Editing Talk:2643: Cosmologist Gift
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:Fixed; thank you. [[Special:Contributions/172.70.210.125|172.70.210.125]] 01:18, 9 July 2022 (UTC) | :Fixed; thank you. [[Special:Contributions/172.70.210.125|172.70.210.125]] 01:18, 9 July 2022 (UTC) | ||
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[https://arxiv.org/abs/2204.09143 Here's] a more recent PBH DM source than those already cited which could comport with Randall's 0.4% DM particles implication, but doesn't do so explicitly. [[Special:Contributions/172.70.206.213|172.70.206.213]] 02:35, 9 July 2022 (UTC) | [https://arxiv.org/abs/2204.09143 Here's] a more recent PBH DM source than those already cited which could comport with Randall's 0.4% DM particles implication, but doesn't do so explicitly. [[Special:Contributions/172.70.206.213|172.70.206.213]] 02:35, 9 July 2022 (UTC) | ||
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I don't see how the box containing dark matter is at all consistent with the premise of dark matter being primordial black holes. PBHs wouldn't be ubiquitously distributed through space such that any given volume contains a constant tiny number of them, would they? Black holes that are ''that'' tiny would have evaporated long ago by Hawking radiation, by my understanding. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 17:26, 11 July 2022 (UTC) | I don't see how the box containing dark matter is at all consistent with the premise of dark matter being primordial black holes. PBHs wouldn't be ubiquitously distributed through space such that any given volume contains a constant tiny number of them, would they? Black holes that are ''that'' tiny would have evaporated long ago by Hawking radiation, by my understanding. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 17:26, 11 July 2022 (UTC) | ||
− | :If dark matter was 100% particles, then a volume on Earth containing 30,000 solar neutrinos would have 12 zeptograms of dark matter, not 4. Since the box is labeled with only a third as much dark matter, the implication is that Randall might think some is clustered in MACHOs. (I'm going to ignore modified gravity, which gets more attention than non-PBH MACHOs but way less than PBHs, and has some foundational issues along with zero successful simulations compared to very successful large-scale simulations using generalized DM.) In the past decade the only MACHO DM theory with more than a handful of papers per year is PBHs, which skyrocketed in popularity after LIGO/Virgo, but are still less popular among mainstream cosmologists | + | :If dark matter was 100% particles, then a volume on Earth containing 30,000 solar neutrinos would have 12 zeptograms of dark matter, not 4. Since the box is labeled with only a third as much dark matter, the implication is that Randall might think some is clustered in MACHOs. (I'm going to ignore modified gravity, which gets more attention than non-PBH MACHOs but way less than PBHs, and has some foundational issues along with zero successful simulations compared to very successful large-scale simulations using generalized DM.) In the past decade the only MACHO DM theory with more than a handful of papers per year is PBHs, which skyrocketed in popularity after LIGO/Virgo, but are still less popular among mainstream cosmologists as 100% WIMPs. The elephant in the room is that there's lots of evidence for intermediate mass black holes (LIGO/Virgo being the most compelling, but recent indirect observations exist too) but only one out of about thirty WIMP detector experiments have painfully meager positive results, which nobody else has been able to replicate. It's been a similar situation for almost four decades now. Back in the mid-1970s dark matter was assumed to be mostly 100,000 solar mass black holes. A couple generations of constraints assuming monochromatic mass suggested it was a particle instead. But all the constraints, including microlensing, which assume all black holes have even approximately similar masses had to be rejected after the LIGO/Virgo results. |
− | :To answer your question about the | + | :To answer your question about the mass range, assuming [https://3iom3142cnb81rlnt6w4mtlr-wpengine.netdna-ssl.com/wp-content/uploads/2020/09/08-GW190521-Mass-Plot-Graveyard.png LIGO/Virgo's 3-160 solar mass range] is representative of typical black holes, and contains their median is kind of unavoidable at this point. If the median is 50 solar masses and all dark matter is black holes, that would work out to around one per star. |
− | :The group to watch [https://iopscience.iop.org/article/10.3847/1538-4357/ac332d/meta as JWST's first light comes in is Yale's,] who propose specific testable hypotheses for its deep IR source count distribution, and use a [https://twitter.com/SheerPriya/status/1472352431468003328 non-monochromatic (platycurtic) mass distribution] for black holes, which is the only correct choice for merging bodies. | + | :The group to watch [https://iopscience.iop.org/article/10.3847/1538-4357/ac332d/meta as JWST's first light comes in is Yale's,] who propose specific testable hypotheses for its deep IR source count distribution, and use a [https://twitter.com/SheerPriya/status/1472352431468003328 non-monochromatic (platycurtic) mass distribution] for black holes, which is the only correct choice for merging bodies. Another author to keep an eye on as JWST results roll in is [https://iopscience.iop.org/article/10.1088/1361-6633/ac1e31 Bernard Carr] ([https://arxiv.org/pdf/2002.12778.pdf paywall-free preprint]) known for his DM literature reviews over the years, and who has become an ardent PBH DM proponent post-LIGO/Virgo. [[Special:Contributions/162.158.166.235|162.158.166.235]] 19:06, 11 July 2022 (UTC) |
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