Production of Purely Gravitational Dark Matter: The Case of Fermion and Vector Boson
(Submitted on 26 Mar 2019)
We consider the simplest possibility for a model of particle dark matter in which dark matter has only gravitational interaction with the standard model sector. Even in such a case, it is known that the gravitational particle production in an expanding universe may lead to a correct relic abundance depending on the inflation scale and the mass of dark matter particle. We provide a comprehensive and systematic analysis of the gravitational particle production of fermionic and vectorial dark matter, and emphasize that particles which are much heavier than the Hubble parameter but lighter than inflaton can also be produced abundantly.
And GR papers:
re
ReplyDeletearXiv:1903.10509 (cross-list from astro-ph.CO) [pdf, other]
Lyman-α forest constraints on Primordial Black Holes as Dark Matter
" Using a grid of hydrodynamic simulations exploring different values of astrophysical parameters, we obtain a marginalized upper limit on the PBH mass of fPBHMPBH∼60 M⊙(170 M⊙) at 2σ (depending on priors), which significantly improves previous constraints from the same physical observable. We also extend our predictions to non-monochromatic PBH mass distributions, ruling out large regions of the parameter space for some of the most viable PBH extended mass functions."
It would seem then that Primordial Black Holes as Dark Matter that are on order of planck mass 10^-6 grams are still viable, stable in some QG theories like LQG.
add in MOND from conformal gravity and the amount and distribution could also differ from conventional CDM
"It would seem then that Primordial Black Holes as Dark Matter that are on order of planck mass 10^-6 grams are still viable, stable in some QG theories like LQG."
ReplyDeleteThe problem with very small PBHs is that they evaporate after 13 billion+ years due to Hawking radiation (which happens at a higher temperature in small PBHs than in big ones), and there is no post-Big Bang era mechanism for creating new ones.
Per Wikipedia "primordial black holes with a mass lower than 10^11 kg would have evaporated due to Hawking radiation in a time much shorter than the age of the Universe, so they would not have survived to the present." https://en.wikipedia.org/wiki/Primordial_black_hole
I haven't seen QC theories in which Hawking radiation doesn't happen. Also, even if the decay rate is much slower, the limits on the maximum decay rates of DM are very strict. Even at 0.01% of the predicted rate, PBHs of that size aren't consistent with the data.
QG not QC. And also: "Fermi data set up the limit that less than one percent of dark matter could be made of primordial black holes with masses up to 10^13 kg. Evaporating primordial black holes would have also had an impact on the Big Bang nucleosynthesis and change the abundances of light elements in the Universe."
ReplyDeleteThe Moon is ca. 10^22 kg.
NB: Hawking (in 1971) was the first person to seriously study PBHs which were first conceived of by others in 1966.
per wiki, there's this article,
ReplyDeletehttps://en.wikipedia.org/wiki/Micro_black_hole#Black_holes_in_quantum_theories_of_gravity
Micro black hole "Micro black holes, also called quantum mechanical black holes or mini black holes, are hypothetical tiny black holes, for which quantum mechanical effects play an important role."
"Black holes in quantum theories of gravity
It is possible, in some theories of quantum gravity, to calculate the quantum corrections to ordinary, classical black holes. Contrarily to conventional black holes, which are solutions of gravitational field equations of the general theory of relativity, quantum gravity black holes incorporate quantum gravity effects in the vicinity of the origin, where classically a curvature singularity occurs. According to the theory employed to model quantum gravity effects, there are different kinds of quantum gravity black holes, namely loop quantum black holes, non-commutative black holes, asymptotically safe black holes."
there's this paper
Self-dual Black Holes in LQG: Theory and Phenomenology
Leonardo Modesto, Isabeau Prémont-Schwarz
https://arxiv.org/abs/0905.3170
"We then show that small LQBH are stable and could be a component of dark matter. Ultra-light LQBHs created shortly after the Big Bang would now have a mass of approximately "10^(-5) mp" and emit radiation with a typical energy of about 10^(13) - 10^(14) eV"
Cited by 54
https://scholar.google.com/scholar?start=30&hl=en&as_sdt=0,5&sciodt=0,5&cites=15649218733563996041&scipsc=
including Sabine Hossfelder!
Emission spectra of self-dual black holes
S Hossenfelder, L Modesto… - arXiv preprint arXiv …, 2012 - arxiv.org
We calculate the particle spectra of evaporating self-dual black holes that are potential dark matter candidates.
54 citations including recent papers from string theorists is pretty healthy I think
I'm not saying it's right, but 54 citations including 1 by Sabine Hossfelder shows active interest.
the most recent citation for this 2009 paper
Quantum Corrected Black Holes from String T-Duality
Piero Nicolini, Euro Spallucci, Michael F. Wondrak
(Submitted on 28 Feb 2019)
there is speculation that black holes lose mass via hawking radiation, until they reach a stable limit due to quantum mechanics, a ground state, and no longer continue to lose mass via hawking radiation.
this would go with your paper of dark matter produced via gravitational sector
Production of Purely Gravitational Dark Matter: The Case of Fermion and Vector Boson
Yohei Ema, Kazunori Nakayama, Yong Tang
(Submitted on 26 Mar 2019)
I do think how nice it would be if both QG and MOND vs DM could be solved in our lifetime, as sadly LHC hasn't found any SUSY or KK in Rencontres de Moriond. 2019 :(
interestingly enough
Sabine also has this paper
Emission spectra of self-dual black holes
Sabine Hossenfelder, Leonardo Modesto, Isabeau Prémont-Schwarz
(Submitted on 2 Feb 2012 (v1), last revised 15 Feb 2012 (this version, v2))
https://arxiv.org/abs/1202.0412
I'm not aware she's ever blogged on it