Erebons: Planck mass Dark Matter particles

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Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of the Planck frequency.

Erebon theory is actually part of Penrose' Conformal Cyclic Cosmology scheme, which is a competitor to the theory of inflation. Moreover, Penrose claims erebons may have already been detected by accident,
quite analogous to the first accidental detection of the CMB. Here is one of the lectures from July 2017 in which Penrose first introduces the idea of erebons:

 

[ohwilleke]

The trouble with Planck mass (1.220910×10¹⁹ GeV/c²⁾ dark matter with only gravitational interactions (i.e. collisionless dark matter) is that there is already a mountain of evidence to disfavor it observationally for the same reasons as pretty much any collisionless cold dark matter candidate of 100 GeV/c² or more, unless it moves with warm dark matter velocities.

For example, the body text of Lin Wang, Da-Ming Chen, Ran Li "The total density profile of DM halos fitted from strong lensing" (July 31, 2017) explains:

It is now well established that, whatever the manners the baryon effects are included in the collisionless CDM N-body cosmological simulations, if the resultant density profiles can match the observations of rotation curves, they cannot simultaneously predict the observations of strong gravitational lensing (under- or over-predict). And for the case of typical galaxies, the reverse is also true, namely, the SIS profile preferred by strong lensing cannot be supported by the observations of rotation curves near the centers of galaxies.

Similarly:

The more we go deep into the knowledge of the dark component which embeds the stellar component of galaxies, the more we realize the profound interconnection between them. We show that the scaling laws among the structural properties of the dark and luminous matter in galaxies are too complex to derive from two inert components that just share the same gravitational field. In this paper we review the 30 years old paradigm of collisionless dark matter in galaxies. We found that their dynamical properties show strong indications that the dark and luminous components have interacted in a more direct way over a Hubble Time. The proofs for this are the presence of central cored regions with constant DM density in which their size is related with the disk length scales. Moreover we find that the quantity ρDM(r,L,RD)ρ⋆(r,L,RD) shows, in all objects, peculiarities very hardly explained in a collisionless DM scenario.

Paolo Salucci and Nicola Turini, "Evidences for Collisional Dark Matter In Galaxies?" (July 4, 2017).

The bullet cluster is also a huge problem for this kind of model:

To quantify how rare the bullet-cluster-like high-velocity merging systems are in the standard LCDM cosmology, we use a large-volume 27 (Gpc/h)^3 MICE simulation to calculate the distribution of infall velocities of subclusters around massive main clusters. The infall-velocity distribution is given at (1-3)R_{200} of the main cluster (where R_{200} is similar to the virial radius), and thus it gives the distribution of realistic initial velocities of subclusters just before collision. These velocities can be compared with the initial velocities used by the non-cosmological hydrodynamical simulations of 1E0657-56 in the literature. The latest parameter search carried out recently by Mastropietro and Burkert showed that the initial velocity of 3000 km/s at about 2R_{200} is required to explain the observed shock velocity, X-ray brightness ratio of the main and subcluster, and displacement of the X-ray peaks from the mass peaks. We show that such a high infall velocity at 2R_{200} is incompatible with the prediction of a LCDM model: the probability of finding 3000 km/s in (2-3)R_{200} is between 3.3X10^{-11} and 3.6X10^{-9}. It is concluded that the existence of 1E0657-56 is incompatible with the prediction of a LCDM model, unless a lower infall velocity solution for 1E0657-56 with < 1800 km/s at 2R_{200} is found.

Jounghun Lee, Eiichiro Komatsu, "Bullet Cluster: A Challenge to LCDM Cosmology" (May 22, 2010).

 

[kodama]

so what is favored? just warm dark matter with k-ev mass?

 

[ohwilleke]

That, or modified gravity, or something new that either hasn't been devised yet or has received little attention and analysis. My bets are on modified gravity, but WDM with kev mass particles and a few axion-like theories are still in the running in the particle dark matter camp.

Most notably, self-interacting dark matter theories are also in deep trouble (and like modified gravity, SIDM models also require a new or modified force as well as BSM particles).

 

[kodama]

That, or modified gravity, or something new that either hasn't been devised yet or has received little attention and analysis. My bets are on modified gravity, but WDM with kev mass particles and a few axion-like theories are still in the running in the particle dark matter camp.

Most notably, self-interacting dark matter theories are also in deep trouble (and like modified gravity, SIDM models also require a new or modified force as well as BSM particles).

I've offered this before - modified gravity that reproduces the success of MOND on the galaxy scale. Planck-mass ultra light quantum mechanical black holes. no modifcation to the standard model, as Planck-mass ultra light quantum mechanical black holes are not fundamental particles. the quantity of dark matter is reduced in modified gravity. so MOND + dark matter, since Planck-mass ultra light quantum mechanical black holes could explain BAO and large scale structure and gravitational lensing. MOND would reduce how much dark matter is needed. dark matter as micro black holes would not require any changes in the standard model.

 

[ohwilleke]

I've offered this before - modified gravity that reproduces the success of MOND on the galaxy scale. Planck-mass ultra light quantum mechanical black holes. no modifcation to the standard model, as Planck-mass ultra light quantum mechanical black holes are not fundamental particles. the quantity of dark matter is reduced in modified gravity. so MOND + dark matter, since Planck-mass ultra light quantum mechanical black holes could explain BAO and large scale structure and gravitational lensing. MOND would reduce how much dark matter is needed. dark matter as micro black holes would not require any changes in the standard model.

I don't think you are quite understanding what I mean to say, which is that the self-interaction between dark matter particles in a SIDM theory is the new force.

 

[kodama]

oh i was thinking of your other point that modified gravity, but that doesn't explain BAO and large scale structure formation.