arXiv subjects

R. J. Smith

Publications and source records attributed to R. J. Smith.

134 records · Page 8Linked to original sources

arXiv1998

Discovery of Radio-loud Broad Absorption Line Quasars Using Ultraviolet Excess and Deep Radio Selection

We report the discovery of five broad-absorption-line (BAL) QSOs in a complete sample of 111 ultraviolet excess (UVX) QSO candidates also detected in the NRAO VLA Sky Survey. All five BAL QSOs, which include two high-ionization BAL QSOs and three low-ionization BAL QSOs, are formally radio-loud. Of QSOs with z > 0.4, 3+/-2% show low-ionization BALs, and of QSOs with z > 1.5, all radio-loud, 9+/-5% show BALs; these frequencies are consistent with those of optical surveys. While the first reported radio-loud BAL QSO, FIRST J155633.8+351758, is likely to be heavily dust reddened and thus less radio-loud than indicated by its observed radio-to-optical luminosity, these QSOs are UVX selected and probably free of significant dust along the line of sight. We point out unusual features in two of the BAL QSOs and discuss the significance finding these heretofore rare objects.

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arXiv1998

QSO clustering and the AAT 2dF redshift survey

We review previous results on the clustering and environments of QSOs. We show that the correlation length for QSOs derived from existing surveys is r~5/h Mpc, similar to the observed correlation length for field galaxies at the present epoch. The galaxy environment for z<1 radio-quiet QSOs is also consistent with field galaxies. The evolution of the QSO correlation length with redshift is currently uncertain, largely due to the small numbers of QSOs (~2000) in surveys suitable for clustering analysis. We report on intial progress with the AAT 2dF QSO redshift survey, which, once completed will comprise almost 30000 QSOs. With over 1000 QSOs already observed, it is already the largest single homogeneous QSO survey. We discuss prospects for deriving limits on cosmological parameters from this survey, and on the evolution of large-scale structure in the Universe.

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arXiv1997

The AAO 2dF QSO Redshift Survey

We describe the aims, strategy and status of the AAO 2dF QSO redshift survey. This goal of the survey is to obtain redshifts for 30000 QSOs in a homogeneous magnitude limited (B<21) survey. The survey began in early 1997 and should be complete by the end of 1999.

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arXiv1997

Galaxy clusters in the Perseus-Pisces region - I. Spectroscopic and photometric data for early-type galaxies

We present new spectroscopic and photometric data for 137 early-type galaxies in nine clusters, and for a set of nearby standard galaxies. The clusters studied are Perseus (A0426), Pisces, A0262, A0347, J8, HMS0122+3305, 7S21, A2199 and A2634. Our spectroscopic data comprise radial velocities (cz), central velocity dispersions (sigma) and magnesium line strength indices (Mg). Internal errors (derived from repeat observations) are 7.6% on each measurement of sigma, and 0.010 mag on each Mg measurement. We correct the major published datasets to a standard aperture size, and define a new `standard system' by the aperture-corrected Lick data of Davies et al. Through extensive intercomparisons with data from the literature, we present the corrections required to bring the major published datasets onto the standard system. We demonstrate that our new velocity dispersion data can be brought into consistency with the standard system, to an uncertainty of <0.01 dex. From R-band CCD photometry, we derive effective diameter (A_e), mean surface brightness within effective diameter (mu_e) and an R-band diameter equivalent to the D_n parameter of Dressler et al. Internal comparisons indicate an average error of 0.005 in each measurement of log(D_n). The combination log(A_e) - 0.3 mu_e, approximately the quantity used in the Fundamental Plane distance indicator, has an uncertainty of 0.006 per measurement. The photometric data can be brought onto a system consistent with external data at the level of 0.5% in distance. These data will be used in a companion paper to derive distance and peculiar velocity estimates for the nine clusters studied. (Abridged)

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arXiv1997

Galaxy clusters in the Perseus-Pisces region - II. The peculiar velocity field

We have measured the mean peculiar motions of 103 early-type galaxies in 7 clusters in the Perseus-Pisces (PP) ridge or PP background, and a further 249 such galaxies in 9 calibrating clusters from the literature, using the inverse Fundamental Plane relation. This relation is found to have a distance error of 20% per galaxy. None of the 6 clusters in the PP ridge has a significant motion with respect to the CMB frame, but the PP background cluster J8 shows marginal evidence of `backside infall' into the PP supercluster. The full 16 cluster sample has a mean CMB-frame bulk motion of 420 +/- 280 km/s, towards l=262, b=-25. This result is consistent both with no bulk motion in the CMB frame and with the ~350 km/s bulk motion found by Courteau et al. It is inconsistent at the 98% confidence level with the ~700 km/s bulk flow found by Lauer & Postman (LP). The PP ridge clusters are found to have a small and statistically insignificant mean radial motion with respect to the CMB frame: -60 +/- 220 km/s. A comparison between our cluster peculiar velocities and the predicted peculiar velocities from the IRAS 1.2 Jy density field, smoothed on a 500 km/s scale, yields beta_I = Omega^0.6/b_I = 0.95 +/- 0.48, consistent with previous results. We find agreement between our peculiar motions and published Tully-Fisher results for the same clusters. The disagreement between the 11 clusters common to our sample and that of LP, based on BCGs, is statistically significant at the >~ 99.7% confidence level indicating that the errors of one or both of these data sets are underestimated. When the BCG distances corrected for the X-ray luminosity of the host cluster are used, the disagreement is reduced to the ~94% confidence level. (Abridged)

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arXiv1997

Peculiar Motions Of Clusters In The Perseus-Pisces Region

We present results of a new study of peculiar motions of 7 clusters in the Perseus-Pisces (PP) region, using the Fundamental Plane as a distance indicator. The sample is calibrated by reference to 9 additional clusters with data from the literature. Careful attention is paid to the matching of spectroscopic and photometric data from several sources. For six clusters in the PP supercluster no significant peculiar motions are detected. For these clusters we derive a bulk motion of 60 +/- 220 km/s, in the CMB frame, directed towards the Local Group. This non-detection is in marginal conflict with previous Tully-Fisher studies. Two clusters in the background of the supercluster exhibit significant negative peculiar velocities, characteristic of backside infall into PP. A bulk-flow fit to all 16 clusters reveals a statistically insignificant motion of 430 +/- 280 km/s towards l=265, b=26 (CMB frame). Comparison with the velocity field predicted from the IRAS 1.2Jy survey yields β= 1.0 +/- 0.5. We find no evidence for residual bulk motions generated by mass concentrations beyond the limiting depth of the IRAS density field.

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arXiv1995

The environments of z<0.3 QSOs

We have carried out an investigation of the galaxy environments of low redshift ($z<0.3$) QSOs by cross-correlating the positions on the sky of X-ray-selected QSOs/AGN identified in the {\it Einstein} Medium Sensitivity Survey (EMSS) with those of $B_J<20.5$ galaxies in the APM galaxy catalogues. At $<5\,$arcmin, we find a significant ($5σ$) galaxy excess around $z<0.3$ QSOs. The amplitude of the low redshift ($z<0.3$) QSO-galaxy angular cross-correlation function is identical to that of the APM galaxy angular correlation function, implying that these (predominantly radio-quiet) QSOs inhabit environments similar to those of normal galaxies. No significant galaxy excess was found around a `control' sample of $z>0.3$ QSOs. Coupled with previous observations, these results imply that the environment of radio-quiet QSOs undergoes little evolution over a wide range in redshift ($0 less than z less than 1.5$). This is in marked contrast to the rapid increase in the richness of the environments associated with radio-loud QSOs over the same redshift range. The similarity between QSO-galaxy clustering and galaxy-galaxy clustering also suggests that QSOs are unbiased with respect to galaxies and make useful tracers of large-scale structure in the Universe.

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arXiv1995

The environments of z<0.3 QSOs

Based on a cross-correlation analysis of X-ray selected QSOs with faint (B<20.5) galaxies, we find a 5sigma galaxy excess around low-redshift (z<0.3) QSOs with an amplitude identical to that of the galaxy angular correlation function. The similarity between QSO-galaxy clustering and galaxy-galaxy clustering suggests that QSOs are unbiased with respect to galaxies and make useful tracers of large-scale structure in the Universe.

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