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Radio galaxies and quasars--quasi-stellar radio

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Radio galaxies and quasars--quasi-stellar radio [#permalink] New post 01 Sep 2012, 05:56
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Radio galaxies and quasars--quasi-stellar radio sources--usually display two symmetric, radio-emitting lobes. These sources can stretch more than 10 million light years across--more than twenty times the visible extent of the typical host galaxy, and more than 100 million times the diameter of the Milky Way.
In 1971, Martin J. Rees suggested that hidden engines located within the nuclei of the parent galaxies generate the energy needed to power the giant radio lobes. He proposed that high-speed particles shooting along narrow channels could transport this energy. A few years later other investigators demonstrated that, in many sources, jet-like features do seem to connect a radio-bright core in the galaxy’s nucleus
with knots of radio emissions emanating from the outer extremities of the lobes. The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery, but most astronomers think a massive rotating black hole lies behind all the commotion. Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior. The superheated particles circling the hole may be responsible for various exotic phenomena that occur in and around the centers of active galaxies, such as the formation of radio jets.
1. According to the passage, which one of the following is an accurate statement concerning radio-emitting lobes?
They are powered by superheated particles spiraling toward black holes.
Their exact energy source remains a question for scientists.
They stretch more than 10 million light years across.
They are probably responsible for the formation of radio jets around the centers of active galaxies.
They are always symmetric in their orientation.
[Reveal] Spoiler:
B


2. According to the passage, scientists' hypotheses about black holes and their part in radio-emissions would be best supported if which of the following were found to be true?
Some particles become greatly condensed and raised to high temperatures as they near the entrances to black holes.
Many exotic phenomena have been observed in and around the centers of active galaxies.
High-speed particles do, in fact, shoot along narrow channels and transport energy from quasars and radio galaxies to their lobes.
Particles inside black holes have been shown to reach temperatures of several million degrees.
Radio emissions of radio galaxies were found to have different wavelengths from those of quasars.
[Reveal] Spoiler:
A

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Re: Radio galaxies and quasars--quasi-stellar radio sources--usu [#permalink] New post 04 Sep 2012, 09:17
Hey can any of the experts help me out here??
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usu [#permalink] New post 05 Sep 2012, 08:53
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It was a nice passage, I would say.

The important thing is to pay attention on what the passage says and what is asked by the questions.

Try to break al the answers one by one, go step by step ahead like me

Quote:
Radio galaxies and quasars--quasi-stellar radio sources--usually display two symmetric, radio-emitting lobes. These sources can stretch more than 10 million light years across--more than twenty times the visible extent of the typical host galaxy, and more than 100 million times the diameter of the Milky Way.
In 1971, Martin J. Rees suggested that hidden engines located within the nuclei of the parent galaxies generate the energy needed to power the giant radio lobes. He proposed that high-speed particles shooting along narrow channels could transport this energy. A few years later other investigators demonstrated that, in many sources, jet-like features do seem to connect a radio-bright core in the galaxy’s nucleus
with knots of radio emissions emanating from the outer extremities of the lobes
. The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery, but most astronomers think a massive rotating black hole lies behind all the commotion. Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior. The superheated particles circling the hole may be responsible for various exotic phenomena that occur in and around the centers of active galaxies, such as the formation of radio jets.


For the first one is B because:

A) They are powered by superheated particles spiraling toward black holes. Is not true

B) Their exact energy source remains a question for scientists. TRUE the passage says " The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery"

C) They stretch more than 10 million light years across. We already know

D) They are probably responsible for the formation of radio jets around the centers of active galaxies. The red part about jets imply that they go toward NOT around

E) They are always symmetric in their orientation. We have symmetric lobes but nothig is said about orientation.

The sesond one is A, same reasoning is applyed to find the correct answer:

A) Some particles become greatly condensed and raised to high temperatures as they near the entrances to black holes. from the passage "Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior"

B) Many exotic phenomena have been observed in and around the centers of active galaxies. is not the point

C) High-speed particles do, in fact, shoot along narrow channels and transport energy from quasars and radio galaxies to their lobes. from the passage "He proposed that high-speed particles shooting along narrow channels could transport this energy" not the word could instead of the word in the answer DO. this shift imply that can't be the correct answer : could is not TRUE. maybe yes or maybe no

D) Particles inside black holes have been shown to reach temperatures of several million degrees. Once again here the theorist SUPPOSE the heat not has observed it

E) adio emissions of radio galaxies were found to have different wavelengths from those of quasars. I didn't read wavelenght anywhere in the passage
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usu [#permalink] New post 05 Sep 2012, 12:21
carcass wrote:
It was a nice passage, I would say.

The important thing is to pay attention on what the passage says and what is asked by the questions.

Try to break al the answers one by one, go step by step ahead like me

Quote:
Radio galaxies and quasars--quasi-stellar radio sources--usually display two symmetric, radio-emitting lobes. These sources can stretch more than 10 million light years across--more than twenty times the visible extent of the typical host galaxy, and more than 100 million times the diameter of the Milky Way.
In 1971, Martin J. Rees suggested that hidden engines located within the nuclei of the parent galaxies generate the energy needed to power the giant radio lobes. He proposed that high-speed particles shooting along narrow channels could transport this energy. A few years later other investigators demonstrated that, in many sources, jet-like features do seem to connect a radio-bright core in the galaxy’s nucleus
with knots of radio emissions emanating from the outer extremities of the lobes
. The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery, but most astronomers think a massive rotating black hole lies behind all the commotion. Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior. The superheated particles circling the hole may be responsible for various exotic phenomena that occur in and around the centers of active galaxies, such as the formation of radio jets.


For the first one is B because:

A) They are powered by superheated particles spiraling toward black holes. Is not true

B) Their exact energy source remains a question for scientists. TRUE the passage says " The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery"

C) They stretch more than 10 million light years across. We already know

D) They are probably responsible for the formation of radio jets around the centers of active galaxies. The red part about jets imply that they go toward NOT around

E) They are always symmetric in their orientation. We have symmetric lobes but nothig is said about orientation.

The sesond one is A, same reasoning is applyed to find the correct answer:

A) Some particles become greatly condensed and raised to high temperatures as they near the entrances to black holes. from the passage "Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior"

B) Many exotic phenomena have been observed in and around the centers of active galaxies. is not the point

C) High-speed particles do, in fact, shoot along narrow channels and transport energy from quasars and radio galaxies to their lobes. from the passage "He proposed that high-speed particles shooting along narrow channels could transport this energy" not the word could instead of the word in the answer DO. this shift imply that can't be the correct answer : could is not TRUE. maybe yes or maybe no

D) Particles inside black holes have been shown to reach temperatures of several million degrees. Once again here the theorist SUPPOSE the heat not has observed it

E) adio emissions of radio galaxies were found to have different wavelengths from those of quasars. I didn't read wavelenght anywhere in the passage


@carcass- Thanks Man! :)
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usu [#permalink] New post 05 Sep 2012, 14:00
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Re: Radio galaxies and quasars--quasi-stellar radio [#permalink] New post 20 Sep 2012, 20:19
@Carcass - could not get your idea behind Qs#2 .I chose -D for 2 .To me its like - if we get evidence of high temperature,we can confirm hypothesis?
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Re: Radio galaxies and quasars--quasi-stellar radio [#permalink] New post 07 Mar 2014, 03:32
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Re: Radio galaxies and quasars--quasi-stellar radio [#permalink] New post 26 Jun 2014, 04:53
Why cant option 'B' be the answer for 1st question.
The question is asking about an accurate statement and i think B is fair enough as it is explicitly mentioned in the passage.

Experts... Please comment.

Thanks,
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Re: Radio galaxies and quasars--quasi-stellar radio [#permalink] New post 28 Jun 2014, 08:39
vishu1414 wrote:
@Carcass - could not get your idea behind Qs#2 .I chose -D for 2 .To me its like - if we get evidence of high temperature,we can confirm hypothesis?


If we do have evidence that the temperature is indeed high --- how does that even prove that the theory is more likely to happen? :)
We don't need evidence to prove that the temperature is high ... We need to add something that will make the theory more likely (of what actually happens that leads to those high temperatures) possible.

Focus on the second-to-last sentence:
"Theorists commonly suppose that material spiraling toward a black hole becomes compressed and heated to a temperature of millions of degrees before it vanishes into the hole’s interior."

If choice A were true, then the theorists' supposition works. Without it, the theory can't even happen.
Choice D actually relies on Choice A, in order to be true. Choice D just says something that has no bearing on whether the theory can happen.

Choice A is what the theorists' theory completely relies on.
Re: Radio galaxies and quasars--quasi-stellar radio   [#permalink] 28 Jun 2014, 08:39
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