Is There a Massive Black Hole at the Centre of our Galaxy, the Milky Way?

Reading Passage Question

This passage is excerpted from material published in 1997.⠀

Is there a massive black hole at the center of our galaxy, the Milky Way? The evidence is inconclusive.

(5)  Just as the Sun's mass can be determined, given knowledge of other variables, by the velocity at which its planets orbit, the mass at the center of the Milky Way can be revealed by the velocities of stars and gas orbiting the galactic center. This dynamical

(10)  evidence, based on recently confirmed assumptions about the stars' velocities, argues for an extremely compact object with a mass two to three million times the mass of our Sun. Although according to current theory this makes the mass at the center

(15)  of the galaxy too dense to be anything but a black hole, the relative lack of energy radiating from the galactic center presents a serious problem. A black hole's gravity attracts surrounding matter, which swirls around the black hole, emitting some energy

(20)  as it is engulfed. Scientists believe that the amount of energy that escapes the black hole should be about 10 percent of the matter's rest energy (the energy equivalent of its mass according to the equation E=mc^2). But when the energy coming from the

(25)  galactic center is compared to widely held predictions based on how much matter should be falling into a theoretical central black hole, there is a discrepancy by a factor of a few thousand.

“Is there a massive black hole at the centre of our galaxy, the Milky Way?” - is a GMAT reading comprehension passage with answers. Candidates need a strong knowledge of English GMAT reading comprehension.

This GMAT Reading Comprehension consists of 4 comprehension questions. The GMAT Reading Comprehension questions are designed for the purpose of testing candidates’ abilities in understanding, analyzing, and applying information or concepts. Candidates can actively prepare with the help of GMAT Reading Comprehension Practice Questions.

Solution and Explanation

1. The primary purpose of the passage is to

1. present several theories that could account for a particular phenomenon
2. argue that a certain question needs to be reframed in light of new evidence
3. resolve an apparent inconsistency between two lines of evidence
4. explain why a certain issue remains unresolved
5. present evidence that calls into question certain assumptions of a current theory

2. According to the passage, the dynamical evidence referred to in lines 9–10 supports which of the following?

1. Recent assumptions about the velocities of stars
2. Widely held predictions about the amount of matter a black hole will engulf
3. The existence of an extremely dense object at the center of the Milky Way
4. The contention that too much energy is coming from the mass at the Milky Way's galactic center for that mass to be a black hole
5. The conclusion that a compact object of two to three million times the mass of our Sun is too dense to be anything but a black hole

3. The “serious problem” referred to in line 17 could be solved if which of the following were true?

1. Current assumptions about how much matter a black hole would engulf proved to be several thousand times too high.
2. Current assumptions about how much matter a black hole would engulf proved to be a few thousand times too low.
3. The object at the center of the Milky Way turned out to be far more dense than it is currently estimated to be.
4. The object at the center of the Milky Way turned out to be far more massive than it is currently estimated to be.
5. Matter being engulfed by a black hole radiated far more energy than is currently assumed

4. The “widely held predictions” mentioned in line 25 are predictions about the

1. compactness of objects whose mass is millions of times the mass of our Sun
2. velocities of stars orbiting the galactic center
3. amount of matter swirling around the object at the center of the Milky Way
4. amount of matter falling into a theoretical central black hole
5. amount of energy that should be coming from a black hole at the center of the Milky Way

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