Eye of Sauron - the ring to "rule" them all ... distance 19 megaparsecs

Eye of Sauron provides new way of measuring distances to galaxies

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The new technique is similar to that used by land surveyors on Earth, who measure both the physical and angular or apparent size of a distant object to calculate its distance from Earth.

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A team of scientists led by Sebastian Hoenig from the University of Southampton in England has accurately measured the distance to the nearby NGC 4151 galaxy, using the W. M. Keck Observatory Interferometer. The team employed a new technique they developed that allows them to measure precise distances to galaxies tens of millions of light-years away.

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Previous reported distances to NGC 4151, which contains a supermassive black hole, ranged from 4 to 29 megaparsecs (13 to 94.5 million light-years), but using this new, more accurate method, the researchers calculated the distance to the supermassive black hole as 19 megaparsecs (62 million light-years).

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To measure the physical size of the dusty ring, the researchers measured the time delay between the emission of light from close to the black hole and the more distant infrared emission. The distance from the center to the hot dust is simply this delay divided by the speed of light.

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By combining the physical size of the dust ring with the apparent size measured with the Keck Interferometer, the researchers were able to determine a distance to NGC 4151.

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One of the key findings is that the distance determined in this new fashion is quite precise with 90 percent accuracy, Hoenig said. In fact, this method, based on simple geometrical principles, gives the most precise distances for remote galaxies. Moreover, it can be readily used on many more sources than current methods. Such distances are key in pinning down the cosmological parameters that characterize our universe or in accurately measuring black hole masses. Indeed, NGC 4151 is a key to calibrating various techniques of estimating black hole masses. Our new distance implies that these masses may have been systematically underestimated by 40 percent.

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So this is basically the same way we determined the distance to SN1987A by knowing the base and the subtended angle of a triangle.EnjoyEdited by RAZD, : ...

Thread moved here from the Proposed New Topics forum.

I found the measurement error from previous methods, which I presume are based on red shift, to be the most interesting part of the article.

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Previous reported distances to NGC 4151, which contains a supermassive black hole, ranged from 4 to 29 megaparsecs (13 to 94.5 million light-years), but using this new, more accurate method, the researchers calculated the distance to the supermassive black hole as 19 megaparsecs (62 million light-years).

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Why were previous measurement attempts so disparate? Any ideas?