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Large primordial black hole (PBH) formation is enhanced if strongly coupled scalar and spinor fields (Φ and ψ) are a stable cosmic component since the primeval radiative expansion (SCDEW models). In particular, we show that PBH formation is easier at a specific time, i.e. when the asymptotic mass m H, acquired by the ψ field at the higgs scale, becomes dominant, so that the typical BH mass M BH depends on m H value. For instance, if |$m_\mathrm{ H} \sim 100\,$|  eV (1 keV) and the coupling β ∼ 8.35 (37), PBH with M BH ≃ 107– |$10^8 \, \mathrm{M}_\odot$| (∼103– |$10^4 \, \mathrm{M}_\odot$|⁠) could form. The very mechanism enhancing PBH formation also causes technical difficulties to evaluate the transfer function of SCDEW models at high k. A tentative solution of this problem leaves only minor discrepancies from Lambda cold dark matter (ΛCDM), also at these scales, gradually vanishing for greater m H values. We conclude that, for suitable parameter choices, SCDEW models could be the real physics underlying ΛCDM, overcoming its fine-tuning and coincidence problems, with the extra bonus of yielding large BH seeds. [ABSTRACT FROM AUTHOR]

Strongly-Coupled Dark Energy plusWarm dark matter (SCDEW) cosmologies admit the stationary presence of ~1% of coupled-DM and DE, since inflationary reheating. Coupled-DM fluctuations therefore grow up to non-linearity even in the early radiative expansion. Such early non-linear stages are modelized here through the evolution of a top-hat density enhancement, reaching an early virial balance when the coupled-DM density contrast is just 25-26, and the DM density enhancement is ~10% of the total density. During the time needed to settle in virial equilibrium, the virial balance conditions, however, continue to modify, so that "virialized" lumps undergo a complete evaporation. Here, we outline that DM particles processed by overdensities preserve a fraction of their virial momentum. Although fully non-relativistic, the resulting velocities (moderately) affect the fluctuation dynamics over greater scales, entering the horizon later on. [ABSTRACT FROM AUTHOR]

In this second paper, we present the first N-body cosmological simulations of strongly coupled Dark Energy (SCDEW) models, a class of models that alleviates theoretical issues related to the nature of dark energy (DE). SCDEW models assume a strong coupling between DE and an ancillary cold dark matter (CDM) component together with the presence of an uncoupled warm dark matter (WDM) component. The strong coupling between CDM and DE allows us to preserve small-scale fluctuations even if the warm particle is quite light (100 eV). Our large-scale simulations show that, for 1011

In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark energy is a scalar field $ ; its coupling to ancillary cold dark matter (CDM), whose today's density is ≪1 percent, is an essential model feature. Such coupling, in fact, allows the formation of cosmic structures, in spite of very low WDM particle masses (~100 eV). SCDEW models yield cosmic microwave background and linear large scale features substantially undistinguishable from ACDM, but thanks to the very low WDM masses they strongly alleviate ACDM issues on small scales, as confirmed via numerical simulations in the second associated paper. Moreover SCDEW cosmologies significantly ease the coincidence and fine tuning problems of ACDM and, by using a field theory approach, we also outline possible links with inflationary models. We also discuss a possible fading of the coupling at low redshifts which prevents non-linearities on the CDM component to cause computational problems. The (possible) low-z coupling suppression, its mechanism, and its consequences are however still open questions - not necessarily problems - for SCDEW models. The coupling intensity and the WDM particle mass, although being extra parameters in respect to ACDM, are found to be substantially constrained a priori so that, if SCDEW is the underlying cosmology, we expect most data to fit also ACDM predictions. [ABSTRACT FROM AUTHOR]

In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark energy is a scalar field Φ; its coupling to ancillary cold dark matter (CDM), whose today's density is <<1 per cent, is an essential model feature. Such coupling, in fact, allows the formation of cosmic structures, in spite of very low WDM particle masses (~100 eV). SCDEW models yield cosmic microwave background and linear large scale features substantially undistinguishable from ΛCDM, but thanks to the very low WDM masses they strongly alleviate ΛCDM issues on small scales, as confirmed via numerical simulations in the second associated paper. Moreover SCDEW cosmologies significantly ease the coincidence and fine tuning problems of ΛCDM and, by using a field theory approach, we also outline possible links with inflationary models. We also discuss a possible fading of the coupling at low redshifts which prevents non-linearities on the CDM component to cause computational problems. The (possible) low-z coupling suppression, its mechanism, and its consequences are however still open questions - not necessarily problems - for SCDEW models. The coupling intensity and the WDM particle mass, although being extra parameters in respect to ΛCDM, are found to be substantially constrained a priori so that, if SCDEW is the underlying cosmology, we expect most data to fit also ΛCDM predictions. [ABSTRACT FROM AUTHOR]

We provide an exhaustive analysis of the Integrated Sachs-Wolfe (ISW) effect in the context of coupled dark energy cosmologies where a component of massive neutrinos is also present. We focus on the effects of both the coupling between dark matter and dark energy and of the neutrino mass on the cross-correlation between galaxy/quasar distributions and ISW effect. We provide a simple expression to appropriately rescale the galaxy bias when comparing different cosmologies. Theoretical predictions of the cross-correlation function are then compared with observational data. We find that, while it is not possible to distinguish among the models at low redshifts, discrepancies between coupled models and ΛACDM increase with z. In spite of this, current data alone does not seem able to distinguish between coupled models and ΛCDM. However, we show that upcoming galaxy surveys will permit tomographic analysis that will allow us to better discriminate among the models. We discuss the effects on cross-correlation measurements of ignoring galaxy bias evolution, b(z), and magnification bias correction and provide fitting formulae for b(z) for the cosmologies considered. We compare three different tomographic schemes and investigate how the expected signal-to-noise ratio, S/N, of the ISW-LSS cross-correlation changes when increasing the number of tomographic bins. The dependence of S/N on the area of the survey and the survey shot noise is also discussed. [ABSTRACT FROM AUTHOR]

The Peccei-Quinn (PQ) solution of the strong CP problem requires the existence of axions, which are viable candidates for dark matter. If the Nambu-Goldstone potential of the PQ model is replaced by a potential V(|Phi|) admitting a tracker solution, the scalar field |Phi| can account for dark energy, while the phase of Phi yields axion dark matter. If V is a supergravity (SUGRA) potential, the model essentially depends on a single parameter, the energy scale Lambda. Once we set Lambda approximately equal to 10(10) GeV at the quark-hadron transition, |Phi| naturally passes through values suitable to solve the strong CP problem, later growing to values providing fair amounts of dark matter and dark energy.