Contrary to some "Afro-Centric" educators, Egypt is darker skinned and has more sub-Saharan ancestry (as confirmed by modern and ancient DNA) now than it did in the classical era and in earlier times.
What happened?
A lot of sub-Saharan Africans were forced into slavery and delivered to the Middle East and North Africa (including Egypt) during the Middle Ages.
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A MOND model applied to the rotation curve of galaxies
Authors: Ana C. M. Ciqueira, Geanderson A. Carvalho, Paulo H. Faccin, FabrÃcio T. Dalmolin
Abstract: In this work, we propose a modified Newton dynamics (MOND) model to study the rotation curves of galaxies. The model is described by an arctangent interpolating function and it fits the rotation curves of several galaxies without invoking the presence of dark matter. We took from the literature the rotation curve data of fifteen spiral galaxies, and used it to constrain the model parameter, a0, as around 5×10−10 m/s2. This parameter is also called the acceleration constant once it gives the acceleration scale where Newton's dynamics fails. The model can be further tested in different astrophysical scenarios, such as, the missing mass problem of galaxy clusters and the accelerated expansion of the Universe, thus leading to a more robust and well constrained model. △ Less
Submitted 27 February, 2025; originally announced February 2025.
Comments: published in IJMPD
Journal ref: International Journal of Modern Physics D (2025) 2550001
Deur is reference
Saw it. Surprised that it was significant enough to publish. Nothing in it breaks any new ground.
The model is described by an arctangent interpolating function
The model can be further tested in different astrophysical scenarios, such as, the missing mass problem of galaxy clusters
the standard MOND model interpolating function 1/r does not work with the missing mass problem of galaxy clusters by a factor of 2, hence the universe also need dark matter in standard MOND.
arctangent interpolating function may get the missing mass problem of galaxy clusters right with out dark matter like extended MOND
Abstract
Context. MOdified Newtonian Dynamics (MOND) is a gravitational framework designed to explain the astronomical observations in the Universe without the inclusion of particle dark matter. MOND, in its current form, cannot explain the missing mass in galaxy clusters without the inclusion of some extra mass, be it in the form of neutrinos or non-luminous baryonic matter. We investigate whether the MOND framework can be generalized to account for the missing mass in galaxy clusters by boosting gravity in high gravitational potential regions. We examine and review Extended MOND (EMOND), which was designed to increase the MOND scale acceleration in high potential regions, thereby boosting the gravity in clusters.
Aims. We seek to investigate galaxy cluster mass profiles in the context of MOND with the primary aim at explaining the missing mass problem fully without the need for dark matter.
Methods. Using the assumption that the clusters are in hydrostatic equilibrium, we can compute the dynamical mass of each cluster and compare the result to the predicted mass of the EMOND formalism.
Results. We find that EMOND has some success in fitting some clusters, but overall has issues when trying to explain the mass deficit fully. We also investigate an empirical relation to solve the cluster problem, which is found by analysing the cluster data and is based on the MOND paradigm. We discuss the limitations in the text.
Generalizing MOND to explain the missing mass in galaxy clusters
Alistair O. Hodson and Hongsheng Zhao
The Hodson and Zhao paper seems more interesting.
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