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If this is recent information, how does it bear on dark matter, i.e. machos? An excellent read, btw.
by wrycoder 8y ago
If this is recent information, how does it bear on dark matter, i.e. machos? An excellent read, btw.
- antognini 8y agoThis is not super recent information. There have been estimates that there are about as many rogue planets as stars since 2011. There's still a pretty wide variation in the estimate of the number of rogue planets from study to study, so the frequency is pretty uncertain. But even if the numbers are on the high side, it's not anywhere close to explain dark matter. Supposing that there are 10 Jupiter mass planets for every star, that would only increase the luminous mass of the Galaxy by 1%. Dark matter accounts for more than ten times the mass of the Galaxy as luminous matter.
- SubiculumCode 8y agoNot a physicist. If napkin calculation goes, that's 1000 Jupiters per star. Is that really improbable? There is a lot of space outside of solar system radii.
- antognini 8y agoI think it would require more like 10,000 Jupiters per star to account for dark matter in the Galaxy. The issue is that these microlensing surveys put an upper bound on the number of rogue Jupiters that can be floating around and this bound is much less than 10,000 per star.
- Eesais2e 8y agoCan microlensing account for the whole continuum of black hole sizes that might be floating around in the galactic halo?