Extragalactic Astrophysics — MCQs

1. Who first discovered that galaxies are moving away from us, leading to the concept of an expanding universe?
(A) Edwin Hubble
(B) Albert Einstein
(C) Vesto Slipher
(D) Georges Lemaître

2. What is the primary evidence for the expansion of the universe?
(A) Cosmic microwave background
(B) Galaxy collisions
(C) Redshift of galaxies
(D) Star formation rates

3. The Hubble Law relates galaxy redshift with:
(A) Luminosity
(B) Age
(C) Distance
(D) Mass

4. What is the value of the Hubble constant approximately?
(A) 7 km/s/Mpc
(B) 70 km/s/Mpc
(C) 700 km/s/Mpc
(D) 7000 km/s/Mpc

5. Which type of galaxies dominate galaxy clusters?
(A) Spiral
(B) Elliptical
(C) Irregular
(D) Dwarf spheroidal

6. What is a supercluster?
(A) A giant elliptical galaxy
(B) A group of star clusters
(C) A collection of galaxy clusters
(D) A large spiral galaxy

7. The Virgo Cluster is part of which supercluster?
(A) Hercules
(B) Local Supercluster
(C) Coma
(D) Shapley

8. The Sloan Digital Sky Survey (SDSS) primarily maps:
(A) Star clusters
(B) Galaxies and large-scale structure
(C) Nebulae
(D) Supernova remnants

9. What is the “cosmic web”?
(A) Network of cosmic rays
(B) Large-scale structure of galaxies and dark matter
(C) Interstellar dust filaments
(D) Network of quasars

10. Which galaxy cluster is one of the richest and most studied?
(A) Virgo Cluster
(B) Coma Cluster
(C) Fornax Cluster
(D) Hercules Cluster

11. Which type of galaxies often host quasars?
(A) Dwarf irregulars
(B) Giant ellipticals
(C) Lenticulars
(D) Globular clusters

12. What is a quasar?
(A) A faint irregular galaxy
(B) A highly luminous active galactic nucleus
(C) A young spiral galaxy
(D) A globular cluster

13. What is the main power source of quasars?
(A) Nuclear fusion in stars
(B) Supernovae explosions
(C) Accretion onto supermassive black holes
(D) Dark matter annihilation

14. Which telescope discovered the first quasars?
(A) Hubble Space Telescope
(B) Palomar Observatory
(C) Keck Observatory
(D) Arecibo Telescope

15. What is a radio galaxy?
(A) Galaxy that emits strong radio waves
(B) Galaxy made of neutron stars
(C) Galaxy discovered with radar
(D) Galaxy that hosts pulsars

16. Seyfert galaxies are a class of:
(A) Dwarf galaxies
(B) Active galaxies
(C) Globular clusters
(D) Irregular galaxies

17. What is a BL Lac object?
(A) A type of star
(B) A type of irregular galaxy
(C) A type of active galaxy with variable brightness
(D) A type of dark matter halo

18. Which feature distinguishes Type I and Type II Seyfert galaxies?
(A) Size of galaxy
(B) Orientation of dusty torus
(C) Presence of dark matter
(D) Redshift

19. What is the approximate age of the universe from extragalactic observations?
(A) 4.5 billion years
(B) 7 billion years
(C) 13.8 billion years
(D) 20 billion years

20. What is gravitational lensing?
(A) Bending of light by interstellar dust
(B) Bending of light by massive objects
(C) Reflection of light by nebulae
(D) Scattering of cosmic rays

21. What does strong lensing often produce?
(A) Supernovae
(B) Multiple images of background galaxies
(C) Higher star formation
(D) Dark matter collapse

22. What does weak lensing help measure?
(A) Stellar populations
(B) Magnetic fields
(C) Dark matter distribution
(D) Galaxy ages

23. Which survey mapped cosmic microwave background with high precision?
(A) SDSS
(B) Planck satellite
(C) Hubble telescope
(D) Chandra X-ray Observatory

24. What is the Great Attractor?
(A) A quasar
(B) A massive region influencing galaxy motions
(C) A black hole in Virgo cluster
(D) A dark matter halo in Andromeda

25. Which is the largest known structure in the universe?
(A) Local Group
(B) Virgo Cluster
(C) Sloan Great Wall
(D) Coma Cluster

26. Which galaxies are the most numerous in the universe?
(A) Giant ellipticals
(B) Spirals
(C) Dwarf galaxies
(D) Starburst galaxies

27. The intracluster medium primarily emits in:
(A) Radio waves
(B) Infrared
(C) X-rays
(D) Gamma rays

28. What is the Sunyaev–Zel’dovich effect related to?
(A) Absorption of starlight by dust
(B) Distortion of CMB by hot intracluster gas
(C) Absorption of gamma rays by dark matter
(D) Interaction of cosmic rays with stars

29. Which method is used to determine extragalactic distances?
(A) Cepheid variables
(B) Type Ia supernovae
(C) Tully–Fisher relation
(D) All of the above

30. Standard candles are astronomical objects of:
(A) Known mass
(B) Known luminosity
(C) Known temperature
(D) Known radius

31. Type Ia supernovae are useful for measuring:
(A) Local star ages
(B) Galactic metallicity
(C) Extragalactic distances
(D) Planetary orbits

32. What discovery was made using distant Type Ia supernovae?
(A) Expansion is slowing down
(B) Universe is static
(C) Expansion is accelerating
(D) No expansion

33. The acceleration of the universe is attributed to:
(A) Dark matter
(B) Dark energy
(C) Cosmic rays
(D) Supernova remnants

34. What fraction of the universe is dark energy approximately?
(A) 5%
(B) 27%
(C) 68%
(D) 95%

35. The Large-Scale Structure of the universe shows:
(A) Random galaxy distribution
(B) Galaxy filaments and voids
(C) Only galaxy clusters
(D) Uniform gas distribution

36. What is a cosmic void?
(A) A black hole
(B) A region with very few galaxies
(C) A dead galaxy
(D) A supernova remnant

37. The Lyman-alpha forest is observed in:
(A) Quasar spectra
(B) Stellar spectra
(C) Galaxy images
(D) X-ray observations

38. Which phenomenon explains the brightness variations in quasars?
(A) Stellar explosions
(B) Accretion disk instabilities
(C) Supernova shocks
(D) Galaxy mergers

39. The cosmic distance ladder refers to:
(A) Steps in galaxy mergers
(B) Techniques to measure distances across the universe
(C) Stellar fusion stages
(D) Layers of the cosmic microwave background

40. What is the approximate distance to the Andromeda Galaxy?
(A) 200,000 light years
(B) 500,000 light years
(C) 2.5 million light years
(D) 10 million light years

41. Galaxy mergers are important because they:
(A) Trigger starbursts
(B) Grow supermassive black holes
(C) Form elliptical galaxies
(D) All of the above

42. Which is the most luminous persistent objects in the universe?
(A) Pulsars
(B) Quasars
(C) Type II supernovae
(D) Gamma-ray bursts

43. Which type of galaxies are often found in rich clusters?
(A) Ellipticals and lenticulars
(B) Spirals
(C) Irregulars
(D) Dwarfs only

44. The hot gas in clusters indicates:
(A) Presence of young stars
(B) Deep gravitational potential wells
(C) No dark matter
(D) Lack of galaxy interactions

45. Which observation provides strong evidence for dark matter in clusters?
(A) Galaxy colors
(B) X-ray emission of hot gas
(C) Gravitational lensing
(D) Supernova remnants

46. What is the Bullet Cluster famous for?
(A) First galaxy discovered
(B) Strongest evidence for dark matter separation from baryonic matter
(C) First quasar host galaxy
(D) Oldest galaxy found

47. What is the observable universe radius approximately?
(A) 1 billion light years
(B) 10 billion light years
(C) 46 billion light years
(D) Infinite

48. What is cosmic homogeneity?
(A) Matter evenly distributed on large scales
(B) Matter clustered only in voids
(C) Galaxies randomly distributed
(D) Universe with no dark matter

49. What is isotropy in cosmology?
(A) Universe looks same in all directions
(B) Universe rotates around center
(C) Galaxies are evenly sized
(D) Universe is flat

50. The Lambda-CDM model is the:
(A) Static model of the universe
(B) Standard cosmological model with dark energy and dark matter
(C) Model without expansion
(D) Purely baryonic matter model