http://arxiv.org/abs/1911.06228
We compute the leading order effect of non-sphericity on the maximum size $R_{\rm TA,max}$ of realistic large scale bound cosmic structures in the framework of $\Lambda{\rm CDM}$. As a first step, we focus on static or stationary axisymmetric cases, in which the departure from spherical symmetry is due to the mass density distribution or to the angular momentum of the structure. Modeled by a Kerr-de Sitter spacetime, the fractional change $\delta R_{\rm TA,max}(\theta)/R^{(0)}{\rm TA,max}$ of $R{\rm TA,max}$ of a given rotating cosmic structure, compared to a spherical one with the same mass, is negative for all values of the polar angle $\theta$, and its average over the angles is $\langle \delta R_{\rm TA,max}(\theta)/R^{(0)}{\rm TA,max}\rangle \simeq -a^2/(3 R^{(0)\, 2}{\rm TA,max})\approx -{\cal O}(v^2_{\rm out}/c^2)$, with $a=J/M$ the parameter angular momentum per unit mass of the Kerr-de Sitter background and $v_{\rm out}$ the azimuthal speed of the outmost members of the structure. In contrast, in the case of a homogeneous static spheroidal distribution the leading order effect of its eccentricity on $\langle \delta R_{\rm TA,max}(\theta)\rangle$ vanishes for all values of the eccentricity parameter.
S. Bhattacharya and T. Tomaras
Fri, 15 Nov 19
16/73
Comments: v1, 13pp
You must be logged in to post a comment.