Bremsstrahlung: Free-Free Emission

• Order of Magnitude Expectations
• Theory: Classical, Non-Relativistic Case
• thermal bremsstrahlung
• self-absorption spectrum from here
• awesome example: intracluster medium
  • galaxy clusters seen in optical light: Virgo, Coma, Abell 1689
  • intracluster medium seen in X-rays: Virgo here and here, Coma, Abell 1689
  • Coma X-ray spectrum from Gastaldello+ 2015
• awesome example: supernova remnants
  • Cas A: Chandra X-ray image, spectrum
  • SN 1006: Chandra X-ray image, spectrum
• awesome examples: eROSITA sky and bubbles; compare gamma-raay Fermi bubbles and microwave WMAP/Planck haze

Radiation and Bound States

Atomic States

• order of magnitude sketch
• sketches of l states
• populating electronic states atomic data online, including, e.g., energy levels of neutral carbon, silicon
• awesome example: technetium seen in stars