scholarly journals Smallest remnants of early matter domination

2021 ◽  
Vol 2021 (12) ◽  
pp. 026
Author(s):  
Gabriela Barenboim ◽  
Nikita Blinov ◽  
Albert Stebbins
Keyword(s):  
Dark Matter ◽  
Power Spectra ◽  
Big Bang ◽  
Rapid Expansion ◽  
Small Scale ◽  
Late Time ◽  
Big Bang Nucleosynthesis ◽  
Density Profiles ◽  
Short Period ◽  
Linear Effects

Abstract The evolution of the universe prior to Big Bang Nucleosynthesis could have gone through a phase of early matter domination which enhanced the growth of small-scale dark matter structure. If this period was long enough, self-gravitating objects formed prior to reheating. We study the evolution of these dense early halos through reheating. At the end of early matter domination, the early halos undergo rapid expansion and eventually eject their matter. We find that this process washes out structure on scales much larger than naively expected from the size of the original halos. We compute the density profiles of the early halo remnants and use them to construct late-time power spectra that include these non-linear effects. We evolve the resulting power spectrum to estimate the properties of microhalos that would form after matter-radiation equality. Surprisingly, cosmologies with a short period of early matter domination lead to an earlier onset of microhalo formation compared to those with a long period. In either case, dark matter structure formation begins much earlier than in the standard cosmology, with most dark matter bound in microhalos in the late universe.

scholarly journals Velocity-dependent self-interacting dark matter from thermal freeze-out and tests in direct detections

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Lian-Bao Jia
Keyword(s):  
Dark Matter ◽  
Wave Process ◽  
Massive Particle ◽  
Big Bang ◽  
Small Scale ◽  
Big Bang Nucleosynthesis ◽  
Light Scalar ◽  
Nucleus Scattering ◽  
Main Component ◽  
Wimp Search

Abstract A small fraction of millicharged dark matter (DM) is considered in the literature to give an interpretation of the enhanced 21-cm absorption at the cosmic dawn. Here we focus on the case that the main component of DM is self-interacting dark matter (SIDM), motivated by the small-scale problems. For self-interactions of SIDM being compatible from dwarf to cluster scales, velocity-dependent self-interactions mediated by a light scalar $$\phi $$ϕ are considered. For fermionic SIDM $$\Psi $$Ψ, the main annihilation mode $$\Psi \bar{\Psi } \rightarrow \phi \phi $$ΨΨ¯→ϕϕ is a p-wave process. The thermal transition of SIDM $$\rightleftarrows \phi \rightleftarrows $$⇄ϕ⇄ standard model (SM) particles in the early universe sets a lower bound on couplings of $$\phi $$ϕ to SM particles, which has been excluded by direct detections of DM, and here we consider SIDM in thermal equilibrium via millicharged DM. For $$m_\phi>$$mϕ> twice millicharged DM mass, $$\phi $$ϕ could decay quickly and avoid excess energy injection to big bang nucleosynthesis. Thus, the $$\phi $$ϕ–SM particle couplings could be very tiny and evade direct detections of DM. The picture of weakly interacting massive particle (WIMP)–nucleus scattering with contact interactions fails for SIDM–nucleus scattering with a light mediator, and a method is explored in this paper with which a WIMP search result can be converted into the hunt for SIDM in direct detections.

scholarly journals Cannibalism's lingering imprint on the matter power spectrum

2022 ◽  
Vol 2022 (01) ◽  
pp. 017
Author(s):  
Adrienne L. Erickcek ◽  
Pranjal Ralegankar ◽  
Jessie Shelton
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Big Bang ◽  
Small Scale ◽  
Thermal Bath ◽  
Dark Sector ◽  
Big Bang Nucleosynthesis ◽  
Particle Properties ◽  
Matter Power Spectrum ◽  
Expansion Of The Universe

Abstract The early universe may have contained internally thermalized dark sectors that were decoupled from the Standard Model. In such scenarios, the relic dark thermal bath, composed of the lightest particle in the dark sector, can give rise to an epoch of early matter domination prior to Big Bang Nucleosynthesis, which has a potentially observable impact on the smallest dark matter structures. This lightest dark particle can easily and generically have number-changing self-interactions that give rise to “cannibal” behavior. We consider cosmologies where an initially sub-dominant cannibal species comes to temporarily drive the expansion of the universe, and we provide a simple map between the particle properties of the cannibal species and the key features of the enhanced dark matter perturbation growth in such cosmologies. We further demonstrate that cannibal self-interactions can determine the small-scale cutoff in the matter power spectrum even when the cannibal self-interactions freeze out prior to cannibal domination.

scholarly journals Impact of neutrino properties and dark matter on the primordial Lithium production

2019 ◽  
Vol 28 (08) ◽  
pp. 1950065 ◽  
Author(s):  
Tahani R. Makki ◽  
Mounib F. El Eid ◽  
Grant J. Mathews
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Nuclear Physics ◽  
Big Bang ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Chemical Potentials ◽  
The Creation ◽  
The Universe

The light elements and their isotopes were produced during standard big bang nucleosynthesis (SBBN) during the first minutes after the creation of the universe. Comparing the calculated abundances of these light species with observed abundances, it appears that all species match very well except for lithium (7Li) which is overproduced by the SBBN. This discrepancy is rather challenging for several reasons to be considered on astrophysical and on nuclear physics ground, or by invoking nonstandard assumptions which are the focus of this paper. In particular, we consider a variation of the chemical potentials of the neutrinos and their temperature. In addition, we investigated the effect of dark matter on 7Li production. We argue that including nonstandard assumptions can lead to a significant reduction of the 7Li abundance compared to that of SBBN. This aspect of lithium production in the early universe may help to resolve the outstanding cosmological lithium problem.

scholarly journals Dark matter freeze-out during matter domination

2018 ◽  
Vol 33 (29) ◽  
pp. 1850181 ◽  
Author(s):  
Saleh Hamdan ◽  
James Unwin
Keyword(s):  
Dark Matter ◽  
Energy Density ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Hubble Rate ◽  
Dark Matter Relic Density ◽  
Relic Density ◽  
The Masses ◽  
The Universe ◽  
Freeze Out

We highlight the general scenario of dark matter freeze-out while the energy density of the universe is dominated by a decoupled non-relativistic species. Decoupling during matter domination changes the freeze-out dynamics, since the Hubble rate is parametrically different for matter and radiation domination. Furthermore, for successful Big Bang Nucleosynthesis the state dominating the early universe energy density must decay, this dilutes (or repopulates) the dark matter. As a result, the masses and couplings required to reproduce the observed dark matter relic density can differ significantly from radiation-dominated freeze-out.

scholarly journals Revisiting constraints on small scale perturbations from big-bang nucleosynthesis

2016 ◽  
Vol 94 (4) ◽  
Author(s):  
Keisuke Inomata ◽  
Masahiro Kawasaki ◽  
Yuichiro Tada
Keyword(s):  
Big Bang ◽  
Small Scale ◽  
Big Bang Nucleosynthesis

scholarly journals Probes for 4th Generation Constituents of Dark Atoms in Higgs Boson Studies at the LHC

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Yu. Khlopov ◽  
R. M. Shibaev
Keyword(s):  
Dark Matter ◽  
Higgs Boson ◽  
Big Bang ◽  
Decay Rates ◽  
Neutral Atoms ◽  
Big Bang Nucleosynthesis ◽  
Charged Species ◽  
The Difference ◽  
The Universe ◽  
Direct Dark Matter

The nonbaryonic dark matter of the Universe can consist of new stable charged species, bound in heavy neutral “atoms” by ordinary Coulomb interaction. StableU-(anti-U)quarks of 4th generation, bound in stable colorless(U- U- U-)clusters, are captured by the primordial helium, produced in Big Bang Nucleosynthesis, thus forming neutral “atoms” of O-helium (OHe), a specific nuclear interacting dark matter that can provide solution for the puzzles of direct dark matter searches. However, the existence of the 4th generation quarks and leptons should influence the production and decay rates of Higgs boson and is ruled out by the experimental results of the Higgs boson searches at the LHC, if the Higgs boson coupling to 4th generation fermions is not suppressed. Here, we argue that the difference between the three known quark-lepton families and the 4th family can naturally lead to suppression of this coupling, relating the accelerator test for such a composite dark matter scenario to the detailed study of the production and modes of decay of the 125.5 GeV boson, discovered at the LHC.

scholarly journals THE STATUS OF NEUTRINO MASS

1998 ◽  
Vol 13 (25) ◽  
pp. 4409-4423 ◽  
Author(s):  
DAVID O. CALDWELL
Keyword(s):  
Dark Matter ◽  
Neutrino Mass ◽  
Heavy Element ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Atmospheric Neutrinos ◽  
Big Bang Nucleosynthesis ◽  
Robust Solution ◽  
The Status ◽  
Mass Pattern

New experimental results, if correct, require at least one light sterile neutrino, in addition to the three active ones, to accommodate the mass differences required to explain the solar νe deficit, the anomalous μ/e ratio produced by atmospheric neutrinos, and either the candidate events for νμ→ νe (or [Formula: see text]) from the LSND experiment, or the possible need for a hot component of dark matter. This neutrino mass pattern can not only accommodate all these four requirements, but also provide a robust solution to a problem presently making heavy-element synthesis by supernovae impossible and resolve a possible discrepancy between big bang nucleosynthesis theory and observations.

Erratum: Cosmic rays from dark matter annihilation and big-bang nucleosynthesis [Phys. Rev. D79, 083522 (2009)]

2009 ◽  
Vol 80 (2) ◽  
Author(s):  
Junji Hisano ◽  
Masahiro Kawasaki ◽  
Kazunori Kohri ◽  
Takeo Moroi ◽  
Kazunori Nakayama
Keyword(s):  
Dark Matter ◽  
Cosmic Rays ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Dark Matter Annihilation
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