Assessing the Universe’s Components: A Comprehensive Quantification of Matter, Dark Matter, and Dark Energy

Researchers have ascertained that the universe comprises 31% matter, employing groundbreaking methods to corroborate this figure, thereby laying the groundwork for subsequent cosmic investigations.

To quantify the mass of galaxy clusters, a team of scientists employs the tactic of counting the number of constituent galaxies.

One of the paramount inquiries in the field of cosmology revolves around the total amount of matter present in the universe. An international consortium of researchers has successfully gauged this quantity for a second instance. Published in The Astrophysical Journal, their findings indicate that matter constitutes 31% of the overall sum of matter and energy in the universe, with the remaining portion being dark energy.

The primary researcher, Dr. Mohamed Abdullah, affiliated with the National Research Institute of Astronomy and Geophysics-Egypt and Chiba University, Japan, clarifies, “Cosmologists assert that merely about 20% of the total matter is what we know as ‘baryonic’ matter, including entities like stars, galaxies, atoms, and even life. Roughly 80% is composed of dark matter, an entity whose enigmatic characteristics are yet to be deciphered and could potentially involve undiscovered subatomic particles.” (Refer to Figure 1.)

Methods Employed for Quantification

Gillian Wilson, Abdullah’s erstwhile academic advisor and currently a Professor of Physics and Vice Chancellor for Research, Innovation, and Economic Development at UC Merced, elaborates, “The team utilized an established method for calculating the universe’s total matter. This involved contrasting the empirically observed number and mass of galaxy clusters per unit volume with anticipations stemming from computational simulations. The prevalence of such clusters in the current cosmological state is highly sensitive to a number of factors, most notably, the overall sum of matter.”

Figure 1 presents a comparison between the empirical number of galaxy clusters and computational predictions to discern the most accurate assessment. Credit goes to Mohamed Abdullah (The National Research Institute of Astronomy and Geophysics, Egypt/Chiba University, Japan).

Anatoly Klypin of the University of Virginia notes, “A greater concentration of matter in the universe would naturally lead to the formation of more clusters. However, ascertaining the mass of a galaxy cluster is fraught with complexities mainly because a majority of the matter is dark, rendering it imperceptible to telescopic observation.”

To circumvent this challenge, the team resorted to an indirect metric for cluster mass. They leveraged the principle that larger clusters harbor a greater number of galaxies (Mass Richness Relation: MRR). Utilizing data from the Sloan Digital Sky Survey, they measured the number of galaxies in each cluster, enabling them to approximate the total mass for each cluster. These empirical figures were then juxtaposed against computational simulations.

The most compatible match between observational data and simulations was a universe comprising 31% matter, a value that is in remarkable concurrence with observations made through cosmic microwave background (CMB) techniques, a completely independent methodology.

Verification Mechanisms and Techniques Employed

Tomoaki Ishiyama of Chiba University states, “Our measurements of matter density via the MRR technique align exceptionally well with those acquired by the Planck team through the CMB methodology. This underscores that the abundance of clusters serves as a formidable tool for constraining cosmological parameters and offers a complement to non-cluster methodologies like CMB anisotropies, baryon acoustic oscillations, Type Ia supernovae, or gravitational lensing.”

The team attributes their success to being pioneers in applying spectroscopy, a method of dispersing radiation into a spectrum of individual frequencies, to accurately determine the distances to each cluster and the genuine galaxies that are gravitationally bound to them.

Conclusion and Prospective Utilizations

Published on September 13 in The Astrophysical Journal, the research substantiates the efficacy of the MRR technique as a robust instrument for constraining cosmological variables. It also outlines its potential applicability to emerging datasets from expansive and deep-field imaging and spectroscopic cosmic surveys like those conducted with the Subaru Telescope, Dark Energy Survey, Dark Energy Spectroscopic Instrument, Euclid Telescope, eROSITA Telescope, and the James Webb Space Telescope.

Reference Citations

The research has received backing from multiple institutions including the IAAR Research Support Program at Chiba University, Japan, as well as various grants and programs from MEXT/JSPS KAKENHI, National Science Foundation, and NASA.

Frequently Asked Questions (FAQs) about universe’s composition

More about universe’s composition

• The Astrophysical Journal
• National Research Institute of Astronomy and Geophysics-Egypt
• Chiba University, Japan
• UC Merced – Department of Physics
• University of Virginia
• Sloan Digital Sky Survey
• Planck Satellite
• Subaru Telescope
• Dark Energy Survey
• Dark Energy Spectroscopic Instrument
• Euclid Telescope
• eROSITA Telescope
• James Webb Space Telescope