Abstract
The Universe may pass through an effectively matter-dominated epoch between inflation and Big Bang Nucleosynthesis during which gravitationally bound structures can form on subhorizon scales. In particular, the inflaton field can collapse into inflaton halos, forming "large scale" structure in the very early universe. We combine N-body simulations with high-resolution zoom-in regions in which the non-relativistic Schr\"odinger-Poisson equations are used to resolve the detailed, wave-like structure of inflaton halos. Solitonic cores form inside them, matching structure formation simulations with axion-like particles in the late-time universe. We denote these objects \textit{inflaton stars}, by analogy with boson stars. Based on a semi-analytic formalism we compute their overall mass distribution which shows that some regions will reach overdensities of $10^{15}$ if the early matter-dominated epoch lasts for 20 $e$-folds. The radii of the most massive inflaton stars can shrink below the Schwarzschild radius, suggesting that they could form primordial black holes prior to thermalization.
Highlights
Cosmological inflation [1,2,3,4] is a period of accelerated expansion in the early Universe
The mass distribution of inflaton stars can be predicted using the mass distribution of inflaton halos and their radii at different times found in the N-body simulations in Ref. [18]
Taking a sample of five halos with masses ranging from 8.5 g to 225 g at N = 17.3 e-folds after the end of inflation, we confirm the existence of solitonic cores in the very early universe
Summary
Cosmological inflation [1,2,3,4] is a period of accelerated expansion in the early Universe. It is possible that this era supports a lengthy period during which the local gravitational dynamics are nonlinear, leading to large overdensities [17, 18] These structures are necessarily evanescent, since thermalization must convert all remnant inflaton material into Standard Model particles and dark matter. Using an N-body particle representation of the scalar field on coarse grid levels and only solving the Schrodinger-Poisson equations in isolated, highly refined regions surrounding pre-selected halos made it possible to observe the formation and growth of solitonic cores from cosmological initial conditions. We use the same hybrid methods to extend our previous N-body simulations of the early matter-dominated post-inflationary era [18] to much smaller length scales This confirms the formation of inflaton stars at the center of inflaton halos during EMD.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
