How is a black hole detected?

[damien211]

How can it be determined that a black hole exists if light cannot escape?

 

[derekmcd]

Keeping in mind, of course, blackholes are theoretical and may remain forever so due to the fact that we can not observe them directly... They are observed indirectly.<br /><br />Cygnus x-1 is a prime example of indirect observation.<br /><br />Another is Gravitational lensing. This is when a massive object moves in front of a luminous object and bend the light around it.<br /><br />Yet another is Accretion Discs. As dust and gas orbit a black hole, they heat up to extraordinary temperatures and emit jets prior to falling into the black hole.<br /><br />Hope that helps ya get started.<br /><br /><br /> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[harmonicaman]

I agree with member <b>Derekmcd</b> and would add the evidence presented by observations of the suspected supermassive BH, Sgr A*, pronounced Sagittarius A-star, which resides at the center of our own Milky Way Galaxy. Here's an APOD image showing a star which is under the influence of something really massive at the center of our galaxy...

 

[nexium]

We suspect a super massive black hole, when we find things (such as stars) orbiting at very high speed without much observable mass in the center. Neil

 

[alokmohan]

Exactly ,its neighbourhood helps out.There is intense radiation near about.

 

[rhodan]

<i>Here's an APOD image showing a star which is under the influence of something really massive at the center of our galaxy...</i><br /><br />This is a cool animation from the Cornell University website:<ul type="square">Massive black hole in the Milky Way. This animation shows the motion of stars over a period of eight years, as they orbit the supermassive black hole at the center of our galaxy. The black hole, which contains a few million times the mass of the Sun, is invisible in this infrared image, though its gravitational effect is apparent! Its location, marked above by the yellow cross, coincides with a mysterious and highly variable source of radio waves and x-rays known to astronomers as Sagittarius A*.</ul><br />

 

[alokmohan]

Useful stuff.

 

[MeteorWayne]

Thanks for the image. It's mind boggling to think how fast those stars are moving around the center of our galaxy to see that much motion in 8 years. Think about it, Jupiter has only gone 2/3 of the way around it's orbit in that time.<br />MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[buckeye101]

is the accretion disc the vertical lines going out from the north and south poles of a black hole star? If not what is it and why does it happen?

 

[harmonicaman]

<b>Buckeye101 -</b><br /><br />I trhink you are asking about Quasars, which are a type of very energetic Black Hole that only occurred in the very early universe. Due to their vast distance they are very difficult objects to study, but headway is being made, including this very recent discovery about Quasars.

 

[supernova65]

I think Buckeye is probably referring to the narrow jets of particles spewing out along the disk's axis at both ends, such as this:<br />http://en.wikipedia.org/wiki/Image:Accretion_disk.jpg

 

[damien211]

Thanks for clearing this up for me.

 

[buckeye101]

Maybe it is quasars. Because they shoot out of the top and bottom of a black hole right? http://www.celestiamotherlode.net/catalog/images/screenshots/various/fictional_Black_Hole_3_1__Cham.jpg<br />this is what im talking about <img src="/images/icons/smile.gif" />

 

[derekmcd]

<i>is the accretion disc the vertical lines going out from the north and south poles of a black hole star? If not what is it and why does it happen?</i><br /><br />The accretion disc is the matter swirling around a black hole. The closer the matter is, the faster it will orbit. Matter very near the event horizon can approach speeds near the speed of light. The 2 jets you see at the axis are x-ray jet emissions from this incredibly energetic matter. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[alokmohan]

Quasar looks similar I think.Any way quasars are basically( Or cousin).type of black hole?

 

[derekmcd]

Sort of... Quasars are a developmental stage of young galaxies with a supermassive black hole at it's center. I think the quasar constitutes not only the black hole, but the surrounding gas and dust and the massive amount energy involved. I don't think you can view a Quasar as one specific object. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[alokmohan]

We may say quasars are quasars.

 

[derekmcd]

Indeed we may <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>