scholarly journals Lighting Up Dark Matter Haloes

Galaxies ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 56
Author(s):  
Gabriella De Lucia
Keyword(s):  
Dark Matter ◽  
Physical Properties ◽  
Structure Formation ◽  
Observational Data ◽  
Complex Network ◽  
Theoretical Models ◽  
Dark Matter Halos ◽  
Close Link ◽  
Radiative Processes ◽  
Formation And Evolution

Previous chapters of this issue have focused on the formation and evolution of cosmic structures under the influence of gravity alone. In order to make a close link between theoretical models of structure formation and observational data, it is necessary to consider the gas-dynamical and radiative processes that drive the evolution of the baryonic components of dark matter halos. These processes cover many orders of magnitude in physical sizes and time-scales and are entangled in a complex network of actions, back-reactions, and self-regulations. In addition, our understanding of them is far from being complete, even when viewed in isolation. This chapter provides a brief review of the techniques that are commonly used to link the physical properties of galaxies with the dark matter halos in which they reside. I discuss the main features of these methods, as well as their aims, limits, and complementarities.

scholarly journals Hierarchical Formation of Dark Matter Halos near the Cutoff Scale and Their Impact on Indirect Detections

2015 ◽  
Vol 11 (A29B) ◽  
pp. 742-742
Author(s):  
Tomoaki Ishiyama
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxy ◽  
Theoretical Models ◽  
Mass Range ◽  
Mass Function ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Present Universe ◽  
Major Merger ◽  
Formation And Evolution

AbstractThe smallest dark matter halos are formed first in the early universe (e.g., Hofmann et al. 2001; Berezinsky et al. 2003; Ishiyama et al. 2010). We present results of very large cosmological N-body simulations of the hierarchical formation and evolution of halos over a wide mass range, beginning from the formation of the smallest halos. In the largest simulation, the motions of 40963 particles in comoving boxes of side lengths 400 pc and 200 pc were followed. The particle masses were 3.4 × 10−11M⊙ and 4.3 × 10−12M⊙, ensuring that halos at the cutoff scale were represented by 30,000 and 230,000 particles, respectively. We found that the central density cusp is much steeper in these halos than in larger halos (dwarf-galaxy-sized to cluster-sized halos), and scales as ρ ∝ r-(1.5–1.3). The cusp slope gradually becomes shallower as the halo mass increases.The slope of halos 50 times more massive than the smallest halo is approximately −1.3. No strong correlation exists between inner slope and the collapse epoch. The cusp slope of halos above the cutoff scale seems to be reduced primarily due to major merger processes. The concentration, estimated at the present universe, is predicted to be 60–70, consistent with theoretical models and earlier simulations, and ruling out simple power law mass-concentration relations. Such halos could still exist in the present universe with the same steep density profiles. Strongly depending on the subhalo mass function and the adopted concentration model, the steeper inner cusps of halos near the cutoff scale enhance the annihilation luminosity of a Milky Way sized halo between 12 to 67 (Ishiyama 2014).

scholarly journals THE STRUCTURE OF COLD DARK MATTER HALOS: RECENT INSIGHTS FROM HIGH RESOLUTION SIMULATIONS

2009 ◽  
Vol 24 (29) ◽  
pp. 2291-2305 ◽  
Author(s):  
MARCEL ZEMP
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Structure Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dark Matter Halos ◽  
General Properties

We review results from recent high resolution cosmological structure formation simulations, namely the Via Lactea I & II and GHALO projects. These simulations study the formation of Milky Way sized objects within a cosmological framework. We discuss the general properties of cold dark matter halos at redshift z = 0 and focus on new insights into the structure of halos we got due to the unprecedented high resolution in these simulations.

THE LINK BETWEEN GALAXIES AND DARK MATTER

2011 ◽  
Vol 20 (10) ◽  
pp. 1771-1777
Author(s):  
HOUJUN MO
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
The Other ◽  
Dark Matter Halos ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
Galaxy Halo ◽  
Formation And Evolution ◽  
The Universe

Given that dark matter is gravitationally dominant in the universe, and that galaxy formation is closely related to dark matter halos, a key first step in understanding galaxy formation and evolution in the CDM paradigm is to quantify the galaxy-halo connection for galaxies of different properties. Here I will present results about the halo/galaxy connection obtained from two different methods. One is based on the conditional luminosity function, which describes the occupation of galaxies in halos of different masses, and the other is based on galaxy systems properly selected to represent dark halos.

scholarly journals Building Galactic Disks in Triaxial Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 24-28
Author(s):  
Isaac Shlosman
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Star Formation ◽  
Numerical Simulations ◽  
Recent Work ◽  
Stellar Evolution ◽  
Dark Matter Halos ◽  
Local Universe ◽  
Broad Agreement ◽  
Formation And Evolution

AbstractWe review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in tandem with the disk and facilitate the angular momentum redistribution in the system and radial gas inflow. Nested bars appear to form as a by-product. Interactions between various non-axisymmetric components—bars, disks and halos lead to decay of bars or washing out of ellipticity in the inner halo.

scholarly journals Structure and Kinematics of Polar Ring Galaxies: New Observations and Estimation of the Dark Halo Shape

2015 ◽  
Vol 24 (1) ◽  
Author(s):  
A. Moiseev ◽  
S. Khoperskov ◽  
A. Khoperskov ◽  
K. Smirnova ◽  
A. Smirnova ◽  
...  
Keyword(s):  
Dark Matter ◽  
Observational Data ◽  
Dark Matter Halo ◽  
Dark Halo ◽  
Dark Matter Halos ◽  
Ionized Gas ◽  
Polar Ring ◽  
Gas Kinematics ◽  
Open Questions ◽  
Ring Galaxies

AbstractThe polar ring galaxies (PRGs) represent an interesting type of peculiar systems in which the outer matter is rotating in the plane which is roughly perpendicular to the disk of the main galaxy. Despite the long-lasting study of the PRGs, the amount of observational data detailed enough is insufficient; there still remain many open questions. Among the most interesting issues, there are: estimating the flattening of dark matter halos in these systems and verifying the assumption that the most massive polar structures were formed by accretion of the matter from intergalactic filaments. The new catalog recently compiled by our team using SDSS images increased, by several times, the number of known PRGs. The current paper gives an overview of our latest results on the study of morphological and photometric structure of the PRGs. Using the stellar and ionized gas kinematics data based on spectroscopic observations with the Russian 6-m telescope, we estimate the shape of dark matter halo in individual galaxies.

scholarly journals Extracting Galaxy Merger Timescales II: A new fitting formula

2020 ◽  
Author(s):  
R J J Poulton ◽  
C Power ◽  
A S G Robotham ◽  
P J Elahi ◽  
C D P Lagos
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Structure Formation ◽  
Structural Properties ◽  
Galaxy Formation ◽  
Fundamental Problem ◽  
Dark Matter Halos ◽  
New Model ◽  
Orbital Parameters ◽  
Improved Model

Abstract Predicting the merger timescale (τmerge) of merging dark matter halos, based on their orbital parameters and the structural properties of their hosts, is a fundamental problem in gravitational dynamics that has important consequences for our understanding of cosmological structure formation and galaxy formation. Previous models predicting τmerge have shown varying degrees of success when compared to the results of cosmological N-body simulations. We build on this previous work and propose a new model for τmerge that draws on insights derived from these simulations. We find that published predictions can provide reasonable estimates for τmerge based on orbital properties at infall, but tend to underpredict τmerge inside the host virial radius (R200) because tidal stripping is neglected, and overpredict it outside R200 because the host mass is underestimated. Furthermore, we find that models that account for orbital angular momentum via the circular radius Rcirc underpredict (overpredict) τmerge for bound (unbound) systems. By fitting for the dependence of τmerge on various orbital and host halo properties, we derive an improved model for τmerge that can be applied to a merging halo at any point in its orbit. Finally, we discuss briefly the implications of our new model for τmerge for semi-analytical galaxy formation modelling.

scholarly journals Hierarchical formation of Dark Matter Halos near the Free Streaming Scale, and Their Implications on Indirect Dark Matter Search

2014 ◽  
Vol 11 (S308) ◽  
pp. 416-419
Author(s):  
Tomoaki Ishiyama
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Power Law ◽  
Mass Concentration ◽  
Milky Way ◽  
Mass Range ◽  
Dark Matter Halos ◽  
Dark Matter Search ◽  
Concentration Parameter ◽  
Formation And Evolution

AbstractThe smallest dark matter halos are formed first in the early universe. According to recent studies, the central density cusp is much steeper in these halos than in larger halos and scales as ρ ∝ r−(1.5−1.3). We present results of very large cosmological N-body simulations of the hierarchical formation and evolution of halos over a wide mass range, beginning from the formation of the smallest halos. We confirmed early studies that the inner density cusps are steeper in halos at the free streaming scale. The cusp slope gradually becomes shallower as the halo mass increases. The slope of halos 50 times more massive than the smallest halo is approximately -1.3. The concentration parameter is nearly independent of halo mass, and ruling out simple power law mass-concentration relations. The steeper inner cusps of halos near the free streaming scale enhance the annihilation luminosity of a Milky Way sized halo between 12 to 67%.

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