How and when did supermassive black holes form?
What will be an ideal response?
The mass of a central black hole is related to the mass of the galaxy's central bulge. This implies that the central black holes formed as the central bulge formed, not later during the disk formation phase.
Galactic central bulges were formed in the first stages of galaxy formation, very early in the Universe. As clouds of gas began forming stars and falling together to form the nucleus of galaxies, supermassive black holes began to form and grow. As matter flooded into these black holes, powerful outbursts of energy erupted.
This is supported by the occurrence of quasars. Quasars are most common during the formation phase of galaxies. Very few quasars are seen at older epochs, because there was no galaxy formation to create the energy outbursts, and supermassive black holes were not yet established.
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A heavy sled and a light sled, both moving horizontally with the same speed, suddenly slide onto a rough patch of snow and eventually come to a stop
The coefficient of kinetic friction between the sleds and the rough snow is the same for both of them. Which of the following statements about these sleds are correct? (There could be more than one correct choice.) A) The friction from the snow will do more negative work on the heavy sled than on the light sled. B) The light sled will slide farther on the rough snow than the heavy sled. C) The heavy sled will slide farther on the rough snow than the light sled. D) Both sleds will slide the same distance on the rough snow before stopping. E) The friction from the snow will do the same amount of work on both sleds.
The star Arcturus shows a large proper motion, almost perpendicular to the galactic plane. What Population might we assume it belongs to, and why?
What will be an ideal response?
Granulation is caused by
a. sunspots. b. rising and sink gases below the photosphere. c. shock waves in the corona. d. the solar wind flowing away from the corona. e. the heating in the chromosphere.
Substance A has a density of 3 g/cm3 and substance B has a density of 4 g/cm3. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to
A) 1 : 4 B) 4 : 3 C) 3 : 4 D) : 1 E) 1 : 3