:0638) quasar MR 2251--178 using the TAURUS Tunable Filter (TTF) on the Anglo-Australian Telescope. Our observations reach a 2-oe detection level of ¸ 5 Theta 10 Gamma18 erg s Gamma1 cm Gamma2 arcsec Gamma2 , more than an order of magnitude deeper than conventional narrowband images previously published on this object. Our data reveal a spiral complex that extends more or less symmetrically over ¸ 200 kpc, making it the largest known quasar nebula. The total mass of ionized gas is 6 Theta 10 10 M fi (upper limit), a large fraction of which is in a very faint,...

14. Is X-ray Absorption from Quasar Absorption Line Systems Detectable? - K. S. O'flaherty,P. Jakobsen
Using the known properties and statistics of intervening quasar absorption systems, we calculate the cumulative absorption out to high redshifts at soft X-ray (E ! 1 keV) energies. Although photoelectric absorption in quasar absorption systems provides a significant source of opacity at the lowest X-ray energies, the imprint of this absorption is not readily observable since it is generally masked by the much stronger Galactic foreground absorption. In particular, the intense HeII equivalent of the `Lyman valley' at energies E ¸ ! 100 eV caused by cumulative absorption in the singly ionized helium component of the Lyman forest is effectively hidden from view. Detectable absorption at higher energies E ¸ ? 200...

15. Variability X-ray Flux from the Jet in Quasar - S. C. Unwin
We present the results of the first systematic study of correlated variability in the X-ray emission and the parsec-scale radio structure of the quasar 3C 345. This quasar is one of a class of core-dominated flat-spectrum radio sources which are believed to emit X-rays via the synchrotrons process. By studying its variability in X-rays, we can test this hypothesis for 3C 345 by modeling the expected inverse- Compton flux from the parsec-scale jet, using parameters derived from quency VLB1 imaging, Since the predicted X-ray flux is very sensitive to the physical parameters of the compact radio-emitting regions, a study of variability, with simultaneous X-ray and data, is of...

16. MeV Quasar Observations with the
Introduction Extragalactic gamma-ray astronomy barely existed prior to the launch of the COMPTON Gamma Ray Observatory (CGRO) but there were good indications that this is a potentially very promising field of research. Particularly good indicators were the detections of 3C273 by the COS-B satellite at energies above 50 MeV (suggesting a peak energy output in the MeV range) and the detections of Cen A and NGC 4151 at MeV energies (Refs. 1-3). Since most of the COS-B observations were concentrated along the galactic plane, there was some hope that the CGRO pointings away from the plane might show additional active galactic nuclei (AGNs). This expectation has been borne...

17. Evidence for a Black Hole in a Radio-Quiet Quasar Nucleus - Katherine M. Blundell,Anthony J. Beasley,Mark Lacy,Simon T. Garrington
We present the first milli-arcsecond resolution radio images of a radio-quiet quasar, detecting a high brightness temperature core with data from the VLBA. On maps made with lower-frequency data from MERLIN and the VLA jets appear to emanate from the core in opposite directions, which correspond to radio-emission on arcsecond scales seen with the VLA at higher frequencies. These provide strong evidence for a black-hole--based jet-producing central engine, rather than a starburst, being responsible for the compact radio emission in this radio-quiet quasar. Subject headings: quasars: radio-quiet, individual E1821+643 1. Introduction The quasar population is divided into two classes: radio-loud quasars (RLQs) and radio-quiet quasars (RQQs). These two populations are...

18. A Study of Quasar Absorption Line Systems with IRAS - A. M. Tanner,Jill Bechtold,R. M. Cutri,C. E. Walker,John H. Black
A survey of quasar absorbers was conducted using the Infrared Astronomical Satellite (IRAS) database. Quasars with known intervening absorption-line systems and broad absorption line (BAL) QSOs were selected primarily from the Junkkarinen, Hewitt & Burbidge catalog (1991). Of the 570 quasars with IRAS data, 52 showed 3oe or better detections in at least one band in SCANPI analysis. The origin of the IRAS flux could be from the absorption line systems, other galaxies or the quasar itself. The spectral energy distributions for quasars detected in the absorption-line sample and BAL QSOs were found to be redder than those of two control samples which suggests that some of the...

19. q-gram Based Database Searching Using a Suffix Array (QUASAR) - Stefan Burkhardt,Andreas Crauser,Paolo Ferragina,Hans-peter Lenhof,Martin Vingron
With the increasing amount of DNA sequence information deposited in public databases, searching for similarity to a query sequence has become a basic operation in molecular biology. But even today's fast algorithms reach their limits when applied to all-versus-all comparisons of large databases. Here we present a new database searching algorithm called QUASAR (Q-gram Alignment based on Suffix ARrays) which was designed to quickly detect sequences with strong similarity to the query in a context where many searches are conducted on one database. Our algorithm applies a modification of q-tuple filtering implemented on top of a suffix array. Two versions were developed, one for a RAM resident suffix array and one for...

20. Deep multicolour imaging of the field towards the quasar pair PC1643+463 AB - Garret Cotter,Toby Haynes
. We present the first results of a deep imaging programme to identify the system responsible for the Cosmic Microwave Background decrement in the field towards the z = 3:8 quasar pair PC1643+4631 A&B. Using the prime focus camera at the William Herschel Telescope we have carried out deep multicolour optical imaging to search for candidate cluster galaxies at extremely high redshift. Using UGR colour selection we find the surface density of z ? 3 Lyman-break galaxy candidates is at least as great as that found in the field of the z = 3:1 structure discovered by Steidel et al. (1998), and may be somewhat greater. 1. Introduction The field towards...

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