Galaxies

Special Issue Editor

Prof. Dr. Peter J. Quinn

E-Mail Website
Guest Editor

International Centre for Radio Astronomy Research, The University of Western Australia, Crawley, WA 6009, Australia
Interests: galaxy formation and evolution; dark matter structure; dynamics and searchers; galaxy encounters and mergers

Special Issue Information

Dear Colleagues,

The steady-state internal dynamics of stellar systems, the linear and non-linear development of large scale structure and the processes associated with galaxy formation and collisions, have been at the heart of modern astrophysics for the past 100 years. Despite the development of beautiful mathematical formalisms and the application of power computational techniques and algorithms, we are still faced with a number of challenges to our understanding of the current structure and evolution of galaxies. Why do the rotation curves of late-type spirals imply large dark matter halo core radii in apparent disagreement with CDM simulations? How much substructure is there in dark matter halos of galaxies and does it change with time? Is the angular momentum content and distribution of observed spiral disks consistent with the tidal-torquing paradigm? Are isolated disk galaxies stable and is the structure and formation of spiral bulges consistent with an encounter-free environment? Do velocity fields in elliptical galaxies contain clues to their formation process? Do we really understand polar disks around some spirals and what are they telling us about dark matter? All of these questions are largely unanswered and present significant challenges and opportunities. They may also probe the interface of dynamical and hydrodynamical processes in galaxy formation and evolution - an interface that can be constrained by a complete appreciation of the dynamical processes involved. This special volume is intended to outline our current level of understanding and our current dilemmas in applying dynamics to the origin and evolution of galaxies.

Prof. Dr. Peter J. Quinn
Guest Editor

Manuscript Submission Information

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Keywords

galaxy dynamics
dark matter
galaxy formation and evolution
structure formation
linear and non-linear dynamical processes in galaxies and the Universe
luminous and non-luminous galaxy structures

Published Papers (2 papers)

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Research

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210 KiB

Open AccessArticle

Galaxy Rotation Curves in Covariant Hořava-Lifshitz Gravity

by Jean Alexandre and Martyna Kostacinska

Galaxies 2014, 2(1), 1-12; https://doi.org/10.3390/galaxies2010001 - 23 Dec 2013

Cited by 6 | Viewed by 3730

Abstract

Using the multiplicity of solutions for the projectable case of the covariant extension of Hořava-Lifshitz gravity, we show that an appropriate choice for the auxiliary field allows for an effective description of galaxy rotation curves. This description is based on static and spherically [...] Read more.

(This article belongs to the Special Issue Advances in Our Understanding of the Dynamics of Galaxies)

Review

Jump to: Research

8381 KiB

Open AccessReview

Monolithic View of Galaxy Formation and Evolution

by Cesare Chiosi, Emiliano Merlin, Lorenzo Piovan and Rosaria Tantalo

Galaxies 2014, 2(3), 300-381; https://doi.org/10.3390/galaxies2030300 - 14 Jul 2014

Cited by 7 | Viewed by 6644

Abstract

We review and critically discuss the current understanding of galaxy formation and evolution limited to Early Type Galaxies (ETGs) as inferred from the observational data and briefly contrast the hierarchical and quasi-monolithic paradigms of formation and evolution. Since in Cold Dark Matter (CDM) cosmogony small scale structures typically collapse early and form low-mass haloes that subsequently can merge to assembly larger haloes, galaxies formed in the gravitational potential well of a halo are also expected to merge thus assembling their mass hierarchically. Mergers should occur all over the Hubble time and large mass galaxies should be in place only recently. However, recent observations of high redshift galaxies tell a different story: massive ETGs are already in place at high redshift. To this aim, we propose here a revision of the quasi-monolithic scenario as an alternative to the hierarchical one, in which mass assembling should occur in early stages of a galaxy lifetime and present recent models of ETGs made of Dark and Baryonic Matter in a Λ-CDM Universe that obey the latter scheme. The galaxies are followed from the detachment from the linear regime and Hubble flow at z ≥ 20 down to the stage of nearly complete assembly of the stellar content (z ∼ 2 − 1) and beyond. It is found that the total mass (M_h = M_DM + M_BM ) and/or initial over-density of the proto-galaxy drive the subsequent star formation histories (SFH). Massive galaxies (M_h ~ _10¹²M_⊙) experience a single, intense burst of star formation (with rates ≥ 10³M⊙/yr) at early epochs, consistently with observations, with a weak dependence on the initial over-density; intermediate mass haloes (M_h~_ 10¹⁰ − 10¹¹M⊙) have star formation histories that strongly depend on their initial over-density; finally, low mass haloes (M_h ~_ 10⁹M⊙) always have erratic, burst-like star forming histories. The present-day properties (morphology, structure, chemistry and photometry) of the model galaxies closely resemble those of the real galaxies. In this context, we also try to cast light on the physical causes of the Stellar Mass-Radius Relation (MRR) of galaxies. The MRR is the result of two complementary mechanisms: i.e., local physical processes that fix the stellar mass and the radius of each galaxy and cosmological global, statistical principles, which shape the distribution of galaxies in the MR-plane. Finally, we also briefly comment on the spectro-photometric properties of the model galaxies and how nicely they match the observational data. The picture emerging from this analysis is that the initial physical conditions of a proto-galaxy, i.e., nature, seem to play the dominant role in building up the ETGs we see today, whereas nurture by recurrent captures of small objects is a secondary actor of the fascinating and intriguing story of galaxy formation and evolution. Full article

(This article belongs to the Special Issue Advances in Our Understanding of the Dynamics of Galaxies)

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