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Cosmological simulations indicate that cold dark matter (CDM) halos should be triaxial. Verifying observationally this theoretical prediction is, however, less than straightforward because the assembly of galaxies is expected to modify the halo shapes and to render them more axisymmetric. We use a suite of N-body simulations to investigate quantitatively the effect of the growth of a central disk galaxy on the shape of triaxial dark matter halos. As expected, the halo responds to the presence of the disk by becoming more spherical. The net effect depends only weakly on the orientation of the disk relative to the halo principal axes or the timescale of disk assembly, but strongly on the overall gravitational importance of the disk. Our results show that exponential disks whose contribution peaks at less than ~50% of their circular velocity are unable to modify noticeably the shape of the gravitational potential of their surrounding halos. Many dwarf and low surface brightness galaxies are expected to be in this regime, and therefore their detailed kinematics could be used to probe halo triaxiality, one of the basic predictions of the CDM paradigm. We argue that the complex disk kinematics of the dwarf galaxy NGC 2976 might be the reflection of a triaxial halo. Such signatures of halo triaxiality should be common in galaxies where the luminous component is subdominant.
We report on the detection of gravitational lensing magnification by a population of galaxy groups, at a significance level of 4.9 sigma. Using X-ray selected groups in the COSMOS 1.64 deg^2 field, and high-redshift Lyman break galaxies as sources, w
Dissipative dark matter self-interactions can affect halo evolution and change its structure. We perform a series of controlled N-body simulations to study impacts of the dissipative interactions on halo properties. The interplay between gravitationa
We assess how much unused strong lensing information is available in the deep emph{Hubble Space Telescope} imaging and VLT/MUSE spectroscopy of the emph{Frontier Field} clusters. As a pilot study, we analyse galaxy cluster MACS,J0416.1-2403 ($z$$=$$0
A self-interacting dark matter halo can experience gravothermal collapse, resulting in a central core with an ultrahigh density. It can further contract and collapse into a black hole, a mechanism proposed to explain the origin of supermassive black
We consider a dark matter halo (DMH) of a spherical galaxy as a Bose-Einstein condensate of the ultra-light axions interacting with the baryonic matter. In the mean-field limit, we have derived the integro-differential equation of the Hartree-Fock ty