The universal rotation curve of dwarf disc galaxies

Abstract

We use the concept of the spiral rotation curves universality to investigate the luminous and dark matter properties of the dwarf disc galaxies in the local volume (size ∼ 11 Mpc). Our sample includes 36 objects with rotation curves carefully selected from the literature. We find that, despite the large variations of our sample in luminosities (∼ 2 of dex), the rotation curves in specifically normalized units, look all alike and lead to the lower-mass version of the universal rotation curve of spiral galaxies found in Persic et al. We mass model the double normalized universal rotation curve V (R/R opt )/V opt of dwarf disc galaxies: the results show that these systems are totally dominated by dark matter whose density shows a core size between 2 and 3 stellar disc scale lengths. Similar to galaxies of different Hubble types and luminosities, the core radius r 0 and the central density ρ 0 of the dark matter halo of these objects are related by ρ 0 r 0 ∼ 100 M pc −2 . The structural properties of the dark and luminous matter emerge very well correlated. In addition, to describe these relations, we need to introduce a new parameter, measuring the compactness of light distribution of a (dwarf) disc galaxy. These structural properties also indicate that there is no evidence of abrupt decline at the faint end of the baryonic to halo mass relation. Finally, we find that the distributions of the stellar disc and its dark matter halo are closely related.

Searching for TeV DM evidence from Dwarf Irregular Galaxies with the HAWC Observatory

“…This is a consequence of: a) their large astrophysical factors (100-1000 times larger) and b) the suboptimal declination of IC10 (peaking at 40deg off zenith for HAWC). As it was mentioned in Section 3.1, J factors are calculated with a Burkert profile, because this profile reproduces the rotation curves for dIrr Galaxies [1]. However, it is possible that cusped profiles can properly fit the rotation curves by considering non-rotational motions in Galaxies [19].…”

“…The source, right ascension (α), declination (δ ), DM mass to luminous mass ratio, virial radius (R vir ), scale density ρ 0 , scale radius r 0 , the Astrophysical Factor J are listed above. The quantities related to the DM halo are taken from [1] and are computed assuming that density profile is described by a Burkert profile. The J factors are calculated over all the spatial extension of each source.…”

“…For the set of dIrr Galaxies we studied here, the structural properties of luminous and DM contributions are constrained using kinematical data taken from [1]. The DM density is constrained to be described by a Burkert Profile [17].…”

“…The virial radius R vir is computed assuming an overdensity parameter ∆ = 100. Additionally, we computed the DM mass to luminous mass ratio (M DM /M Lum , column 4 in Table 1) using the masses obtained for fit results in [1]. From these values, it is observed that the mean amount of DM in these galaxies is 56.43 times their luminous matter.…”

“…It has been shown that local (d < 11Mpc) Dwarf Irregular (dIrr) Galaxies are Dark Matter (DM) dominated systems [1]. Using available data for rotation curves, the DM distribution is constrained to be described by an spherical DM halo with a Burkert density profile which extends up to radius greater than 15 times the optical radius r opt 1 .…”