Concept explainers
(a)
The speed at which the blazar is moving away from the Earth.
Answer to Problem 26Q
The speed at which the blazar is moving away from the Earth is
Explanation of Solution
Given:
The red shift of the given blazar is,
Formula used:
The expression for the ratio of the speed of the object moving away from the earth and speed of the light is given by,
Here,
Calculation:
The speed of the blazar in moving away from the Earth is calculated as,
Solve further,
Conclusion:
The speed at which the blazar is moving away from the earth is
(b)
The time for which the fluctuation lasted for an astronomers within the blazar’s host galaxy.
Answer to Problem 26Q
The time for which the fluctuation lasted for an astronomer within the blazar’s host galaxy is
Explanation of Solution
Given:
The time span for which the fluctuation was seen on the earth is
Formula used:
The expression for the time dilation as per theory of relativity is given by,
Here,
Calculation:
The time for which the fluctuation lasted for an astronomer within the blazar’s host galaxy is calculated as,
Conclusion:
Therefore, the time for which the fluctuation lasted for an astronomer within the blazar’s host galaxy is
(c)
The maximum size of the region for emitting energy by the blazar.
Answer to Problem 26Q
The maximum size of the region for emitting energy by the blazar is
Explanation of Solution
Given:
The time for which the fluctuation lasted for an astronomer within the blazar’s host galaxy is
Formula used:
The size of the blazar is given by,
Here,
Calculation:
The maximum size of energy emitting region of the blazar is calculated as,
Solve further,
Conclusion:
The maximum size of the region for emitting energy by the blazar is
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Chapter 24 Solutions
Universe: Stars And Galaxies
- In the Check Your Learning section of Example 27.1, you were told that several lines of hydrogen absorption in the visible spectrum have rest wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm. In a spectrum of a distant galaxy, these same lines are observed to have wavelengths of 492 nm, 521 nm, 583 nm, and 787 nm, respectively. The example demonstrated that z=0.20 for the 410 nm line. Show that you will obtain the same redshift regardless of which absorption line you measure.arrow_forwardFigure P9.21 shows a jet of material (at the upper right) being ejected by galaxy M87 (at the lower left). Such jets are believed to be evidence of supermassive black holes at the center of a galaxy. Suppose two jets of material from the center of a galaxy are ejected in opposite directions. Both jets move at 0.750c relative to the galaxy center. Determine the speed of one jet relative to the other. Figure P9.21arrow_forwardesc a) 10 points) Gravitational Time Dilation. The escape velocity from the surface (radius r) of a star or planet of mass M is given by the formula v = (2GM/r). Use this expression to write the time-dilation fraction, At/t, in terms of the ratio of vesc to the speed of light, c. Hint: This is just a simple exercise in substitution. 5.98 x 1024 kg b) (10 points) Extra Lifetime on the Surface of Earth. The Earth has mass MEarth and radius REarth 6.38 x 10 m. What is the fractional time-dilation (At/t) for someone on the Earth's surface? How much longer (At) is a typical lifetime on the surface of Earth, compared to someone in deep space, far away from Earth? Assume a typical human life span of t = 80 years. Iarrow_forward
- If a galaxy moving away from the Earth has a speed of 1000 km/s and emits 656 nm light characteristic of hydrogen (the most common element in the universe). Why is the speed of the Earth in its orbit negligible here?arrow_forwardA galaxy is observed to recede from Earth with an approximate speed of 0.81c. Approximately how far d from Earth is this galaxy? Give an answer in units of megaparsecs (Mpc). d = ? Mpc How long ago t was the light that we see emitted by the galaxy? Give an answer in units of years. t = ? yearsarrow_forwardIn 1998 a galaxy named RD1 was discovered with a redshift of 5.34. (a) What is the speed of this galaxy with respect to us? (b) Use Hubble’s law to determine how far away the galaxy is.arrow_forward
- The visible section of the Universe is a sphere centered on the bridge of your nose, with radius 13.7 billion light-years. (a) Explain why the visible Universe is getting larger, with its radius increasing by one light-year in every year. (b) Find the rate at which the volume of the visible section of the Universe is increasing.arrow_forwardName: Hubble Distances Redshift z parameter The relativistic redshift is parametrized by z and given by Δ In terms of the scale factor, 2= X do - de de 1+z= ao a (2) Problem 01. Find the redshift z for a Hydrogen spectral line originally at 656 nm which has been observed at a wavelength of 1.64 μm. Astro 001 Fall 2022 Problem 02. How much smaller was the universe when this light was emitted? U₁ = DHO Using the redshift to measure the velocity, we find D~ (1) 0.1 Hubble's Law Hubble's Law states that the recession velocity of a redshifted galaxy is given by the product of the distance and the Hubble constant. (3) ZC Ho where c = 3 x 108 m/s and Ho = 2.3 x 10-18 s in standard units. The standard measurement of the Hubble constant is Ho = 71 (km/s)/Mpc. Problem 03. What is the distance in Mpc and ly to the galaxy measured in problem 01? 1 pc = 3.26 ly.arrow_forwardThe kinetic energy of the ejecta from a supernova explosion is about 10^44 joules. Use the formula for kinetic energy to determine the typical speed at which matter is ejected from a supernova with a mass of 10 Msun. Compare that speed with the Sunʹs orbital speed around our galaxy. Based on your comparison, do you think the galaxyʹs gravity would be strong enough to retain the supernova debris if there were no interstellar medium to slow it down? Explain.arrow_forward
- The Millennium Falcon is approximately 35.2 m long. There are conflicting reports, but the Falcon made the Kessel Run in approximately 12.27 parsecs. This is an odd unit to measure speed with as a parsec is a unit of length equal to 3.26 light-year. The science FICTION comes in when you consider that ships in Star Wars use hyperdrive to travel faster than the speed of light, so they are able to make jumps through space. Han Solo picked difficult or dangerous points to jump between to make the trip so short. Let's imagine that the Millennium Falcon travels at 0.96c during the 12.27 parsec Kessel Run. What distance, in light-year, does an observer at the finish line measure for the trip? Don't forget to convert parsec to light-year. X light-year What distance, in light-year, does Han Solo measure for the trip as he pilots the ship? light-year Which person measures the proper distance of the trip? Which person would measure the proper length of the Millennium Falcon?arrow_forwardThe Millennium Falcon is approximately 35.2 m long. There are conflicting reports, but the Fàlcon made the Kessel Run in approximately 12.95 parsecs. This is an odd unit to measure speed with as a parsec is a unit of length equal to 3.26 light-year. The science FICTION comes in when you consider that ships in Star Wars use hyperdrive to travel faster than the speed of light, so they are able to make jumps through space. Han Solo picked difficult or dangerous points to jump between to make the trip so short.tet's imagine that the Millennium Falcon travels at 0.95c during the 12.95 parsec Kessel Run. What distance, in light-year, does an observer at the finish line measure for the trip? Don't forget to convert parsec to light-year. light-year What distance, in light-year, does Han Solo measure for the trip as he pilots the ship? | light-yeararrow_forwardConsider the energy-momentum tensor Tμv = (p+p) uu+P9μ applied to the matter/energy distribution in the universe on large scales, and assume an equation of state of the form p = wp, with w a constant. Determine the type of matter/energy dominating the universe if the energy-momentum tensor is traceless, that is, T"μ = 0.arrow_forward
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