Record-breaking supermassive black hole found in heart of far-off galaxy

[Yousuf Khan]

A supermassive black hole — with the mass 21 billion times that of our
own sun — has been found at the heart of a distant galaxy.

NGC 4889 is an elliptical galaxy. Rather than being the galaxy most
people think of, elliptical galaxies look like they have no real
structure, with their collection of stars looking more like blobs in space.

The galaxy is about 300 million light years away, in the heart of a
galaxy cluster known as the Coma Cluster. The black hole has an event
horizon — a location where not even light can escape — with diameter of
130 billion km. That’s approximately the distance between the sun and
Neptune, the last planet in our solar system. Comparatively, the black
hole at the heart of our galaxy has an event horizon about one-fifth the
orbit of Mercury, the closest planet to the sun and a mass of about four
million times that of the sun.

Astronomers believe that the black hole is no longer gobbling up matter.
In fact, they believe that stars have begun to form in the surrounding
region.

http://globalnews.ca/news/2511541/record-breaking-supermassive-black-hole-found-in-heart-of-far-off-galaxy/

[Odd Bodkin]

Note, John Sefton, that black holes are not presented in GR as things
that swallow everything in their vicinity, and that star formation in
the region outside a black hole is perfectly consistent with general
relativity.

No matter what magazine article you think you might have read sometime
that suggested to you otherwise.

--
Odd Bodkin --- maker of fine toys, tools, tables

[Mike Duffy]

On Fri, 12 Feb 2016 10:26:28 -0600, Odd Bodkin wrote:

> Note, John Sefton, that black holes are not presented in GR as things
> that swallow everything in their vicinity, and that star formation in
> the region outside a black hole is perfectly consistent with general
> relativity.

How does that work? My limited understanding of the mechanism for black
holes emitting matter via 'Hawking' radiation works best for black holes
just barely big enough to hold thenselves together. Bigger ones would thus
emit less.

[Sam Wormley]

Thanks for posting this.


--

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to the discussion of physics, news from the physics
community, and physics-related social issues.

[Odd Bodkin]

Because of the gravitational pull of the black hole, matter can accrete
outside the black hole's event horizon WITHOUT being sucked in. This is
for the same reason that the matter in the rings of Saturn accrete in
those rings without falling into Saturn, and for the same reason the
asteroid belt orbits the sun without falling into the sun.

If the density of the accretion is high enough, you can seed stars.

If the black hole has angular momentum, then you can also get effects
that come from the rotation of the orbiting matter, such as magnetic
fields and ejected jets along the axis.

None of this has anything to do with Hawking radiation, which (as you
say) is tiny, tiny, tiny for a supermassive black hole.

[Thomas 'PointedEars' Lahn]

Mike Duffy wrote:

> On Fri, 12 Feb 2016 10:26:28 -0600, Odd Bodkin wrote:
>> Note, John Sefton, that black holes are not presented in GR as things
>> that swallow everything in their vicinity, and that star formation in
>> the region outside a black hole is perfectly consistent with general
>> relativity.
>
> How does that work?

Very simple. An object has to *pass* the event horizon of a black hole in
order to be “swallowed” by it. That does not happen if the object is far
enough away from the event horizon and/or has an orbital speed that is high
enough. For example, light can circulate forever around a black hole on a
trajectory outside the event horizon called the “photon sphere”.

Popular-scientific version: <https://www.youtube.com/watch?v=eI9CvipHl_c>
Corresponding science: <http://jila.colorado.edu/~ajsh/insidebh/>

> My limited understanding of the mechanism for black holes emitting matter
> via 'Hawking' radiation works best for black holes just barely big enough
> to hold thenselves together. Bigger ones would thus emit less.

Hawking radiation – which AFAIK is yet to be detected – has nothing to do
with this.

<https://en.wikipedia.org/wiki/Hawking_radiation>


X-Post & F'up2 <news:sci.physics.relativity>

PointedEars
--
Q: Who's on the case when the electricity goes out?
A: Sherlock Ohms.

(from: WolframAlpha)

[dlzc]

Dear Thomas Lahn:

On Friday, February 12, 2016 at 5:37:45 PM UTC-7, Thomas 'PointedEars' Lahn wrote:
...
> Hawking radiation - which AFAIK is yet to be detected

Starting with the Tevatron, energetic collisions produced massive composites that evaporated as "fireballs"... so lots of light. No claim of black holes being produced, but the evaporation mechanism appears to be sound.

David A. Smith