Astronomy current events question: black hole mapped with x-ray echoes

Astronomy 210L, spring semester 2020
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

News release, "XMM-Newton Uses Light Echoes to Map Dynamic Black Hole" (January 20, 2020)
bristol.ac.uk/news/2020/january/light-echoes-black-hole.html

The central area of galaxy IRAS 13224–3809 was mapped using __________ generated by gases falling into its supermassive black hole.
(A) x-ray echoes.
(B) sound waves.
(C) gravitational waves.
(D) strong magnetic fields.
(E) matter and antimatter pockets.

Correct answer: (A)

Student responses
Sections 30679, 30680
(A) : 28 students
(B) : 2 students
(C) : 5 students
(D) : 2 students
(E) : 2 students