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DilithiumMatrix
DilithiumMatrix
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Good numbers for this have only been coming out for a decade or so, so its a relatively new topic. There does seem to be a strong tendency for dwarf and satellite galaxies to have much lowerhigher mass-to-light ratios, and correspondingly smaller baryon-to-DM ratios. See, for example, Stringer+2009, Strigari+2008.

These observations are backed up by simulations which show that lower total mass galaxies have larger portions of baryons blown off by feedback processes from star formation, and supernovae. Lower total mass galaxies tend to have mass fractions of baryons much smaller than the cosmological average ($\sim 15\%$). Once you get to larger mass (Milky-Way like, $L_\star$-ish) galaxies, the gravity is sufficient to keep most of the material there, despite feedback --- bringing the baryon fraction closer to average. In much higher mass galaxies---the most massive ellipticals---it seems that the fraction drops again, likely due to AGN feedback processes --- but this is a very active an uncertain area of research.

In addition to being lower mass and thus better stripped by stellar feedback, satellite galaxies can also be stripped by interactions (tidal and dynamical) with the central/host galaxy.

Good numbers for this have only been coming out for a decade or so, so its a relatively new topic. There does seem to be a strong tendency for dwarf and satellite galaxies to have much lower mass-to-light ratios, and correspondingly smaller baryon-to-DM ratios. See, for example, Stringer+2009, Strigari+2008.

These observations are backed up by simulations which show that lower total mass galaxies have larger portions of baryons blown off by feedback processes from star formation, and supernovae. Lower total mass galaxies tend to have mass fractions of baryons much smaller than the cosmological average ($\sim 15\%$). Once you get to larger mass (Milky-Way like, $L_\star$-ish) galaxies, the gravity is sufficient to keep most of the material there, despite feedback --- bringing the baryon fraction closer to average. In much higher mass galaxies---the most massive ellipticals---it seems that the fraction drops again, likely due to AGN feedback processes --- but this is a very active an uncertain area of research.

In addition to being lower mass and thus better stripped by stellar feedback, satellite galaxies can also be stripped by interactions (tidal and dynamical) with the central/host galaxy.

Good numbers for this have only been coming out for a decade or so, so its a relatively new topic. There does seem to be a strong tendency for dwarf and satellite galaxies to have much higher mass-to-light ratios, and correspondingly smaller baryon-to-DM ratios. See, for example, Stringer+2009, Strigari+2008.

These observations are backed up by simulations which show that lower total mass galaxies have larger portions of baryons blown off by feedback processes from star formation, and supernovae. Lower total mass galaxies tend to have mass fractions of baryons much smaller than the cosmological average ($\sim 15\%$). Once you get to larger mass (Milky-Way like, $L_\star$-ish) galaxies, the gravity is sufficient to keep most of the material there, despite feedback --- bringing the baryon fraction closer to average. In much higher mass galaxies---the most massive ellipticals---it seems that the fraction drops again, likely due to AGN feedback processes --- but this is a very active an uncertain area of research.

In addition to being lower mass and thus better stripped by stellar feedback, satellite galaxies can also be stripped by interactions (tidal and dynamical) with the central/host galaxy.

Source Link
DilithiumMatrix
DilithiumMatrix
  • 14.3k
  • 2
  • 41
  • 71

Good numbers for this have only been coming out for a decade or so, so its a relatively new topic. There does seem to be a strong tendency for dwarf and satellite galaxies to have much lower mass-to-light ratios, and correspondingly smaller baryon-to-DM ratios. See, for example, Stringer+2009, Strigari+2008.

These observations are backed up by simulations which show that lower total mass galaxies have larger portions of baryons blown off by feedback processes from star formation, and supernovae. Lower total mass galaxies tend to have mass fractions of baryons much smaller than the cosmological average ($\sim 15\%$). Once you get to larger mass (Milky-Way like, $L_\star$-ish) galaxies, the gravity is sufficient to keep most of the material there, despite feedback --- bringing the baryon fraction closer to average. In much higher mass galaxies---the most massive ellipticals---it seems that the fraction drops again, likely due to AGN feedback processes --- but this is a very active an uncertain area of research.

In addition to being lower mass and thus better stripped by stellar feedback, satellite galaxies can also be stripped by interactions (tidal and dynamical) with the central/host galaxy.