Lesson Worksheet: Active Galactic Nuclei Physics
In this worksheet, we will practice describing and determining the properties of active galactic nuclei.
Q1:
Which of the following is the most correct definition of the term accretion disk?
- AAn accretion disk is a thin disk of hot matter that surrounds a black hole. The matter in the disk stays in orbit of the black hole forever.
- BAn accretion disk is a thin disk of hot matter that surrounds a black hole. The matter in the disk gradually loses angular momentum and falls into the black hole.
- CAn accretion disk is a thin disk of matter that has been expelled from the black hole. The matter in the disk gradually gains angular momentum and moves away from the black hole.
- DAn accretion disk is a thin disk of cool matter that surrounds a black hole. The matter in the disk gradually loses angular momentum and falls into the black hole.
- EAn accretion disk is a large region of cool interstellar gas that is within the gravitational influence of a black hole.
Q2:
Which of the following is the most correct definition of the term relativistic jet?
- AA relativistic jet is an outflow of ionized matter perpendicular to the axis of rotation of a black hole. The matter is accelerated to speeds close to the speed of light.
- BA relativistic jet is a stream of matter falling into a black hole perpendicular to its axis of rotation. As the matter gets closer to the black hole, the gravitational pull of the black hole accelerates it close to the speed of light.
- CA relativistic jet is a beam of photons directed along the axis of rotation of the black hole, generated by the magnetic field of the black hole.
- DA relativistic jet is a stream of matter falling into a black hole along its axis of rotation. As the matter gets closer to the black hole, the gravitational pull of the black hole accelerates it close to the speed of light.
- EA relativistic jet is an outflow of ionized matter along the axis of rotation of a black hole. The matter is accelerated to speeds close to the speed of light.
Q3:
The light from a distant quasar has the same intensity as the light from a star 15,000 light-years away. If the star has a luminosity of W and the quasar is a distance of light-years away, what is the luminosity of the quasar? Give your answer in scientific notation to 1 decimal place.
- A W
- B W
- C W
- D W
- E W
Q4:
Which of the following is the most correct definition of the term active galactic nucleus?
- AAn active galactic nucleus is a very dense region at the center of a galaxy that has a much higher than normal luminosity, and which has an electromagnetic spectrum that only contains spectral lines of high-atomic-number elements.
- BAn active galactic nucleus is a very dense region at the center of a galaxy that produces dark matter.
- CAn active galactic nucleus is a very dense region at the center of a galaxy that has a very strong magnetic field, which leads to the production of axion beams.
- DAn active galactic nucleus is a very dense region at the center of a galaxy that has a much higher than normal luminosity, and which has an electromagnetic spectrum that is not characteristic of stars.
- EAn active galactic nucleus is a very dense region at the center of a galaxy that produces antimatter.
Q5:
What type of stellar object is thought to exist at the center of most galaxies?
- AAn Earth-like planet
- BA void
- CA neutron star
- DA supermassive white hole
- EA supermassive black hole
Q6:
Which of the following is the most correct definition of the term quasar?
- AA quasar is an extremely luminous active galactic nucleus.
- BA quasar is an electrically charged neutron star.
- CA quasar is an O-type star with a highly variable luminosity.
- DA quasar is a star that is mostly made of dark matter.
- EA quasar is a star that mostly emits high-energy gamma rays.
Q7:
Which of the following is the most correct definition of the term galactic nucleus?
- AA galactic nucleus is the gravitational center of a galaxy. Each galactic nucleus is thought to contain a supermassive black hole.
- BA galactic nucleus is a dense region of dark matter found at the center of a galaxy.
- CA galactic nucleus is an exotic atomic nucleus thought to have originated from the center of a galaxy.
- DA galactic nucleus is the geometric center of a galaxy.
- EA galactic nucleus is a dense region of interstellar dust and gas found at the center of a galaxy.
Q8:
List the following in order of luminosity from least to greatest.
- The Sun
- A type Ia supernova at peak luminosity
- An O-type main sequence star
- A brown dwarf star
- A quasar
- Aiv, iii, v, i, ii
- Bv, iv, ii, iii, i
- Cii, iii, i, iv, v
- Div, i, iii, ii, v
- Ei, iii, iv, v, ii
Q9:
The light from a distant quasar has the same intensity as the light from a star 23,000 light-years away. If the star has a luminosity of and the quasar is a distance of light-years away, what is the luminosity of the quasar? Give your answer in units of in scientific notation to 1 decimal place.
- A
- B
- C
- D
- E
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