Measuring Black Holes
QPOs can be used to determine the mass of black holes. The technique uses a relationship between black holes and the inner part of their surrounding disks, where gas spirals inward before reaching the event horizon. The hot gas piles up near the black hole and radiates a torrent of X-rays, with an intensity that varies in a pattern that repeats itself over a nearly regular interval. This signal is the QPO. Astronomers have long suspected that a QPO’s frequency depends on the black hole’s mass. The congestion zone lies close in for small black holes, so the QPO clock ticks quickly. As black holes increase in mass, the congestion zone is pushed farther out, so the QPO clock ticks slower and slower.
Read more about this topic: Quasi-periodic Oscillation
Famous quotes containing the words black holes, measuring, black and/or holes:
“The shadow of the Venetian blind on the painted wall,
Shadows of the snake-plant and cacti, the plaster animals,
Focus the tragic melancholy of the bright stare
Into nowhere, a hole like the black holes in space.”
—John Ashbery (b. 1927)
“By measuring individual human worth, the novelist reveals the full enormity of the State’s crime when it sets out to crush that individuality.”
—Ian McEwan (b. 1938)
“There with vast wings across the canceled skies,
There in the sudden blackness the black pall
Of nothing, nothing, nothing—nothing at all.”
—Archibald MacLeish (1892–1982)
“A person taking stock in middle age is like an artist or composer looking at an unfinished work; but whereas the composer and the painter can erase some of their past efforts, we cannot. We are stuck with what we have lived through. The trick is to finish it with a sense of design and a flourish rather than to patch up the holes or merely to add new patches to it.”
—Harry S. Broudy (b. 1905)