Related papers: Polar ring galaxies as tests of gravity
Dark matter is the generally accepted paradigm in astrophysics and cosmology as a solution to the higher rate of rotation in galaxies, among many other reasons. But since there are still some problems encountered by the standard dark matter…
We study the possibility that galactic rotation curves can be explained by a gravitational potential that contains a linear term as well as a Newtonian one. This hypothesis, suggested by conformal gravity, does allow good fits to the…
Polar ring galaxies are flattened stellar systems with an extended ring of gas and stars rotating in a plane almost perpendicular to the central galaxy. We show that their formation can occur naturally in a hierarchical universe where most…
Polar-ring galaxies are systems with two nearly orthogonal rotational axes, and are therefore clearly the result of galaxy-galaxy interactions. The host galaxies of polar rings are typically gas-poor early-type systems. The rings…
Modified gravity theories may provide an alternative to dark energy to explain cosmic acceleration. We argue that the observational program developed to test dark energy needs to be augmented to capture new tests of gravity on astrophysical…
Generally, the dynamics of test particles around galaxies, as well as the corresponding mass deficit, is explained by postulating the existence of a hypothetical dark matter. In fact, the behavior of the rotation curves shows the existence…
We propose to determine the stellar velocity dispersions of globular clusters in the outer halo of the Milky Way in order to decide whether the dynamics of the universe on large scales is governed by dark matter or modified Newtonian…
In the currently accepted paradigm, dark matter is hypothesized as an explanation of the flat rotation curves of galaxies under the assumption of virialized orbits. The use of millisecond pulsar timing as a probe of Galactic dark matter…
Stellar streams have proven to be powerful tools for measuring the Milky Way's gravitational potential and hence its dark matter halo. In the coming years, Vera Rubin, Euclid, ARRAKIHS, and NGRST will uncover a plethora of streams around…
General structural properties and low surface brightness tidal features hold important clues to the formation of galaxies. In this paper, we study a sample of polar-ring galaxies (PRGs) based on optical imaging from the Sloan Digital Sky…
The stability of galaxies is either explained by the existence of dark matter or caused by a modification of Newtonian acceleration (MOND). Here we show that the modification of the Newtonian dynamics can equally well be obtained by a…
The rotation curves of regularly rotating disc galaxies are a unique probe of the gravitational potential and dark matter distribution. Until recently, matter decomposition of rotation curves at $z>0.5$ was challenging, not only due to the…
We have considered polar ring galaxy candidates, the images of which can be found in the SDSS. The sample of 78 galaxies includes the most reliable candidates from the SPRC and PRC catalogs, some of which already have kinematic…
The presence of dark matter, though well established by indirect evidence, is yet to be observed directly. Various dark matter detection experiments running for several years have yielded no positive results. In view of these negative…
Using two-dimensional velocity maps and I-band photometry, we have created mass models of 40 spiral galaxies using the Milgrom relation (the basis of modified Newtonian dynamics, or MOND) to complement previous work. A Bayesian technique is…
Higher order curvature gravity has recently received a lot of attention due to the fact that it gives rise to cosmological models which seem capable of solving dark energy and quintessence issues without using "ad hoc" scalar fields. In…
Polarization wiggling is an observational effect of a gravitational field on the polarization of electromagnetic radiation traversing it. We find that in linear gravity, the polarization wiggle rate contributions from scalar, vector and…
In this review we consider various ring structures that are observed in galaxies. Formation and evolution of the rings are interesting problems in studies of galactic morphology. They are related to such fundamental aspects of galactic…
We provide a holographic dual description of Milgrom's scaling associated with galactic rotation curves. Our argument is based on the recent entropic reinterpretation of Newton's laws of motion. We propose a duality between cold dark matter…
Observational studies of galaxy isophotal shapes have shown that galaxy orientations are anisotropic: a galaxy's long axis tends to be oriented toward the center of its host. This radial alignment is seen across a wide range of scales, from…