scholarly journals Subhalo destruction in the Apostle and Auriga simulations

2019 ◽  
Vol 492 (4) ◽  
pp. 5780-5793 ◽  
Author(s):  
Jack Richings ◽  
Carlos Frenk ◽  
Adrian Jenkins ◽  
Andrew Robertson ◽  
Azadeh Fattahi ◽  
...  
Keyword(s):  
Dark Matter ◽  
Velocity Distribution ◽  
Galaxy Formation ◽  
Milky Way ◽  
State Of The Art ◽  
Systematic Errors ◽  
Mass Function ◽  
New Method ◽  
The Galaxy

ABSTRACT N-body simulations make unambiguous predictions for the abundance of substructures within dark matter haloes. However, the inclusion of baryons in the simulations changes the picture because processes associated with the presence of a large galaxy in the halo can destroy subhaloes and substantially alter the mass function and velocity distribution of subhaloes. We compare the effect of galaxy formation on subhalo populations in two state-of-the-art sets of hydrodynamical Λcold dark matter (ΛCDM) simulations of Milky Way mass haloes, Apostle and Auriga. We introduce a new method for tracking the orbits of subhaloes between simulation snapshots that gives accurate results down to a few kiloparsecs from the centre of the halo. Relative to a dark matter-only simulation, the abundance of subhaloes in Apostle is reduced by 50 per cent near the centre and by 10 per cent within r200. In Auriga, the corresponding numbers are 80 per cent and 40 per cent. The velocity distributions of subhaloes are also affected by the presence of the galaxy, much more so in Auriga than in Apostle. The differences on subhalo properties in the two simulations can be traced back to the mass of the central galaxies, which in Auriga are typically twice as massive as those in Apostle. We show that some of the results from previous studies are inaccurate due to systematic errors in the modelling of subhalo orbits near the centre of haloes.

scholarly journals Chemical Evolution of the Galactic Disk and Bulge

1995 ◽  
Vol 164 ◽  
pp. 133-149
Author(s):  
Rosemary F.G. Wyse
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Milky Way ◽  
Galactic Disk ◽  
Mass Function ◽  
Initial Mass Function ◽  
List Type ◽  
Dark Halo ◽  
Milky Way Galaxy ◽  
The Galaxy

The Milky Way Galaxy offers a unique opportunity for testing theories of galaxy formation and evolution. The study of the spatial distribution, kinematics and chemical abundances of stars in the Milky Way Galaxy allows one to address specific questions pertinent to this meeting such as (i)When was the Galaxy assembled? Is this an ongoing process? What was the merging history of the Milky Way?(ii)When did star formation occur in what is now “The Milky Way Galaxy”? Where did the star formation occur then? What was the stellar Initial Mass Function?(iii)How much dissipation of energy was there before and during the formation of the different stellar components of the Galaxy?(iv)What are the relationships among the different stellar components of the Galaxy?(v)Was angular momentum conserved during formation of the disk(s) of the Galaxy?(vi)What is the shape of the dark halo?(vii)Is there dissipative (disk) dark matter?

DARK MATTER IN SPIRAL HALOS AND THE HALO MASS FUNCTION

1994 ◽  
Vol 03 (supp01) ◽  
pp. 87-92
Author(s):  
KEITH M. ASHMAN ◽  
PAOLO SALUCCI ◽  
MASSIMO PERSIC
Keyword(s):  
Dark Matter ◽  
Hierarchical Clustering ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Mass Function ◽  
Dark Halo ◽  
Constant Mass ◽  
High Luminosity ◽  
The Galaxy ◽  
Galaxy Luminosity Function

Evidence that low-luminosity spirals have a higher dark matter fraction than their high-luminosity counterparts is discussed. The empirical correlation between dark matter fraction and luminosity is used, in conjunction with the galaxy luminosity function of spirals, to derive the dark halo mass function of these galaxies. The mass function is shown to be consistent with hierarchical clustering models of galaxy formation. This contrasts with previous results based on the assumption of a constant mass-to-light ratio for all spirals, which predict too many low-luminosity galaxies.

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 A systematic search for galaxy proto-cluster cores at z ∼ 2

2019 ◽  
Vol 15 (S359) ◽  
pp. 166-167
Author(s):  
Makoto Ando ◽  
Kazuhiro Shimasaku ◽  
Rieko Momose
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Clustering Analysis ◽  
Mass Function ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Mass Assembly ◽  
Cluster Cores

AbstractA proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at z ˜ 2 in ˜1.5deg2 of the COSMOS field. Using pairs of massive galaxies (log (M*/Mʘ) ≥ 11) as tracers of cores, we find 75 candidate cores. A clustering analysis and the extended Press-Schechter model show that their descendant mass at z = 0 is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function and the quiescent fraction for member galaxies of the 75 candidate cores. We find that stellar mass assembly and quenching are accelerated as early as z ˜ 2 in proto-cluster cores.

scholarly journals The mass of the Milky Way from satellite dynamics

2019 ◽  
Vol 484 (4) ◽  
pp. 5453-5467 ◽  
Author(s):  
Thomas M Callingham ◽  
Marius Cautun ◽  
Alis J Deason ◽  
Carlos S Frenk ◽  
Wenting Wang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dimensional Space ◽  
Dimensional Phase Space ◽  
The Galaxy ◽  
Galactic Satellites ◽  
Mass Estimate ◽  
True Mass

Abstract We present and apply a method to infer the mass of the Milky Way (MW) by comparing the dynamics of MW satellites to those of model satellites in the eagle cosmological hydrodynamics simulations. A distribution function (DF) for galactic satellites is constructed from eagle using specific angular momentum and specific energy, which are scaled so as to be independent of host halo mass. In this two-dimensional space, the orbital properties of satellite galaxies vary according to the host halo mass. The halo mass can be inferred by calculating the likelihood that the observed satellite population is drawn from this DF. Our method is robustly calibrated on mock eagle systems. We validate it by applying it to the completely independent suite of 30 auriga high-resolution simulations of MW-like galaxies: the method accurately recovers their true mass and associated uncertainties. We then apply it to 10 classical satellites of the MW with six-dimensional phase-space measurements, including updated proper motions from the Gaia satellite. The mass of the MW is estimated to be $M_{200}^{\rm {MW}}=1.17_{-0.15}^{+0.21}\times 10^{12}\, \mathrm{M}_{\odot }$ (68 per cent confidence limits). We combine our total mass estimate with recent mass estimates in the inner regions of the Galaxy to infer an inner dark matter (DM) mass fraction $M^\rm {DM}(\lt 20~\rm {kpc})/M^\rm {DM}_{200}=0.12$, which is typical of ${\sim }10^{12}\, \mathrm{M}_{\odot }$ lambda cold dark matter haloes in hydrodynamical galaxy formation simulations. Assuming a Navarro, Frenk and White (NFW) profile, this is equivalent to a halo concentration of $c_{200}^{\rm {MW}}=10.9^{+2.6}_{-2.0}$.

scholarly journals The detailed structure and the onset of galaxy formation in low-mass gaseous dark matter haloes

2020 ◽  
Vol 498 (4) ◽  
pp. 4887-4900
Author(s):  
Alejandro Benitez-Llambay ◽  
Carlos Frenk
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Background Radiation ◽  
Critical Mass ◽  
Mass Function ◽  
Hydrostatic Equilibrium ◽  
Before And After ◽  
The Galaxy ◽  
Hydrogen Cooling ◽  
First Galaxies

ABSTRACT We present a model for the formation of the first galaxies before and after the reionization of hydrogen in the early universe. In this model, galaxy formation can only take place in dark matter haloes whose mass exceeds a redshift-dependent critical value, which, before reionization, is equal (in the simplest case) to the mass at which atomic hydrogen cooling becomes effective and, after reionization, is equal to the mass above which gas cannot remain in hydrostatic equilibrium. We define the Halo Occupation Fraction (HOF) as the fraction of haloes that host a luminous galaxy as a function of halo mass. The HOF is established by the interplay between the evolution of the critical mass and the assembly history of haloes and depends on three factors: the minimum halo mass for galaxy formation before reionization, the redshift of reionization, and the intensity of the (evolving) external photoheating rate. Our fiducial model predicts a cutoff in the galaxy mass function at a present-day halo mass, $M_{200} \sim 3\times 10^{8} \, \mathrm{M}_{\odot }$; 100 per cent occupation at $M_{200} \gt 5\times 10^9 \, \mathrm{M}_{\odot }$; and a population of starless gaseous haloes of present-day mass in the range 106 ≲ M200/M⊙ ≲ 5 × 109, in which the gas is in thermal equilibrium with the ultraviolet background radiation and in hydrostatic equilibrium in the gravitational potential of the halo. The transition between HOF = 0 and HOF = 1 reflects the stochastic nature of halo mass growth. We explore how these characteristic masses vary with model assumptions and parameter values. The results of our model are in excellent agreement with cosmological hydrodynamic simulations of galaxy formation.

scholarly journals Kinematical & Chemical Characteristics of the Thin and Thick Disks

2008 ◽  
Vol 4 (S254) ◽  
pp. 179-190 ◽  
Author(s):  
Rosemary F. G. Wyse
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Observational Evidence ◽  
Chemical Characteristics ◽  
Chemical Abundance ◽  
The Galaxy ◽  
History Of ◽  
Thin And Thick Disks ◽  
Thick Disks

AbstractI discuss how the chemical abundance distributions, kinematics and age distributions of stars in the thin and thick disks of the Galaxy can be used to decipher the merger history of the Milky Way, a typical large galaxy. The observational evidence points to a rather quiescent past merging history, unusual in the context of the ‘consensus’ cold-dark-matter cosmology favoured from observations of structure on scales larger than individual galaxies.

scholarly journals The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

2021 ◽  
Vol 650 ◽  
pp. A113
Author(s):  
Margot M. Brouwer ◽  
Kyle A. Oman ◽  
Edwin A. Valentijn ◽  
Maciej Bilicki ◽  
Catherine Heymans ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Modified Gravity ◽  
Cold Dark Matter ◽  
Weak Lensing ◽  
Mass Relation ◽  
Gravitational Acceleration ◽  
Radial Acceleration ◽  
The Galaxy ◽  
The Difference

We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.

scholarly journals NIHAO project II: halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

2016 ◽  
Vol 462 (1) ◽  
pp. 663-680 ◽  
Author(s):  
Iryna Butsky ◽  
Andrea V. Macciò ◽  
Aaron A. Dutton ◽  
Liang Wang ◽  
Aura Obreja ◽  
...  
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Velocity Distribution ◽  
Galaxy Formation ◽  
Phase Space Density ◽  
Space Density

scholarly journals Heating of Milky Way disc stars by dark matter fluctuations in cold dark matter and fuzzy dark matter paradigms

2019 ◽  
Vol 485 (2) ◽  
pp. 2861-2876 ◽  
Author(s):  
Benjamin V Church ◽  
Philip Mocz ◽  
Jeremiah P Ostriker
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Quantum Interference ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Formation Rate ◽  
Density Fluctuations ◽  
Particle Mass ◽  
Small Scale

ABSTRACT Although highly successful on cosmological scales, cold dark matter (CDM) models predict unobserved overdense ‘cusps’ in dwarf galaxies and overestimate their formation rate. We consider an ultralight axion-like scalar boson which promises to reduce these observational discrepancies at galactic scales. The model, known as fuzzy dark matter (FDM), avoids cusps, suppresses small-scale power, and delays galaxy formation via macroscopic quantum pressure. We compare the substructure and density fluctuations of galactic dark matter haloes comprised of ultralight axions to conventional CDM results. Besides self-gravitating subhaloes, FDM includes non-virialized overdense wavelets formed by quantum interference patterns, which are an efficient source of heating to galactic discs. We find that, in the solar neighbourhood, wavelet heating is sufficient to give the oldest disc stars a velocity dispersion of ${\sim } {30}{\, \mathrm{km\, s}^{-1}}$ within a Hubble time if energy is not lost from the disc, the velocity dispersion increasing with stellar age as σD ∝ t0.4 in agreement with observations. Furthermore, we calculate the radius-dependent velocity dispersion and corresponding scaleheight caused by the heating of this dynamical substructure in both CDM and FDM with the determination that these effects will produce a flaring that terminates the Milky Way disc at $15\!-\!20{\, \mathrm{kpc}}$. Although the source of thickened discs is not known, the heating due to perturbations caused by dark substructure cannot exceed the total disc velocity dispersion. Therefore, this work provides a lower bound on the FDM particle mass of ma > 0.6 × 10−22 eV. Furthermore, FDM wavelets with this particle mass should be considered a viable mechanism for producing the observed disc thickening with time.

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