Spreading out and staying sharp - Creating diverse rotation curves via baryonic and self-interaction effects

Peter Creasey*, Omid Sameie, Laura V. Sales, Hai Bo Yu, Mark Vogelsberger, Jesús Zavala

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Galactic rotation curves are a fundamental constraint for any cosmological model. We use controlled N-body simulations of galaxies to study the gravitational effect of baryons in a scenario with collisionless cold dark matter (CDM) versus one with a self-interacting dark matter (SIDM) component. In particular, we examine the inner profiles of the rotation curves in the velocity range Vmax = [30-250] km s−1, whose diversity has been found to be greater than predicted by the ΛCDM scenario. We find that the scatter in the observed rotation curves exceeds that predicted by dark matter only mass-concentration relations in either the CDM nor SIDM models. Allowing for realistic baryonic content and spatial distributions, however, helps create a large variety of rotation curve shapes, which is in a better agreement with observations in the case of self-interactions due to the characteristic cored profiles being more accommodating to the slowly rising rotation curves than CDM. We find individual fits to model two of the most remarkable outliers of similar Vmax, UGC 5721 and IC 2574 - the former a cusp-like rotation curve and the latter a seemingly 8-kpc-cored profile. This diversity in SIDM arises as permutations of overly concentrated haloes with compact baryonic distributions versus underdense haloes with extended baryonic discs. The SIDM solution is promising and its feasibility ultimately depends on the sampling of the halo mass-concentration relation and its interplay with the baryonic profiles, emphasizing the need for a better understanding of the frequency of extreme outliers present in current observational samples.

Original languageEnglish
Pages (from-to)2283-2295
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume468
Issue number2
DOIs
Publication statusPublished - 1 Jun 2017

Bibliographical note

Publisher Copyright:
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Other keywords

  • Cosmology: theory
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: structure
  • Methods: numerical

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