Stellar mass black holes are black holes formed by the gravitational collapse of massive stars. Astronomers at the University of Waterloo have developed a new method for identifying them.
The improved black hole search method will bring the number of new stellar mass black holes discovered each year to 10, enough to double the number of known black holes in just two years. Researchers detailed their new method in the Astrophysical Journal.
“Within the next 10 years, there will be sufficient accumulated data on enough black holes that researchers can statistically analyze their properties as a population,” Avery Broderick, an associate faculty member at Waterloo’s Perimeter Institute for Theoretical Physics, said in a news release. “This information will allow us to study stellar mass black holes at various stages that often extend billions of years.”
Detecting black holes is extremely difficult. They swallow light and don’t emit visible radiation themselves. Their presence is indirectly inferred by their gravitational effects on surrounding radiation.
Scientists confirmed the first direct evidence of black holes in early 2016 when the Interferometer Gravitational-Wave Observatory detected ripples in space-time caused by the merger of two black holes.
The discovery method proposed by Waterloo researchers forgoes the search for individual black holes in favor of systematic analysis, combining microlensing and radio wave interferometry.
Microlensing is the magnification of light from a distant star or galaxy as the radiation passes around a dark object on its way toward Earth. Current observatories tracking microlensing events can glean very little information about what kind of object caused the magnification. Observatories outfitted with radio wave interferometry instruments can improve microlensing observations.
“When you look at the same event using a radio telescope — interferometry — you can actually resolve more than one image,” said Mansour Karami, a doctoral student in astrophysics at Waterloo. “That’s what gives us the power to extract all kinds of parameters, like the object’s mass, distance and velocity.”
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