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|The Cusp/Core Problem in Galactic Halos: Long-Slit Spectra for a Large Dwarf Galaxy Sample|
We derive inner dark matter halo density profiles for a sample of 165low-mass galaxies using rotation curves obtained from high-quality,long-slit optical spectra assuming minimal disks and spherical symmetry.For ρ(r)~r-α near the galaxy center, we measuremedian inner slopes ranging from αm=0.22+/-0.08 to0.28+/-0.06 for various subsamples of the data. This is similar tovalues found by other authors and in stark contrast to the intrinsiccusps (αint~1) predicted by simulations of haloassembly in cold dark matter (CDM) cosmologies. To elucidate therelationship between αm and αint inour data, we simulate long-slit observations of model galaxies with haloshapes broadly consistent with the CDM paradigm. Simulations withαint=1/2 and 1 recover both the observed distributionof αm and correlations between αm andprimary observational parameters such as distance and disk inclination,whereas those with αint=5/4 are marginally consistentwith the data. Conversely, the hypothesis that low-mass galaxies haveαint=3/2 is rejected. While the simulations do notimply that the data favor intrinsic cusps over cores, they demonstratethat the discrepancy between αm andαint~1 for our sample does not necessarily imply agenuine conflict between our results and CDM predictions; rather, theapparent cusp/core problem may be reconciled by considering the impactof observing and data-processing techniques on rotation curves derivedfrom long-slit spectra.
|FLASH redshift survey - I. Observations and catalogue|
The FLAIR Shapley-Hydra (FLASH) redshift survey catalogue consists of4613 galaxies brighter than bJ= 16.7 (corrected for Galacticextinction) over a 700-deg2 region of sky in the generaldirection of the Local Group motion. The survey region is a70°× 10° strip spanning the sky from the ShapleySupercluster to the Hydra cluster, and contains 3141 galaxies withmeasured redshifts. Designed to explore the effect of the galaxyconcentrations in this direction (in particular the Supergalactic planeand the Shapley Supercluster) upon the Local Group motion, the 68 percent completeness allows us to sample the large-scale structure betterthan similar sparsely-sampled surveys. The survey region does notoverlap with the areas covered by ongoing wide-angle (Sloan or 2dF)complete redshift surveys. In this paper, the first in a series, wedescribe the observation and data reduction procedures, the analysis forthe redshift errors and survey completeness, and present the surveydata.
|Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation|
I-band luminosities, rotational velocities, and redshifts of 1092 spiralgalaxies have been measured by CCD photometry and Hα spectroscopyusing the 1 m and 2.3 m telescopes at Siding Spring Observatory,respectively. The results are tabulated. Luminosity profiles andHα rotation curves are given for the galaxies. When these resultsare combined with similar data for 1355 spiral galaxies publishedpreviously (Mathewson, Ford, & Buchhorn, hereafter Paper I), itprovides a large, uniform, and unique data set with which to measure,via the Tully-Fisher relation, the peculiar velocities of galaxies inthe local universe to a distance of 11,000 km s^-1^ (Mathewson &Ford). Taking advantage of the opportunity for publishing this data inmachine-readable form, in the CD-ROM, we have also included similar datafor the 1355 galaxies in Paper I.
|Ultraviolet observations of galaxies with the FAUST experiment|
We have used the set of point sources detected by the Far UltravioletSpace Telescope (FAUST) instrument to identify galaxies and study thetotal galaxy flux in a 250 A wide band peaking at 1650 A. A sample of144 galaxies has been obtained after cross-reference with the RC3catalog, elimination of objects confused with stars and variouscorrections for the photometry. The UV-B color dispersion is found toincrease while the galaxies get redder from late to early types. Theirregular galaxies appear on average redder and the Sbc galaxies bluerthan indicated by the spectral energy distributions currently used forthe calculations of K-corrections. Various arguments lead us to make theassumption of a constant dust extinction within each galaxy. The UV fluxper unit area decreases on average from late to early type spirals. Wefind a weak correlation between the UV and far infra-red emission whilethe infra-red to UV flux ratio gets lower when galaxies get bluer (asmeasured by the UV to B flux ratio). The UV flux per unit areacorrelates with the HI gas surface density and the total gas surfacedensity when this quantity is available. The correlation with themolecular gas alone is weak. In the Virgo cluster, the UV flux per unitarea does not decrease in direct proportion to the HI deficiency. Galaxycounts per square degree and per magnitude interval have been obtainedat high-galactic latitudes. Combined with data at fainter magnitudes,they show a variation as a function of magnitude with a near-euclideanslope over a range of 8 magnitudes.
|Redshifts for galaxies in southern clusters|
Redshifts for galaxies, including the clusters ZW 9-19 and Klemola 27,in the ESO/SRC survey field 444 are presented based on observationscarried out in May 1980 and April 1981 with the 1.52-m ESO telescope inLa Silla. Satisfactory agreement is found with previous data. Thesurveyed sky area contains the Hydra/Centaurus supercluster with meanradial velocities between 3000 and 5000 km/s, behind which seems to be alarge empty space extending out to a redshift of about 9000 km s.
|Static properties of galaxies in the Shapley-Centaurus cluster. I - The catalogue|
A catalogue of the positions, sizes, orientations, ellipticities, andmorphological descriptions of 127 galaxies measured in the Southern SkySurvey Field 444 is given. The measurement errors, both internal andexternal, are discussed.
|Redshifts in Klemola 27|
Observational data for galaxies in the galaxy cluster Klemola 27gathered over the last few years are presented. These are mostly newredshifts and further, accurate coordinates and morphological types fora large number of 'prominent' galaxies in the ESO/SRC-Survey fields 444and 445. A few preliminary H I radial velocities are also reported. Thedata available for this cluster are briefly discussed.
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