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Old November 28th 18, 09:49 PM posted to sci.astro.research
Richard D. Saam
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Posts: 240
Default dark matter hypothesis

On 11/27/18 1:03 PM, Phillip Helbig (undress to reply) wrote:
In article ,
writes:

aIs it possible that the missing mass, the 'dark matter',
consists of two generations of burned out stars?


No.

These would be short lifetimes, hence large masses,
according to star formation theory, hence mostly black holes
or neutron stars. I don't see that as a problem.

What are the counter-arguments?


There are several.

[[Mod. note -- Microlensing studies show that at most a small fraction
of the dark matter in the Milky Way's halo can be in compact objects
of stellar mass. For example, the EROS project
https://arxiv.org/abs/astro-ph/0607207
concluded that "machos in the mass range 0.6e-7 M_sun M 15 M_sun
are ruled out as the primary occupants of the Milky Way Halo".


Right.

I don't know offhand what (if any) limits there are for M31 or maybe
other galaxies.
-- jt]]


I was co-author on a paper which pointed out that a significant fraction
of dark matter can't be on compact objects between us and quasars (i.e.
in most of the observable universe), otherwise this would be seen in
quasar light curves (which, despite some claims to the contrary, is not
the case):

http://www.astro.multivax.de:8000/he...sing_qsos.html
http://adsabs.harvard.edu/abs/2003A&A...408...17Z

[[Mod. note -- URL corrected with author's permission. -- jt]]

Also, big-bang nucleosynthesis tells us what fraction of the universe is
in baryons; there is no way that stars, being baryonic, could make up a
significant fraction of dark matter.


The Big-bang nucleosynthesis hypothesis does not warrant
such an absolute telling baryon fraction statement
in terms of on going BBN mechanistic derivation efforts
https://arxiv.org/abs/1810.05976v2
RDS