For this I guess you need

  • accurate circular velocity measurements of the stars in the galaxy
  • a decent luminosity profile for the galaxy
  • some analysis which looks at the discrepancy between the two

The Milky Way seems to have been studied a lot, with decent mass models (e.g. McMillan 2011) and circular velocity observations (e.g. Eilers 2019 which includes mean observational data actually tabulated rather than graphed) is readily available.

What I'm wondering is which other galaxies have this kind of data? Or indeed at least have decent luminosity profiles & circular velocity observations even if the halo has yet to be analysed.

Massive thank you!

  • 1
    $\begingroup$ The dark matter halos usually extend much farther out than the star distribution. The velocity maps of atomic hydrogen help to go farther than the star distribution, but still do not extend as far as the dark matter. The precision of these velocity measurements are typically very high, as are the photometric profiles, so there is no best except that near is better than far and edge on is better than face on for this. Nearly every major galaxy within 10 Mpc was measured decades ago. $\endgroup$
    – eshaya
    Commented Mar 27, 2022 at 16:04

1 Answer 1


To my knowledge, strong gravitational lensing models exquisitely constrain the distribution of a galaxy's total mass (which is mostly dark matter; on average about 85%, if I remember correctly). Studying those systems would allow you to find the best mass profile of the dark matter halo and some parameters, such as the halo radius. Moreover, if the best lensing models are those relative to galaxies showing Einstein rings, I would consider those systems. In particular, I would consider data from the JWST. Here you can find some HST examples of rings (in bluish colors) around bright galaxies (in reddish colors): https://www.nasa.gov/feature/astronomers-revisit-first-einstein-ring-in-archival-data


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