Testing baryon-induced core formation in ΛCDM: A comparison of the DC14 and coreNFW dark matter halo models on galaxy rotation curves
1 Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium
2 Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
Received: 6 January 2017
Accepted: 15 June 2017
Recent cosmological hydrodynamical simulations suggest that baryonic processes, and in particular supernova feedback following bursts of star formation, can alter the structure of dark matter haloes and transform primordial cusps into shallower cores. To assess whether this mechanism offers a solution to the long-standing cusp-core controversy, simulated haloes must be compared to real dark matter haloes inferred from galaxy rotation curves. For this purpose, two new dark matter density profiles were recently derived from simulations of galaxies in complementary mass ranges: the DC14 halo (1010 < Mhalo/M⊙ < 8 × 1011) and the coreNFW halo (107 < Mhalo/M⊙ < 109). Both models have individually been found to give good fits to observed rotation curves. For the DC14 model, however, the agreement of the predicted halo properties with cosmological scaling relations was confirmed by one study, but strongly refuted by another. A next important question is whether, despite their different approaches, the two models converge to the same solution in the mass range where both should be appropriate. To investigate this, we tested the DC14 and coreNFW halo models on the rotation curves of a selection of galaxies with halo masses in the range 4 × 109M⊙ – 7 × 1010M⊙ and compared their predictions. We further applied the DC14 model to a set of rotation curves at higher halo masses, up to 9 × 1011M⊙, to verify the agreement with the cosmological scaling relations. Both models are generally able to reproduce the observed rotation curves, in line with earlier results, and the predicted dark matter haloes are consistent with the cosmological c−Mhalo and M∗−Mhalo relations. We find that the DC14 and coreNFW models are also in fairly good agreement with each other, even though DC14 tends to predict slightly less extended cores and somewhat more concentrated haloes than coreNFW. While the quality of the fits is generally similar for both halo models, DC14 does perform significantly better than coreNFW for three galaxies. In each of these cases, the problem for coreNFW is related to connection of the core size to the stellar half-mass radius, although we argue that it is justifiable to relax this connection for NGC 3741. A larger core radius brings the coreNFW model for this galaxy in good agreement with the data and the DC14 model.
Key words: galaxies: kinematics and dynamics / galaxies: halos / galaxies: evolution / dark matter
© ESO, 2017