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 Formation of massive globular clusters with dark matter and its implication on dark matter annihilation

2020 ◽  
Vol 496 (1) ◽  
pp. L70-L74
Author(s):  
Henriette Wirth ◽  
Kenji Bekki ◽  
Kohei Hayashi
Keyword(s):  
Dark Matter ◽  
Observational Studies ◽  
Globular Clusters ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Large Range ◽  
Dark Matter Annihilation ◽  
Central Regions ◽  
Γ Ray ◽  
The Masses

ABSTRACT Recent observational studies of γ-ray emission from massive globular clusters (GCs) have revealed possible evidence of dark matter (DM) annihilation within GCs. It is, however, still controversial whether the emission comes from DM or from millisecond pulsars. We here present the new results of numerical simulations, which demonstrate that GCs with DM can originate from nucleated dwarfs orbiting the ancient Milky Way. The simulated stripped nuclei (i.e. GCs) have the central DM densities ranging from 0.1 to several M⊙ pc−3, depending on the orbits and the masses of the host dwarf galaxies. However, GCs born outside the central regions of their hosts can have no/little DM after their hosts are destroyed and the GCs become the Galactic halo GCs. These results suggest that only GCs originating from stellar nuclei of dwarfs can possibly have DM. We further calculate the expected γ-ray emission from these simulated GCs and compare them to observations of ω Cen. Given the large range of DM densities in the simulated GCs, we suggest that the recent possible detection of DM annihilation from GCs should be more carefully interpreted.

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 Dark-matter-deficient galaxies in hydrodynamical simulations

2019 ◽  
Vol 488 (3) ◽  
pp. 3298-3307 ◽  
Author(s):  
Yingjie Jing ◽  
Chunxiang Wang ◽  
Ran Li ◽  
Shihong Liao ◽  
Jie Wang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Binding Energy ◽  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
State Of The Art ◽  
Tidal Interactions ◽  
Group Environment ◽  
Central Regions ◽  
Low Mass ◽  
Hydrodynamical Simulations

Abstract Low-mass galaxies are expected to be dark-matter-dominated even within their central regions. Recently, two observations reported two dwarf galaxies in a group environment with very little dark matter in their central regions. We explore the population and origins of dark-matter-deficient galaxies (DMDGs) using two state-of-the-art hydrodynamical simulations, the EAGLE and Illustris projects. For all satellite galaxies with 109 < M* < 1010 M$\odot$ in groups with M200 > 1013 M$\odot$, we find that about $2.6\, {\rm per\, cent}$ of them in EAGLE, and $1.5\, {\rm per\, cent}$ in Illustris are DMDGs with dark matter fractions below $50\, {\rm per\, cent}$ inside two times the half-stellar-mass radius. We demonstrate that DMDGs are highly tidally disrupted galaxies, and that because dark matter has a higher binding energy than stars, mass loss of the dark matter is much more rapid than that of stars in DMDGs during tidal interactions. If DMDGs were confirmed in observations, they are expected in current galaxy formation models.

scholarly journals Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

2010 ◽  
Vol 514 ◽  
pp. A47 ◽  
Author(s):  
S. Pasetto ◽  
E. K. Grebel ◽  
P. Berczik ◽  
R. Spurzem ◽  
W. Dehnen
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Matter Density ◽  
Density Profiles ◽  
Dark Matter Density

scholarly journals Universal relations with fermionic dark matter

2018 ◽  
Vol 168 ◽  
pp. 04015
Author(s):  
A. Krut ◽  
C. R. Argüelles ◽  
J. A. Rueda ◽  
R. Ruffini
Keyword(s):  
Dark Matter ◽  
Finite Size ◽  
Elliptical Galaxies ◽  
Compact Objects ◽  
Space Distribution ◽  
Fermion Mass ◽  
Fermion Masses ◽  
Natural Mechanism ◽  
First Time ◽  
Good Agreement

We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc2 ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×106M⊙ within the S2 star pericenter. In particular, for a fermion mass of mc2 ∼ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ∼ 103M⊙ tp to 108M⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ∼ 108M⊙. We argue that larger BH masses (few ∼ 109−10M⊙) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.

scholarly journals A VLA/Merlin/VLBA For Intermediate Scale Lenses and the Discovery of a New Lens System?

1996 ◽  
Vol 173 ◽  
pp. 399-400
Author(s):  
P. Augusto ◽  
P.N. Wilkinson ◽  
I.W.A. Browne
Keyword(s):  
Dwarf Galaxies ◽  
Mass Range ◽  
Compact Objects ◽  
Radio Sources ◽  
Early Type ◽  
Lens System ◽  
Spectrum Radio ◽  
Deep Survey ◽  
First Time ◽  
Better Than

We are searching for small lens systems (50-250 mas or 108–109M⊙) in a sample of ∼ 1800 flat spectrum radio sources. This is the first time a systematic search has been made “between” the VLA and VLBI resolutions. Finding any would indicate the existence of other than the “conventional” spiral/elliptical lenses (only ∼ 0.01% chance - Turner et al. (1984)). For example, faint galaxies are numerous (∼ 106 gal/deg2 - Lilly (1993), Glazebrook et al. 1995), compact (HST Medium Deep Survey (MDS) - Griffiths et al. 1994) and ideally placed for lensing (< z >∼ 0.6 - MDS, Smail et al. (1994); c.f. Turner et al. 1984). Early-type dwarf galaxies (dE,N and cE), if extant at intermediate-z as favored by MDS are also obvious lens candidates. If no lenses are found, a limit 400 times better than the current one (Surdej et al. 1993), ΩL < 0.001, will be placed on the cosmological density of compact objects (e.g. black holes) for the above mass range.

scholarly journals Chemo-dynamical evolution of dwarf galaxies: from flat to cuspy dark matter density profiles

2009 ◽  
Vol 5 (H15) ◽  
pp. 78-78
Author(s):  
S. Pasetto ◽  
E. K. Grebel ◽  
P. Berczik ◽  
R. Spurzem
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Initial Conditions ◽  
Smooth Particle Hydrodynamic ◽  
Dynamical Evolution ◽  
Mass Range ◽  
Density Profiles ◽  
Hydrodynamic Approach ◽  
The Stability ◽  
Evolution With Time

A model of an isolated dwarf spherical galaxy (dSph) is considered in its chemo-dynamical evolution with time. The system is composed by 3 γ-model density profiles: gas, stellar and dark matter, and it is realized in a spherical symmetric equilibrium configuration. The total masses used in our simulations are covering the dwarf galaxies mass range. The stability of this configuration is first tested for the system evolving under the gravity effect alone and then evolved taking into account for the most relevant stellar astrophysical processes implemented with a Smooth Particle Hydrodynamic approach. The two different kinds of evolution are compared. The dark matter evolves naturally from a centrally cuspy density profile into a flatter one within a timescale of several Gyr. The effect manifests itself naturally, without any tuned initial conditions, as soon as few standard criteria on star formation are assumedand the SN feedback on the ISM has been adopted the prescription in (Cioffi & Shull 1991) and (Bradamante et al. 1998). This result is expected to be a possible natural explanation for the discrepancy between observations that want flatter dark matter profiles (e.g. de Block 2005), and N-body simulations that predict cuspy dark matter profiles (Navarro et al. 1997). Chemical considerations are presented as a tool to follow with observational parameters the theory predictions.

scholarly journals Dark Matter Substructure and Dwarf Galactic Satellites

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
Andrey Kravtsov
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Cold Dark Matter ◽  
Dynamical Friction ◽  
Density Profiles ◽  
Tidal Forces ◽  
Central Regions ◽  
Galactic Satellites ◽  
Virial Mass

A decade ago cosmological simulations of increasingly higher resolution were used to demonstrate that virialized regions of Cold Dark Matter (CDM) halos are filled with a multitude of dense, gravitationally bound clumps. These dark mattersubhalosare central regions of halos that survived strong gravitational tidal forces and dynamical friction during the hierarchical sequence of merging and accretion via which the CDM halos form. Comparisons with observations revealed that there is a glaring discrepancy between abundance of subhalos and luminous satellites of the Milky Way and Andromeda as a function of their circular velocity or bound mass within a fixed aperture. This large discrepancy, which became known as the “substructure” or the “missing satellites” problem, begs for an explanation. In this paper, the author reviews the progress made during the last several years both in quantifying the problem and in exploring possible scenarios in which it could be accommodated and explained in the context of galaxy formation in the framework of the CDM paradigm of structure formation. In particular, he shows that the observed luminosity function, radial distribution, and the remarkable similarity of the inner density profiles of luminous satellites can be understood within hierarchical CDM framework using a simple model in which efficiency of star formation monotonically decreases with decreasing virial mass satellites had before their accretionwithout any actual sharp galaxy formation threshold.

The inner structure of dark matter haloes in the Hubble sequence

2016 ◽  
Vol 25 (10) ◽  
pp. 1650093
Author(s):  
Antonino Del Popolo ◽  
Anna Saburova ◽  
Gaetano Belvedere
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Qualitative Agreement ◽  
Dwarf Galaxies ◽  
Rotation Velocity ◽  
Mass Range ◽  
Density Profiles ◽  
Hubble Sequence ◽  
Stellar Masses ◽  
Morphology Changes

We study how galaxy morphology changes the relation among the inner slope [Formula: see text] of galactic density profiles and the stellar mass, and rotation velocity. We find that the slope [Formula: see text] flattens monotonically from [Formula: see text] to [Formula: see text] going from giant galaxies (ellipticals, spirals) to dwarf galaxies ([Formula: see text]). At masses smaller than [Formula: see text], in the mass range dominated by nonrotational supported galaxies (e.g. dSphs), the slope steepens due to the offset in angular momentum of rotational dominated, and nonrotational dominated galaxies. A comparison with SPH simulations finds our result in qualitative agreement with them, but the inner slope [Formula: see text] at small stellar masses is flatter than that in their simulations. Density profiles become cuspy for [Formula: see text] in the range [Formula: see text]–[Formula: see text], similarly to Õnorbe.

scholarly journals Split SIMPs with decays

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Andrey Katz ◽  
Ennio Salvioni ◽  
Bibhushan Shakya
Keyword(s):  
Dark Matter ◽  
Massive Particle ◽  
Minimal Realization ◽  
General Applicability ◽  
Dark Matter Relic Density ◽  
The Standard Model ◽  
Potential Impact ◽  
The Masses ◽  
First Time ◽  
Kinetic Equilibrium

Abstract We discuss a minimal realization of the strongly interacting massive particle (SIMP) framework. The model includes a dark copy of QCD with three colors and three light flavors. A massive dark photon, kinetically mixed with the Standard Model hypercharge, maintains kinetic equilibrium between the dark and visible sectors. One of the dark mesons is necessarily unstable but long-lived, with potential impact on CMB observables. We show that an approximate “isospin” symmetry acting on the down-type quarks is an essential ingredient of the model. This symmetry stabilizes the dark matter and allows to split sufficiently the masses of the other states to suppress strongly their relic abundances. We discuss for the first time the SIMP cosmology with sizable mass splittings between all meson multiplets. We demonstrate that the SIMP mechanism remains efficient in setting the dark matter relic density, while CMB constraints on unstable relics can be robustly avoided. We also consider the phenomenological consequences of isospin breaking, including dark matter decay. Cosmological, astrophysical, and terrestrial probes are combined into a global picture of the parameter space. In addition, we outline an ultraviolet completion in the context of neutral naturalness, where confinement at the GeV scale is generic. We emphasize the general applicability of several novel features of the SIMP mechanism that we discuss here.

Sign in / Sign up

Export Citation Format

Share Document