Summary of Course

Astronomers are typically not able to make direct measurements and hence most information reaches us through electro-magnetic radiation. To interpret the radiation we detect we need to understand the physical processes that can generate it. The topics covered in this course are:

  • Fundamentals of electro-magnetic radiation and radiation transport.

  • Thermal radiation (bremsstrahlung, black-body radiation).

  • Non-thermal radiation (synchrotron, inverse Compton).

This course forms an essential link between physics and astronomy courses. It is a challenging course requiring a degree of mathematical proficiency and the use  of knowledge newly acquired from physics courses (e.g., special relativity, electro-magnetism and quantum physics). In the lectures general physical principles will be applied to astrophysical conditions to develop a general understanding of the radiative processes required to interpret astrophysical data. Going from very general statements to quantitative results requires a lot of practise in problem solving. The lectures will outline the general principles but to successfully complete this course the student must do a lot of private study understanding how to solve problems for themselves.


Learning Objectives:

  • Fundamentals of radiative transfer: the radiative transfer equation, optical depth, source function, black body radiation, the second law of thermodynamics, Kirchhoff's law, and thermal radiation and the thermodynamics of black body radiation, Einstein coefficients for spontaneous emission, absorption, stimulated emission.

  • Theory of radiation fields: Lorentz force, Maxwell's equations, electro-magnetic waves, polarization, scalar potential and vector potential.

  • Radiation from moving charges: Lienard-Wiechart potentials, beaming effect, Larmor's formula, the dipole approximation, Thomson scattering.

  • Relativistic covariance and kinematics: Lorentz transformation, the aberration of light and the beaming effect, four vectors. Covariance formulation of the special theory of relativity and electromagnetism as a relativistic theory.

  • Bremsstrahlung: free-free scattering in the small angle scattering regime, Gaunt factor, thermal and non-thermal bremsstrahlung.

  • Synchrotron radiation: the total emitted power, observed pulses, radiation from a power-law electron distribution, polarization of synchrotron emission, synchrotron self-absorption and stimulated emission.

  • Compton Scattering: Compton wavelength, inverse Compton scattering, the Compton y-parameter.

Textbook:


Radiative Processes in Astrophysics, Rybicki & Lightman, chapters 1-7


Useful:


Units & Constants

 


Grading

The grade for this class will depend on a combination of the final exam on the 5th July (50%); the test on the 31st May (25%) and the 5 homework sets which should be handed in during the quarter in as indicated on the schedule (25%).


Final Grades (7/7/7):


student number
 course work
  final exam
 final grade
1580728
 6.0
 4.0
 5.0
1554751
 -
 2.5
 2.5
1554166
 9.0
 9.0
 9.0
1553682
 7.0
 5.5
 6.5
1544233
 8.0
 6.5
 7.5
1534351
 8.0
 5.5
 7.0
1532456
 8.0
 6.0
 7.0
1528726
 6.5
 5.5
 6.0
1411926
 6.0
 5.0
 5.5


Please check I got your student number correct & let me know if you have any questions about the exam & grading before 13th July (by email) - after this I send the final grades in. The course work mark includes the exercises & mid-term test.


There will be a hertentamen on friday 21st September, 9-12. It will have the same form as the final exam (4 questions if you didn't complete the class work; 3 if you did). Please let me know by the 31st august (by email) if you want to do this exam, so I know how many people to plan for.



Schedule

Lectures typically take place on Monday and Thursday mornings from 09:15 to 11:00 in ZG161. Werkcolleges are typically on Tuesday afternoon from 13.15 to 15. There are a few exceptions, here is the schedule:



Tuesday 1st May 13.15 - 15 Lecture 1 Introduction to Radiative Transfer
Thursday 3rd May 9.15 - 11 Lecture 2
 Thermal Radiation
Monday 7th May 9.15 - 11 Lecture 3
 Radiation Fields
Tuesday 8th May 13.15 - 15
 Exercises 1
Thursday 10th May
 9.15 - 11
 Lecture 4
 Radiation from Moving Charges

Hand-in 1 due
Monday 14th May
 9.15 - 11
 Lecture 5
 Radiation & Relativity
Tuesday 15th May
 13.15 - 15
 Exercises 2


Monday 21st May
 9.15 - 11
 Lecture 6
 Relativistic Covariance & Kinematics

Hand-in 2 due
Tuesday 22nd May
 13.15 - 15
Exercises 3


Thursday 24th May
 9.15 - 11
 Lecture 7
 Radiation Processes & Bremsstrahlung

Tuesday 29th May
 13.15 - 15
 Exercises 4

Hand-in 3 due




Thursday 31st May
 9.15 - 11
 TEST!




Monday 4th June
 9.15 - 11
 Lecture 8
 Bremsstrahlung
Tuesday 5th June
 13.15 - 15
 Exercises 5
Thursday 7th June
 9.15 - 11
 Lecture 9
 Synchrotron Radiation

Hand-in 4 due
Monday 11th June
 9.15 - 11
 Lecture 10
 Synchrotron Radiation
Tuesday 12th June
 13.15 - 15
Exercises 6
Thursday 14th June
 9.15 - 11
 Lecture 11
 Synchrotron & Compton Scattering

Hand-in 5 due
Monday 18th June
 9.15 - 11
 Lecture 12
 Compton Scattering




Thursday 5th July
 9 - 12
 FINAL EXAM!

Lecture Notes

(links will activate after each lecture)

Lecture 1 : 1st May  Introduction to Radiative Transfer  (R&L Chp. 1)
Lecture 2 : 3rd May Thermal Radiation (R&L Chp. 1)
Lecture 3 : 7th May Theory of Radiation Fields  (R&L Chp. 2)
Lecture 4 : 10th May Radiation from Moving Charges (R&L Chp. 3)
Lecture 5 : 14th May Radiation & Relativity (R&L Chp 3/4)
Lecture 6 : 21st May Relativistic Covariance & Kinematics (R&L Chp 4)
Lecture 7 : 24th May Radiation Processes, Bremsstrahlung (R&L Chp 4/5)
Lecture 8 : 4th June Bremsstrahlung (R&L Chp 5)
Lecture 9 : 7th June Synchrotron Radiation (R&L Chp 6)
Lecture 10 : 11th June Synchrotron Radiation (R&L Chp 6)
Lecture 11 : 14th June Synchrotron Radiation & Compton (R&L Chp 6/7)
Lecture 12 : 18th June Compton Scattering (R&L Chp 7)

Problem Sets


Hand-In 1 : Due 11th May
Hand-In 2 : Due 21st May
Hand-In 3 : Due 29th May
Hand-In 4 : Due 7th June
Hand-In 5 : Due 14th June