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Dark Matter: Large versus Small Scale Structures
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Dark Matter: Large versus Small Scale Structures

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: closed (30 September 2016) | Viewed by 23018

Special Issue Editors

Prof. Dr. Antonaldo Diaferio

E-Mail Website
Guest Editor
Department of Physics, University of Torino, 10125 Torino, Italy
Interests: cosmology; theory of gravitation; large-scale structure of the universe
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jose Gaite

E-Mail Website
Guest Editor
Physics Department, ETSIAE, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, E-28040 Madrid, Spain
Interests: dark matter structure and evolution; galaxy clusters
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The standard cold dark matter cosmology (the LCDM model) is successful overall but leaves open a number of questions that may lead to significant or even revolutionary changes. On large scales, galaxy surveys, gravitational lensing measurements, and N-body simulations show that the dark matter forms a cosmic web structure with self-similar features: the web filaments and walls are arranged in a hierarchy that extends from galactic-cluster sizes to puzzling sizes of more than 100 Mpc. On small scales, the structure of dark-matter halos seen in cold dark matter N-body simulations is in conflict with observations, as manifested by the core-cusp and dwarf-galaxy problems.

Some open questions are: What are the largest structures in the universe? Do galaxies and dark matter form the same large scale structures? Are these structures self-similar? In this regard, let us recall Peebles' anomaly: “scale-dependent biasing seems an awkward way to account for the powerlaw forms of the low order galaxy position correlation functions.” What new do the recent improvements on the calculation of higher-order correlations tell us? Can the soluble adhesion model allow the analytical calculation of correlations? In what range of scales the cosmic web predicted by this model is valid? On small scales, are the halos seen in N-body simulations real or are they rather numerical artifacts?

This Special Issue of Galaxies is addressed to answering these questions without much departure from the cold dark matter model, that is to say, limiting the introduction of new ad hoc ingredients, such as warm or self-interacting dark matter, gravity modifications, etc. Contributions to specific questions are welcome as well as wide scope papers, including topical reviews.

Prof. José Gaite
Prof. Antonaldo Diaferio
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Galaxies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

References:

  1. Peebles, P.J.E. Nonlinear Cosmological Tests. Observatoire de la Côte d'Azur, Nice, 2006. http://www.oca.eu/etc7/ncp06/peebles.html
  2. Weinberg, D.H. et al. Cold dark matter: controversies on small scales. arXiv:1306.0913.
  3. Gaite, J. Halo Models of Large Scale Structure and Reliability of Cosmological N-Body Simulations. Galaxies 2013, 1, 31–43.

Keywords

  • cosmic web
  • dark matter halos
  • dark matter bias
  • self-similarity
  • adhesion model
  • N-body simulations
  • correlation functions

Published Papers (3 papers)

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Research

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2624 KiB  
Article
Small Scale Problems of the ΛCDM Model: A Short Review
by Antonino Del Popolo and Morgan Le Delliou
Galaxies 2017, 5(1), 17; https://doi.org/10.3390/galaxies5010017 - 20 Feb 2017
Cited by 204 | Viewed by 12390
Abstract
The ΛCDM model, or concordance cosmology, as it is often called, is a paradigm at its maturity. It is clearly able to describe the universe at large scale, even if some issues remain open, such as the cosmological constant problem, the small-scale problems [...] Read more.
The ΛCDM model, or concordance cosmology, as it is often called, is a paradigm at its maturity. It is clearly able to describe the universe at large scale, even if some issues remain open, such as the cosmological constant problem, the small-scale problems in galaxy formation, or the unexplained anomalies in the CMB. ΛCDM clearly shows difficulty at small scales, which could be related to our scant understanding, from the nature of dark matter to that of gravity; or to the role of baryon physics, which is not well understood and implemented in simulation codes or in semi-analytic models. At this stage, it is of fundamental importance to understand whether the problems encountered by the ΛDCM model are a sign of its limits or a sign of our failures in getting the finer details right. In the present paper, we will review the small-scale problems of the ΛCDM model, and we will discuss the proposed solutions and to what extent they are able to give us a theory accurately describing the phenomena in the complete range of scale of the observed universe. Full article
(This article belongs to the Special Issue Dark Matter: Large versus Small Scale Structures)
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2776 KiB  
Article
Tidal Disruption of Milky Way Satellites with Shallow Dark Matter Density Profiles
by Ewa L. Łokas
Galaxies 2016, 4(4), 74; https://doi.org/10.3390/galaxies4040074 - 30 Nov 2016
Cited by 2 | Viewed by 4651
Abstract
Dwarf galaxies of the Local Group provide unique possibilities to test current theories of structure formation. Their number and properties have put the broadly accepted cold dark matter model into question, posing a few problems. These problems now seem close to resolution due [...] Read more.
Dwarf galaxies of the Local Group provide unique possibilities to test current theories of structure formation. Their number and properties have put the broadly accepted cold dark matter model into question, posing a few problems. These problems now seem close to resolution due to the improved treatment of baryonic processes in dwarf galaxy simulations which now predict cored rather than cuspy dark matter profiles in isolated dwarfs with important consequences for their subsequent environmental evolution. Using N-body simulations, we study the evolution of a disky dwarf galaxy with such a shallow dark matter profile on a typical orbit around the Milky Way. The dwarf survives the first pericenter passage but is disrupted after the second due to tidal forces from the host. We discuss the evolution of the dwarf’s properties in time prior to and at the time of disruption. We demonstrate that the dissolution occurs on a rather short timescale as the dwarf expands from a spheroid into a stream with non-zero mean radial velocity. We point out that the properties of the dwarf at the time of disruption may be difficult to distinguish from bound configurations, such as tidally induced bars, both in terms of surface density and line-of-sight kinematics. Full article
(This article belongs to the Special Issue Dark Matter: Large versus Small Scale Structures)
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Review

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20060 KiB  
Review
Approximate Methods for the Generation of Dark Matter Halo Catalogs in the Age of Precision Cosmology
by Pierluigi Monaco
Galaxies 2016, 4(4), 53; https://doi.org/10.3390/galaxies4040053 - 27 Oct 2016
Cited by 54 | Viewed by 5115
Abstract
Precision cosmology has recently triggered new attention on the topic of approximate methods for the clustering of matter on large scales, whose foundations date back to the period from the late 1960s to early 1990s. Indeed, although the prospect of reaching sub-percent accuracy [...] Read more.
Precision cosmology has recently triggered new attention on the topic of approximate methods for the clustering of matter on large scales, whose foundations date back to the period from the late 1960s to early 1990s. Indeed, although the prospect of reaching sub-percent accuracy in the measurement of clustering poses a challenge even to full N-body simulations, an accurate estimation of the covariance matrix of clustering statistics, not to mention the sampling of parameter space, requires usage of a large number (hundreds in the most favourable cases) of simulated (mock) galaxy catalogs. Combination of few N-body simulations with a large number of realizations performed with approximate methods gives the most promising approach to solve these problems with a reasonable amount of resources. In this paper I review this topic, starting from the foundations of the methods, then going through the pioneering efforts of the 1990s, and finally presenting the latest extensions and a few codes that are now being used in present-generation surveys and thoroughly tested to assess their performance in the context of future surveys. Full article
(This article belongs to the Special Issue Dark Matter: Large versus Small Scale Structures)
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