RE: The Klan Is Not Going To Be Happy About This
March 4, 2018 at 10:56 am
(This post was last modified: March 4, 2018 at 10:59 am by polymath257.)
OK, I read a followup article on this phenomenon:
https://arxiv.org/pdf/1802.10577.pdf
The mechanism of action here isn't what I thought it was from the popular articles.
What we are detecting is the time when the first stars form, 'Cosmic Dawn'. Just before this, the hydrogen is a bit cooler than the background radiation, but after it is much hotter because it is heated up by the new stars. We are focusing on that prior temperature, just before the stars actually light up.
What is found is that the temperature of that hydrogen is much lower than the predicitons made from pure astrophysics. Given the usual scenario, this low temeprature is hard to explain. BUT, it is expected that dark matter, because of its unique properties, has a much lower temperature than ordinary matter (the same happens for neutrinos, by the way), in part because dark matter doesn't interact strongly with ordinary matter, so it is not heated up by that matter.
The potential explanation for the cool matter, however, is that there is *some* interaction between the dark matter and the ordinary matter. And that interaction cools the ordinary matter (and probably heats the dark matter). Papers are now coming out trying to constrain those interactions, and there is already an estimate for the mass of any dark matter particle.
Several things are surprising and really cool (j/k) here. One is that if dark matter and ordinary matter interact in this way, this opens up more possibilities for detecting dark matter, and potentially making in our labs to study closer. The second surprise is the low mass of the dark matter particles implied by this study. Previous estimates of dark matter mass were much larger. This could have major impact on the search for dark matter particles, making it much easier in some senses.
Now, these measurements need to be verified still and the theoretical possibilities examined carefully. This is still *very* early in the process and it is quite possible this signal will go away or have a more ordinary explanation. Nonetheless, this is very exciting.
And, we have several experiments that were already being built that will be relevant to chekcing these results. So it should not be long before we know much more.
https://arxiv.org/pdf/1802.10577.pdf
The mechanism of action here isn't what I thought it was from the popular articles.
What we are detecting is the time when the first stars form, 'Cosmic Dawn'. Just before this, the hydrogen is a bit cooler than the background radiation, but after it is much hotter because it is heated up by the new stars. We are focusing on that prior temperature, just before the stars actually light up.
What is found is that the temperature of that hydrogen is much lower than the predicitons made from pure astrophysics. Given the usual scenario, this low temeprature is hard to explain. BUT, it is expected that dark matter, because of its unique properties, has a much lower temperature than ordinary matter (the same happens for neutrinos, by the way), in part because dark matter doesn't interact strongly with ordinary matter, so it is not heated up by that matter.
The potential explanation for the cool matter, however, is that there is *some* interaction between the dark matter and the ordinary matter. And that interaction cools the ordinary matter (and probably heats the dark matter). Papers are now coming out trying to constrain those interactions, and there is already an estimate for the mass of any dark matter particle.
Several things are surprising and really cool (j/k) here. One is that if dark matter and ordinary matter interact in this way, this opens up more possibilities for detecting dark matter, and potentially making in our labs to study closer. The second surprise is the low mass of the dark matter particles implied by this study. Previous estimates of dark matter mass were much larger. This could have major impact on the search for dark matter particles, making it much easier in some senses.
Now, these measurements need to be verified still and the theoretical possibilities examined carefully. This is still *very* early in the process and it is quite possible this signal will go away or have a more ordinary explanation. Nonetheless, this is very exciting.
And, we have several experiments that were already being built that will be relevant to chekcing these results. So it should not be long before we know much more.
