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|Measuring Stellar Velocity Dispersions in Active Galaxies|
We present stellar velocity dispersion (σ*)measurements for a significant sample of 40 broad-line (type 1) activegalaxies for use in testing the well-known relation black hole mass andstellar velocity dispersion. The objects are selected to contain Ca IItriplet, Mg I b triplet, and Ca H+K stellar absorption features in theiroptical spectra so that we may use them to perform extensive tests ofthe systematic biases introduced by both template mismatch andcontamination from the active galactic nucleus (AGN). We use the Ca IItriplet as a benchmark to evaluate the utility of the other spectralregions in the presence of AGN contamination. Broad Fe II emission,extending from ~5050 to 5520 Å, in combination with narrow coronalemission lines, can seriously bias σ* measurements fromthe Mg I b region, highlighting the need for extreme caution in its use.However, we argue that at luminosities constituting a moderate fractionof the Eddington limit, when the Fe II lines are both weak and smoothrelative to the stellar lines, it is possible to derive meaningfulmeasurements with careful selection of the fitting region. Inparticular, to avoid the contamination of coronal lines, we advocate theuse of the region 5250-5820 Å, which is rich in Fe absorptionfeatures. At higher AGN contaminations, the Ca H+K region may providethe only recourse for estimating σ*. These features arenotoriously unreliable, due to a strong dependence on spectral type, asteep local continuum, and large intrinsic broadening. Indeed, we find astrong systematic trend in comparisons of Ca H+K with other spectralregions. Luckily the offset is well described by a simple linear fit asa function of σ*, which enables us to remove the biasand thus extract unbiased σ* measurements from thisregion. We lay the groundwork for an extensive comparison between blackhole mass and bulge velocity dispersion in active galaxies, as describedin a companion paper by Greene & Ho.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|H I survey of face-on galaxies - The frequency of distortions in H I disks|
The full results of an H I survey of face-on galaxies are presented andit is shown that narrow H I profiles are rare in normal spiral galaxies.This is due in part to the wider-than-expected range of the integraldispersion and in part to the frequent occurrence of large-scaledistortions in the H I disk. These factors reduce the number of galaxieswith half-power widths less than 30 km/s to about 24 percent of thosethat would occur if galaxies generally had quiescent, coplanar H Idisks. Two useful subsets may be drawn from this study of 212 face-ongalaxies with axial ratios greater than 0.87. Fifty-two spirals of allmorphological types have half-power widths smaller than 100 km/s and maybe used for studies that benefit from a small velocity spread and anenhanced beam-filling factor. About 40 galaxies have velocity widthsmuch larger than expected and are of interest in studies of dynamicallypeculiar systems.
|A study of the large-scale structure in the distribution of galaxies in a region centered about the Cancer cluster. III - Further observational results|
Further observational results are presented from a study of thelarge-scale structure in the distribution of galaxies in anapproximately 4000 sq deg region nominally centered about the Cancercluster. The criteria used in defining the galaxy sample and theobservational methods used in its study are reviewed. The H I spectraand the associated measured parameters and derived properties for the134 sample galaxies are presented.
|The distribution of the spiral galaxies in the direction of the Coma/A 1367 supercluster|
The three-dimensional distribution of spiral galaxies is analyzed for a1080 sq deg region surrounding the Coma cluster, A 1367 and Zw 74-23(NGC 5416 cluster). H I observations of spiral galaxies having angulardiameters less than 2 arcmin, with the exception of six NGC objects andone IC object, are used, detecting 87 galaxies with 67 redshiftsreported for the first time. A population of faint isolated galaxies asmuch as 30 deg from Coma or A 1367 is found having radial velocitiesnear 7000 km/s, and a group between Coma and A 1367 is found containingno galaxies with m(p) less than 15.0. South of A 1367 three groups arefound located 12 deg from the core with radial velocities near 7000 km/sand a projected diameter less than 2 Mpc. South of 20 deg declination atleast four clusters and isolated galaxies are found which could be partof the southern extension of the Coma-A 1367 supercluster. Assuming allthe detected isolated spirals belong to the Coma-A 1367 supercluster,the angular extent of the supercluster is almost a radian in the planeof the sky.
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