scholarly journals SAURON’s Challenge for the Major Merger Scenario of Elliptical Galaxy Formation

2008 ◽  
Vol 685 (2) ◽  
pp. 897-903 ◽  
Author(s):  
Andreas Burkert ◽  
Thorsten Naab ◽  
Peter H. Johansson ◽  
Roland Jesseit
Keyword(s):  
Galaxy Formation ◽  
Elliptical Galaxy ◽  
Major Merger

scholarly journals Emerge: Empirical predictions of galaxy merger rates since z ∼ 6

2020 ◽  
Author(s):  
Joseph A O’Leary ◽  
Benjamin P Moster ◽  
Thorsten Naab ◽  
Rachel S Somerville
Keyword(s):  
Galaxy Formation ◽  
Power Law ◽  
Stellar Mass ◽  
Direct Result ◽  
Mass Relation ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Major Merger ◽  
Low Mass ◽  
Merger Rate

Abstract We explore the galaxy-galaxy merger rate with the empirical model for galaxy formation, emerge. On average, we find that between 2 per cent and 20 per cent of massive galaxies (log10(m*/M⊙) ≥ 10.3) will experience a major merger per Gyr. Our model predicts galaxy merger rates that do not scale as a power-law with redshift when selected by descendant stellar mass, and exhibit a clear stellar mass and mass-ratio dependence. Specifically, major mergers are more frequent at high masses and at low redshift. We show mergers are significant for the stellar mass growth of galaxies log10(m*/M⊙) ≳ 11.0. For the most massive galaxies major mergers dominate the accreted mass fraction, contributing as much as 90 per cent of the total accreted stellar mass. We reinforce that these phenomena are a direct result of the stellar-to-halo mass relation, which results in massive galaxies having a higher likelihood of experiencing major mergers than low mass galaxies. Our model produces a galaxy pair fraction consistent with recent observations, exhibiting a form best described by a power-law exponential function. Translating these pair fractions into merger rates results in an inaccurate prediction compared to the model intrinsic values when using published observation timescales. We find the pair fraction can be well mapped to the intrinsic merger rate by adopting an observation timescale that decreases linearly with redshift as Tobs = −0.36(1 + z) + 2.39 [Gyr], assuming all observed pairs merge by z = 0.

scholarly journals A Model for the Sequence of Elliptical Galaxies

1987 ◽  
Vol 117 ◽  
pp. 367-367
Author(s):  
Rosemary F. G. Wyse ◽  
Bernard J. T. Jones
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Density Fluctuations ◽  
Analytic Approximation ◽  
Non Linear

We present a simple model for the formation of elliptical galaxies, based on a binary clustering hierarchy of dark matter, the chemical enrichment of the gas at each level being controlled by supernovae. The initial conditions for the non-linear phases of galaxy formation are set by the post-recombination power spectrum of density fluctuations. We investigate two models for this power spectrum - the first is a straightforward power law, |δk|2 ∝ kn, and the second is Peeble's analytic approximation to the emergent spectrum in a universe dominated by cold dark matter. The normalisation is chosen such that on some scale, say M ∼ 1012M⊙, the objects that condense out have properties - radius and velocity dispersion - resembling ‘typical’ galaxies. There is some ambiguity in this due to the poorly determined mass-to-light ratio of a typical elliptical galaxy — we look at two normalisations, σ1D ∼ 350kms−1 and σ1D ∼ 140kms−1. The choice determines which of Compton cooling or hydrogen cooling is more important during the galaxy formation period. The non-linear behaviour of the perturbations is treated by the homogeneous sphere approximation.

scholarly journals Measuring the GC luminosity function up to z ~ 0.2

2009 ◽  
Vol 5 (S266) ◽  
pp. 351-351
Author(s):  
K. A. Alamo-Martínez ◽  
R. A. González-Lópezlira ◽  
J. Blakeslee
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Luminosity Function ◽  
Elliptical Galaxy ◽  
Angular Size ◽  
Spectroscopic Studies ◽  
Stellar Systems ◽  
Surface Brightness Fluctuations ◽  
Specific Frequency

AbstractGlobular clusters (GCs) are stellar systems (~106 M⊙) with very regular symmetry, single age, and single metallicity. Spectroscopic studies have revealed very old ages, suggesting that GCs were formed in the earliest stages of galaxy formation and assembly. The aim of this work is to find out how far we can measure the GC luminosity function, specific frequency, and radial distribution, applying the surface-brightness-fluctuations (SBF) technique to deep ACS images. To this end, we apply the effects caused by higher redshift to HST/ACS images (in two optical bands, F606W and F814W) of M87, an elliptical galaxy with a very well-studied GC system. The effects involved are: (i) evolution, (ii) inverse k correction, (iii) binning of the image to smaller angular size, (iv) cosmological dimming of surface brightness, and (v) noise addition to account for different exposure times. After processing the images we detect the brightest GCs through direct photometry (e.g., with SExtractor), whereas the unresolved clusters are measured through SBFs. The above treatment is repeated for z=0.05, 0.1, 0.14, and 0.18, and the results are compared to the measurements at z=0 to estimate biases and incompleteness.

Constraints on Elliptical Galaxy Formation from Dry Mergers

2006 ◽  
Vol 2 (S235) ◽  
pp. 195-195
Author(s):  
Julia M. Comerford ◽  
Eliot Quataert ◽  
Chung-Pei Ma
Keyword(s):  
Galaxy Formation ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Analytic Model ◽  
Dark Matter Halos ◽  
Early Type ◽  
Mass Assembly ◽  
Minor Mergers ◽  
Analytic Models

Recent observations suggest that dissipationless mergers of elliptical galaxies build up the population of massive early-type galaxies (Bell et al. 2004; Faber et al. 2006). This type of merger is observed in galaxy clusters (Tran et al. 2005) and predicted by semi-analytic models which find mass assembly times significantly later than star-formation times for the most massive elliptical galaxies (de Lucia & Blaizot 2006). Here, we use a semi-analytic model of minor mergers of dark matter halos to examine the role of dry minor mergers in elliptical galaxy formation.

Models for the Formation and Evolution of Spherical Galaxies

1974 ◽  
Vol 58 ◽  
pp. 191-194
Author(s):  
Richard B. Larson
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Stellar Evolution ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Dynamical Model ◽  
Model Calculations ◽  
Formation And Evolution

Detailed dynamical model calculations based on a conventional collapse picture of galaxy formation, and conventional assumptions concerning star formation and stellar evolution, are found to be able to reproduce satisfactorily the basic structural and photometric properties of elliptical galaxies. The quasar phenomenon may be identifiable with the formation of the nucleus of a giant elliptical galaxy.

scholarly journals Globular Clusters as Probes of the Formation History of Elliptical Galaxies: Results for NGC 4472

2002 ◽  
Vol 207 ◽  
pp. 333-335
Author(s):  
K.L. Rhode ◽  
S.E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Large Sample ◽  
Formation History ◽  
History Of

We have undertaken a survey of the globular cluster systems of a large sample of elliptical and spiral galaxies in order to test predictions of elliptical galaxy formation models. Here we outline the survey and present a summary of our results for the Virgo elliptical NGC 4472.

scholarly journals Elliptical Galaxies: Darkly Cloaked or Scantily Clad?

2004 ◽  
Vol 220 ◽  
pp. 165-170
Author(s):  
A. J. Romanowsky ◽  
N. G. Douglas ◽  
K. Kuijken ◽  
M. R. Merrifield ◽  
M. Arnaboldi ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Velocity Dispersion ◽  
Elliptical Galaxies ◽  
Small Sample ◽  
Early Type ◽  
Dynamical Models ◽  
Show Evidence ◽  
Major Merger ◽  
Nearby Galaxies ◽  
Ab Initio Models

Planetary nebulae (PNe) may be the most promising tracers in the halos of early-type galaxies. We have used multi-object spectrographs on the WHT and the VLT, and the new Planetary Nebula Spectrograph on the WHT, to obtain hundreds of PN velocities in a small sample of nearby galaxies. These ellipticals show weak halo rotation, which may be consistent with ab initio models of galaxy formation, but not with more detailed major merger simulations. the galaxies near L* show evidence of a universal declining velocity dispersion profile, and dynamical models indicate the presence of little dark matter within 5 Reff—implying halos either not as massive or not as centrally concentrated as CDM predicts.

scholarly journals An Atlas of Mixed-Morphology Pairs

1990 ◽  
Vol 124 ◽  
pp. 53-54
Author(s):  
N. A. Sharp
Keyword(s):  
Northern Hemisphere ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Elliptical Galaxy ◽  
Starting Point

Current theories of galaxy formation imply that environment is the most important factor in deciding whether a collapsing region becomes a spiral galaxy or an elliptical galaxy. If this is the case, then isolated pairs comprising a galaxy of each morphology provide an especially interesting test, since, strictly speaking, they should not exist.The first phase of studying E-S pairs is to define a sample which is genuinely isolated and genuinely E-S. The catalog compiled by Karachentsev is the most useful northern hemisphere starting point, containing 603 pairs which obeyed certain well-defined angular isolation criteria. All of these pairs now have velocities, enabling further removal of at least some of the non-physical binaries. The conventional cutoff at 500 km s−1 was used for this purpose.

scholarly journals THE FORMATION OF LARGE GALACTIC DISKS THROUGH THE HIERARCHICAL SCENARIO: FURTHER CONSEQUENCES

2012 ◽  
Vol 27 (33) ◽  
pp. 1230034 ◽  
Author(s):  
FRANCOIS HAMMER ◽  
YANBIN YANG ◽  
HECTOR FLORES ◽  
MATHIEU PUECH
Keyword(s):  
Galaxy Formation ◽  
Hydrodynamic Models ◽  
Future Directions ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Hubble Sequence ◽  
Distant Galaxies ◽  
Major Merger ◽  
Merger Rate ◽  
Semi Empirical

Using the deepest and most complete observations of distant galaxies, we investigate the progenitors of present-day large spirals. Observations include spatially-resolved kinematics, detailed morphologies and photometry from UV to mid-IR. Six billion years ago, half of the present-day spirals were starbursts experiencing major mergers, evidenced by their anomalous kinematics and morphologies. They are consequently modeled using hydrodynamic models of mergers and it perfectly matches with merger rate predictions by state-of-the-art-ΛCDM semi-empirical models. Furthermore imprints in the halo of local galaxies such as M31 or NGC5907 are likely caused by major merger relics. This suggests that the hierarchical scenario has played a major role in shaping the massive galaxies of the Hubble sequence. Linking galaxy properties at different epochs is the best way to fully understand galaxy formation processes and we have tested such a link through generated series of simulations of gas-rich mergers. Mergers have expelled material in galactic haloes and beyond, possibly explaining 60% of the missing baryons in Milky-Way (MW) mass galaxies. A past major merger in M31 might affect drastically our understanding of Local Group galaxies, including MW dwarves. We also propose future directions to observationally constrain the necessary ingredients in galaxy simulations.

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