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Radio galaxies and quasars--quasi-stellar radio sources--usually displ

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mehulsayani
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Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   Updated on: 05 Sep 2019, 01:35
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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.

Show 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.

Show Spoiler
A



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Originally posted by mehulsayani on 01 Sep 2012, 06:56.
Last edited by Sajjad1994 on 05 Sep 2019, 01:35, edited 1 time in total.
Updated - Complete topic (423).
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   05 Sep 2012, 09:53
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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--usually displ [#permalink] New post   20 Sep 2012, 21:19
@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 sources--usually displ [#permalink] New post   28 Jun 2014, 09:39
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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.
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   18 Mar 2015, 09:49
Did not get the first question.
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   14 Apr 2015, 04:32
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Ergenekon wrote:
Did not get the first question.

let me try the first question.
1. According to the passage, which one of the following is an accurate statement concerning radio-emitting lobes? So we need to find the statement that is considered accurate.
They are powered by superheated particles spiraling toward black holes. They are maybe powered by superheated particles...But according to the passage, this statement is only one of possible explanations. The underlying explanation is still unknown. So this is not accurate. This answer could be correct if "They are probaly powered by superheated particles spiraling toward black holes.
Their exact energy source remains a question for scientists. Correct! This is mentioned in the passage: The nature of the engine that powers the processes in radio galaxies and quasars is still a mystery.
They stretch more than 10 million light years across. Radio galaxies and quasars can stretch more than 10 million light years across; however, Wwe don't know whether their radio-emitting lobes can.
They are probably responsible for the formation of radio jets around the centers of active galaxies. The superheated particles circling the hole (not radio-emitting lobes) may be responsible for various exotic phenomena that occur in and around the centers of active galaxies, such as the formation of radio jets.
They are always symmetric in their orientation. We know that they are symmetric, but the way in which they are symmetric is unknown.

Hope it helps!
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   10 May 2015, 04:55
I spent a chunk of time on the second question. My issue is that the correct answer choice is, with some tweaking, a direct lift of the relevant sentence from the passage, and I was thinking "the answer is too obvious so it must be wrong". I was hesitating between A and B - the other option were horrible - and figured that B depended on A, and therefore chose A.

Phew...
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   31 Aug 2017, 01:40
For the first question :

A) They are powered by superheated particles spiraling toward black holes. - This is some astronomers' hypothesis which is not shown to be the accurate and final hypothesis and we can't take a side here. Not a correct one.

B) Their exact energy source remains a question for scientists. CORRECT - Lobes are powered by some engines in the center of the galaxy. The nature of the engine is not clear(even though a plausible hypothesis exists)

C) They stretch more than 10 million light years across. - Lobes "can usually stretch" for more than 10 million light years across NOT for sure

D) They are probably responsible for the formation of radio jets around the centers of active galaxies. - Radio jets connect the center/engine of the galaxy and emissions from outer extremes of the radio lobes

E) They are always symmetric in their orientation. - Always is incorrect here.

If you like the reasoning, please press "KUDOS"
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   09 Nov 2018, 22:59
mehulsayani wrote:
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.

Show 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.

Show Spoiler
A


For question 1, my analysis is the following,
Option A is incorrect because of the word spiralling.
Option B is close.
The paragraph says "These sources can stretch more than 10 million light years across". This mentions about the sources but not the lobes. Sources are different from lobes because according to the passage, sources is the collective word for the whole system where each system has a couple of lobes present as a part of it. So, because of this, we can eliminate Option C which points to the distance between the lobes between 10 light years.
Option D can be eliminated because the superheated particles and not the lobes are responsible for the formation of radio jets. "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." can be seen in the paragraph.
Option E can be eliminated because of the word "always". The paragraph mentioned usually displays two symmetric lobes.
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   09 Nov 2018, 23:14
mehulsayani wrote:
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.

Show 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.

Show Spoiler
A


For question 2, my reasoning is the below,
Option A is correct because the supposition which was mentioned in the paragraph is being said to be true here. So, if this is true, it indeed strengthens the hypothesis. So, this is correct.
Option B is irrelevant because it doesn't help us get more information about the black holes.
Option C talks about the energy transmission happening from the core (black holes) to the lobes but does not talk about the part played by black holes or how it generates the energy.
Option D talks about particles inside black holes reaching temperatures of several million degrees. However, we are concerned about what happens outside the black hole, so, this can option can be eliminated.
Option E talks about wavelengths and since it wasn't mentioned anywhere in the paragraph, we can eliminate this.
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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink] New post   08 Sep 2019, 22:42
Hi..
Whenever I find the question like Sr. 1) in this RC, I get panicked . Especially when you were already not able to understand most of the content in the passage .

(1. According to the passage, which one of the following is an accurate statement concerning radio-emitting lobes?)

I don't understand how to deal with such questions. This is A specific question but based upon entire knowledge given in the para.
Can anyone please address, how to approach such questions? What is the best method to deal with such questions?

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Re: Radio galaxies and quasars--quasi-stellar radio sources--usually displ [#permalink]
08 Sep 2019, 22:42
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