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Black Holes and Galaxy Formation: Group 14 December 9, 2009

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Xiao Li Black Holes

David Hurley The History of BLack Holes

Stephanie Weber Black Holes and Galaxy Formation

Peter Ford Evidence the Milky Way’s Central Black Hole Exist

Chris HartkeEvidence Central Black Holes Exist Outside the Milky Way

Nicole Theobald – Evidence Central Black Holes Dont Exist


Black Holes: An Overview December 9, 2009

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Back hole may be the most mysterious places in the universe, since the black hole theory has been proposed, Einstein and Hawking have affirmed the existence of black holes, many scientists have dedicated their careers to finding the exact black hole. There is evidence to improve the black hole theory, National Aeronautics and Space Administration and even to give in the vicinity of the black hole do “census.” However, there are a group of U.S. scientists has proposed a new current view that the so-called black hole is simply non-existent.

Black holes are collapsed supergiant stars that that distroy any material that enters, and nothing can escape once passing their event horizon. They have not yet been scientifically proven to exist, yet there are few scientists still who doubt they exist. They are unexplainable by the current laws of physics and we currently only have theories as to how they work or what they are capable of.

The History of Black Holes December 9, 2009

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The theory of black holes dates back to 1783 when geologist John Michell wrote a letter to Henry Cavendish stating that he believed, in theory, black holes could exist somewhere in the universe.  At this time though, the world of science called this theoretical place a dark star.  Later on, Pierre-Simon Laplace supported Michell’s idea is his book Exposition du système du Monde translated as The System of the Worldly which was published in 1796.  The basic idea of black holes and their nature would go untouched for about a century before someone else would expand our understanding of this mysterious place in the universe.  The century long hiatus happened because at this time people believed that light had no mass and was simply a wave which gravity would have no effect on.  The main idea of Michell’s theory was that at this point, light was bent so much that it could not escape because the mass of the object was too great and the gravitational pull was larger than the escape speed of light.

In 1915, Albert Einstein came up with an idea that would revolutionize the understanding of black holes and the universe as a whole.  The theory was called the Theory of Relativity.  Einstein had proven in a number of experiments before 1915 that gravity does in fact have an influence on light and its motion.  Once he was able to prove this fact, the idea of black holes began to gain a solid theoretical foundation.  The idea was that just as the Earth is able to pull a rock back to the its surface because it has such a greater mass than the rock, there should be a object where the mass of the object is so enormous that its gravitational force bends the path of light and ultimately traps it forever.

The late 1950s and the 1960s produced some very interesting discovers that would greatly affect the understanding of black holes.  In 1958, David Finkelstein came up with the idea of the event horizon in a black hole.  The theorists before him had said that black holes were merely singularities.  He was able to prove that there was a specific point where light ceases to escape but instead of being a point it was more of a membrane or boundary.  Until 1963, scientists thought that black holes did not rotate.  Roy Kerr was the first to prove that the singularity of a black hole was not a point but a rotating ring.  Roger Penrose then came along and was able to prove that every black hole had a singularity.  John Wheeler is given credit for coining the term black hole in a speech he gave in 1967.

Stephen Hawking was the next great theorist in black holes.  In 1974, he stated that through his calculations and tests, he believed that black holes actually emit tiny amounts of thermal radiation.  Many other scientists have been able to test Hawking’s claim since then and they all agree with the theory.  This radiation is often referred to as Hawking Radiation.  The startling thing about this theory is if black holes do emit radiation, they then have to be losing mass.  This constant loss of mass would then eventually cause the black hole to evaporate.

In recent years, Stephen Hawking has been able to study black holes extensively but has suffered from a severe form of ALS that affects his spinal cord and caused him to lose his vocal capabilities.  He is often renowned as the best modern scientist of our time.  Through more careful observation of potential black hole sites, people like Stephen Hawking and those who come after him will have more evidence to look at and hopefully be able to fully understand the nature of these mysterious objects.

Black Holes and Galaxy Formation December 9, 2009

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Do black holes really exist, and if they do, then do they actually have anything to do with the formation of galaxies?  This has recently been a very strongly debated topic amongst scientists studying nearby galaxies. What actually lies at the center of a galaxy is something that has yet to be proven, but strong evidence suggests that black holes may thrive at the center of all galaxies. That being said, the biggest question now is which one came first? Or is it possible they developed together to form a galaxy? The answer lies in research concluded by looking at galaxies whose centers are no longer active. Studies done have concluded that the mass of central black holes of many galaxies are the same ratio as compared to the central bulge in various types of galaxies, it has been concluded that the development of galaxies is connected to the growth of central back holes. It has not yet been proven how this process works, or if black holes even exist for that matter, so for now their connection is still unknown.

There are many different theories that explain how galaxy formation and super massive black holes are related, but surprisingly quasars are supposedly connected. Quasars are powerful stars that contain visible light and X-rays that are so bright that they can be seen from over 12 billion light years away. The theory is that black holes formed from quasars, which contained extreme amounts of high-energy gas. The gas was consumed by the black hole in such tremendous amounts that it created its own surrounding galaxy from the gas jets that were released.  This is one of the many theories that are being debated within the astronomy community for why black holes might have such high mass in comparison to each of their surrounding galaxies.
Studies have been conducted of nearby galaxies, such as the M87 Galaxy to see if we can find if black holes really exist at the center. The spectra of its core were interesting seeing the gas on one side had been blueshifted, while the other was redshifted. The gas had been determined to be orbiting an undetectable object at extreme and unexplainable speeds, causing scientists to be suspicious of a black hole being the cause. Upon further investigation, the object in the center was calculated to be “3 billion times the mass of our sun”, which is very odd, especially since the mass is undetectable.

Although this is only one galaxy, others have been discovered having the same strange characteristics of invisible objects with tremendous masses. In these cases, a black hole seems to be the only reasonable answer for what is occurring in the center of the galaxies, but until it can be proven that they exist we will never be certain that they truly are the cause for this strange phenomenon.

Evidence the Milky Way’s Central Black Hole Exists December 9, 2009

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Recent astronomical observations have sighted a star swiftly orbiting the center of the Milky Way Galaxy. Through this observation and other X-ray binary observations, there is almost certainty that a black hole exists at the Center of our galaxy. Perhaps the most prominent evidence supporting the argument for a black hole is the X-ray binary called Cygnus X-1. This system has a very bright star with an estimated mass of 18 solar masses. Over the past several years, astronomers have been tracking the path of this star and it has been concluded that no other astronomical object has reached this close to the center of our galaxy. It is believed that this star orbiting the center of the galaxy is moving at speeds close to 11 million miles per hour and at one point in its orbit, it came within 17 light hours of the conceived black hole.

There have been other theories as to what’s at the center of our galaxy, but the fact that a seemingly invisible object with a matter equal to 2.6 million suns is enough for most to assume that a black hole is indeed at the center of the Milky Way. According to Rainer Schoedel, a German physicist, “If one accepts the universal validity of the laws of physics, it is extremely hard to avoid the conclusion that the supermassive black hole in the Milky Way does indeed exist.” What he’s referring to is that a White Dwarf star cannot exceed 1.4 solar masses. And a neutron star cannot exceed 3 solar masses. Anything above this mass will prohibit neutron degeneracy from holding off the crush of gravity in a stellar core. Since the dark object in the center of our galaxy greatly exceeds this number, the most and perhaps only logical solution is a supermassive black hole.

With compelling X-ray binary and other objective observation, there is strong evidence that a supermassive black hole does exist at the center of the Milky Way Galaxy. And since this mysterious object incapable of emitting light cannot be a White Dwarf or a neutron star, evidence shows that only a black hole can exist.

Is There Evidence the Milky Way’s Central Black Hole Does Not Exist? December 9, 2009

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Most scientists think and trying to prove that there are black holes at the center of the Milky Way galaxy, along with other galaxies.  Are there true black holes? What if it wasn’t a black hole at the center of the galaxy but maybe a black star?

From a distant observer, others say the event horizon would take forever to form, so the event horizon never really forms which means there is not true black hole.

A man by the name of Tanmay Vachaspati believes it to be a black star. He says that a distant observer, us on earth, gravity messes with time. So time would appear to be moving slowly inwards. With the black hole, time would stop and light and everything else would fall in the hole. According to Vachaspati, that light disappears with a black star because the light’s wavelengths get so long that they wouldn’t be able to detect them due to the black star’s gravity.

Also along the lines of a black star, Dr. Oliver Manuel thinks that if there was a black hole at the center of the galaxy wouldn’t the stars fall into the hole instead of moving away from the center. Manuel believes that it’s a neutron star at the center of the galaxy and others. Him along with other researchers found that there was a small neutron star inside the sun and many other stars. They believe that there was a massive neutron star which broke up into to smaller stars. This can also explain other high energy events and the regions of space that have high densities.

There is evidence that black holes don’t exist at the center of the Milky Way or other galaxies. Or maybe it’s just a black star or a neutron star. Only furthur scientific expieriments will let us know.

Evidence Central Black Holes Exist Outside the Milky Way December 9, 2009

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Is it currently believed that at the center of nearly all galaxies, lies a super massive black hole. The black holes themselves cannot be seen, but the effect that they have on their surrounding galaxy is proof of their existence. The effect that the black holes have, can be witnessed and measured with the M-Sigma relation, which relates the velocity dispersion of the galaxy’s bulge, with the mass of the black hole at it’s center.

By using a Doppler measurement of the surrounding nucleus of a galaxy, scientists found that these galaxies contain strong Keplerian motion. This motion can only be explained by a strong concentration of mass at the center of the galaxy, only explainable by a black hole. For similar galaxies further away, reverberation mapping is used to calculate the mass of the central black hole. Reverberation mapping uses the orbiting gas of the galaxy that circles the event horizon by mapping it’s path using spectral lines. Once mapped, this data can calculate mass and spin of the black hole.

Another indicator of the presence of black holes at a galaxy’s center, is the common sight of massive amounts of energy dispersion from a galaxy’s center. Often massive amounts of matter in the form of a jet of electrons is ejected from the galactic nucleus of a galaxy, being explained by a black holes natural process of matter consumption. This process also emits radio waves which are named as “Hawking Radiation”.