High-Resolution Dark Matter Density Profiles of Two THINGS Dwarf Galaxies

ABSTRACT We construct mass models of eight gas rich dwarf galaxies that lie in the Lynx–Cancer void. From NFW fits to the dark matter halo profile, we find that the concentration parameters of haloes of void dwarf galaxies are similar to those of dwarf galaxies in normal density regions. We also measure the slope of the central dark matter density profiles, obtained by converting the rotation curves derived using 3D (fat) and 2D (ROTCUR) tilted ring fitting routines, into mass densities. We find that the average slope (α = −1.39 ± 0.19), obtained from 3D fitting is consistent with that expected from an NFW profile. On the other hand, the average slope measured using the 2D approach is closer to what would be expected for an isothermal profile. This suggests that systematic effects in velocity field analysis have a significant effect on the slope of the central dark matter density profiles. Given the modest number of galaxies we use for our analysis, it is important to check these results using a larger sample.

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Tidal evolution of dwarf galaxies with shallow dark matter density profiles

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314011181 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 346-346

Author(s):

Ewa L. Łokas

Keyword(s):

Dark Matter ◽

Milky Way ◽

Local Group ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Morphological Evolution ◽

Matter Density ◽

Density Profiles ◽

Tidal Evolution ◽

Dark Matter Density

AbstractOne of the scenarios for the formation of dwarf spheroidal galaxies in the Local Group proposes that the objects formed from late type dwarfs via tidal interaction with bigger galaxies such as the Milky Way and Andromeda. The scenario naturally explains the morphology-density relation observed for dwarf galaxies in the Local Group. Using N-body simulations we study the long-term tidal evolution of dwarf galaxies in the vicinity of the Milky Way. The dwarf galaxies were initially composed of stellar disks embedded in dark matter haloes of different inner density slopes including shallow ones recently obtained in N-body+hydro simulations of dwarf galaxy formation in isolation. Such progenitors were placed on five different orbits around the Milky Way and their evolution was followed for 10 Gyr. The outcome of the evolution, in terms of the mass loss, morphological transformation and randomization of stellar orbits depends very sensitively on the inner density slope of dark matter. The effects of tides are stronger for dwarfs with shallower slopes; they are more heavily stripped, in some cases down to the scale of ultra-faint satellites of the Milky Way or even dissolved completely with obvious implications for the missing satellites problem. The morphological evolution of the stellar component, from rotationally supported disks to spheroids dominated by random motions, also proceeds faster. In addition, bars which usually form at the first pericenter passage are created more easily and live longer in dwarfs with shallow dark matter density profiles on extended orbits.

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NIHAO – IV: core creation and destruction in dark matter density profiles across cosmic time

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stv2856 ◽

2016 ◽

Vol 456 (4) ◽

pp. 3542-3552 ◽

Cited By ~ 109

Author(s):

Edouard Tollet ◽

Andrea V. Macciò ◽

Aaron A. Dutton ◽

Greg S. Stinson ◽

Liang Wang ◽

...

Keyword(s):

Dark Matter ◽

Cosmic Time ◽

Matter Density ◽

Density Profiles ◽

Dark Matter Density

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Dark Matter in Dwarf Galaxies: High Resolution Observations

Symposium - International Astronomical Union ◽

10.1017/s0074180900183639 ◽

2004 ◽

Vol 220 ◽

pp. 353-358 ◽

Cited By ~ 1

Author(s):

Alberto D. Bolatto ◽

Joshua D. Simon ◽

Adam Leroy ◽

Leo Blitz

Keyword(s):

Dark Matter ◽

High Resolution ◽

Rotation Curve ◽

Dwarf Galaxies ◽

Full Range ◽

Dark Matter Halo ◽

Central Density ◽

Constant Density ◽

Density Profiles ◽

Central Regions

We present observations and analysis of rotation curves and dark matter halo density profiles in the central regions of four nearby dwarf galaxies. This observing program has been designed to overcome some of the limitations of other rotation curve studies that rely mostly on longslit spectra. We find that these objects exhibit the full range of central density profiles between ρ ∝ r0 (constant density) and ρ ∝ r–1 (NFW halo). This result suggests that there is a distribution of central density slopes rather than a unique halo density profile.

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