Earthsky Interviews
Marc Seigar says galaxy’s spiral arms may reveal black hole mass
02-27-2009 - Space
That’s astronomer Marc Seigar. He’s talking about using the shape of a galaxy’s spiral arms to measure the possible gargantuan black hole at the galaxy’s core.
Marc Seigar: As the material moving around the center of the black hole moves faster and faster, that would also indicate a more massive black hole.
Seigar’s 2008 study involved 27 galaxies – including the galaxy we live in, the Milky Way.
Marc Seigar: The mass of the black hole in the Milky Way is about three million times the mass of the sun. And the spiral arm of the Milky Way, there’s a pitch angle that’s been measured, so the Milky Way falls very nicely on the relationship that we see.
He said invisible dark matter might be driving the spiral arm/black hole relationship.
Marc Seigar: So the visible galaxy that we see is sitting at the center of a huge dark matter halo. And the distribution of mass in that halo, or even the total mass of the halo itself, might be affecting how big the central super massive black hole is, and how tightly wound the spiral structure is.
Our thanks to:
Marc S. Seigar
Department of Physics & Astronomy
University of Arkansas at Little Rock
Little Rock, AR
Photo Credit: NASA
It is comforting to know that our solar system is near the outer edge of the galaxy and far away from the event horizon (the Bermuda Triangle of the black hole – where stars and planets just disappear).
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