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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.
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com
| 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.
| Forbidden O III emission in two magnitude-limited field-galaxy surveys
The paper presents emission-line strengths for 394 galaxies from thefield-galaxy redshift surveys of Kirshner, Oemler, and Schechter (1978)and Kirshner et al. (1983) as part of a study of the nature of field andvoid galaxies. These data are 95 percent complete in their coverage ofthe forbidden O III 5007, 4959 A emission lines. It is found that 8.8 +or - 1.5 percent of a J magnitude-limited data set have forbidden O III5007 A emission equivalent widths greater than 10 A. There is noevidence that the spatial distribution of emission-line galaxies in eachfield differs from that of galaxies without emission. However, there isa significant increase in the fraction of galaxies with strong forbiddenO III emission in the southern fields of the Kirshner, Oemler, andSchechter (1978) survey as compared with the other survey fields. Theresults are consistent with the conclusion that the fraction of galaxieswith emission is larger in the Bootes void than in the general field,but tighter constraints on the void normal galaxy population are neededto improve the statistics.
| Southern Galaxy Catalogue.
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| A study of field galaxies. I - Redshifts and photometry of a complete sample of galaxies
As a first step towards a redetermination of the luminosity function andspace distribution of field galaxies, data are presented on amagnitude-limited sample of galaxies in eight fields in the north andsouth galactic polar caps. Redshifts, accurate to about 100 km/s havebeen obtained for 164 of 184 galaxies brighter than J=15.0 (Bapproximately equal to 15.5). Magnitudes and colors have also beenmeasured for a large sample of 807 galaxies, complete to J approximatelyequal to 15.7.
| The composite photography of Stephan's Quintet.
Not Available
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