QUIZ - 5.9.13

1. What do we mean by dark matter and dark energy?

• Dark matter is the name given to the unseen mass whose gravity governs that observed motions of stars and gas clouds. Dark energy is the name given to whatever might be causing the expansion of the universe to accelerate.

2. What is the evidence for dark matter in galaxies?

• Orbital velocities within galaxies remain nearly constant at large radii, indicating that most of the matter lies outside the visible regions.

3. What is the evidence for dark matter in clusters of galaxies?

• Masses measured from galaxy motions, temperature of hot gas, and gravitational lensing all indicate that the vast majority of matter in clusters is dark.

4. Does dark matter really exist?

• Either dark matter exists or our understanding of our gravity must be revised.

5. What might dark matter be made of?

• There does not seem to be enough normal (baryonic) matter to account for all the dark matter, so most astronomers suspect that dark matter is made of (nonbaryonic) particles that have not yet been discovered.

6. What is the role of dark matter in galaxy formation?

• The gravity of dark matter seems to be what draws gas together into protogalactic clouds, initiating the process of galaxy formation.

7. What are the largest structures in the universe?

• Galaxies appear to be distributed in gigantic chains and sheets that surround great voids.

8. Who was Fritz Zwicky?

• Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology. He made many important contributions in theoretical and observational astronomy. His scientific work included ionic crystals / electrolytes, supernovae / neutron stars, standard candles, gravitational lenses, dark matter, tired light, morphological analysis, Catalog of Galaxies and Clusters, and finally guns / goblins.

9. Who is Vera Rubin?

• Vera Cooper Rubin is an American astronomer. In 1951, she completed her education and she made one of the first observations and deviations from the Hubble flow in the motions of galaxies. She argued that galaxies might be rotating around unknown centres, rather than simply moving outwards, as suggested by the Big Bang theory at that time. In 1954, her PhD these for graduation concluded that that galaxies clumped together, rather than being randomly distributed through the universe. The idea that clusters of galaxies existed was not pursued seriously by others until two decades later. In 1965, she became the first woman "allowed" to use the instruments at the Palomar Observatory. In 1965, she landed a job at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington and has worked there as an astronomer since that time. Her work is best described as "Galactic and extragalactic dynamics; large-scale structure and dynamics of the universe." In the 1970's, Ms. Rubin produced clear observational evidence that finally convinced astronomers worldwide that the vast bulk of the mass in the universe is invisible and unknown in origin and character. (Dark Matter)

10. Who is Alex Filippenko?

• Alex Filippenko is an American astrophysicist and professor of astronomy at the University of California, Berkeley. His research focuses on supernovae and active galaxies at optical, ultraviolet, and near-infrared wavelengths. Mr. Filippenko was a member of the Supernova Cosmology Project and the High-z Supernova Search Team that used observations of extragalactic supernovae to discover the accelerating universe. The universal acceleration implies the existence of dark energy and was voted the top science breakthrough of 1998 by Science magazine. Mr. Filippenko developed and runs the Katzman Automatic Imaging Telescope. KAIT is a fully robotic telescope which conducts the Lick Observatory Supernova Search, the most successful nearby supernova search. He is also a member of the Nuker Team which uses the Hubble space telescope to examine supermassive black holes and determined the relationship between a galaxy's central black hole's mass and velocity dispersion. The Thompson-Reuters "incites" index ranked Filippenko as the most cited researcher in space science for the ten-year period between 1996 and 2006. Alex Filippenko is frequently featured in the History Channel series, The Universe.