Inflaton Clusters and Inflaton Stars

Niemeyer, Jens C.; Easther, Richard

doi:10.48550/arxiv.1911.01661

Cited by 3 publications

(3 citation statements)

References 41 publications

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“…The same perturbation evolution applies to oscillating scalar fields with quadratic potentials. Since the pressure averages to zero over many oscillations, perturbations with k/a < 3Hm φ , where m φ is the mass of the scalar field φ, grow linearly with the scale factor [129,130] and can even form bound structures [80,591,592]. Furthermore, scalar fields with potentials that become shallower than quadratic away from their minima quickly form localized structures called oscillons that behave like massive particles [79,119].…”

Section: Growth Of Density Perturbationsmentioning

confidence: 99%

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

Allahverdi,

Amin,

Berlin

et al. 2020

Preprint

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It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. In this paper, we review various possible causes and consequences of deviations from radiation domination in the early Universe -taking place either before or after BBN -and the constraints on them, as they have been discussed in the literature during the recent years.

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Section: Growth Of Density Perturbationsmentioning

confidence: 99%

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

Allahverdi,

Amin,

Berlin

et al. 2020

Preprint

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“…AxioNyx can easily be adapted to address these cases, and boson star condensation [48] is one of the tests used to verify the code (see Appendix A 3). Further, in many early-universe scenarios the post-inflationary universe can host the formation of transient, gravitationally collapsed overdensities, whose evolution is governed by the Schrödinger-Poisson equation [49,50].…”

Section: Introductionmentioning

confidence: 99%

AxioNyx: Simulating Mixed Fuzzy and Cold Dark Matter

Schwabe,

Gosenca,

Behrens

et al. 2020

Preprint

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The distinctive effects of fuzzy dark matter are most visible at non-linear galactic scales. We present the first simulations of mixed fuzzy and cold dark matter, obtained with an extended version of the Nyx code. Fuzzy (or ultralight, or axion-like) dark matter dynamics are governed by the comoving Schrödinger-Poisson equation. This is evolved with a pseudospectral algorithm on the root grid, and with finite differencing at up to six levels of adaptive refinement. Cold dark matter is evolved with the existing N-body implementation in Nyx. We present the first investigations of spherical collapse in mixed dark matter models, focusing on radial density profiles, velocity spectra and soliton formation in collapsed halos. We find that the effective granule masses decrease in proportion to the fraction of fuzzy dark matter which quadratically suppresses soliton growth, and that a central soliton only forms if the fuzzy dark matter fraction is greater than 10%. The Nyx framework supports baryonic physics and key astrophysical processes such as star formation. Consequently, AxioNyx will enable increasingly realistic studies of fuzzy dark matter astrophysics.

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“…Reheating after inflation is an integral part of the inflationary scenario (see, for example, [1][2][3][4][5][6][7][8][9][10]). Non-nonlinear dynamics during reheating can lead to novel phenomenon such as: (i) changes in the post-inflationary equation of state (e.g., [11][12][13]), (ii) formation of defects (for example, cosmic strings [14,15]) and solitons (e.g., oscillons, [15][16][17], and related structures [18][19][20][21]), (iii) production of non-gaussian gravitational perturbations (e.g., [22][23][24]), (iv) stochastic gravitational waves (e.g., [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]), and (v) formation of primordial black holes (e.g., [45]…”

mentioning

confidence: 99%

GFiRe—Gauge Field integrator for Reheating

Lozanov

Amin

2020

J. Cosmol. Astropart. Phys.

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We present a new numerical algorithm and code, GFiRe, for solving the non-linear evolution of Abelian gauge fields coupled to complex scalar fields in homogeneous and isotropic spacetimes. We adopt a hybrid approach to solving the system: the spatial derivatives are discretized using standard Lattice Gauge Field Theory techniques, whereas the time evolution of the fields and scale factor is implemented with explicit, composite, symplectic integrators. An important property of our compound algorithm is that the discretized Gauss constraint is respected exactly, regardless of the order of the symplectic integrator. This remains true even when the background expansion is computed “self-consistently”; that is, when the expansion history is computed using spatial averaged components of the energy momentum tensor in the simulation volume. Hence, our code can also be used in cases where the fields dominate the energy density of the universe, for example, during reheating after inflation. We test the algorithm in scenarios of reheating where the inflaton is a complex scalar field with a potential ∝(2|φ|2−v2)2 and is coupled to an Abelian gauge field. Tracing the evolution of the system through complex dynamics (including resonant excitation of fields, backreaction, formation of solitons, and changes in the equation of state) in a self-consistently expanding universe, we find the energy conservation violation (<10−4) to be very stable and the Gauss constraint violation (<10−6) to be dominated by differencing noise.

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Inflaton Clusters and Inflaton Stars

Cited by 3 publications

References 41 publications

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

AxioNyx: Simulating Mixed Fuzzy and Cold Dark Matter

GFiRe—Gauge Field integrator for Reheating

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