scholarly journals Simulations of satellite tidal debris in the Milky Way halo

2020 ◽  
Vol 636 ◽  
pp. A106
Author(s):  
Matteo Mazzarini ◽  
Andreas Just ◽  
Andrea V. Macciò ◽  
Reza Moetazedian
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Host Galaxy ◽  
Massive Galaxies ◽  
Stellar Component ◽  
Radial Profiles ◽  
Hydrodynamical Simulations ◽  
A Minor ◽  
Power Law Index ◽  
Milky Way Halo

Aims. We study the distribution of the stellar and dark matter debris of the Milky Way satellites. Methods. For the first time we address the question of the tidal disruption of satellites in simulations by utilising simultaneously (a) a realistic set of orbits extracted from cosmological simulations; (b) a three-component host galaxy with live halo, disc, and bulge components; and (c) satellites from hydrodynamical simulations. We analyse the statistical properties of the satellite debris of all massive galaxies reaching the inner Milky Way on a timescale of 2 Gyr. Results. Up to 80% of the dark matter is stripped from the satellites, while this happens for up to 30% of their stars. The stellar debris ends mostly in the inner Milky Way halo, whereas the dark matter debris shows a flat mass distribution over the full main halo. The dark matter debris follows a density profile with inner power law index αDM = −0.66 and outer index βDM = 2.94, while for stars α* = −0.44 and β* = 6.17. In the inner 25 kpc the distribution of the stellar debris is flatter than that of the dark matter debris, and the orientations of their short axes differ significantly. Changing the orientation of the stellar disc by 90° has a minor impact on the distribution of the satellite debris. Conclusions. Our results indicate that dark matter is more easily stripped than stars from the Milky Way satellites. The structure of the debris is dominated by the satellite orbital properties. The radial profiles, the flattening, and the orientation of the stellar and dark matter debris are significantly different, which prevents the prediction of the dark matter distribution from the observed stellar component.

scholarly journals Cold Dark Matter Substructure and the Heating of Galactic Disks

2003 ◽  
Vol 208 ◽  
pp. 391-392
Author(s):  
Andreea S. Font ◽  
Julio F. Navarro
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dark Matter Halo ◽  
Stellar Disk ◽  
Minor Role ◽  
Galactic Disks ◽  
Cosmological Simulations ◽  
A Minor

We investigate recent suggestions that substructure in cold dark matter (CDM) halos has potentially destructive effects on galactic disks. N-body simulations of disk/bulge models of the Milky Way, embedded in a dark matter halo with substructure similar to that found in cosmological simulations, show that tides from substructure halos play only a minor role in the dynamical heating of the stellar disk. This suggests that substructure might not preclude CDM halos from being acceptable hosts of thin stellar disks.

scholarly journals The artemis simulations: stellar haloes of Milky Way-mass galaxies

2020 ◽  
Vol 498 (2) ◽  
pp. 1765-1785 ◽  
Author(s):  
Andreea S Font ◽  
Ian G McCarthy ◽  
Robert Poole-Mckenzie ◽  
Sam G Stafford ◽  
Shaun T Brown ◽  
...  
Keyword(s):  
High Resolution ◽  
Galaxy Formation ◽  
Large Scale ◽  
Milky Way ◽  
Mass Density ◽  
Power Laws ◽  
Stellar Feedback ◽  
Radial Profiles ◽  
Hydrodynamical Simulations

ABSTRACT We introduce the Assembly of high-ResoluTion Eagle-simulations of MIlky Way-type galaxieS (artemis) simulations, a new set of 42 zoomed-in, high-resolution (baryon particle mass of $\approx 2\times 10^4 \, {\rm M}_{\odot }\, h^{-1}$), hydrodynamical simulations of galaxies residing in haloes of Milky Way mass, simulated with the eagle galaxy formation code with re-calibrated stellar feedback. In this study, we analyse the structure of stellar haloes, specifically the mass density, surface brightness, metallicity, colour, and age radial profiles, finding generally very good agreement with recent observations of local galaxies. The stellar density profiles are well fitted by broken power laws, with inner slopes of ≈−3, outer slopes of ≈−4, and break radii that are typically ≈20–40 kpc. The break radii generally mark the transition between in situ formation and accretion-driven formation of the halo. The metallicity, colour, and age profiles show mild large-scale gradients, particularly when spherically averaged or viewed along the major axes. Along the minor axes, however, the profiles are nearly flat, in agreement with observations. Overall, the structural properties can be understood by two factors: that in situ stars dominate the inner regions and that they reside in a spatially flattened distribution that is aligned with the disc. Observations targeting both the major and minor axes of galaxies are thus required to obtain a complete picture of stellar haloes.

scholarly journals The effect of warm gas on the buckling instability in galactic bars

2020 ◽  
Vol 634 ◽  
pp. A122
Author(s):  
Ewa L. Łokas
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Gas Content ◽  
Dark Matter Halo ◽  
Buckling Instability ◽  
Radial Profiles ◽  
Formation And Evolution ◽  
The One ◽  
Gas Fractions ◽  
Gas Component

By using N-body and hydro simulations, we study the formation and evolution of bars in galaxies with significant gas content focusing on the phenomenon of the buckling instability. The galaxies are initially composed of a spherical dark matter halo and only stellar, or stellar and gaseous, disks with parameters that are similar to the Milky Way and are evolved for 10 Gyr. We consider different values of the gas fraction f = 0−0.3 and in order to isolate the effect of the gas, we kept the fraction constant during the evolution by not allowing the gas to cool and form stars. The stellar bars that form in simulations with higher gas fractions are weaker and shorter, and they do not form at all for gas fractions that are higher than 0.3. The bar with a gas fraction of 0.1 forms sooner due to initial perturbations in the gas, but despite the longer evolution, it does not become stronger than the one in the collisionless case at the end of evolution. The bars in the gas component are weaker; they reach their maximum strength around 4 Gyr and later decline to transform into spheroidal shapes. The distortion of the stellar bar during the buckling instability is weaker for higher gas fractions and weakens the bar less significantly, but it has a similar structure both in terms of radial profiles and in face-on projections. For f = 0.2, the first buckling lasts significantly longer and the bar does not undergo the secondary buckling event, while for f = 0.3, the buckling does not occur. Despite these differences, all bars develop boxy/peanut shapes in the stellar and gas component by the end of the evolution, although their thickness is smaller for higher gas fractions.

scholarly journals Implications of hydrodynamical simulations for the interpretation of direct dark matter searches

2017 ◽  
Vol 32 (21) ◽  
pp. 1730016 ◽  
Author(s):  
Nassim Bozorgnia ◽  
Gianfranco Bertone
Keyword(s):  
Dark Matter ◽  
Velocity Distribution ◽  
Milky Way ◽  
Direct Detection ◽  
Solar Neighborhood ◽  
Reliable Estimate ◽  
The Status ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Direct Dark Matter

In recent years, realistic hydrodynamical simulations of galaxies like the Milky Way have become available, enabling a reliable estimate of the dark matter density and velocity distribution in the Solar neighborhood. We review here the status of hydrodynamical simulations and their implications for the interpretation of direct dark matter searches. We focus in particular on: the criteria to identify Milky Way-like galaxies; the impact of baryonic physics on the dark matter velocity distribution; the possible presence of substructures like clumps, streams, or dark disks; and on the implications for the direct detection of dark matter with standard and nonstandard interactions.

scholarly journals The spatial distribution of Milky Way satellites, gaps in streams and the nature of dark matter

2021 ◽  
Author(s):  
Mark R Lovell ◽  
Marius Cautun ◽  
Carlos S Frenk ◽  
Wojciech A Hellwing ◽  
Oliver Newton
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
High Resolution ◽  
Radial Distribution ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Self Consistent ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
The Impact

Abstract The spatial distribution of Milky Way (MW) subhaloes provides an important set of observables for testing cosmological models. These include the radial distribution of luminous satellites, planar configurations, and the abundance of dark subhaloes whose existence or absence is key to distinguishing amongst dark matter models. We use the coco N-body simulations of cold dark matter (CDM) and 3.3 keV thermal relic warm dark matter (WDM) to predict the satellite spatial distribution in the limit that the impact of baryonic physics is minimal. We demonstrate that the radial distributions of CDM and 3.3 keV-WDM luminous satellites are identical if the minimum pre-infall halo mass to form a galaxy is >108.5 ${\, \rm M_\odot }$. The distribution of dark subhaloes is significantly more concentrated in WDM due to the absence of low mass, recently accreted substructures that typically inhabit the outer parts of a MW halo in CDM. We show that subhaloes of mass [107, 108] ${\, \rm M_\odot }$ and within 30 kpc of the centre are the stripped remnants of larger haloes in both models. Therefore their abundance in WDM is 3 × higher than one would anticipate from the overall WDM subhalo population. We estimate that differences between CDM and WDM concentration–mass relations can be probed for subhalo–stream impact parameters <2 kpc. Finally, we find that the impact of WDM on planes of satellites is likely negligible. Comprehensive comparisons with observations will require further work with high resolution, self-consistent hydrodynamical simulations.

scholarly journals Stellar halos and the link to galaxy formation

2015 ◽  
Vol 11 (S317) ◽  
pp. 228-234
Author(s):  
Amina Helmi
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Galaxy Formation ◽  
Globular Cluster ◽  
Milky Way ◽  
Cluster System ◽  
Host Galaxy ◽  
Globular Cluster System

AbstractI present a brief overview of how stellar halos may be used to constrain the process of galaxy formation. In particular, streams and substructure in stellar halos trace merger events but can also be used to determine the mass distribution of the host galaxy and hence put constraints on the nature of dark matter. Much of the focus of this contribution is on the Milky Way, but I also present an attempt to understand the kinematics of the globular cluster system of M31.

scholarly journals The orbital phase space of contracted dark matter haloes

2020 ◽  
Vol 495 (1) ◽  
pp. 12-28 ◽  
Author(s):  
Thomas M Callingham ◽  
Marius Cautun ◽  
Alis J Deason ◽  
Carlos S Frenk ◽  
Robert J J Grand ◽  
...  
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Total Mass ◽  
Milky Way ◽  
Direct Detection ◽  
Baryon Density ◽  
Orbital Phase ◽  
Mass Profile ◽  
Hydrodynamical Simulations ◽  
Radial Action

ABSTRACT We study the orbital phase space of dark matter (DM) haloes in the auriga suite of cosmological hydrodynamics simulations of Milky Way (MW) analogues. We characterize haloes by their spherical action distribution, $F\left(J_{{r}},L\right)$, a function of the specific angular momentum, L, and the radial action, Jr, of the DM particles. By comparing DM-only and hydrodynamical simulations of the same haloes, we investigate the contraction of DM haloes caused by the accumulation of baryons at the centre. We find a small systematic suppression of the radial action in the DM haloes of the hydrodynamical simulations, suggesting that the commonly used adiabatic contraction approximation can result in an underestimate of the density by $\sim 8{{ \rm {per\ cent}}}$. We apply an iterative algorithm to contract the auriga DM haloes given a baryon density profile and halo mass, recovering the true contracted DM profiles with an accuracy of $\sim 15{{ \rm {per\ cent}}}$, that reflects halo-to-halo variation. Using this algorithm, we infer the total mass profile of the MW’s contracted DM halo. We derive updated values for the key astrophysical inputs to DM direct detection experiments: the DM density and velocity distribution in the Solar neighbourhood.

scholarly journals Alignments of galaxies and halos in hydrodynamical simulations

2014 ◽  
Vol 11 (S308) ◽  
pp. 477-478
Author(s):  
Isha Pahwa ◽  
Noam I. Libeskind
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Separate Study ◽  
Hydrodynamical Simulation ◽  
Stellar Component ◽  
Hydrodynamical Simulations

AbstractWe use a 200 h−1Mpc cosmological hydrodynamical simulation to examine the alignments of galaxies with respect to the host halo. We do separate study for the different components of the halo, such as stars, gas and dark matter. We show that angular momentum of gas is more aligned with the angular momentum of host halo compared with the stellar component.

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