Revised Minimum Mass of Dark Matter Particles

Sub :Sci

Sec: Space sector

Why in News

The minimum possible mass of dark matter particles has been revised by theoretical physicists. This update reshapes our understanding of dark matter’s role and distribution in the universe.

About Dark Matter:

Dark matter is an elusive, invisible substance that constitutes approximately 85% of the universe’s matter. It doesn’t emit, absorb, or reflect light, making it undetectable by conventional sensors.
Its presence is inferred from gravitational effects on visible matter and the large-scale structure of the universe.
In 1922, Dutch astronomer Jacobus Kapteyn estimated the density of dark matter by studying stellar motions near the Sun, concluding a density of 0.0003 solar masses per cubic light-year. This estimate has remained remarkably accurate over the past century.
Revised Mass Estimates: Traditionally, scientists believed the minimum mass of dark matter particles was about 10^-31 times that of a proton.
However, recent theoretical work has increased this estimate to approximately 2.3 × 10^-30 proton masses, marking a significant shift in our understanding.
Researchers analysed stellar motion data from dwarf galaxies like Leo II, inferring dark matter density profiles. By solving modified Schrödinger equations that account for gravity, they matched empirical data with theoretical models, leading to the updated mass constraints.
Distribution and Detection: The mass of dark matter particles influences their distribution and the likelihood of detection. Heavier particles suggest a different spatial distribution, affecting experimental search strategies.

Weakly Interacting Massive Particles (WIMPs):

Hypothetical particles proposed as a candidate for dark matter.
Weakly interact with normal matter via gravitational and weak nuclear forces.
Expected mass range: 10 to 1,000 times the mass of a proton.
Offer an explanation for the observed gravitational effects of dark matter. Explored through direct detection experiments like LUX-ZEPLIN.
Many experiments have constrained the parameter space for WIMPs, with no definitive detection yet.

Proton:

Subatomic particle with a positive charge, found in the nucleus of an atom.
Used as a reference for estimating the mass of dark matter particles.
Applications: Fundamental in understanding atomic structures, nuclear reactions, and particle physics.

Leo II Galaxy:

Dwarf spheroidal galaxy orbiting the Milky Way.
Distance from Earth: Approximately 690,000 light-years.
Stellar motion data from Leo II is used to study dark matter density profiles. Provides insights into the mass and distribution of dark matter particles.
Inner regions contain high densities of invisible mass, driving the revision of dark matter mass limits.