Year-end Sale % OFF 
Abstract
WLM is a dwarf irregular that is seen almost edge-on that has prompted a number of kinematical studies investigating its rotation curve and its dark matter content. In this paper, we investigate the origin of the strong asymmetry of the rotation curve, which shows a significant discrepancy between the approaching and the receding side. We first examine whether an m = 1 perturbation (lopsidedness) in the halo potential could be a mechanism creating such kinematical asymmetry. To do so, we fit a theoretical rotational velocity associated with an m = 1 perturbation in the halo potential model to the observed data via a χ−squared minimization method. We show that a lopsided halo potential model can explain the asymmetry in the kinematic data reasonably well. We then verify that the kinematical classification of WLM shows that its velocity field is significantly perturbed due to both its asymmetrical rotation curve and also its peculiar velocity dispersion map. In addition, based on a kinemetry analysis, we find that it is possible for WLM to lie in the transition region, where the disk and merger coexist. In conclusion, it appears that the rotation curve of WLM diverges significantly from that of an ideal rotating disk, which may significantly affect investigations of its dark matter content.
Highlights
It has been found that disk galaxies have massive dark matter halos but little is known about the shape of such halos and their content
We show that a lopsided halo potential model can explain the asymmetry in the kinematic data reasonably well
In this study, we investigate the origin of the strong asymmetric rotation curve of the dwarf irregular galaxy WLM by examining whether an m = 1 perturbation in a halo potential could be considered the mechanism behind such kinematical asymmetry
Summary
It has been found that disk galaxies have massive dark matter halos but little is known about the shape of such halos and their content. Dwarf irregulars are the most common type of galaxies in the local universe (see, e.g., Dale et al 2009) Such galaxies with extended HI disk distributions allow measurement of rotation curves and investigate dark matter halo properties and its shape to large radial distances, beyond the optical disk. M. Khademi et al.: Kinematical asymmetry in the dwarf irregular galaxy motion of gas in a spiral galaxy is rotation and the observed velocity fields of disk galaxies generally can be fitted perfectly by circular motion. The observed LOS radial velocity, vlos, toward or away from an observer, is usually measured using the Doppler shift of emission line or absorption line in the spectra of HI gas or stars
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
