Universe Center and Dark Matter

Abbreviations

CDM: Cold Dark Matter; ΛCDM: Lambda Cold Dark Matter.

Introduction

The beginning of the universe is believed to have occurred with the Big Bang, a massive explosion that happened approximately 13.8 billion years ago. This event marked the start of the universe’s expansion and the formation of the first stars and galaxies. The exact cause of the Big Bang is still unknown.

Our universe is everything that exists, including all matter, energy, and space. It encompasses all galaxies, stars, planets, and other celestial bodies, as well as all physical laws and constants that govern their behavior. The observable universe has a diameter of about 93 billion light-years and is not only expanding but is expanding at an accelerated rate.

The Milky Way galaxy is part of the Local Group, which it dominates along with the Andromeda Galaxy. The group is part of the Virgo Supercluster. At the largest scale, these associations are generally arranged into sheets and filaments surrounded by immense voids. Both the Local Group and the Virgo Supercluster are contained in a much larger cosmic structure named Laniakea [1, 2, 3].

Hubble’s law is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving away. For this purpose, the recessional velocity of a galaxy is typically determined by measuring redshift. Hubble’s law states that the velocity of recession between our galaxy and the other galaxies are directly proportional to the distance between them.

Hubble’s law is considered the first observational basis for the expansion of the universe, and today it serves as one of the pieces of evidence most often cited in support of the Big Bang model. The motion of astronomical objects due solely to this expansion is known as the Hubble law [4, 5, 6].

o v H D = (1)

v is the recessional velocity, Ho is Hubble’s constant and D is the proper distance from the galaxy to the observer According to the cosmological principle and all models that use the Friedman-Lamaitre-Robertson-Walker metric including the current version of the Lambda Cold Dark Matter (ΛCDM) model, the distribution of matter in the universe is homogeneous and isotropic this means that the universe is the same in all locations and in all directions respectively [7, 8]. ΛCDM model is a mathematical model of the big bang theory with three major components (Cosmological Constant associated with Dark Energy, postulated Cold Dark Matter CDM, Ordinary Matter). The diameter of the observable universe is nearly 93 billion light years

$$ 8. 8 \times 1 0 ^ {2 6} $$ (m) with 1012 galaxies, 1022 stars, 1078 atoms,

$$ 1. 5 \times 1 0 ^ {7 9} $$ $$ e l e c t r o n s, 1. 5 \times 1 0 ^ {7 9} $$

protons and 1088 photons. The mass of the observable universe is

$$ 2. 6 \times 1 0 ^ {5 2} \mathrm {k g} [ 9 ]. $$ According to Newton’s law of universal gravitation, the attractive force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance along their center of masses [10, 11, 12, 13, 14, 15].

Dark matter, a component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity. Dark matter’s existence was first inferred by Swiss American astronomer Zwicky F [17] who in 1933 discovered that the mass of all the stars in the Coma cluster of galaxies provided only about 1 percent of the mass needed to keep the galaxies from escaping the cluster’s gravitational pull [16]. The mass of the stars visible within a typical galaxy is only about 10 percent of that required to keep those stars orbiting the galaxy’s center [17, 18].

Conclusion

From Hubble’s law it is deduced that the galaxies are moving in orbits around certain center (universe center) and the orbital velocities near the center is greater than the orbital velocity far away from it. The mass of the center of atom (nuclei) and the center of solar system (Sun) represents more than 99.9 of the system mass this means that the mass of the center of the universe is tremendous and may be the dark matter. The center of the universe represents the residual of the primordial matter of the universe without expansion with spherical shape and large mass and it is homogenous and isotropic and maintain the geometrical shape of the universe to be spherical.

The orbital velocities of celestial objects and galaxies depend on the gravitational force, distance between them, other velocities and their mass.

Acknowledgment

The author would like to express his sincere appreciation and deepest gratitude to all the staff of the Open Access Journal of Astronomy (OAJA) whose contribution and support have greatly enhanced the quality, accuracy and publication of this research.