scholarly journals Aging haloes: implications of the magnitude gap on conditional statistics of stellar and gas properties of massive haloes

2020 ◽  
Vol 493 (1) ◽  
pp. 1361-1374 ◽  
Author(s):  
Arya Farahi ◽  
Matthew Ho ◽  
Hy Trac
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Formation Time ◽  
Gas Content ◽  
Mass Relation ◽  
Cold Dark Matter Model ◽  
Conditional Statistics

ABSTRACT Cold dark matter model predicts that the large-scale structure grows hierarchically. Small dark matter haloes form first. Then, they grow gradually via continuous merger and accretion. These haloes host the majority of baryonic matter in the Universe in the form of hot gas and cold stellar phase. Determining how baryons are partitioned into these phases requires detailed modelling of galaxy formation and their assembly history. It is speculated that formation time of the same mass haloes might be correlated with their baryonic content. To evaluate this hypothesis, we employ haloes of mass above $10^{14}\, \mathrm{M}_{\odot }$ realized by TNG300 solution of the IllustrisTNG project. Formation time is not directly observable. Hence, we rely on the magnitude gap between the brightest and the fourth brightest halo galaxy member, which is shown that traces formation time of the host halo. We compute the conditional statistics of the stellar and gas content of haloes conditioned on their total mass and magnitude gap. We find a strong correlation between magnitude gap and gas mass, BCG stellar mass, and satellite galaxies stellar mass, but not the total stellar mass of halo. Conditioning on the magnitude gap can reduce the scatter about halo property–halo mass relation and has a significant impact on the conditional covariance. Reduction in the scatter can be as significant as 30 per cent, which implies more accurate halo mass prediction. Incorporating the magnitude gap has a potential to improve cosmological constraints using halo abundance and allows us to gain insight into the baryon evolution within these systems.

scholarly journals Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

2021 ◽  
Vol 502 (2) ◽  
pp. 1785-1796
Author(s):  
R A Jackson ◽  
S Kaviraj ◽  
G Martin ◽  
J E G Devriendt ◽  
A Slyz ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Matter Content ◽  
Mass Relation ◽  
Potential Wells ◽  
Tidal Interactions ◽  
New Interactions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ < 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

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 N-body Simulations of Galaxy Formation

1988 ◽  
Vol 130 ◽  
pp. 259-271
Author(s):  
Carlos S. Frenk
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Large Scale Structure ◽  
High Density ◽  
Galactic Halos ◽  
Body Techniques ◽  
Massive Halos ◽  
The Universe

Modern N-body techniques allow the study of galaxy formation in the wider context of the formation of large-scale structure in the Universe. The results of such a study within the cold dark matter cosmogony are described. Dark galactic halos form at relatively recent epochs. Their properties and abundance are similar to those inferred for the halos of real galaxies. Massive halos tend to form preferentially in high density regions and as a result the galaxies that form within them are significantly more clustered than the underlying mass. This natural bias may be strong enough to reconcile the observed clustering of galaxies with the assumption that Ω = 1.

scholarly journals Dark Matters on the Scale of Galaxies

Universe ◽  
2020 ◽  
Vol 6 (8) ◽  
pp. 107 ◽  
Author(s):  
Ivan de Martino ◽  
Sankha S. Chakrabarty ◽  
Valentina Cesare ◽  
Arianna Gallo ◽  
Luisa Ostorero ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Research Field ◽  
Cold Dark Matter Model ◽  
Matter Model ◽  
Dark Matters ◽  
Theory Of Gravity ◽  
Different Origins ◽  
Dark Matter Model

The cold dark-matter model successfully explains both the emergence and evolution of cosmic structures on large scales and, when we include a cosmological constant, the properties of the homogeneous and isotropic Universe. However, the cold dark-matter model faces persistent challenges on the scales of galaxies. Indeed, N-body simulations predict some galaxy properties that are at odds with the observations. These discrepancies are primarily related to the dark-matter distribution in the innermost regions of the halos of galaxies and to the dynamical properties of dwarf galaxies. They may have three different origins: (1) the baryonic physics affecting galaxy formation is still poorly understood and it is thus not properly included in the model; (2) the actual properties of dark matter differs from those of the conventional cold dark matter; (3) the theory of gravity departs from General Relativity. Solving these discrepancies is a rapidly evolving research field. We illustrate some of the solutions proposed within the cold dark-matter model, and solutions when including warm dark matter, self-interacting dark matter, axion-like particles, or fuzzy dark matter. We also illustrate some modifications of the theory of gravity: Modified Newtonian Dynamics (MOND), MOdified Gravity (MOG), and f(R) gravity.

scholarly journals How dark are filaments in the cosmic web?

2020 ◽  
Vol 498 (3) ◽  
pp. 3158-3170
Author(s):  
Tianyi Yang ◽  
Michael J Hudson ◽  
Niayesh Afshordi
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
Mass Fractions ◽  
The Masses ◽  
Red Galaxies

ABSTRACT The cold dark matter model predicts that dark matter haloes are connected by filaments. Direct measurements of the masses and structure of these filaments are difficult, but recently several studies have detected these dark-matter-dominated filaments using weak lensing. Here we study the efficiency of galaxy formation within the filaments by measuring their total mass-to-light ratios and stellar mass fractions. Specifically, we stack pairs of luminous red galaxies (LRGs) with a typical separation on the sky of 8 h−1 Mpc. We stack background galaxy shapes around pairs to obtain mass maps through weak lensing, and we stack galaxies from the Sloan Digital Sky Survey to obtain maps of light and stellar mass. To isolate the signal from the filament, we construct two matched catalogues of physical and non-physical (projected) LRG pairs, with the same distributions of redshift and separation. We then subtract the two stacked maps. Using LRG pair samples from the Baryon Oscillation Spectroscopic Survey at two different redshifts, we find that the evolution of the mass in filament is consistent with the predictions from perturbation theory. The filaments are not entirely dark: Their mass-to-light ratios (M/L = 351 ± 137 in solar units in the rband) and stellar mass fractions (Mstellar/M = 0.0073 ± 0.0030) are consistent with the cosmic values (and with their redshift evolutions).

scholarly journals Baryons in the Cosmic Web of IllustrisTNG – II. The connection among galaxies, haloes, their formation time, and their location in the Cosmic Web

2019 ◽  
Vol 491 (4) ◽  
pp. 5747-5758 ◽  
Author(s):  
Davide Martizzi ◽  
Mark Vogelsberger ◽  
Paul Torrey ◽  
Annalisa Pillepich ◽  
Steen H Hansen ◽  
...  
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Stellar Mass ◽  
Density Field ◽  
Formation Time ◽  
Deformation Tensor ◽  
Dynamical Mass ◽  
Hydrodynamical Simulation

ABSTRACT The connections among galaxies, the dark matter haloes where they form and the properties of the large-scale Cosmic Web still need to be completely disentangled. We use the cosmological hydrodynamical simulation TNG100 of the IllustrisTNG suite to quantify the effects played by the large-scale density field and the Cosmic Web morphology on the relation between halo mass and galaxy stellar mass. We select objects with total dynamical mass in the range ${\ge}6.3\times 10^{10} \,h ^{-1}\, \mathrm{ M}_{\odot }$ up to a few $10^{14}\, h^{-1} \, \mathrm{ M}_{\odot }$ between redshift z = 4 and redshift z = 0. A Cosmic Web class (knot, filament, sheet, void) is assigned to each region of the volume using a density field deformation tensor-based method. We find that galaxy stellar mass strongly correlates with total dynamical mass and formation time, and more weakly with large-scale overdensity and Cosmic Web class. The latter two quantities correlate with each other, but are not entirely degenerate. Furthermore, we find that at fixed halo mass, galaxies with stellar mass lower than the median value are more likely to be found in voids and sheets, whereas galaxies with stellar mass higher than the median are more likely to be found in filaments and knots. Finally, we find that the dependence on environment is stronger for satellites than for centrals, and discuss the physical implications of these results.

INFLATION AFTER WMAP

2011 ◽  
Vol 20 (08) ◽  
pp. 1471-1477
Author(s):  
KIN-WANG NG
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Microwave Background ◽  
Cold Dark Matter Model ◽  
Cosmic Microwave Background Anisotropy ◽  
Matter Model ◽  
Reflection Asymmetry ◽  
Dark Matter Model

Recent measurements of the large-scale cosmic microwave background anisotropy made by the Wilkinson Microwave Anisotropy Probe (WMAP) mission indicate a reflection asymmetry, an axis of evil, a low quadrupole, and a few multipoles deviated from predicted in the cold dark matter model with a cosmological constant. All of these may give us a hint about the physics of inflation during the first few e-folds or during the inflating period. Efforts taken along this direction will be reviewed and our recent work will be discussed.

scholarly journals The roles of atomic and molecular gas on the redshift evolution of star formation and metallicity in galaxy formation models

2012 ◽  
Vol 8 (S292) ◽  
pp. 245-245
Author(s):  
Jian Fu ◽  
Guinevere Kauffmann
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Time Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Formation Time ◽  
Model Parameters ◽  
Molecular Gas ◽  
Mass Relation

AbstractWe study the redshift evolution of neutral and molecular gas in the interstellar medium with the results from semi-analytic models of galaxy formation and evolution, which track the cold gas related physical processes in radially resolved galaxy disks. Two kinds of prescriptions are adopted to describe the conversion between molecular and neutral gas in the ISM: one is related to the gas surface density and gas metallicity based on the model results by Krumholz, Mckee & Tumlinson; the other is related the pressure of ISM. We try four types of star formation laws in the models to study the effect of the molecular gas component and the star formation time scale on the model results, and find that the H2 dependent star formation rate with constant star formation efficiency is the preferred star formation law. We run the models based on both Millennium and Millennium II Simulation haloes, and the model parameters are adjusted to fit the observations at z = 0 from THINGS/HERACLES and ALFALFA/COLD GASS. We give predictions for the redshift evolution of cosmic star formation density, H2 to HI cosmic ratios, gas to star mass ratios and gas metallicity vs stellar mass relation. Based on the model results, we find that: (i) the difference in the H2 to HI ratio at z > 3 between the two H2 fraction prescriptions can help future observations to test which prescription is better; (ii) a constant redshift independent star formation time scale will postpone the star formation processes at high redshift and cause obvious redshift evolution for the relation between gas metallicity and stellar mass in galaxies at z < 3.

scholarly journals Cosmological baryon transfer in the simba simulations

2019 ◽  
Vol 491 (4) ◽  
pp. 6102-6119 ◽  
Author(s):  
Josh Borrow ◽  
Daniel Anglés-Alcázar ◽  
Romeel Davé
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Initial Conditions ◽  
Mass Range ◽  
Gas Content ◽  
Final State ◽  
Cosmological Simulations ◽  
Baryon Transfer ◽  
Matter Component

ABSTRACT We present a framework for characterizing the large-scale movement of baryons relative to dark matter in cosmological simulations, requiring only the initial conditions and final state of the simulation. This is performed using the spread metric that quantifies the distance in the final conditions between initially neighbouring particles, and by analysing the baryonic content of final haloes relative to that of the initial Lagrangian regions (LRs) defined by their dark matter component. Applying this framework to the simba cosmological simulations, we show that 40 per cent (10 per cent) of cosmological baryons have moved $\gt 1\, h^{-1}\, {\rm Mpc}{}$ ($3\, h^{-1}\, {\rm Mpc}{}$) by z = 0, primarily due to entrainment of gas by jets powered by an active galactic nucleus, with baryons moving up to $12\, h^{-1}\, {\rm Mpc}{}$ away in extreme cases. Baryons decouple from the dynamics of the dark matter component due to hydrodynamic forces, radiative cooling, and feedback processes. As a result, only 60 per cent of the gas content in a given halo at z = 0 originates from its LR, roughly independent of halo mass. A typical halo in the mass range Mvir = 1012–1013 M⊙ only retains 20 per cent of the gas originally contained in its LR. We show that up to 20 per cent of the gas content in a typical Milky Way-mass halo may originate in the region defined by the dark matter of another halo. This inter-Lagrangian baryon transfer may have important implications for the origin of gas and metals in the circumgalactic medium of galaxies, as well as for semi-analytic models of galaxy formation and ‘zoom-in’ simulations.

scholarly journals Constraining scatter in the stellar mass–halo mass relation for haloes less massive than the Milky Way

2019 ◽  
Vol 488 (4) ◽  
pp. 4916-4925 ◽  
Author(s):  
Magdelena Allen ◽  
Peter Behroozi ◽  
Chung-Pei Ma
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Distribution Functions ◽  
Sloan Digital Sky Survey ◽  
Data Sets ◽  
Mass Relation ◽  
Velocity Distribution Functions ◽  
Halo Masses ◽  
Stellar Masses

ABSTRACT Most galaxies are hosted by massive, invisible dark matter haloes, yet little is known about the scatter in the stellar mass–halo mass relation for galaxies with host halo masses Mh ≤ 1011M⊙. Using mock catalogues based on dark matter simulations, we find that two observable signatures are sensitive to scatter in the stellar mass–halo mass relation even at these mass scales; i.e. conditional stellar mass functions and velocity distribution functions for neighbouring galaxies. We compute these observables for  179,373 galaxies in the Sloan Digital Sky Survey (SDSS) with stellar masses M* &gt; 109 M⊙ and redshifts 0.01 &lt; z &lt; 0.307. We then compare to mock observations generated from the Bolshoi-Planck dark matter simulation for stellar mass–halo mass scatters ranging from 0 to 0.6 dex. The observed results are consistent with simulated results for most values of scatter (&lt;0.6 dex), and SDSS statistics are insufficient to provide firm constraints. However, this method could provide much tighter constraints on stellar mass–halo mass scatter in the future if applied to larger data sets, especially the anticipated Dark Energy Spectroscopic Instrument Bright Galaxy Survey. Constraining the value of scatter could have important implications for galaxy formation and evolution.

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