Indian Study Explains Dark Matter Deficit Mystery

Why in the News ?

Astronomers at the Indian Institute of Astrophysics have proposed a model to explain the unusual lack of dark matter in galaxy NGC 1052-DF2, challenging existing galaxy formation theories and offering new insights into the structure of the universe.

Galaxy Defies Standard Dark Matter Models:

  • NGC 1052-DF2, an ultra-diffuse galaxy, shows a striking deficiency in dark matter.
  • Earlier estimates found its total mass to be about 340 million solar masses, closely matching its stellar mass of 200 million, leaving little room for dark matter.
  • This contradicts the accepted model where galaxies are believed to require dark matter for structure and stability.

Indian Research Offers Fresh Perspective

  • Aditya of the Indian Institute of Astrophysics used stellar density-based models to analyze the galaxy’s mass.
  • His findings, published in Astronomy & Astrophysics, suggest that mass models with a “cuspy” dark matter halo (denser at the center) produce similar results as models with no dark matter.
  • This questions existing understanding of galaxy formation and dark matter distribution.

Implications for Astrophysics and Cosmology

  • The research raises critical questions about how galaxies with minimal dark matter form and evolve.
  • It also urges a re-evaluation of dark matter’s role in cosmic structure formation.
  • The findings may guide future studies on the nature and behavior of dark matter, a still mysterious component of the universe.

Dark Matter & Dark Energy :

Dark Matter

●Hypothetical non-baryonic matter that doesn’t interact with light or EM radiation.
● First inferred in 1933 by Zwicky via galaxy cluster dynamics.
●Galactic rotation curves in 1970s indicated its presence in invisible halos.
●Not made of baryons, antimatter, MACHOs, or black holes.
● Likely candidates include WIMPs like axions, neutrinos, and neutralinos.
●Comprises ~27% of the universe; detected through gravitational effects.

Dark Energy:

●Hypothetical energy responsible for the accelerated expansion of the universe.
● Makes up ~68% of the universe’s total energy.
●Possible explanations:
○Cosmological constant (Einstein)
○Quantum vacuum energy
○ Quintessence (dynamic energy field)
○ Modified gravity theories
●Observed via supernovae, CMB, and large-scale structure studies.

Key Differences:

Property Dark Matter Dark Energy
Effect Attractive gravity Repulsive expansion
Role Structure formation Cosmic acceleration
Spread Clumped around galaxies Uniform across space