Hundreds of Rogue Black Holes May Roam Milky Way

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Discussion Overview

The discussion revolves around the concept of "rogue" black holes in the Milky Way galaxy, exploring their potential existence, implications, and the relationship with rogue stars. Participants examine various aspects of black hole formation, their trajectories, and the risks associated with their presence in the galaxy.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants reference a study suggesting that hundreds of rogue black holes could exist in the Milky Way, questioning the implications of this finding.
  • Concerns are raised about the visibility and potential risk posed by these rogue black holes, with some expressing skepticism about the likelihood of encountering one.
  • Several participants note that the formation of black holes from stars is a common occurrence, leading to the expectation of numerous black holes in the galaxy.
  • One participant argues that the estimated number of rogue black holes is not alarming when considering the ratio to the number of stars in the galaxy.
  • Another participant introduces the idea that rogue black holes may be more common than rogue stars due to gravitational recoil, while also noting the rarity of stellar collisions.
  • A question is posed regarding the proportion of rogue stars and whether this varies by location within the galaxy.

Areas of Agreement / Disagreement

Participants express a mix of skepticism and acceptance regarding the existence of rogue black holes, with no consensus on the implications or risks associated with them. The discussion remains unresolved on several points, particularly concerning the relationship between rogue stars and black holes.

Contextual Notes

Participants highlight the need for further clarification on the definitions of rogue stars and black holes, as well as the assumptions underlying the estimates of their populations in the galaxy.

Astronuc
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Hundreds of "Rogue" Black Holes May Roam Milky Way
http://news.nationalgeographic.com/news/2008/01/080110-black-holes.html
Newly merged black holes might be so jarred by the experience that they go "rogue," careening into space on unexpected trajectories.

In fact, hundreds of these rogue black holes could exist in the Milky Way galaxy alone, according to a new study.

The research is just one of several new findings on black holes presented Wednesday at a meeting of the American Astronomical Society in Austin, Texas.
. . . .
Scientists at the presentation, for instance, offered up new explanations about odd x-ray sources coming from black holes.

They also found hints that dark matter may play an important role in the hot disks that form around companion-consuming black holes.
. . . .
Astronomers have long known about rogue black holes? How long? Is this a new revelation about DM and BHs?
 
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'Hundreds' of rogue black holes in our galaxy? So where are they [Fermi thing]? I doubt we are at risk.
 
Chronos said:
'Hundreds' of rogue black holes in our galaxy? So where are they [Fermi thing]? I doubt we are at risk.

Haha I can see the news article now.

"There is a black hole careening towards earth."

Oh my what would we do? lol
 
It is not uncommon for a star to implode and become a black hole. It happens all the time. Why not in our galaxy.

______________________________________________________________________________________________________
Society lives by faith, and develops by science.
 
Philosophaie said:
It is not uncommon for a star to implode and become a black hole. It happens all the time. Why not in our galaxy.

______________________________________________________________________________________________________
Society lives by faith, and develops by science.

i fully agree with you there, given the timespan that the milky way has been active and the average lifespam of a star of the size needed to become a black hole, the numbers of black holes predicted in our galaxy are enormous, for research now to suggest that we have hundreds of "rogue" black holes roaming around isn't surprising, as for us being in any sort of risk or running into one, well, i wouldn't like to take them odds! the galaxy is a very big place.
 
Hundreds of 'rogue' black holes in our galaxy is not an alarming number - something on the order of less than 1 per hundred million stars.
 
It occurs to me that the precursors to rogue BH are rogue stars. So what proportion of stars are rogue? Does that vary with location in the galaxy, e.g., halo vs disk/arms vs nucleus (central bulge)?

Rogue Stars: The Miscreants of Our Galaxy
http://www.space.com/scienceastronomy/080129-st-rogue-stars.html

Hubble Catches Heavyweight Runaway Star Speeding from 30 Doradus
http://hubblesite.org/newscenter/archive/releases/2010/14/full/

http://news.discovery.com/space/hubble-spies-trailblazing-star-ripped-from-stellar-nursery.html

Somewhat related
A young undergraduate named Marianne Heida was just combing through the Chandra Source Catalog, when she noticed a supermassive black hole that appeared to be leaving its home galaxy at very high speed, despite its mass of well over 1 billion Suns.
http://news.discovery.com/space/rogue-stars-non-constant-constants-holes-in-space-our-universe-is-rebelling.html
 
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Actually rogue black holes may be more plentiful than ordinary rogue stars due to gravitational recoil. But, stellar collisions of any kind are extremely rare. It is estimated they occur no more than once every 10 million years in this galaxy.
 

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