The dichotomy of dark matter fraction and total mass density slope of galaxies over five dex in mass

Tortora, C., Posti, L., Koopmans, L. V. E. & Napolitano, N. R., Nov-2019, In : Monthly Notices of the Royal Astronomical Society. 489, 4, p. 5483-5493 11 p.

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We analyse the mass density distribution in the centres of galaxies across five orders of magnitude in mass range. Using high-quality spiral galaxy rotation curves and infrared photometry from SPARC, we conduct a systematic study of their central dark matter (DM) fraction (f(DM)) and their mass density slope (alpha), within their effective radius. We show that lower mass spiral galaxies are more DM dominated and have more shallow mass density slopes when compared with more massive galaxies, which have density profiles closer to isothermal. Low-mass (M-* less than or similar to 10(10)M(circle dot)) gas-rich spirals span a wide range of fDM values, but systematically lower than in gas-poor systems of similar mass. With increasing galaxy mass, the values of f(DM) decrease and the density profiles steepen. In the most massive late-type gas-poor galaxies, a possible flattening of these trends is observed. When comparing these results to massive (M-* less than or similar to 10(10)M(circle dot)) elliptical galaxies from SPIDER and to dwarf ellipticals (dEs) from SMACKED, these trends result to be inverted. Hence, the values of both fDM and a, as a function of M-*, exhibit a U-shape trend. At a fixed stellar mass, the mass density profiles in dEs are steeper than in spirals. These trends can be understood by stellar feedback from a more prolonged star formation period in spirals, causing a transformation of the initial steep density cusp to a more shallow profile via differential feedback efficiency by supernovae, and by galaxy mergers or AGN feedback in higher mass galaxies.

Original languageEnglish
Pages (from-to)5483-5493
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date22-Aug-2019
Publication statusPublished - Nov-2019


  • galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: general, galaxies: structure, galaxies: spirals, LENS ACS SURVEY, TO-LIGHT RATIO, SCALING RELATIONS, STELLAR MASS, ELLIPTIC GALAXIES, DATA RELEASE, SAURON PROJECT, SIZE EVOLUTION, MINOR MERGERS, MOLECULAR GAS

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