Universe

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

25 pages, 2077 KiB

Open AccessArticle

The Rotation of Classical Bulges in Barred Galaxies in the Presence of Gas

by Rubens E. G. Machado, Kenzo R. Sakamoto, Andressa Wille and Gustavo F. Gonçalves

Universe 2024, 10(5), 223; https://doi.org/10.3390/universe10050223 - 16 May 2024

Viewed by 451

Abstract

Barred galaxies often develop a box/peanut pseudobulge, but they can also host a nearly spherical classical bulge, which is known to gain rotation due to the bar. We aim to explore how the presence of gas impacts the rotation of classical bulges. We carried out a comprehensive set of hydrodynamical N-body simulations with different combinations of bulge masses and gas fractions. In these models, both massive bulges and high gas content tend to inhibit the formation of strong bars. For low-mass bulges, the resulting bar is stronger in cases of low gas content. In the stronger bar models, bulges acquire more angular momentum and thus display considerable rotational velocity. Such bulges also develop anisotropic velocity dispersions and become triaxial in shape. We found that the rotation of the bulge becomes less pronounced as the gas fraction is increased from 0 to 30%. These results indicate that the gas content has a significant effect on the dynamics of the classical bulge, because it influences bar strength. Particularly in the case of the low-mass bulges (10% bulge mass fraction), all of the measured rotational and structural properties of the classical bulge depend strongly and systematically on the gas content of the galaxy. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2024—"Galaxies and Clusters")

► Show Figures

Figure 1

26 pages, 17785 KiB

Open AccessArticle

The κ-Model under the Test of the SPARC Database

by Gianni Pascoli

Universe 2024, 10(3), 151; https://doi.org/10.3390/universe10030151 - 21 Mar 2024

Viewed by 895

Abstract

Our main goal here is to conduct a comparative analysis between the well-known MOND theory and a more recent model called the

κ

-model. An additional connection, between the

κ

-model and two other novel MOND-type theories, Newtonian Fractional-Dimension Gravity (NFDG) and Refracted [...] Read more.

Our main goal here is to conduct a comparative analysis between the well-known MOND theory and a more recent model called the

κ

-model. An additional connection, between the

κ

-model and two other novel MOND-type theories, Newtonian Fractional-Dimension Gravity (NFDG) and Refracted Gravity (RG), is likewise presented. All these models are built to overtake the DM paradigm, or at least to strongly reduce the dark matter content. Whereas they rely on different formalisms, however, all four seem to suggest that the universal parameter,

a_{0}

, appearing in MOND theory could intrinsically be correlated to either the sole baryonic mean mass density (RG and

κ

-model) and/or to the dimension of the object under consideration (NFDG and

κ

-model). We then confer to parameter

a_{0}

a more flexible status of multiscale parameter, as required to explain the dynamics together in galaxies and in galaxy clusters. Eventually, the conformal gravity theory (CFT) also seems to have some remote link with the

κ

-model, even though the first one is an extension of general relativity, and the second one is Newtonian in essence. The

κ

-model has been tested on a small sample of spiral galaxies and in galaxy clusters. Now, we test this model on a large sample of galaxies issued from the SPARC database. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2024—"Galaxies and Clusters")

► Show Figures

Figure 1

19 pages, 1623 KiB

Open AccessArticle

Dark Matter in Fractional Gravity III: Dwarf Galaxies Kinematics

by Francesco Benetti, Andrea Lapi, Giovanni Gandolfi, Minahil Adil Butt, Yacer Boumechta, Balakrishna S. Haridasu and Carlo Baccigalupi

Universe 2023, 9(11), 478; https://doi.org/10.3390/universe9110478 - 8 Nov 2023

Viewed by 1251

Abstract

Recently, we put forward a framework where the dark matter (DM) component within virialized halos is subject to a non-local interaction originated by fractional gravity (FG) effects. In previous works, we demonstrated that such a framework can substantially alleviate the small-scale issues of [...] Read more.

Λ

CDM paradigm, without altering the DM mass profile predicted by N-body simulations, and retaining its successes on large cosmological scales. In this paper, we investigate further, to probe FG via the high-quality data of individual dwarf galaxies, by exploiting the rotation velocity profiles inferred from stellar and gas kinematic measurements in eight dwarf irregulars, and the projected velocity dispersion profiles inferred from the observed dynamics of stellar tracers in seven dwarf spheroidals and in the ultra-diffuse galaxy DragonFly 44. We find that FG can reproduce extremely well the rotation and dispersion curves of the analyzed galaxies, performing in most instances significantly better than the standard Newtonian setup. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2024—"Galaxies and Clusters")

► Show Figures

Journal Menu

Journal Browser

Universe: Feature Papers 2024—"Galaxies and Clusters"

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (3 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI