61841
Such a detector would observe signals from binary stars within our galaxy ( the Milky Way ) ; signals from binary supermassive black holes in other galaxies ; and extreme-mass-ratio inspirals and bursts produced by a stellar-mass compact object orbiting a supermassive black hole .
 Milky Way, galaxies
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Milky Way, galaxies