Astronomical Signatures of Dark Matter

Paul Gorenstein,Wallace Tucker

doi:10.1155/2014/878203

Paul Gorenstein, Wallace Tucker

Open Access

https://doi.org/10.1155/2014/878203

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Abstract

Several independent astronomical observations in different wavelength bands reveal the existence of much larger quantities of matter than what we would deduce from assuming a solar mass to light ratio. They are very high velocities of individual galaxies within clusters of galaxies, higher than expected rotation rates of stars in the outer regions of galaxies, 21 cm line studies indicative of increasing mass to light ratios with radius in the halos of spiral galaxies, hot gaseous X-ray emitting halos around many elliptical galaxies, and clusters of galaxies requiring a much larger component of unseen mass for the hot gas to be bound. The level of gravitational attraction needed for the spatial distribution of galaxies to evolve from the small perturbations implied by the very slightly anisotropic cosmic microwave background radiation to its current web-like configuration requires much more mass than is observed across the entire electromagnetic spectrum. Distorted shapes of galaxies and other features created by gravitational lensing in the images of many astronomical objects require an amount of dark matter consistent with other estimates. The unambiguous detection of dark matter and more recently evidence for dark energy has positioned astronomy at the frontier of fundamental physics as it was in the 17th century.

Highlights

Astronomy and physics have had a mutually beneficial partnership
That excludes as candidates such very low luminosity stars whose emission is below the detection threshold and isolated planetary objects, known as “Massive Compact Halo Objects” or MACHOs, they could account for a small fraction of dark matter (DM)
As in the 16th and 17th centuries, the interests of astronomers, more appropriately called astrophysicists, and laboratory physicists are converging upon the same issue at the frontier of fundamental physics, identifying the source and nature of the elusive dark matter

Summary

Introduction

Astronomy and physics have had a mutually beneficial partnership. The late 16th century astronomical observations of planetary positions as a function of time by the Danish astronomer Tycho Brahe were analyzed and interpreted by Johannes Kepler. Simon Newcomb the most distinguished American astronomer of his era, founding member and first president of the American Astronomical Society said in 1888, “We are probably nearing the limit of all we can know about astronomy.” This proved to be as accurate as the belief of many physicists— buoyed by the great success of Maxwell’s equations at the turn of the 20th century, prior to the discovery of X-rays and radioactivity, that the only things left to do in fundamental physics was design better measuring devices and build faster computational aids to facilitate applications of Newton’s laws and Maxwell’s equations [1, 2]. The cosmological connection is described by, for example, Bergstrom [4]

Evidence for the Existence of Dark Matter

Identity of Dark Matter

Findings

Conclusions