Aug. 18, 2014, 11 a.m.
Watch this video on the NASA Goddard YouTube channel.For complete transcript, click here.Explore M82 X-1 and learn more about how astronomers used X-ray fluctuations to determine its status as an intermediate-mass black hole.Credit: NASA s general relativity come into play, resulting in X-ray variations that repeat at nearly regular intervals.Astronomers call these signals quasi-periodic oscillations, or QPOs, and have shown that for black holes produced by stars, their frequencies scale up or down depending on the size of the black hole.When astronomers study X-ray fluctuations from many stellar-mass black holes, they see both slow and fast QPOs, but the fast ones often come in pairs with a specific 3:2 rhythmic relationship. For every three flashes from one member of the QPO pair, its partner flashes twice.The combined presence of slow QPOs and a faster pair in a 3:2 rhythm effectively sets a standard scale that gives scientists a powerful tool for establishing the masses of stellar black holes.A decade ago, Strohmayer and Mushotzky showed the presence of slow QPO signals from M82 X-1. In order to apply the tried-and-true relationship used for stellar-mass black holes, the researchers needed to identify a pair of steady fluctuations exhibiting the same 3:2 beat in RXTE observations. By analyzing six years of data, they located X-ray variations that reliably repeated about 3.3 and 5.1 times each second, just the 3:2 relationship they needed.This allowed them to calculate that M82 X-1 weighs about 400 solar masses — the most accurate determination to date for this object and one that clearly places it in the category of intermediate-mass black holes.Read the paper at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13710.html.Read the press release at http://www.nasa.gov/topics/universe/index.html. || This movie shows how X-ray signals from M82 X-1 become clearer as additional RXTE observations are included in the analysis. Strong signals repeating at 5.1 and 3.3 times each second — a 3:2 relationship — gradually emerge. Detecting this pattern helps determine a black hole’s mass.Credit: Dheeraj Pasham