Jeans instability in non-minimal matter-curvature coupling gravity

Abstract

The weak field limit of the nonminimally coupled Boltzmann equation is studied, and relations between the invariant Bardeen scalar potentials are derived. The Jean’s criterion for instabilities is found through the modified dispersion relation. Special cases are scrutinised and considerations on the model parameters are discussed for Bok globules.

Gravitational instability with a dark matter background: Exploring the different scenarios

“…To proceed, one may observe from table I that a correct stability for all Bok globules is achieved if the Jeans mass is reduced by a factor 2/5 (as first noticed in [13]). This is illustrated in Fig.…”

“…One may observe that 7 of the Bok globules therein have a mass smaller than their corresponding Jeans mass (hence, they are predicted as stable), yet the observation reveals that they do experience star formation. This discrepancy between prediction and observation has been studied from various angles in the literature, and several solutions have been suggested based on modified gravity theories [12,13], nonequilibrium thermodynamics [38], and generalized uncertainty principles [39,40]. We explore here the possibility that the presence of a dark matter background can provide an explanation to this discrepancy.…”

“…We are 120 years later now and the Jeans instability still stands as an actively studied physical problem, revisited from various modern standpoints. One may cite for example its extension to general relativity [2] and to an expanding universe background [2][3][4], its formulation in the language of kinetic theory [5][6][7], its generalization to alternative gravity theories [8][9][10][11], where it regularly serves as a possible phenomenon to constraint their parameters [12,13]. The Jeans mechanism has also been extensively studied in various dark matter models [14][15][16][17][18] and for mixtures of baryonic and dark matter particles [7,19].…”

Cassini and extra force constraints to nonminimally coupled gravity with screening mechanism

“…The function f 1 (R) has a role analogous to f (R) gravity theory, and the function f 2 (R) multiplies the matter Lagrangian density giving rise to a nonminimal coupling between geometry and matter. This possibility has been extensively studied in the context of dark matter [6], dark energy [7], inflation [8], energy density fluctuations [9], gravitational waves [10], cosmic virial theorem [11], Jeans' instability and star formation in Bok globules [12]. This model has also been examined with the Newton-Schrodinger approach [13,14].…”

A note on the comments of arXiv:2003.10154 [gr-qc] to our paper Nonminimally Coupled Boltzmann Equation I: Foundations (arXiv:2002.08184 [gr-qc])

“…1 Futhermore, we regard our work as a first attempt to study the deep connection between entropy and gravity in the context of non-minimal curvature-matter coupling gravity theories (NMCCMGT), a connection which is known to exist, for instance, in black hole physics. And indeed, one of us (CG) has pursued the matter further on in a recent work [4]. In this spirit, we were quite surprised to see the curious claim that the H-theorem does not hold in nonminimally coupled curvarture-matter models.…”