Theos-Talk Archives (March 2004 Message tt00019)

Creation Force: Black Holes Linked to Star Birth



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Artist's conception of the disk of star-forming gas around the center 
of the galaxy hosting the quasar PSS J2322+1944 The disk is about 
13,000 light-years in diameter. The luminous quasar, powered by the 
infall of matter into a supermassive black hole, is at the center. 
Credit: Geraint Lewis, University of Sydney, NRAO/AUI/NSF
(PureInsight.org) Using the National Science Foundation's Very Large 
Array (VLA) radio telescope and aided by a gigantic cosmic lens 
conveniently provided by nature, an international team of astronomers 
has discovered that a young galaxy had a central disk of gas in which 
hundreds of new stars were being born every year -- at a time when 
the Universe was only a fraction of its current age.
"This unique look into a very distant, young galaxy gives us 
unprecedented insight into the process that produced both tremendous 
numbers of stars and supermassive black holes in forming galaxies," 
said Chris Carilli, of the National Radio Astronomy Observatory 
(NRAO) in Socorro, NM, leader of the research team. "This work 
strongly supports the idea that the stars and the black holes formed 
simultaneously," he added. The research was published in the April 4 
issue of Science Express.

The astronomers studied a quasar called PSS J2322+1944, about 12 
billion light-years from Earth. The quasar is an extremely luminous 
object powered by the supermassive black hole at the core of a 
galaxy. At the distance of this quasar, the scientists see the object 
as it was when the Universe was less than 2 billion years old, about 
15 percent of its current age.

The discovery required great assistance from nature. To find the star-
forming disk, the astronomers needed to observe natural radio 
emission from the carbon monoxide (CO) molecule, an important 
component of the gas that forms stars. However, this molecule emits 
radio waves at frequencies much higher than the VLA is capable of 
receiving. At PSS J2322+1944's distance of 12 billion light-years, 
however, the expansion of the Universe stretched the radio waves, 
reducing their frequency. CO emission at 230 GigaHertz was shifted to 
45 GigaHertz, within the VLA's range.

That alone was not enough. The distance that made it possible to 
receive the radio waves from the quasar also meant that the object 
was too far away for the VLA to discern the detail required to show 
the disk. Once again, nature stepped in to help, providing another 
galaxy directly between the quasar and Earth to form a gravitational 
lens.

"What we needed wasn't just any old gravitational lens, but a nearly-
perfect alignment of the distant quasar, mid-distance galaxy, and 
Earth -- and that's what we got," said Geraint Lewis of the 
University of Sydney in Australia, another member of the team. With 
such a perfect alignment, the quasar image was distorted into a ring, 
called an "Einstein Ring." The VLA images were the first to show the 
Einstein Ring of PSS J2322+1944.

"We never would have seen the disk of CO gas near the center of this 
galaxy without the gravitational lens," said Carilli. "The lens 
boosted the signal and magnified the image to reveal the disk's 
structure in unprecedented detail," he added.

For several years, astronomers have noted that the masses of black 
holes are directly proportional to the sizes of central bulges of 
stars in galaxies. This led to the speculation that formations of the 
black holes and of the stars are somehow related to each other. 
Scientists hypothesized that gas being drawn towards a galaxy's 
central black hole is the same gas from which large numbers of stars 
are forming.

Studies of more-nearby galaxies supported such speculation, but the 
question remained whether the idea could be applied to the very early 
Universe, when the first galaxies and black holes formed.

"This new observation gives strong support to the idea that large 
numbers of stars were forming in young galaxies at the same time that 
their central black holes were pulling in additional mass," said 
Pierre Cox, of the Institute for Space Astrophysics of the University 
of Paris.

The astronomers believe that galaxies in the early Universe were 
frequently disrupted by nearby encounters with other 
galaxies, "feeding" the central black hole with gas. The gas formed 
an extensive, spinning disk around the galaxy's center, some of it 
eventually falling into the black hole and some of it forming new 
stars.

In PSS J2322+1944, the astronomers believe that new stars with a 
total mass equal to some 900 times that of the Sun were forming in 
the 13,000-light-year-diameter disk every year. At that rate, the 
scientists say, most of the stars in a large elliptical galaxy could 
form in only about 100 million years.

PSS J2322+1944 is one of the most luminous quasars in the Universe. 
It also had a huge reservoir of dust and molecular gas, the fuel for 
star formation. Optical observation at the W.M. Keck Observatory in 
Hawaii showed a double image that indicated gravitational lensing. 
All these factors, the scientists said, made it an ideal candidate 
for study with the VLA.

"Our guess paid off handsomely. Finding that Einstein Ring with the 
VLA gave us the tool we needed to see what was going on inside that 
very distant galaxy," said Carilli. "There are fewer than 100 
gravitational lenses known so far, and we were extremely lucky to 
find one that allowed us to help resolve the specific scientific 
question we were studying."

Gravitational lenses were predicted, based on Albert Einstein's 
General Theory of Relativity, in 1919. Einstein himself showed in 
1936 that a perfectly-aligned gravitational lens would produce a 
circular image, but felt that the chances of actually observing such 
an object were nearly zero. The first gravitational lens was 
discovered in 1979, and the first Einstein Ring was discovered by 
researchers using the VLA in 1987. PSS J2322+1944 is the first 
Einstein Ring detected through the signature emission of a molecule 
and the most distant yet found.

PSS J2322+1944 may be able to make another contribution to science. 
Astronomers believe that gravitational lenses may serve as a tool for 
precisely measuring great distances in the Universe. If a distant 
quasar varies in brightness over time, the multiple images formed by 
a gravitational lens would show that variation at different times. By 
monitoring such time differences and using a mathematical model of 
the specific gravitational lens, the distance to the quasar can be 
measured.

"This quasar, if it shows brightness variations in the future, may be 
such a 'Golden Lens,' long sought to refine our measurement of very 
great distances," said Lewis.

The National Radio Astronomy Observatory is a facility of the 
National Science Foundation, operated under cooperative agreement by 
Associated Universities, Inc.




> -----Original Message-----

















--- In theos-talk@yahoogroups.com, "Dallas TenBroeck" <dalval14@e...> 
wrote:
> Mar 3 2004
> 
> Dear Friends:
> 
> Re "Dark" matter
> 
> Is it really "dark" or is it that it appears that way to our
> eyes? Inn
> order to "see" it has to radiate some kind of influence (which
> may be in
> another level of the electro-magnetic range of vibrations) but to
> our
> eyesight is seems "dark."
> 
> However. The fact that it exists implies there are transparencies
> and
> opaque nesses all over the Universe of which we are gradually
> becoming
> aware.
> 
> In fact it is highly probable that there is a very fine balance
> between
> "light" and :darkness" that has existed for billions of years,
> and which
> forms the pivotal point of life and living in the entire
> universe.
> 
> I was just reading that the "pure water" we get from mountain
> springs,
> etc. has been endlessly recycled for billions of years since it
> was
> first formed.
> 

> 
> 
> 
> 
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