scholarly journals The hestia project: simulations of the Local Group

2020 ◽  
Vol 498 (2) ◽  
pp. 2968-2983
Author(s):  
Noam I Libeskind ◽  
Edoardo Carlesi ◽  
Robert J J Grand ◽  
Arman Khalatyan ◽  
Alexander Knebe ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Local Group ◽  
Initial Conditions ◽  
Mass Function ◽  
Mass Ratio ◽  
Hydrodynamic Simulation ◽  
Satellite Galaxy ◽  
Nearby Galaxies ◽  
Environmental Simulations

ABSTRACT We present the hestia simulation suite: High-resolutions Environmental Simulations of The Immediate Area, a set of cosmological simulations of the Local Group. Initial conditions constrained by the observed peculiar velocity of nearby galaxies are employed to accurately simulate the local cosmography. Halo pairs that resemble the Local Group are found in low resolutions constrained, dark matter only simulations, and selected for higher resolution magneto hydrodynamic simulation using the arepo code. Baryonic physics follows the auriga model of galaxy formation. The simulations contain a high-resolution region of 3–5 Mpc in radius from the Local Group mid-point embedded in the correct cosmographic landscape. Within this region, a simulated Local Group consisting of a Milky Way and Andromeda like galaxy forms, whose description is in excellent agreement with observations. The simulated Local Group galaxies resemble the Milky Way and Andromeda in terms of their halo mass, mass ratio, stellar disc mass, morphology separation, relative velocity, rotation curves, bulge-disc morphology, satellite galaxy stellar mass function, satellite radial distribution, and in some cases, the presence of a Magellanic cloud like object. Because these simulations properly model the Local Group in their cosmographic context, they provide a testing ground for questions where environment is thought to play an important role.

scholarly journals Are Disks of Satellites Comprised of Tidal Dwarf Galaxies?

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 100
Author(s):  
Michal Bílek ◽  
Ingo Thies ◽  
Pavel Kroupa ◽  
Benoit Famaey
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Initial Conditions ◽  
Proper Motions ◽  
Promising Alternative ◽  
Open Questions ◽  
Nearby Galaxies ◽  
First Time ◽  
Tidal Tails

It was found that satellites of nearby galaxies can form flattened co-rotating structures called disks of satellites or planes of satellites. Their existence is not expected by the current galaxy formation simulations in the standard dark matter-based cosmology. On the contrary, modified gravity offers a promising alternative: the objects in the disks of satellites are tidal dwarf galaxies, that is, small galaxies that form from tidal tails of interacting galaxies. After introducing the topic, we review here our work on simulating the formation of the disks of satellites of the Milky Way and Andromeda galaxies. The initial conditions of the simulation were tuned to reproduce the observed positions, velocities and disk orientations of the galaxies. The simulation showed that the galaxies had a close flyby 6.8 Gyr ago. One of the tidal tails produced by the Milky Way was captured by Andromeda. It formed a cloud of particles resembling the disk of satellites at Andromeda by its size, orientation, rotation and mass. A hint of a disk of satellites was formed at the Milky Way too. In addition, the encounter induced a warp in the disk of the simulated Milky Way that resembles the real warp by its magnitude and orientation. We present here, for the first time, the proper motions of the members of the disk of satellites of Andromeda predicted by our simulation. Finally, we point out some of the remaining open questions which this hypothesis, for the formation of disks of satellites, brings up.

scholarly journals Shaping Disk Galaxy Stellar Populations via Internal and External Processes

2012 ◽  
Vol 10 (H16) ◽  
pp. 372-372
Author(s):  
Rok Roškar
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Stellar Populations ◽  
Radial Migration ◽  
Disk Formation ◽  
Process Understanding ◽  
History Of ◽  
Nearby Galaxies ◽  
Gas Accretion

AbstractIn recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

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?

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 Formation of the large nearby galaxies

2020 ◽  
Vol 498 (3) ◽  
pp. 4386-4395 ◽  
Author(s):  
P J E Peebles
Keyword(s):  
Galaxy Formation ◽  
Initial Conditions ◽  
Nearby Galaxies ◽  
Non Gaussian

ABSTRACT Simulations of galaxy formation tend to place star particles in orbits seriously different from circular in numbers far larger than seem reasonable for the bulges and stellar haloes of the nearby L ∼ L* galaxies that can be examined in particularly close detail. I offer an example of how the situation might be improved: a prescription for non-Gaussian initial conditions on the scale of galaxies.

scholarly journals Simulating galaxy formation in f(R) modified gravity: matter, halo, and galaxy statistics

2019 ◽  
Vol 490 (2) ◽  
pp. 2507-2520 ◽  
Author(s):  
Christian Arnold ◽  
Baojiu Li
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Mass Function ◽  
Back Reaction ◽  
Satellite Galaxy ◽  
Matter Power Spectrum ◽  
Hydrodynamical Simulation ◽  
The Galaxy ◽  
Galaxy Count

ABSTRACT We present an analysis of the matter, halo, and galaxy clustering in f(R)-gravity employing the SHYBONE full-physics hydrodynamical simulation suite. Our analysis focuses on the interplay between baryonic feedback and f(R)-gravity in the matter power spectrum, the matter and halo correlation functions, the halo and galaxy–host–halo mass function, the subhalo and satellite–galaxy count, and the correlation function of the stars in our simulations. Our studies of the matter power spectrum in full-physics simulations in f(R)-gravity show that it will be very difficult to derive accurate fitting formulae for the power spectrum enhancement in f(R)-gravity which include baryonic effects. We find that the enhancement of the halo mass function due to f(R)-gravity and its suppression due to feedback effects do not show significant back-reaction effects and can thus be estimated from independent general relativity-hydro and f(R) dark matter only simulations. Our simulations furthermore show that the number of subhaloes and satellite-galaxies per halo is not significantly affected by f(R)-gravity. Low-mass haloes are nevertheless more likely to be populated by galaxies in f(R)-gravity. This suppresses the clustering of stars and the galaxy correlation function in the theory compared to standard cosmology.

scholarly journals LARgE survey – III. Environments of ultra-massive passive galaxies at cosmic noon: BCG progenitors growing through mergers

2020 ◽  
Vol 494 (1) ◽  
pp. 1366-1374
Author(s):  
Marcin Sawicki ◽  
Liz Arcila-Osejo ◽  
Anneya Golob ◽  
Thibaud Moutard ◽  
Stéphane Arnouts ◽  
...  
Keyword(s):  
Growth Rate ◽  
Galaxy Cluster ◽  
Large Mass ◽  
Mass Function ◽  
Mass Ratio ◽  
Cluster Galaxy ◽  
Star Forming ◽  
Satellite Galaxy ◽  
Stellar Masses ◽  
Star Text

ABSTRACT We study the environments of a sample of 61 extremely rare $z\, \sim$1.6 Ultra-Massive Passively Evolving Galaxies (UMPEGs: stellar masses M⋆ >1011.5 M⊙) which – based on clustering analysis presented in Cheema et al. (2020) – appear to be associated with very massive (Mhalo ∼ 1014.1h−1 M⊙) dark matter haloes that are likely to be the progenitors of $z\, \sim$0 massive (Coma- and Virgo-like) galaxy clusters. We find that UMPEGs on average have fewer than one satellite galaxy with mass ratio $M_{\star }^{\text{sat}}$:$M_{\star }^{{\text{UMPEG}}}$ ≥ 1:5 (i.e. $M_{\star }^{\text{sat}}$$\gtrsim 10^{10.8}$ M⊙) within 0.5 Mpc; the large mass gap that we observe between the typical UMPEG and its most massive satellite implies that the $z\, \sim$1.6 UMPEGs assembled through major mergers. Using observed satellite counts with merger time-scales from the literature, we estimate the growth rate due to mergers with mass ratio of ≥1:4 to be ∼13 per cent Gyr−1 (with a $\sim \, 2 \times$ systematic uncertainty). This relatively low growth rate is unlikely to significantly affect the shape of the massive end of the stellar mass function, whose evolution must instead be driven by the quenching of new cohorts of ultra-massive star-forming galaxies. However, this growth rate is high enough that, if sustained to $z\, \sim$0, the typical $z\, \sim$1.6 $M_{\star }^{{\text{UMPEG}}}$ =1011.6 M⊙ UMPEG can grow into a M⋆ ≈1012 M⊙ brightest cluster galaxy (BCG) of a present-day massive galaxy cluster. Our observations favour a scenario in which our UMPEGs are main-branch progenitors of some of the present-day BCGs that have first assembled through major mergers at high redshifts and grown further through (likely minor) merging at later times.

scholarly journals The LBT satellites of Nearby Galaxies Survey (LBT-SONG): the satellite population of NGC 628

2020 ◽  
Vol 500 (3) ◽  
pp. 3854-3869
Author(s):  
A Bianca Davis ◽  
Anna M Nierenberg ◽  
Annika H G Peter ◽  
Christopher T Garling ◽  
Johnny P Greco ◽  
...  
Keyword(s):  
Milky Way ◽  
Large Magellanic Cloud ◽  
Satellite System ◽  
Mass Star ◽  
Star Forming ◽  
Local Volume ◽  
Satellite Galaxy ◽  
Measurement Methodology ◽  
Close Satellite ◽  
Nearby Galaxies

ABSTRACT We present the first satellite system of the Large Binocular Telescope Satellites Of Nearby Galaxies Survey (LBT-SONG), a survey to characterize the close satellite populations of Large Magellanic Cloud to Milky-Way-mass, star-forming galaxies in the Local Volume. In this paper, we describe our unresolved diffuse satellite finding and completeness measurement methodology and apply this framework to NGC 628, an isolated galaxy with ∼1/4 the stellar mass of the Milky Way. We present two new dwarf satellite galaxy candidates: NGC 628 dwA, and dwB with MV = −12.2 and −7.7, respectively. NGC 628 dwA is a classical dwarf while NGC 628 dwB is a low-luminosity galaxy that appears to have been quenched after reionization. Completeness corrections indicate that the presence of these two satellites is consistent with CDM predictions. The satellite colours indicate that the galaxies are neither actively star forming nor do they have the purely ancient stellar populations characteristic of ultrafaint dwarfs. Instead, and consistent with our previous work on the NGC 4214 system, they show signs of recent quenching, further indicating that environmental quenching can play a role in modifying satellite populations even for hosts smaller than the Milky Way.

scholarly journals HI Gas in Disk and Dwarf Galaxies in the Semi-analytic Models of Galaxy Formation

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jian Fu ◽  
Jing Wang ◽  
Yu Luo
Keyword(s):  
Galaxy Formation ◽  
Surface Density ◽  
Dwarf Galaxies ◽  
Mass Function ◽  
Molecular Gas ◽  
Mass Relation ◽  
Model Framework ◽  
Satellite Problem ◽  
Nearby Galaxies ◽  
Analytic Models

AbstractWe construct the radially-resolved semi-analytic models of galaxy formation based on the L-Galaxies model framework, which include both atomic and molecular gas phase in ISM. The models run on the halo outputs of ΛCDM cosmology N-body simulation. Our models can reproduce varies observations of HI gas in nearby galaxies, e.g. the HI mass function, the HI-to-star ratio vs stellar mass and stellar surface density, universal HI radial surface density profile in outer disks etc. We also give the physical origin of HI size-mass relation. Based on our model results for local dwarf galaxies, we show that the “missing satellite problem” also exists in the HI component, i.e., the models over-predict dwarf galaxies with low HI mass around the Milky Way. That is a shortcoming of current ΛCDM cosmology framework. Future survey for HI gas in local dwarf galaxies (e.g. MeerKAT, SKA & FAST) can help to verify the nature of dark matter (cold or warm).

HI gas component in dwarf and disk galaxies in the view of semi-analytic models

2018 ◽  
Vol 14 (S344) ◽  
pp. 274-275
Author(s):  
Jian Fu
Keyword(s):  
Galaxy Formation ◽  
Recent Progress ◽  
Milky Way ◽  
Mass Function ◽  
The Other ◽  
Disk Galaxies ◽  
Model Based ◽  
Low Mass ◽  
Analytic Models ◽  
Gas Component

AbstractWe show our recent progress on the L-Galaxies semi-analytic models of galaxy formation, which focuses on the HI gas in low mass galaxies. We find that the model based on ELUCID haloes can reproduce the HI mass function from ALFALFA 100 at low mass end. On the other hand, our models predict some gas rich low mass galaxies around the Milky Way, which may offer opportunities for future HI 21cm survey in nearby universe by FAST and SKA-1.

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