We investigate the idea that the interaction of Dark Matter (DM) sub-halos with the gaseous disk of galaxies can be the origin for the observed holes and shells found in their neutral hydrogen (HI) distributions. We use high resolution hydrodynamic simulations to show that pure DM sub-halos impacting a galactic disk are not able to produce holes; on the contrary, they result in high density regions in the disk. However, sub-halos containing a small amount of gas (a few percent of the total DM mass of the sub-halo) are able to displace the gas in the disk and form holes and shells. The size and lifetime of these holes depend on the sub-halo gas mass, density and impact velocity. A DM sub-halo of mass $10^8$ $M_{\odot}$ and a gas mass fraction of $\sim 3$%, is able to create a kpc scale hole, with a lifetime similar to those observed in nearby galaxies. We also register an increase in the star formation rate at the rim of the hole, again in agreement with observations. Even though the properties off these simulated structures resemble those found in observations we find that the number of predicted holes (based on mass and orbital distributions of DM halos derived from cosmological N-body simulations) falls short compared to the observations. Only a handful of holes are produced per Giga year. This leads us to conclude that DM halo impact is not the major channel through which these holes are formed.
Introducing the Descriptive Parametric Model: Gaseous Profiles for Galaxies, Groups, and Clusters
University of Colorado, Center for Astrophysics and Space Astronomy（科罗拉多大学天体物理与空间天文中心）；Michigan State University, Department of Physics and Astronomy（密歇根州立大学物理与天文系）；School of Physics and Astronomy, University of Nottingham（诺丁汉大学物理与天文学院）；Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院天体物理实验室）；Department of Astronomy, Cornell University（康奈尔大学天文系）；Université Paris Cité, CNRS, Astroparticule et Cosmologie（巴黎西岱大学、法国国家科学研究中心、粒子与宇宙学研究所）；Department of Astronomy University of Michigan（密歇根大学天文系）；Department of Astronomy, New Mexico State University（新墨西哥州立大学天文系）；Department of Astronomy, University of Geneva（日内瓦大学天文系）；University of Washington, Department of Astronomy（华盛顿大学天文系）；TAPIR, California Institute of Technology（加州理工学院理论天体物理、仪器与研究组）；Department of Astronomy, Yale University（耶鲁大学天文系）；Department of Physics, Yale University（耶鲁大学物理系）；Department of Astronomy, Columbia University（哥伦比亚大学天文系）；Department of Astronomy & Astrophysics, The University of Chicago（芝加哥大学天文与天体物理系）；Department of Astronomy, Tsinghua University（清华大学天文系）；Department of Physics and Astronomy, University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校物理与天文系）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）
