http://hdl.handle.net/1903/1587 2013-05-20T00:32:57Z http://hdl.handle.net/1903/8935 Title: Two Dimensional Velocity Fields of Low Surface Brightness Galaxies Authors: Kuzio de Naray, R.; McGaugh, S. S.; de Blok, W. J. G.; Bosma, A. Abstract: We present high resolution two dimensional velocity fields from integral field spectroscopy along with derived rotation curves for nine low surface brightness galaxies. This is a positive step forward in terms of both data quality and number of objects studied. We fit NFW and pseudo-isothermal halo models to the observations. We find that the pseudo-isothermal halo better represents the data in most cases than the NFW halo, as the resulting concentrations are lower than would be expected for CDM. 2005-01-01T00:00:00Z http://hdl.handle.net/1903/8720 Title: The Tully-Fisher Relation for Low Surface Brightness Galaxies - Implications for Galaxy Evolution Authors: Zwaan, M. A.; van der Hulst, J. M.; de Blok, W. J. G.; McGaugh, S. S. 1995-01-01T00:00:00Z http://hdl.handle.net/1903/8719 Title: HI Observations of Low Surface Brightness Galaxies: Probing Low Density Galaxies Authors: de Blok, W.J.G.; McGaugh, S.S.; van der Hulst, J.M. Abstract: We present Very Large Array (vla) and Westerbork Synthesis Radio Telescope (wsrt) 21-cm Hi observations of 19 late-type low surface brightness (LSB) galaxies. Our main findings are that these galaxies, as well as having low surface brightnesses, have low Hi surface densities, about a factor of � 3 lower than in normal late-type galaxies. We show that LSB galaxies in some respects resemble the outer parts of late-type normal galaxies, but may be less evolved. LSB galaxies are more gas-rich than their high surface brightness counterparts. The rotation curves of LSB galaxies rise more slowly than those of HSB galaxies of the same luminosity, with amplitudes between 50 and 120 km s−1, and are often still increasing at the outermost measured point. The shape of the rotation curves suggests that LSB galaxies have low matter surface densities. We use the average total mass surface density of a galaxy as a measure for the evolutionary state, and show that LSB galaxies are among the least compact, least evolved galaxies. We show that both MHI/LB and Mdyn/LB depend strongly on central surface brightness, consistent with the surface brightness–mass-to-light ratio relation required by the Tully-Fisher relation. LSB galaxies are therefore slowly evolving galaxies, and may well be low surface density systems in all respects. 1996-01-01T00:00:00Z http://hdl.handle.net/1903/8718 Title: The Dark and Baryonic Matter Content of Low Surface Brightness Galaxies Authors: de Blok, W.J.G.; McGaugh, S.S. Abstract: We present mass models of a sample of 19 low surface brightness (LSB) galaxies and compare the properties of their constituent mass components with those of a sample of high surface brightness (HSB) galaxies. We find that LSB galaxies are dark matter dominated. Their halo parameters are only slightly affected by assumptions on stellar mass-to-light ratios. Comparing LSB and HSB galaxies we find that mass models derived using the maximum disk hypothesis result in the disks of LSB galaxies having systematically higher stellar mass-to-light ratios than HSB galaxies of similar rotation velocity. This is inconsistent with all other available evidence on the evolution of LSB galaxies. We argue therefore that the maximum disk hypothesis does not provide a representative description of the LSB galaxies and their evolution. Mass models with stellar mass-to-light ratios determined by the colors and stellar velocity dispersions of galactic disks imply that LSB galaxies have dark matter halos that are more extended and less dense than those of HSB galaxies. Surface brightness is thus related to the halo properties. LSB galaxies are slowly evolving, low density and dark matter dominated galaxies. 1997-01-01T00:00:00Z