Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Solving the Dark Matter Problem

  • Please log in to reply
2 replies to this topic

#1 CygnusBob

CygnusBob

    Vostok 1

  • -----
  • topic starter
  • Posts: 121
  • Joined: 30 Jun 2018
  • Loc: Las Vegas, NV

Posted 20 April 2019 - 11:55 AM

I believe that the solution to the dark matter problem is primordial black holes.  At the moment the most popular idea for solving the dark matter problem is WIMPS (weakly interacting massive particles).  However, after decades of searching, there is no evidence that they exist.  Unlike the WIMPS, there is a lot of evidence that black holes exist.  We even have a picture of one!  However black holes that were created as a result of stellar collapse will not solve the problem.  The reason is that in Big Bang nucleosynthesis, the light elements (helium-4, helium-3, deuterium and lithium-7) were created during the first few minutes.  The abundance of these light elements in the present universe requires that the abundance of protons and neutrons today to be only a few percent of the total critical density of the universe.  Primordial black holes that formed within the first few seconds and acted as dark matter would be consistent with the Big Bang model.

 

Also, the fact that at the core of just about every galaxy we find a supermassive black hole.  How did these black holes get there?  Did the galaxies form first and then these black holes just found their way to the cores? That seems rather unlikely.  I believe that they were there to act as seeds for galaxy formation even before stars formed.  Unlike the WIMP approach, primordial black holes might explain how the supermassive black holes formed and why they are at the cores of galaxies.

 

So to prove this we must find primordial black holes.  Stellar collapse theories predict that black holes with a mass of less than ~ 1.4 solar masses cannot form.  Thus, the discovery a black hole of less than 1.4 solar masses would make a strong case for primordial black holes.  We can do this by finding stars that are in orbit around such black holes. The way to do this would be measuring the stars radial velocity as a function of time.  Recently a black hole of greater than 4 solar masses was found in the globular cluster NGC 3201 by making radial velocity measurements.  The total change of radial velocity seen in this case exceeded 100 km/sec.  I believe that such measurements are within the range possible for amateur astronomers.  The real trick will be figuring out which stars to monitor.  Perhaps the GAIA data base can be used to find a list of candidate stars. 

 

I will admit this is a real long shot.  However the payoff would be very large.

 

Bob


Edited by CygnusBob, 20 April 2019 - 06:01 PM.


#2 ShortLobster

ShortLobster

    Sputnik

  • -----
  • Posts: 42
  • Joined: 17 Sep 2016
  • Loc: Stamford, CT, USA

Posted 20 April 2019 - 12:28 PM

A team at the Subaru telescope in Hawai'i has been conducting research based on a similar hypothesis, which was proposed as a candidate for dark matter by Hawking. 

 

Here's a recent update from them (sorry, only a link to the abstract, I don't have access from this computer):

 

https://www.nature.c...1550-019-0723-1



#3 CygnusBob

CygnusBob

    Vostok 1

  • -----
  • topic starter
  • Posts: 121
  • Joined: 30 Jun 2018
  • Loc: Las Vegas, NV

Posted 20 April 2019 - 01:36 PM

It looks like that team is looking for microlensing to find the primordial black holes.  Yes, looking for microlensing is definitely a way to go.  I think amateurs could try to do this sort of thing as well.  I started to look into the Kepler data base to see, if I could find evidence for this sort of thing.  However its not that easy because the data base is rather large.  It would be even better to have radial velocity data and microlensing data on the same star.  Seeing microlensing would really pin down the orbital inclination.  I think it would really clinch the discovery.

 

By the way, the GAIA and Kepler data bases can be downloaded by anyone.  So a discovery could be made without spending a lot of time at the telescope.

 

The only problem with microlensing is that the black hole must pass directly across the line of sight to the star.  This makes something of low probability have an even lower probability, but a success would be golden!

 

If a star is observed at closer range than most past microlensing observations, there would not be a typical transit dip as is seen with exo-planet transits.  The black hole in this case is tiny (for a less than solar mass black hole), smaller than the Earth.  However, the gravitational lensing would still work to increase the brightness of the star during the "transit".  However, the increase in brightness might only be a few percent, but probably no worse a change in magnitude than for observing exo-planet transits.

 

Bob


Edited by CygnusBob, 20 April 2019 - 04:13 PM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics