Physics 616

  • Prof. Andrew W. Steiner
    (or Andrew or "Dr. Steiner")
  • Office hour: 103 South College, Thursday 11am
  • Email:
  • Homework: Electronically as .pdf
  • You may work with each other on the homework, but you must write the solution in your own words
Use down and up arrows to proceed to the next or previous slide.


Distance Indicators

Distance Indicators I - Tully-Fisher

  • Phenomenological correlation between angular velocity of stars in a galaxy around center and the luminosity of that galaxy
  • Standard correlation includes only stars
  • Slightly different correlations in different bands
  • Found tighter correlation when luminosity includes stars and gas
  • Mass $\propto v^{3-4}$
  • Originally applied to spiral galaxies, applied to ellipticals in "Faber-Jackson" relation
  • Also evidence for dark matter
Tully and Fisher (1977), this figure from Karachentsev et al. (2002)

Distance Indicators II - Type Ia supernova

  • White dwarf always has a mass near the Chandrasekhar limit
  • Luminosity correlated with rise and decline time of the emitted light
  • Emitted light is from the decay of Nickel-56
  • "Phillips relationship"
  • In detail, $$ M_{\mathrm{max}}(B) = -21.7 + 2.7 \Delta m_{15}(B) $$
  • Calibrate correlation with other distance measurements
  • "Standardizable candle"
From Phillips

More General Cosmological Models

More General Cosmological Models II

Cosmic Microwave Background

Cosmic Microwave Background


Dipole Anisotropy

Sunayev-Zel'dovich effect

Big Bang Nucleosynthesis

Big Bang Nucleosynthesis II

  • More helium-4 in the universe than can be explained by stellar evolution
  • Deuterium is difficult to create (low binding energy)
  • Observational determinations generally agree with model predictions based on CMB determinations of $\eta$
  • Except lithium 7, "no solution that is either not tuned or requires substantial departures from standard model physics" Cyburt et al. (2016)
  • Stellar depletion of lithium-7 to explain why observed value is smaller than BBN prediction

Big Bang Nucleosynthesis III

Cold Dark Matter

  • Cold if (i) non-relativistic, and (at the time of radiation-matter equality) (ii) dissipationless and (iii) collisionless
  • Cold dark matter leads to bottom-up structure formation
  • Bottom-up: small objects clump first, then merge to form larger object
  • What is the opposite of "bottom-up"?
  • WIMPs and axions

WIMP Miracle

Group Work