Ask Ethan: How many Black Holes are there in the Universe? (Synopsis) [Starts With A Bang]

“Black holes are the seductive dragons of the universe, outwardly quiescent yet violent at the heart, uncanny, hostile, primeval, emitting a negative radiance that draws all toward them, gobbling up all who come too close…these strange galactic monsters, for whom creation is destruction, death life, chaos order.” -Robert Coover

For the third time since it began taking data, the LIGO collaboration discovered direct evidence for merging black holes in the Universe. There’s an incredible amount we’ve learned about black holes and where they’re located, however, and very little of it comes from gravitational waves.

What we perceive as a gamma ray burst may have its origin in merging neutron stars, which expel matter into the Universe, creating the heaviest elements known, but also give rise to a black hole in the end. Image credit: NASA / JPL.

Instead, we know how black holes are made, where their progenitors are and were located, and how they’re likely to be distributed today. If we put this picture all together, we can come up with a numerical estimate for how many are likely to be present in our galaxy, along with where they’re expected to be concentrated. It’s an incredible picture!

NASA’s Fermi Satellite has constructed the highest resolution, high-energy map of the Universe ever created. The map of the galaxy’s black holes will likely trace the emissions seen here with a little more scatter, and resolved into millions of individual point sources. Image credit: NASA / DoE / Fermi LAT Collaboration.

Just a few decades ago, we weren’t sure black holes even existed; now we think we know where millions ought to be in every galaxy. Come get the remarkable story on this week’s Ask Ethan!

from ScienceBlogs http://ift.tt/2sB3SKs

“Black holes are the seductive dragons of the universe, outwardly quiescent yet violent at the heart, uncanny, hostile, primeval, emitting a negative radiance that draws all toward them, gobbling up all who come too close…these strange galactic monsters, for whom creation is destruction, death life, chaos order.” -Robert Coover

For the third time since it began taking data, the LIGO collaboration discovered direct evidence for merging black holes in the Universe. There’s an incredible amount we’ve learned about black holes and where they’re located, however, and very little of it comes from gravitational waves.

What we perceive as a gamma ray burst may have its origin in merging neutron stars, which expel matter into the Universe, creating the heaviest elements known, but also give rise to a black hole in the end. Image credit: NASA / JPL.

Instead, we know how black holes are made, where their progenitors are and were located, and how they’re likely to be distributed today. If we put this picture all together, we can come up with a numerical estimate for how many are likely to be present in our galaxy, along with where they’re expected to be concentrated. It’s an incredible picture!

NASA’s Fermi Satellite has constructed the highest resolution, high-energy map of the Universe ever created. The map of the galaxy’s black holes will likely trace the emissions seen here with a little more scatter, and resolved into millions of individual point sources. Image credit: NASA / DoE / Fermi LAT Collaboration.

Just a few decades ago, we weren’t sure black holes even existed; now we think we know where millions ought to be in every galaxy. Come get the remarkable story on this week’s Ask Ethan!

from ScienceBlogs http://ift.tt/2sB3SKs