space hard MCQ

Galaxy rotation curves remain flat at large radii instead of declining Keplerian, providing evidence for _______.

  1. Modified gravity
  2. Dark matter halos
  3. Stellar population gradients
  4. Gas pressure support

Answer: Dark matter halos

Flat rotation curves imply enclosed mass increases linearly with radius beyond visible disk, requiring extended dark matter halo dominating gravitational potential.

Topic Astronomy - Dark Matter
Exam Relevance UPSC Prelims, SSC CGL