scholarly journals Dark Matter in Dwarf Galaxies: High Resolution Observations

2004 ◽  
Vol 220 ◽  
pp. 353-358 ◽  
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.

scholarly journals Globular clusters as probes of dark matter cusp-core transformations

2019 ◽  
Vol 488 (3) ◽  
pp. 2977-2988 ◽  
Author(s):  
M D A Orkney ◽  
J I Read ◽  
J A Petts ◽  
M Gieles
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Massive Star ◽  
Dwarf Galaxies ◽  
Dynamical Evolution ◽  
Dark Matter Halo ◽  
Constant Density ◽  
Ngc 6822 ◽  
Hubble Time

Abstract Bursty star formation in dwarf galaxies can slowly transform a steep dark matter cusp into a constant density core. We explore the possibility that globular clusters (GCs) retain a dynamical memory of this transformation. To test this, we use the nbody6df code to simulate the dynamical evolution of GCs, including stellar evolution, orbiting in static and time-varying potentials for a Hubble time. We find that GCs orbiting within a cored dark matter halo, or within a halo that has undergone a cusp-core transformation, grow to a size that is substantially larger (Reff > 10 pc) than those in a static cusped dark matter halo. They also produce much less tidal debris. We find that the cleanest signal of an historic cusp-core transformation is the presence of large GCs with tidal debris. However, the effect is small and will be challenging to observe in real galaxies. Finally, we qualitatively compare our simulated GCs with the observed GC populations in the Fornax, NGC 6822, IKN, and Sagittarius dwarf galaxies. We find that the GCs in these dwarf galaxies are systematically larger (〈Reff〉 ≃ 7.8 pc), and have substantially more scatter in their sizes than in situ metal-rich GCs in the Milky Way and young massive star clusters forming in M83 (〈Reff〉 ≃ 2.5 pc). We show that the size, scatter, and survival of GCs in dwarf galaxies are all consistent with them having evolved in a constant density core, or a potential that has undergone a cusp-core transformation, but not in a dark matter cusp.

scholarly journals THE ASYMPTOTIC STRUCTURE OF SPACE-TIME

2003 ◽  
Vol 12 (09) ◽  
pp. 1743-1750 ◽  
Author(s):  
FRED C. ADAMS ◽  
MICHAEL T. BUSHA ◽  
AUGUST E. EVRARD ◽  
RISA H. WECHSLER
Keyword(s):  
Dark Matter ◽  
Vacuum Energy ◽  
Space Time ◽  
Dark Matter Halo ◽  
Constant Density ◽  
Dark Matter Halos ◽  
Asymptotic Structure ◽  
Density Profiles ◽  
Near Future ◽  
Universal Geometry

Astronomical observations strongly suggest that our universe is now accelerating and contains a substantial admixture of dark vacuum energy. Using numerical simulations to study this newly consolidated cosmological model (with a constant density of dark energy), we show that astronomical structures freeze out in the near future and that the density profiles of dark matter halos approach the same general form. Every dark matter halo grows asymptotically isolated and thereby becomes the center of its own island universe. Each of these isolated regions of space-time approaches a universal geometry and we calculate the corresponding form of the space-time metric.

scholarly journals A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes

2020 ◽  
Vol 497 (2) ◽  
pp. 2393-2417 ◽  
Author(s):  
Alexandres Lazar ◽  
James S Bullock ◽  
Michael Boylan-Kolchin ◽  
T K Chan ◽  
Philip F Hopkins ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dark Matter Halo ◽  
Constant Density ◽  
Core Formation ◽  
Density Profiles ◽  
The Galaxy ◽  
Two Parameter

ABSTRACT We analyse the cold dark matter density profiles of 54 galaxy haloes simulated with Feedback In Realistic Environments (FIRE)-2 galaxy formation physics, each resolved within $0.5{{\ \rm per\ cent}}$ of the halo virial radius. These haloes contain galaxies with masses that range from ultrafaint dwarfs ($M_\star \simeq 10^{4.5}\, \mathrm{M}_{\odot }$) to the largest spirals ($M_\star \simeq 10^{11}\, \mathrm{M}_{\odot }$) and have density profiles that are both cored and cuspy. We characterize our results using a new, analytic density profile that extends the standard two-parameter Einasto form to allow for a pronounced constant density core in the resolved innermost radius. With one additional core-radius parameter, rc, this three-parameter core-Einasto profile is able to characterize our feedback-impacted dark matter haloes more accurately than other three-parameter profiles proposed in the literature. To enable comparisons with observations, we provide fitting functions for rc and other profile parameters as a function of both M⋆ and M⋆/Mhalo. In agreement with past studies, we find that dark matter core formation is most efficient at the characteristic stellar-to-halo mass ratio M⋆/Mhalo ≃ 5 × 10−3, or $M_{\star } \sim 10^9 \, \mathrm{M}_{\odot }$, with cores that are roughly the size of the galaxy half-light radius, rc ≃ 1−5 kpc. Furthermore, we find no evidence for core formation at radii $\gtrsim 100\ \rm pc$ in galaxies with M⋆/Mhalo < 5 × 10−4 or $M_\star \lesssim 10^6 \, \mathrm{M}_{\odot }$. For Milky Way-size galaxies, baryonic contraction often makes haloes significantly more concentrated and dense at the stellar half-light radius than DMO runs. However, even at the Milky Way scale, FIRE-2 galaxy formation still produces small dark matter cores of ≃ 0.5−2 kpc in size. Recent evidence for a ∼2 kpc core in the Milky Way’s dark matter halo is consistent with this expectation.

scholarly journals Dwarf galaxies in CDM, WDM, and SIDM: disentangling baryons and dark matter physics

2019 ◽  
Vol 490 (1) ◽  
pp. 962-977 ◽  
Author(s):  
Alex Fitts ◽  
Michael Boylan-Kolchin ◽  
Brandon Bozek ◽  
James S Bullock ◽  
Andrew Graus ◽  
...  
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Compact Objects ◽  
Density Profiles ◽  
Unique Challenge ◽  
Spatially Resolved ◽  
Central Regions ◽  
Hydrodynamical Simulations ◽  
The Masses ◽  
First Time

ABSTRACT We present a suite of FIRE-2 cosmological zoom-in simulations of isolated field dwarf galaxies, all with masses of $M_{\rm halo} \approx 10^{10}\, {\rm M}_{\odot }$ at z = 0, across a range of dark matter models. For the first time, we compare how both self-interacting dark matter (SIDM) and/or warm dark matter (WDM) models affect the assembly histories as well as the central density structure in fully hydrodynamical simulations of dwarfs. Dwarfs with smaller stellar half-mass radii (r1/2 < 500 pc) have lower σ⋆/Vmax ratios, reinforcing the idea that smaller dwarfs may reside in haloes that are more massive than is naively expected. The majority of dwarfs simulated with self-interactions actually experience contraction of their inner density profiles with the addition of baryons relative to the cores produced in dark-matter-only runs, though the simulated dwarfs are always less centrally dense than in ΛCDM. The V1/2–r1/2 relation across all simulations is generally consistent with observations of Local Field dwarfs, though compact objects such as Tucana provide a unique challenge. Overall, the inclusion of baryons substantially reduces any distinct signatures of dark matter physics in the observable properties of dwarf galaxies. Spatially resolved rotation curves in the central regions (<400 pc) of small dwarfs could provide a way to distinguish between CDM, WDM, and SIDM, however: at the masses probed in this simulation suite, cored density profiles in dwarfs with small r1/2 values can only originate from dark matter self-interactions.

scholarly journals Dark Matter Distribution in Nearby Galaxies

2004 ◽  
Vol 220 ◽  
pp. 327-328
Author(s):  
Olivia Garrido ◽  
Philippe Amram ◽  
Claude Carignan ◽  
Sébastien Blais-Ouellette ◽  
Michel Marcelin ◽  
...  
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Mass Distribution ◽  
Rotation Curve ◽  
Velocity Fields ◽  
Constant Density ◽  
Matter Distribution ◽  
Fabry Perot ◽  
Nearby Galaxies ◽  
Dark Matter Distribution

We present results obtained from a study of the mass distribution of 24 galaxies observed using Fabry-Pérot techniques, as part of the GHASP survey (see Russeil et al., this meeting). For each galaxy, we combined high resolution Hα rotation curves derived from 2-D velocity fields, with low resolution HI data, in order to determine accurately the inner slope of the rotation curve which strongly constrains the distribution of matter. Our work suggests the existence of a constant density core in the center of the dark halos.

scholarly journals Mass models of gas-rich void dwarf galaxies

2019 ◽  
Vol 491 (4) ◽  
pp. 4993-5014 ◽  
Author(s):  
Sushma Kurapati ◽  
Jayaram N Chengalur ◽  
Peter Kamphuis ◽  
Simon Pustilnik
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Matter Density ◽  
Field Analysis ◽  
Dark Matter Halo ◽  
Normal Density ◽  
Density Profiles ◽  
Dark Matter Density ◽  
Average Slope ◽  
Systematic Effects

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.

scholarly journals Voids in the Local Volume: a Limit on Appearance of a Galaxy in a Dark Matter Halo

2007 ◽  
Vol 3 (S244) ◽  
pp. 152-156
Author(s):  
Anton V. Tikhonov ◽  
Anatoly A. Klypin
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Host Galaxies ◽  
Group Data ◽  
Luminous Matter ◽  
Very High

AbstractCurrent explanation of the overabundance of dark matter subhalos in the Local Group (LG) indicates that there maybe a limit on mass of a halo, which can host a galaxy. This idea can be tested using voids in the distribution of galaxies: at some level small voids should not contain any (even dwarf) galaxies. We use observational samples complete to MB = −12 with distances less than 8 Mpc to construct the void function (VF): the distribution of sizes of voids empty of any galaxies. There are ~ 30 voids with sizes ranging from 1 to 5 Mpc. We then study the distribution of dark matter halos in very high resolution simulations of the LCDM model. The theoretical VF matches the observations remarkably well only if we use halos with circular velocities larger than 45 ± 10 km/s. This agrees with the Local Group predictions. There are smaller halos in the voids, but they should not produce any luminous matter. Small voids look quite similar to their giant cousins: the density has a minimum at the center of a void and it increases as we get closer to the border. Small nonluminous halos inside the void form a web of tiny filaments. Thus, both the Local Group data and the nearby voids indicate that isolated halos below 45 ± 10 km/s must not host galaxies and that small (few Mpc) voids are truly dark.

scholarly journals HIGH-RESOLUTION DARK MATTER DENSITY PROFILES OF THINGS DWARF GALAXIES: CORRECTING FOR NONCIRCULAR MOTIONS

2008 ◽  
Vol 136 (6) ◽  
pp. 2761-2781 ◽  
Author(s):  
Se-Heon Oh ◽  
W. J. G. de Blok ◽  
Fabian Walter ◽  
Elias Brinks ◽  
Robert C. Kennicutt
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Dwarf Galaxies ◽  
Matter Density ◽  
Density Profiles ◽  
Dark Matter Density

scholarly journals The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Marc S. Seigar
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Density Profile ◽  
Pitch Angle ◽  
Rotation Curve ◽  
Dark Matter Halo ◽  
Black Hole Mass ◽  
Supermassive Black Hole ◽  
Virial Mass ◽  
Spiral Arm

We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of and a virial mass of . We go on to use the NFW concentration of M33, along with the values derived for other galaxies (as found in the literature), to show that correlates with both spiral arm pitch angle and supermassive black hole mass.

Sign in / Sign up

Export Citation Format

Share Document