2001/09/28 by J. A. Sellwood, Sellwood, J. A., A. Kosowsky +2
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0109555
To appear in "The Dynamics, Structure and History of Galaxies" (eds. G. S. Da Costa & E. M. Sadler) 10 pages, no figures, LaTeX (.sty file included)
arxiv created 2001/09/28 · openalex publication_date 2001/09/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Dynamical mass discrepancies in galaxies have two possible explanations: the existence of large amounts of dark matter or the breakdown of Newtonian gravity. True dark matter halos of galaxies could differ in several respects from apparent halos inferred from misinterpreted modified gravity, and we discuss two observational tests to probe these differences. Modified gravity gives generic, geometrical predictions for the shapes of apparent halos, and also requires that the inferred excess mass strongly correlates with the visible baryonic mass. Thus modified gravity is more easily falsified, but we find both hypotheses to be consistent with the meager data on galaxy and cluster halos; dark matter is not required by current data. We strongly encourage the acquisition of more data, which could ultimately eliminate one or other of these possibilities.