scholarly journals Angular Momentum – Conference Summary

2018 ◽  
Vol 14 (A30) ◽  
pp. 197-202
Author(s):  
Francoise Combes
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Galaxy Formation ◽  
Subsequent Evolution ◽  
Local Universe ◽  
Secular Evolution ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Tidal Torques ◽  
Key Parameter

AbstractAngular momentum (AM) is a key parameter to understand galaxy formation and evolution. AM originates in tidal torques between proto-structures at turn around, and from this the specific AM is expected to scale as a power-law of slope 2/3 with mass. However, subsequent evolution re-shuffles this through matter accretion from filaments, mergers, star formation and feedback, secular evolution and AM exchange between baryons and dark matter. Outer parts of galaxies are essential to study since they retain most of the AM and the diagnostics of the evolution. Galaxy IFU surveys have recently provided a wealth of kinematical information in the local universe. In the future, we can expect more statistics in the outer parts, and evolution at high z, including atomic gas with SKA.

scholarly journals Baryonic Dark Halos: a model with MACHOS and cold gas globules

1996 ◽  
Vol 171 ◽  
pp. 167-170
Author(s):  
Ortwin Gerhard ◽  
Joseph Silk
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Active Role ◽  
Galaxy Formation And Evolution ◽  
Substellar Objects ◽  
Formation And Evolution ◽  
Cold Gas

The dark matter in the halos of galaxies may well be baryonic, and much of the mass within them could be in the form of clusters of substellar objects within which are embedded cold gas globules. Such halos might play an active role in galaxy formation and evolution.

scholarly journals Where is the Light? Tracing the Evolution of Bulges and Disks since z ~ 0.8

2010 ◽  
Vol 6 (S277) ◽  
pp. 282-286
Author(s):  
Lidia A. M. Tasca ◽  
Laurence Tresse ◽  
Keyword(s):  
Galaxy Formation ◽  
Future Study ◽  
Luminosity Function ◽  
Rest Frame ◽  
Observational Constraints ◽  
Local Universe ◽  
Disk Formation ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Disk Component

AbstractThe chronology of galactic bulge and disk formation is studied by analysing the relative contributions of these components to the B band rest–frame luminosity density (LD) at two different cosmological epochs. The luminosity function (LF) of the bulge and disk components at z ~ 0.8 is computed on a galaxy subsample of the final zCOSMOS “bright” catalogue of roughly 20,000 objects with spectroscopic redshift in the COSMOS field. The comparison is then performed on galaxies in the local universe. Our preliminary results show that the LD in the disk component strongly decreases from ~ 80% at z ~ 0.8 to ~ 50% at z = 0, the bulges having a specular behaviour. The observational constraints provided in this work are aimed to discriminate among competing scenarios of galaxy formation and evolution. An appropriate comparison with hydrodynamical semianalytical models will be considered in a future study to understand further the formation and evolution of galaxies.

THE LINK BETWEEN GALAXIES AND DARK MATTER

2011 ◽  
Vol 20 (10) ◽  
pp. 1771-1777
Author(s):  
HOUJUN MO
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
The Other ◽  
Dark Matter Halos ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
Galaxy Halo ◽  
Formation And Evolution ◽  
The Universe

Given that dark matter is gravitationally dominant in the universe, and that galaxy formation is closely related to dark matter halos, a key first step in understanding galaxy formation and evolution in the CDM paradigm is to quantify the galaxy-halo connection for galaxies of different properties. Here I will present results about the halo/galaxy connection obtained from two different methods. One is based on the conditional luminosity function, which describes the occupation of galaxies in halos of different masses, and the other is based on galaxy systems properly selected to represent dark halos.

scholarly journals Building Galactic Disks in Triaxial Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 24-28
Author(s):  
Isaac Shlosman
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Star Formation ◽  
Numerical Simulations ◽  
Recent Work ◽  
Stellar Evolution ◽  
Dark Matter Halos ◽  
Local Universe ◽  
Broad Agreement ◽  
Formation And Evolution

AbstractWe review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in tandem with the disk and facilitate the angular momentum redistribution in the system and radial gas inflow. Nested bars appear to form as a by-product. Interactions between various non-axisymmetric components—bars, disks and halos lead to decay of bars or washing out of ellipticity in the inner halo.

scholarly journals Faint features in the isolated galaxy CIG96

2016 ◽  
Vol 11 (S321) ◽  
pp. 292-292
Author(s):  
P. Ramírez-Moreta ◽  
L. Verdes-Montenegro ◽  
S. Leon ◽  
J. Blasco-Herrera ◽  
M. Fernández-Lorenzo ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Optical Observations ◽  
Local Universe ◽  
Isolated Galaxies ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Minor Mergers ◽  
Gas Accretion ◽  
Shed Light

The AMIGA project carries out a multiwavelength study of the largest catalogue of isolated galaxies from the Local Universe (CIG, Karachentseva 1973). Compared to any other sample —field galaxies included— and using highly strict isolation criteria (unperturbed for at least ~3 Gyr, Verdes-Montenegro et al. 2005), all the results show that these galaxies have the lowest values of the physical magnitudes expected to be enhanced by interactions. This strongly supports isolated galaxies as ideal laboratories for the study of galaxy formation and evolution. Despite CIG galaxies show the lowest HI integrated profile asymmetry level when compared to any other sample, some cases present up to 50% HI asymmetry (Espada et al. 2011b). We aim to shed light over the causes and sources of such asymmetries with our deep radiointerferometric and optical observations of CIG targets. Since major mergers are ruled out by the isolation criteria, in this work we are addressing whether minor mergers, internal processes or primordial gas accretion are responsible for such asymmetries.

scholarly journals Light Speed Expansion and Rotation of a Very Dark Machian Universe Having Internal Acceleration

2020 ◽  
Author(s):  
U.V.S. Seshavatharam ◽  
S. Lakshminarayana
Keyword(s):  
Dark Matter ◽  
Angular Velocity ◽  
Galaxy Formation ◽  
Hubble Parameter ◽  
Angular Acceleration ◽  
Big Bang ◽  
Light Speed ◽  
Distant Galaxies ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution

We present a Machian model of Quantum Cosmology with full dark matter and light speed expansion and rotation. During galaxy formation and evolution, fraction of dark matter transforms to visual matter with a relation of the form, m_vis = constant * (m_dark)^2/3. Using this relation and replacing MOND’s ‘critical acceleration’ with “current cosmic maximum angular acceleration”, galactic flat rotation speed range of (50 to 500) km/sec can be fitted well. Estimated flat rotation speeds of DD168, Milky Way and UGC12591 are 49.96 km/sec, 199.66 km/sec and 521.75 km/sec respectively. Based on these striking coincidences, it is possible to say that, MOND’s approach is implicitly connected with cosmological estimation of 95% invisible matter. Considering galactic total matter and current cosmic maximum angular acceleration, galactic working radii, angular velocity and visual matter density can be estimated. Even though, this model is free from ‘big bang’, ‘inflation’, ‘dark energy’, ‘flatness’ and ‘red shift’ issues, at 2.722 K, estimated present Hubble parameter is 66.24 km/sec/Mpc, cosmic radius is 146.3 times the Hubble radius, angular velocity is 146.3 times lower than the Hubble parameter and cosmic age is 146.3 times the Hubble age. With future observations and advanced telescopes, it may be possible to see far distant galaxies and very old stars far beyond the current observable cosmic radius.

A full pipeline for modelling low surface brightness galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 279-280
Author(s):  
Marius Peper ◽  
Boudewijn F. Roukema ◽  
Krzysztof Bolejko
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Surface Brightness ◽  
Dark Matter Halo ◽  
Cosmological Simulations ◽  
Galaxy Formation And Evolution ◽  
Low Surface Brightness ◽  
Formation And Evolution ◽  
Low Surface Brightness Galaxies

AbstractCosmological simulations are a powerful tool to test various cosmological and galaxy formation scenarios. The discovery of low surface brightness objects has been a challenge for both of these fields. Our work aims to create a fully reproducible pipeline to generate a realistic dark matter halo catalog with corresponding information on galaxy formation and evolution.

scholarly journals Dwarf Cosmology with the Stromlo Missing Satellites Survey

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Helmut Jerjen
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Primary Objective ◽  
Sloan Digital Sky Survey ◽  
Galaxy Formation And Evolution ◽  
National University ◽  
Formation And Evolution ◽  
Satellite Galaxies

The standard Lambda Cold Dark Matter model is considered to be a triumph of theoretical astrophysics but observations of the Milky Way and its system of satellite galaxies irresistibly signal that theory is incomplete on galactic and subgalactic scales. The Stromlo Missing Satellites (SMS) Survey is a critical endeavor to investigate at what level predictions of CDM cosmology are consistent with the observed matter distribution in the Milky Way halo. It will be the deepest, most extended search for optically elusive satellite galaxies to date, covering 20 000 square degrees of sky. The international SMS Survey collaboration will exploit 150 TB of CCD images in six filters acquired by the new SkyMapper telescope of the Australian National University over the next five years, expecting on completion photometric limits 0.5–1.0 mag fainter than the Sloan Digital Sky Survey. The primary objective of the program is to characterise the baryonic and dark matter components of a complete sample of MW satellites in the Southern hemisphere to provide stringent observational constraints for improving our understanding of how the Milky Way formed and what physical processes governed galaxy formation and evolution in general.

scholarly journals Trends in Galaxy Formation and Evolution in the Context of the Virial and Fundamental Planes

1999 ◽  
Vol 186 ◽  
pp. 195-195
Author(s):  
Tapan K. Chatterjee ◽  
V.B. Magalinsky
Keyword(s):  
Galaxy Formation ◽  
Homogeneous Medium ◽  
Parametric Form ◽  
Subsequent Evolution ◽  
Scale Separation ◽  
Small Perturbations ◽  
Fundamental Plane ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Gravitating Systems

The kinetic description of gravitating systems has acquired vital importance in the context of trends in galaxy formation and evolution as evidenced by the existence of the virial and fundamental planes. The fundamental plane deviates for brighter and fainter ellipticals; until the brightest cluster members (BCMs), whose structures have been most modified by interactions, seem to occupy a fundamental plane with a different slope as compared to normal ellipticals. Extending the work of Magalinsky (1972, AZh, 49, 1017; Sov. Astron.-AJ, 16, 830), the Vlasov equation is applied to study small perturbations (considered as protogalaxies) of the exact solution corresponding to a spatially homogeneous medium in expansion. It is found that a perturbation attains a saturated size whose scale length, as a function of a reduced parameter of evolution (in terms of the characteristic frequency of dispersion of momenta, τ), R(τ) ∝ K.E./P.E. ∝ (K.E.)2/σ ∝ (δV)2/Proj.density ∝ σ2/I, which has the parametric form of the virial plane. The subsequent evolution is characterized principally by the variation of the energy due to the gravitational interactions between stars (considered as mass points), given by the potential energy such that the harmonic mean separation scale (between stars) characterizes this evolution. In this stage of the evolution the harmonic scale separation has the parametric form, 〈r−1〉 ∝ (K.E.)1/2, and 〈r−1〉 ∝ (P-E.) such that 〈r−1〉 ∝ (K.E.)1/2/(P.E.) ∝ σ/I. Notice that this is the parametric form of the fundamental plane of evolved ellipticals since the harmonic scale separation determines a physically significant scale.

scholarly journals The radial distribution in nearby galaxies of the ionizing field of radiation of hii regions using photoionization models

2018 ◽  
Vol 14 (A30) ◽  
pp. 258-258
Author(s):  
Enrique Pérez-Montero ◽  
Rubén García-Benito ◽  
José M. Vílchez
Keyword(s):  
Galaxy Formation ◽  
Radial Distribution ◽  
Disk Galaxies ◽  
Ionized Gas ◽  
Local Universe ◽  
Galaxy Formation And Evolution ◽  
Nearby Galaxies ◽  
Formation And Evolution ◽  
Ionization Parameter

AbstractHii regions in galaxy disks can be used as a powerful tool to trace the radial distribution of several of their properties and shed some light on the different relevant processes on galaxy formation and evolution. Among the properties that can be extracted from the study of the ionized gas are the metallicity, the excitation and the hardness of the ionizing field of radiation. In this contribution we focus on the determination of both the ionization parameter (U) and the effective temperature of the ionizing clusters (T) by means of a bayesian-like comparison between the observed relative fluxes of several emission-lines with the predictions from a set of photoionization models. We also show the implications that the use of our method has for the study of the radial variation of both U and T in some very well-studied disk galaxies of the Local Universe.

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