Alaknanda Galaxy Discovery: Rewriting Early Universe Galaxy Formation
Astronomers recently identified a Milky Way-like spiral galaxy nicknamed "Alaknanda," existing in the universe's infancy, challenging standard models of galaxy evolution. This well-ordered structure formed far earlier than predicted, prompting revisions to theories on cosmic structure development.
Key Scientific Details
The Alaknanda galaxy mirrors the Milky Way's spiral arms and disk morphology but appeared during the universe's "Cosmic Dawn" era, roughly 1-2 billion years post-Big Bang. Observations likely came from advanced telescopes like JWST, detecting its redshift indicating extreme distance. This rapid formation defies hierarchical merger models, where galaxies grow slowly via smaller clump mergers, suggesting accelerated processes like efficient gas cooling or dark matter dynamics.
UPSC Static Linkages
GS Paper 1 (Geography & Astronomy): Galaxy formation ties to Big Bang cosmology, cosmic microwave background (CMB), and Hubble's law ($$ v = H_0 d $$), where redshift $$ z $$ measures expansion. Static concepts include stellar populations (Type I/II), Hertzsprung-Russell diagram, and interstellar medium roles in star formation.
GS Paper 3 (Science & Tech): Aligns with India's space program—ISRO's AstroSat observed Milky Way structures; upcoming Aditya-L1 studies solar influences on cosmic evolution. Links to dark energy (68% universe composition) and JWST-like missions under NISAR collaboration.
Exam Relevance: Questions often test early universe timelines (Reionization epoch ~400 million years post-BB) and India's contributions via PRL Ahmedabad's cosmology research.
Prelims MCQs
1. The 'Alaknanda' galaxy discovery primarily challenges which model of galaxy formation?
(a) Monolithic collapse
(b) Hierarchical merging
(c) Secular evolution
(d) Tidal torque theory
Answer: (b)
2. Which era of the universe is associated with the formation of the Alaknanda galaxy?
(a) Inflationary epoch
(b) Cosmic Dawn/Reionization
(c) Stelliferous era
(d) Degenerate era
Answer: (b)
Mains Question
GS Paper 1: "The discovery of early spiral galaxies like Alaknanda underscores gaps in our Big Bang model. Discuss its implications for understanding cosmic evolution and India's role in observational astronomy." (15 marks)