Modelling the Canes Venatici I dwarf spheroidal galaxy

TL;DR

This study models the tidal disruption of a dark matter free progenitor to explain the observed properties of the Canes Venatici I dwarf galaxy, matching its current mass, brightness, size, and velocity dispersion.

Contribution

It presents a novel dynamical model of CVn I as a dark matter free, tidally disrupted galaxy, fitting multiple observed properties simultaneously.

Findings

Best-fit orbit with specific proper motions and distances.

Model reproduces CVn I's mass, brightness, size, and velocity dispersion.

Remnant after 10 Gyr matches observed ellipticity and position angle.

Abstract

The aim of this work is to find a progenitor for Canes Venatici I (CVn I), under the assumption that it is a dark matter free object that is undergoing tidal disruption. With a simple point mass integrator, we searched for an orbit for this galaxy using its current position, position angle, and radial velocity in the sky as constraints. The orbit that gives the best results has the pair of proper motions $\mu_\alpha$ = -0.099 mas yr$^{-1}$ and $\mu_\delta$ = -0.147 mas yr$^{-1}$, that is an apogalactic distance of 242.79 kpc and a perigalactic distance of 20.01 kpc. Using a dark matter free progenitor that undergoes tidal disruption, the best-fitting model matches the final mass, surface brightness, effective radius, and velocity dispersion of CVn I simultaneously. This model has an initial Plummer mass of 2.47 x $10^7$ M$_\odot$ and a Plummer radius of 653 pc, producing a remnant after 10 Gyr with a final mass of 2.45 x 10$^5$ M$_\odot$, a central surface brightness of 26.9 mag arcsec$^{-2}$, an effective radius of 545.7 pc, and a velocity dispersion with the value 7.58 km s$^{-1}$. Furthermore, it is matching the position angle and ellipticity of the projected object in the sky.