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7. Dark matter axions

Author

Sikivie, P [California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics Florida Univ., Gainesville, FL (United States). Dept. of Physics]

Published
1992

8. The Milky Way's plane of satellites is consistent with ΛCDM

Author

Till Sawala, Marius Cautun, Carlos Frenk, John Helly, Jens Jasche, Adrian Jenkins, Peter H. Johansson, Guilhem Lavaux, Stuart McAlpine, Matthieu Schaller, Faculty of Science, Department of Physics, and Particle Physics and Astrophysics

Subjects
Simulations, Evolution, Astrophysics - astrophysics of galaxies, Astrophysics - cosmology and nongalactic astrophysics, Population, Astronomy and Astrophysics, Mass, 115 Astronomy, Space science, Galaxies, Standard, Depletion, Universe, Substructure, Local group
Abstract

The Milky Way is surrounded by 11 ‘classical’ satellite galaxies in a remarkable configuration: a thin plane that is possibly rotationally supported. Such a structure is thought to be highly unlikely to arise in the standard (ΛCDM) cosmological model (Λ cold dark matter model, where Λ is the cosmological constant). While other apparent discrepancies between predictions and observations of Milky Way satellite galaxies may be explained either through baryonic effects or by invoking alternative forms of dark matter particles, there is no known mechanism for making rotating satellite planes within the dispersion-supported dark matter haloes predicted to surround galaxies such as the Milky Way. This is the so-called ‘plane of satellites problem’, which challenges not only the ΛCDM model but the entire concept of dark matter. Here we show that the reportedly exceptional anisotropy of the Milky Way satellites is explained, in large part, by their lopsided radial distribution combined with the temporary conjunction of the two most distant satellites, Leo I and Leo II. Using Gaia proper motions, we show that the orbital pole alignment is much more common than previously reported, and reveal the plane of satellites to be transient rather than rotationally supported. Comparing with new simulations, where such short-lived planes are common, we find the Milky Way satellites to be compatible with standard model expectations.

Published
2023

10. Dark matter and dark energy denote the gravitation of the expanding universe

Author

Arto Annila, Mårten Wikström, Department of Physics, and Institute of Biotechnology

Subjects
NEWTONIAN DYNAMICS, Materials Science (miscellaneous), photon, vacuum, Biophysics, RED-SHIFT, General Physics and Astronomy, LINES, MASS, quantum of action, 115 Astronomy, Space science, 114 Physical sciences, dark matter, GALAXIES, LIGHT, flatness problem, horizon problem, CONSTANT, graviton, COSMOLOGY, ROTATION, Physical and Theoretical Chemistry, dark energy, POWER-LAW DISTRIBUTIONS, Mathematical Physics
Abstract

We reason that it is the gravitation of all ordinary matter, extending from the dense distant past to the sparse present, rather than dark matter, that shows up in galaxy rotation and velocity dispersion. Likewise, we argue that it is this gradient in the gravitational energy due to the expansion, rather than dark energy, that explains Type 1a supernovae brightness vs. redshift data. Our conclusions follow from statistical mechanics, the thermodynamic theory based on the atomistic axiom that everything comprises quanta. In line with the Einstein field equations, the vacuum quanta embodying gravitation, geometrized as spacetime, equate in dynamic balance to the quanta embodying the substance of the stress–energy tensor. In accordance with quantum field theory, the proposed ground-state field of paired light quanta complies with Bose–Einstein statistics and assumes an excited state around a particle.

Published
2022

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