scholarly journals L-GALAXIES 2020: The formation and chemical evolution of stellar haloes in Milky Way Analogues and galaxy clusters

2021 ◽  
Author(s):  
Geoff G Murphy ◽  
Robert M Yates ◽  
Shazrene S Mohamed
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Evolution ◽  
Chemical Evolution ◽  
Milky Way ◽  
Good Correspondence ◽  
Cluster Galaxy ◽  
Radial Profiles ◽  
Stellar Halo ◽  
Stellar Masses ◽  
Good Agreement

Abstract We present an analysis of the formation and chemical evolution of stellar haloes around (a) Milky Way Analogue (MWA) galaxies and (b) galaxy clusters in the L-Galaxies 2020 semi-analytic model of galaxy evolution. Observed stellar halo properties are better reproduced when assuming a gradual stripping model for the removal of cold gas and stars from satellites, compared to an instantaneous stripping model. The slope of the stellar mass – metallicity relation for MWA stellar haloes is in good agreement with that observed in the local Universe. This extends the good agreement between L-Galaxies 2020 and metallicity observations from the gas and stars inside galaxies to those outside. Halo stars contribute on average only ∼0.1 per cent of the total circumgalactic medium (CGM) enrichment by z = 0 in MWAs, ejecting predominantly carbon produced by AGB stars. Around a quarter of MWAs have a single ‘significant progenitor’ with a mean mass of ∼ 2.3 × 109M⊙, similar to that measured for Gaia Enceladus. For galaxy clusters, L-Galaxies 2020 shows good correspondence with observations of stellar halo mass fractions, but slightly over-predicts stellar masses. Assuming a Navarro-Frenk-White profile for the stellar halo mass distribution provides the best agreement. On average, the intracluster stellar component (ICS) is responsible for 5.4 per cent of the total intracluster medium (ICM) iron enrichment, exceeding the contribution from the brightest cluster galaxy (BCG) by z = 0. We find that considering gradual stripping of satellites and realistic radial profiles is crucial for accurately modelling stellar halo formation on all scales in semi-analytic models.

scholarly journals Milky Way analogues in MaNGA: multiparameter homogeneity and comparison to the Milky Way

2019 ◽  
Vol 491 (3) ◽  
pp. 3672-3701 ◽  
Author(s):  
N Boardman ◽  
G Zasowski ◽  
A Seth ◽  
J Newman ◽  
B Andrews ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Milky Way ◽  
Central Star ◽  
Stellar Kinematics ◽  
Star Forming ◽  
Wide Range ◽  
The Galaxy ◽  
Central Regions ◽  
Galaxy Population ◽  
Stellar Masses

ABSTRACT The Milky Way provides an ideal laboratory to test our understanding of galaxy evolution, owing to our ability to observe our Galaxy over fine scales. However, connecting the Galaxy to the wider galaxy population remains difficult, due to the challenges posed by our internal perspective and to the different observational techniques employed. Here, we present a sample of galaxies identified as Milky Way analogues on the basis of their stellar masses and bulge-to-total ratios, observed as part of the Mapping Nearby Galaxies at Apache Point Observatory survey. We analyse the galaxies in terms of their stellar kinematics and populations as well as their ionized gas contents. We find our sample to contain generally young stellar populations in their outskirts. However, we find a wide range of stellar ages in their central regions, and we detect central active galactic nucleus-like or composite-like activity in roughly half of the sample galaxies, with the other half consisting of galaxies with central star-forming emission or emission consistent with old stars. We measure gradients in gas metallicity and stellar metallicity that are generally flatter in physical units than those measured for the Milky Way; however, we find far better agreement with the Milky Way when scaling gradients by galaxies’ disc scale lengths. From this, we argue much of the discrepancy in metallicity gradients to be due to the relative compactness of the Milky Way, with differences in observing perspective also likely to be a factor.

scholarly journals VMC proper motions of the Magellanic Bridge

2018 ◽  
Vol 14 (S344) ◽  
pp. 130-133 ◽  
Author(s):  
Thomas Schmidt ◽  
Maria-Rosa Cioni ◽  
Florian Niederhofer ◽  
Jonathan Diaz ◽  
Gal Matijevic
Keyword(s):  
Galaxy Evolution ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Large Mass ◽  
Proper Motions ◽  
Dynamical Simulation ◽  
Open Questions ◽  
The Hierarchical Structure ◽  
The Universe ◽  
Good Agreement

AbstractDwarf galaxies enable us to study early phases of galaxy evolution and are key to many open questions about the hierarchical structure of the Universe. The Large and Small Magellanic Cloud (LMC and SMC) are the most luminous dwarf galaxy satellites of the Milky Way (MW). They are most likely gravitationally bound to each other, and their last interaction occurred about 200 Myr ago. Also, they are in an early phase of minor merging with the MW and will impact the Galactic structure in the future because of their relatively large mass. However, there are still major uncertainties regarding their origin and their interactions with one another and with the Milky Way. We cross-correlated the VMC and Gaia DR2 data to select a sample of stars that likely belong to the Magellanic Bridge, a feature formed of gas and stars which is connecting the LMC and the SMC. We removed potential MW foregound stars using a combination of parallax and colour-magnitude criteria and calculated the proper motions of the Bridge member stars. Our analysis supports a motion of star towards the LMC, which was found to be in good agreement with a dynamical simulation, of the SMC being stripped by the LMC.

scholarly journals Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations

2020 ◽  
Vol 498 (2) ◽  
pp. 2472-2491 ◽  
Author(s):  
J M Diederik Kruijssen ◽  
Joel L Pfeffer ◽  
Mélanie Chevance ◽  
Ana Bonaca ◽  
Sebastian Trujillo-Gomez ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Mass Range ◽  
Stellar Mass ◽  
Host Galaxies ◽  
Stellar Halo ◽  
Major Merger ◽  
Virial Mass ◽  
Minor Mergers ◽  
Stellar Masses

ABSTRACT Globular clusters (GCs) formed when the Milky Way experienced a phase of rapid assembly. We use the wealth of information contained in the Galactic GC population to quantify the properties of the satellite galaxies from which the Milky Way assembled. To achieve this, we train an artificial neural network on the E-MOSAICS cosmological simulations of the co-formation and co-evolution of GCs and their host galaxies. The network uses the ages, metallicities, and orbital properties of GCs that formed in the same progenitor galaxies to predict the stellar masses and accretion redshifts of these progenitors. We apply the network to Galactic GCs associated with five progenitors: Gaia-Enceladus, the Helmi streams, Sequoia, Sagittarius, and the recently discovered ‘low-energy’ GCs, which provide an excellent match to the predicted properties of the enigmatic galaxy ‘Kraken’. The five galaxies cover a narrow stellar mass range [M⋆ = (0.6–4.6) × 108 M⊙], but have widely different accretion redshifts ($\mbox{$z_{\rm acc}$}=0.57\!-\!2.65$). All accretion events represent minor mergers, but Kraken likely represents the most major merger ever experienced by the Milky Way, with stellar and virial mass ratios of $\mbox{$r_{M_\star }$}=1$:$31^{+34}_{-16}$ and $\mbox{$r_{M_{\rm h}}$}=1$:$7^{+4}_{-2}$, respectively. The progenitors match the z = 0 relation between GC number and halo virial mass, but have elevated specific frequencies, suggesting an evolution with redshift. Even though these progenitors likely were the Milky Way’s most massive accretion events, they contributed a total mass of only log (M⋆, tot/M⊙) = 9.0 ± 0.1, similar to the stellar halo. This implies that the Milky Way grew its stellar mass mostly by in-situ star formation. We conclude by organizing these accretion events into the most detailed reconstruction to date of the Milky Way’s merger tree.

scholarly journals Infalling groups and galaxy transformations in the cluster A2142

2018 ◽  
Vol 610 ◽  
pp. A82 ◽  
Author(s):  
Maret Einasto ◽  
Boris Deshev ◽  
Heidi Lietzen ◽  
Rain Kipper ◽  
Elmo Tempel ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Stellar Populations ◽  
Normal Mixture ◽  
Cluster Galaxy ◽  
X Ray ◽  
Main Cluster ◽  
Formation And Evolution ◽  
Galaxy Populations ◽  
Stellar Masses

Context. Superclusters of galaxies provide dynamical environments for the study of the formation and evolution of structures in the cosmic web from galaxies, to the richest galaxy clusters, and superclusters themselves. Aims. We study galaxy populations and search for possible merging substructures in the rich galaxy cluster A2142 in the collapsing core of the supercluster SCl A2142, which may give rise to radio and X-ray structures in the cluster, and affect galaxy properties of this cluster. Methods. We used normal mixture modelling to select substructure of the cluster A2142. We compared alignments of the cluster, its brightest galaxies (hereafter BCGs), subclusters, and supercluster axes. The projected phase space (PPS) diagram and clustercentric distributions are used to analyse the dynamics of the cluster and study the distribution of various galaxy populations in the cluster and subclusters. Results. We find several infalling galaxy groups and subclusters. The cluster, supercluster, BCGs, and one infalling subcluster are all aligned. Their orientation is correlated with the alignment of the radio and X-ray haloes of the cluster. Galaxy populations in the main cluster and in the outskirts subclusters are different. Galaxies in the centre of the main cluster at the clustercentric distances 0.5 h−1 Mpc (Dc∕Rvir < 0.5, Rvir = 0.9 h−1 Mpc) have older stellar populations (with the median age of 10−11 Gyr) than galaxies at larger clustercentric distances. Star-forming and recently quenched galaxies are located mostly at the clustercentric distances Dc ≈ 1.8 h−1 Mpc, where subclusters fall into the cluster and the properties of galaxies change rapidly. In this region the median age of stellar populations of galaxies is about 2 Gyr. Galaxies in A2142 on average have higher stellar masses, lower star formation rates, and redder colours than galaxies in rich groups. The total mass in infalling groups and subclusters is M ≈ 6 × 1014 h−1 M⊙, that is approximately half of the mass of the cluster. This mass is sufficient for the mass growth of the cluster from redshift z = 0.5 (half-mass epoch) to the present. Conclusions. Our analysis suggests that the cluster A2142 has formed as a result of past and present mergers and infallen groups, predominantly along the supercluster axis. Mergers cause complex radio and X-ray structure of the cluster and affect the properties of galaxies in the cluster, especially at the boundaries of the cluster in the infall region. Explaining the differences between galaxy populations, mass, and richness of A2142, and other groups and clusters may lead to better insight about the formation and evolution of rich galaxy clusters.

scholarly journals The MUSEHubbleUltra Deep Field Survey

2017 ◽  
Vol 608 ◽  
pp. A9 ◽  
Author(s):  
E. Ventou ◽  
T. Contini ◽  
N. Bouché ◽  
B. Epinat ◽  
J. Brinchmann ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Cosmic Time ◽  
Spectral Energy ◽  
Close Pair ◽  
Major Merger ◽  
Stellar Masses ◽  
Good Agreement ◽  
Close Pairs

We provide, for the first time, robust observational constraints on the galaxy major merger fraction up toz≈ 6 using spectroscopic close pair counts. Deep Multi Unit Spectroscopic Explorer (MUSE) observations in theHubbleUltra Deep Field (HUDF) andHubbleDeep Field South (HDF-S) are used to identify 113 secure close pairs of galaxies among a parent sample of 1801 galaxies spread over a large redshift range (0.2 <z< 6) and stellar masses (107−1011M⊙), thus probing about 12 Gyr of galaxy evolution. Stellar masses are estimated from spectral energy distribution (SED) fitting over the extensive UV-to-NIR HST photometry available in these deepHubblefields, addingSpitzerIRAC bands to better constrain masses for high-redshift (z⩾ 3) galaxies. These stellar masses are used to isolate a sample of 54 major close pairs with a galaxy mass ratio limit of 1:6. Among this sample, 23 pairs are identified at high redshift (z⩾ 3) through their Lyαemission. The sample of major close pairs is divided into five redshift intervals in order to probe the evolution of the merger fraction with cosmic time. Our estimates are in very good agreement with previous close pair counts with a constant increase of the merger fraction up toz≈ 3 where it reaches a maximum of 20%. At higher redshift, we show that the fraction slowly decreases down to about 10% atz≈ 6. The sample is further divided into two ranges of stellar masses using either a constant separation limit of 109.5M⊙or the median value of stellar mass computed in each redshift bin. Overall, the major close pair fraction for low-mass and massive galaxies follows the same trend. These new, homogeneous, and robust estimates of the major merger fraction sincez≈ 6 are in good agreement with recent predictions of cosmological numerical simulations.

scholarly journals The evolution of sizes and specific angular momenta in hierarchical models of galaxy formation and evolution

2019 ◽  
Vol 487 (4) ◽  
pp. 5649-5665 ◽  
Author(s):  
Anna Zoldan ◽  
Gabriella De Lucia ◽  
Lizhi Xie ◽  
Fabio Fontanot ◽  
Michaela Hirschmann
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Retention Factor ◽  
Mass Relation ◽  
Massive Galaxies ◽  
Star Forming ◽  
Stellar Halo ◽  
Compact Galaxies ◽  
Good Agreement

ABSTRACTWe extend our previous work focused at z ∼ 0, studying the redshift evolution of galaxy dynamical properties using the state-of-the-art semi-analytic model GAEA (GAlaxy Evolution and Assembly): we show that the predicted size–mass relation for discy/star-forming and quiescent galaxies is in good agreement with observational estimates, up to z ∼ 2. Bulge-dominated galaxies have sizes that are offset low with respect to observational estimates, mainly due to our implementation of disc instability at high redshift. At large masses, both quiescent and bulge-dominated galaxies have sizes smaller than observed. We interpret this as a consequence of our most massive galaxies having larger gas masses than observed, and therefore being more affected by dissipation. We argue that a proper treatment of quasar-driven winds is needed to alleviate this problem. Our model compact galaxies have number densities in agreement with observational estimates and they form most of their stars in small and low angular momentum high-z haloes. GAEA predicts that a significant fraction of compact galaxies forming at high-z is bound to merge with larger structures at lower redshifts: therefore they are not the progenitors of normal-size passive galaxies at z = 0. Our model also predicts a stellar–halo size relation that is in good agreement with observational estimates. The ratio between stellar size and halo size is proportional to the halo spin and does not depend on stellar mass but for the most massive galaxies, where active galactic nucleus feedback leads to a significant decrease of the retention factor (from about 80 per cent to 20 per cent).

scholarly journals The Galaxy and its stellar halo - insights from a hybrid cosmological approach

2008 ◽  
Vol 4 (S254) ◽  
pp. 423-428
Author(s):  
Gabriella De Lucia ◽  
Amina Helmi
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Milky Way ◽  
Dynamical Friction ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
Stellar Halo ◽  
Good Agreement ◽  
Milky Way Halo

AbstractWe use a series of high-resolution N-body simulations of a ‘Milky-Way’ halo, coupled to semi-analytic techniques, to study the formation of our own Galaxy and of its stellar halo. Our model Milky Way galaxy is a relatively young system whose physical properties are in quite good agreement with observational determinations. In our model, the stellar halo is mainly formed from a few massive satellites accreted early on during the galaxy's lifetime. The stars in the halo do not exhibit any metallicity gradient, but higher metallicity stars are more centrally concentrated than stars with lower abundances. This is due to the fact that the most massive satellites contributing to the stellar halo are also more metal rich, and dynamical friction drags them closer to the inner regions of the host halo.

scholarly journals Galactic Chemical Evolution

2003 ◽  
Vol 20 (4) ◽  
pp. 401-415 ◽  
Author(s):  
Brad K. Gibson ◽  
Yeshe Fenner ◽  
Agostino Renda ◽  
Daisuke Kawata ◽  
Hyun-chul Lee
Keyword(s):  
Boundary Condition ◽  
Galaxy Evolution ◽  
Chemical Evolution ◽  
Milky Way ◽  
State Of The Art ◽  
Galactic Chemical Evolution ◽  
Current State ◽  
Important Constraint

AbstractThe primary present-day observables upon which theories of galaxy evolution are based are a system’s morphology, dynamics, colour, and chemistry. Individually, each provides an important constraint to any given model; in concert, the four represent a fundamental (intractable) boundary condition for chemodynamical simulations. We review the current state-of-the-art semi-analytical and chemodynamical models for the Milky Way, emphasising the strengths and weaknesses of both approaches.

Structure and evolution of metallicity and age radial profiles in Milky-Way-like galaxies

2018 ◽  
Vol 14 (A30) ◽  
pp. 284-284
Author(s):  
E. Athanassoula
Keyword(s):  
Chemical Evolution ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Short Summary ◽  
Radial Profiles

AbstractI will give here a very short summary of some of the work I have been doing lately on the chemical evolution in Milky-Way-like spiral galaxies.

Cluster Galaxy Evolution from a New Sample of Galaxy Clusters at 0.3

2001 ◽  
Vol 563 (2) ◽  
pp. 629-652 ◽  
Author(s):  
Amy E. Nelson ◽  
Anthony H. Gonzalez ◽  
Dennis Zaritsky ◽  
Julianne J. Dalcanton
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Evolution ◽  
Cluster Galaxy
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