Homework #5

Extragalactic Astronomy - Fall 2012
Homework #5 - due October 1

1. Using python, matplotlib, and PyFits make a histogram of the pixel values in this image.

2. A MgII 2798 Angstrom line has a FHWM of 47 Angstroms. Describe the velocity distribution of the gas that produced this line.

3. What electron gamma factor is required to produce optical photons via synchrotron radiation in a 100 microG magnetic field?

4. What is the lifetime of the electrons in the previous problem?

5. What is the Eddington luminosity in solar luminosities for a 10⁶ solar mass black hole? How does this compare with the total luminosity of the Milky Way?

6. Find the mass accretion rate for the black hole in the previous problem in units of solar masses assuming that it is accreting at its Eddington luminosity.

7. If the line in question 2 is produced in an accretion disk, at what radius, in units of the Schwarschild radius, is the line produced?

8. In reverberation mapping, how is the characteristic radius of each emission line determined?

9. Why was NGC 1068 critical in constructing the unified model of AGN?

10. What is the K-correction?