Coupled Boltzmann calculation of mixed axion/neutralino cold dark matter production in the early universe

Abstract We study a novel dark matter production mechanism based on the freeze-in through semi-production, i.e. the inverse semi-annihilation processes. A peculiar feature of this scenario is that the production rate is suppressed by a small initial abundance of dark matter and consequently creating the observed abundance requires much larger coupling values than for the usual freeze-in. We provide a concrete example model exhibiting such production mechanism and study it in detail, extending the standard formalism to include the evolution of dark matter temperature alongside its number density and discuss the importance of this improved treatment. Finally, we confront the relic density constraint with the limits and prospects for the dark matter indirect detection searches. We show that, even if it was never in full thermal equilibrium in the early Universe, dark matter could, nevertheless, have strong enough present-day annihilation cross section to lead to observable signals.

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The Lyman-α forest as a diagnostic of the nature of the dark matter

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2188 ◽

2019 ◽

Vol 489 (3) ◽

pp. 3456-3471 ◽

Cited By ~ 15

Author(s):

Antonella Garzilli ◽

Andrii Magalich ◽

Tom Theuns ◽

Carlos S Frenk ◽

Christoph Weniger ◽

...

Keyword(s):

Dark Matter ◽

High Temperature ◽

High Resolution ◽

Power Spectrum ◽

Early Universe ◽

Thermal Effects ◽

Cold Dark Matter ◽

Sterile Neutrinos ◽

Hydrodynamic Simulations ◽

Very High

ABSTRACT The observed Lyman-α flux power spectrum (FPS) is suppressed on scales below ${\sim} ~ 30\, {\rm km\, s}^{-1}$. This cut-off could be due to the high temperature, T0, and pressure, p0, of the absorbing gas or, alternatively, it could reflect the free streaming of dark matter particles in the early universe. We perform a set of very high resolution cosmological hydrodynamic simulations in which we vary T0, p0, and the amplitude of the dark matter free streaming, and compare the FPS of mock spectra to the data. We show that the location of the dark matter free-streaming cut-off scales differently with redshift than the cut-off produced by thermal effects and is more pronounced at higher redshift. We, therefore, focus on a comparison to the observed FPS at z > 5. We demonstrate that the FPS cut-off can be fit assuming cold dark matter, but it can be equally well fit assuming that the dark matter consists of ∼7 keV sterile neutrinos in which case the cut-off is due primarily to the dark matter free streaming.

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Extended General Relativity for a Curved Universe

10.20944/preprints202010.0320.v4 ◽

2021 ◽

Author(s):

Mohammed B. Al-Fadhli

Keyword(s):

General Relativity ◽

Dark Matter ◽

Early Universe ◽

Cold Dark Matter ◽

Positive Curvature ◽

Boundary Term ◽

Radius Of Curvature ◽

Field Equations ◽

Extended Field ◽

Background Curvature

The recent Planck Legacy release revealed the presence of an enhanced lensing amplitude in the cosmic microwave background (CMB). Notably, this amplitude is higher than that estimated by the lambda cold dark matter model (ΛCDM), which endorses the positive curvature of the early Universe with a confidence level greater than 99%. Although General Relativity (GR) performs accurately in the local/present Universe where spacetime is almost flat, its lost boundary term, incompatibility with quantum mechanics and the necessity of dark matter and dark energy might indicate its incompleteness. By utilising the Einstein–Hilbert action, this study presents extended field equations considering the pre-existing/background curvature and the boundary contribution. The extended field equations consist of Einstein field equations with a conformal transformation feature in addition to the boundary term, which could remove singularities from the theory and facilitate its quantisation. The extended equations have been utilised to derive the evolution of the Universe with reference to the scale factor of the early Universe and its radius of curvature.

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Dark matter production in the early Universe: Beyond the thermal WIMP paradigm

Physics Reports ◽

10.1016/j.physrep.2014.10.002 ◽

2015 ◽

Vol 555 ◽

pp. 1-60 ◽

Cited By ~ 162

Author(s):

Howard Baer ◽

Ki-Young Choi ◽

Jihn E. Kim ◽

Leszek Roszkowski

Keyword(s):

Dark Matter ◽

Early Universe ◽

Matter Production

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Deep 10 and 15 GHZ Searches for CMB Anisotropies

Highlights of Astronomy ◽

10.1017/s1539299600009138 ◽

1992 ◽

Vol 9 ◽

pp. 323-325

Author(s):

R. D. Davies ◽

A. N. Lasenby

Keyword(s):

Dark Matter ◽

Cosmic Microwave Background ◽

Early Universe ◽

Galaxy Formation ◽

Cold Dark Matter ◽

Galactic Structure ◽

Observational Cosmology ◽

Significant Progress ◽

Microwave Background ◽

Observing Systems

The search for anisotropies in the Cosmic Microwave Background (CMB) is fundamental to observational cosmology: it requires observations on a range of angular scales and at a range of frequencies to distinguish CMB structure from foreground galactic structure. We have made significant progress in setting new limits to CMB anisotropies on angular scales of 3°-12° using scaled observing systems at 10 and 15 GHz. This regime of angular scales is particularly matched to the predictions of Cold Dark Matter (CDM) and isocurvature scenarios of galaxy formation in the early Universe.

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Chemistry in the Early Universe

Symposium - International Astronomical Union ◽

10.1017/s0074180900089737 ◽

1992 ◽

Vol 150 ◽

pp. 73-82

Author(s):

Paul R. Shapiro

Keyword(s):

Dark Matter ◽

Shock Waves ◽

Early Universe ◽

Gravitational Collapse ◽

Cold Dark Matter ◽

First Stars ◽

Cooperative Effects ◽

And Shock Waves ◽

Nonequilibrium Chemistry ◽

The Universe

Galaxies and the first stars in the universe formed billions of years ago as a result of the cooperative effects of gravitational collapse and nonequilibrium chemistry. Gravity drew the primordial gas together into lumps; the formation of the first molecules in the universe, simple diatomic molecules like H2, H2+, HD, HeH+, LiH, and LiH+, may then have ensured that the heat generated by gravitational collapse and shock waves was radiated away rapidly enough to allow the gravitational collapse and fragmentation of these gaseous lumps to proceed to the point of forming stars and galaxies. We briefly mention a few of the latest studies of this primordial chemistry, including that in the evolving intergalactic medium (IGM) in a Cold Dark Matter (CDM) model cosmology and that in radiative shocks in the early universe.

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Physics of superheavy dark matter in supergravity

International Journal of Modern Physics D ◽

10.1142/s0218271818410110 ◽

2018 ◽

Vol 27 (06) ◽

pp. 1841011 ◽

Cited By ~ 13

Author(s):

Andrea Addazi ◽

Antonino Marciano ◽

Sergei V. Ketov ◽

Maxim Yu. Khlopov

Keyword(s):

Dark Matter ◽

Gauge Symmetry ◽

Particle Physics ◽

Cold Dark Matter ◽

Model Building ◽

Density Fluctuations ◽

String Compactifications ◽

Matter Production ◽

The Right ◽

Superheavy Dark Matter

New trends in inflationary model building and dark matter production in supergravity are considered. Starobinsky inflation is embedded into [Formula: see text] supergravity, avoiding instability problems, when the inflaton belongs to a vector superfield associated with a [Formula: see text] gauge symmetry, instead of a chiral superfield. This gauge symmetry can be spontaneously broken by the super-Higgs mechanism resulting in a massive vector supermultiplet including the (real scalar) inflaton field. Both supersymmetry (SUSY) and the R-symmetry can also be spontaneously broken by the Polonyi mechanism at high scales close to the inflationary scale. In this case, Polonyi particles and gravitinos become superheavy, and can be copiously produced during inflation by the Schwinger mechanism sourced by the universe expansion. The Polonyi mass slightly exceeds twice the gravitino mass, so that Polonyi particles are unstable and decay into gravitinos. Considering the mechanisms of superheavy gravitino production, we find that the right amount of cold dark matter composed of gravitinos can be achieved. In our scenario, the parameter space of the inflaton potential is directly related to the dark matter one, providing a new unifying framework of inflation and dark matter genesis. A multi-superfield extension of the supergravity framework with a single (inflaton) superfield can result in a formation of primordial nonlinear structures like mini- and stellar-mass black holes, primordial nongaussianity, and the running spectral index of density fluctuations. This framework can be embedded into the SUSY GUTs inspired by heterotic string compactifications on Calabi–Yau three-folds, thus unifying particle physics with quantum gravity.

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DARK-MATTER PARTICLES AND BARYONS FROM INFLATION AND SPONTANEOUS CP VIOLATION IN THE EARLY UNIVERSE

Modern Physics Letters A ◽

10.1142/s0217732306020615 ◽

2006 ◽

Vol 21 (15) ◽

pp. 1183-1188 ◽

Cited By ~ 1

Author(s):

SAUL BARSHAY ◽

GEORG KREYERHOFF

Keyword(s):

Dark Matter ◽

Early Universe ◽

Cold Dark Matter ◽

Vacuum Energy ◽

Vacuum Expectation ◽

Vacuum Expectation Value ◽

Baryon Asymmetry ◽

Vacuum Energy Density ◽

Expectation Value ◽

Residual Vacuum

We present aspects of a model which attempts to unify the creation of cold dark matter, a CP-violating baryon asymmetry, and also a small, residual vacuum energy density, in the early universe. The model contains a primary scalar (inflaton) field and a primary pseudoscalar field, which are initially related by a cosmological, chiral symmetry. The nonzero vacuum expectation value of the pseudoscalar field spontaneously breaks CP invariance.

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