Nucleosynthesis Data Research Articles

Implications for Primordial Black Holes from Cosmological Constraints on Scalar-induced Gravitational Waves

Sufficiently large scalar perturbations in the early universe can create overdense regions that collapse into primordial black holes (PBHs). This process is accompanied by the emission of scalar-induced gravitational waves that behave like an extra radiation component, thus contributing to the relativistic degrees of freedom (N eff). We show that the cosmological constraints on N eff can be used to pose stringent limits on PBHs created from this particular scenario as well as the relevant small-scale curvature perturbation (). We show that the combination of cosmic microwave background (CMB), baryon acoustic oscillation, and Big Bang nucleosynthesis data sets can exclude supermassive PBHs with peak mass M • ∈ [5 × 105, 5 × 1010] M ⊙ as the major component of dark matter, while the detailed constraints depend on the shape of the PBHs’ mass distribution. A future CMB mission such as CMB-S4 can greatly broaden this constraint window to M • ∈ [8 × 10−5, 5 × 1010] M ⊙, covering substellar masses. These limits on PBHs correspond to a tightened constraint on on scales of k ∈ [10, 1022] Mpc−1, much smaller than those probed by direct CMB and large-scale structure power spectra.

Big bang nucleosynthesis constraints on higher-order modified gravities

We use Big Bang Nucleosynthesis (BBN) data in order to impose constraints on higher-order modified gravity, and in particular on: (i) $f(G)$ Gauss-Bonnet gravity, and $f(P)$ cubic gravities, arising respectively through the use of the quadratic-curvature Gauss-Bonnet $G$ term, and the cubic-curvature combination, (ii) string-inspired quadratic Gauss-Bonnet gravity coupled to the dilaton field, (iii) models with string-inspired quartic curvature corrections, and (iv) running vacuum models. We perform a detailed investigation of the BBN epoch and we calculate the deviations of the freeze-out temperature $T_f$ in comparison to $\Lambda$CDM paradigm. We then use the observational bound on $ \left|\frac{\delta {T}_f}{{T}_f}\right|$ in order to extract constraints on the involved parameters of various models. We find that all models can satisfy the BBN constraints and thus they constitute viable cosmological scenarios, since they can additionally account for the dark energy sector and the late-time acceleration, in a quantitative manner, without spoiling the formation of light elements during the BBN epoch. Nevertheless, the obtained constraints on the relevant model parameters are quite strong.

Distance-duality in theories with a nonminimal coupling to gravity

We show that gravitational theories with a nonminimal coupling (NMC) to the matter fields lead to a violation of Etherington's distance-duality relation, which relates the luminosity and angular diameter distances. We derive constraints on power-law and exponential NMC models using existing measurements of type Ia supernovae and baryon acoustic oscillations throughout the redshift range $0<z<1.5$. These complement previous constrains derived from cosmic-microwave background radiation and big-bang nucleosynthesis data.

Dark sector interaction and the supernova absolute magnitude tension

It has been intensively discussed if modifications in the dynamics of the Universe at late times is able or not to solve the $H_0$ tension. On the other hand, it has also been argued that the $H_0$ tension is actually a tension on the supernova absolute magnitude $M_B$. In this work, we robustly constraint $M_B$ using Pantheon Supernovae Ia (SN) sample, Baryon Acoustic Oscillations (BAO), and Big Bang Nucleosynthesis (BBN) data, and assess the $M_B$ tension by comparing three theoretical models, namely the standard $\Lambda$CDM, the $w$CDM and a non-gravitational interaction (IDE) between dark energy (DE) and dark matter (DM). We find that the IDE model can solve the $M_B$ tension with a coupling different from zero at 95\% CL, confirming the results obtained using a $H_0$ prior.

Big Bang Nucleosynthesis constraints on Barrow entropy

We use Big Bang Nucleosynthesis (BBN) data in order to impose constraints on the exponent of Barrow entropy. The latter is an extended entropy relation arising from the incorporation of quantum-gravitational effects on the black-hole structure, parameterized effectively by the new parameter Δ. When considered in a cosmological framework and under the light of the gravity-thermodynamics conjecture, Barrow entropy leads to modified cosmological scenarios whose Friedmann equations contain extra terms. We perform a detailed analysis of the BBN era and we calculate the deviation of the freeze-out temperature comparing to the result of standard cosmology. We use the observationally determined bound on |δTfTf| in order to extract the upper bound on Δ. As we find, the Barrow exponent should be inside the bound Δ≲1.4×10−4 in order not to spoil the BBN epoch, which shows that the deformation from standard Bekenstein-Hawking expression should be small as expected.

Late-time and Big Bang Nucleosynthesis constraints for generic modified gravity surveys

In this work, a new generic parameterisation for $f(R)$ theories is presented. Our proposal for a new equation of state can reproduce an $f(R)$-like evolution that describes late and early time universe within 1-$\sigma$ C.L when we use a combination of distance ladder measurements based on Cosmic Chronometers, Supernovae Ia, Baryon Acoustic Oscillation and finally, Cosmic Microwave Background and Lyman-$\alpha$ forest. Indeed, a family of $f(R)$ cosmological viable scenarios were extensively analysed in the light of late-time measurements, were an Eos reaches a precision better than $99.2\%$ over the numerical solutions for the field equations of this theory. Moreover, in this proposal we extended the study to find constraints at the very early time that can satisfy the Big Bang Nucleosynthesis data on helium fraction, $Y_{p}$. To perform this analysis, and with our generic $w_{f(R)}$ --which can be seemed it at the same level as other parameterisations into the pipeline and analysis of observational surveys-- we consider both background and linear perturbations evolution and constrain beyond the standard $\Lambda$CDM six cosmological parameters. While there are strong constraints at background on the free parameters of our $w_{f(R)}$, we found that $f(R)$ background viable models can set early constraints to the current Hubble constant $H_0$, which is in agreement with CMB data, but when late-time model-independent measurements are considered, $H_0$ is fully compatible with the $R^{H18}$ value. Finally, as an extension of these results, our proposal is capable to distinguish between $f(R)$ scenarios at both routes of the distance ladder showing a good approach to modify gravity at this level.

Updating constraints on f(T) teleparallel cosmology and the consistency with big bang nucleosynthesis

ABSTRACT We focus on viable f(T) teleparallel cosmological models, namely power law, exponential, and square-root exponential, carrying out a detailed study of their evolution at all scales. Indeed, these models were extensively analysed in the light of late time measurements, while it is possible to find only upper limits looking at the very early time behaviour, i.e. satisfying the big bang nucleosynthesis (BBN) data on primordial abundance of 4He. Starting from these indications, we perform our analysis considering both background and linear perturbations evolution and constrain, beyond the standard six cosmological parameters, the free parameters of f(T) models in both cases whether the BBN consistency relation is considered or not. We use a combination of Cosmic Microwave Background, Baryon Acoustic Oscillation, Supernovae Ia and galaxy clustering measurements, and find that very narrow constraints on the free parameters of specific f(T) cosmology can be obtained, beyond any previous precision. While no degeneration is found between the helium fraction, YP, and the free parameter of f(T), we note that these models constrain the current Hubble parameter, H0, higher extent than the standard model one, fully compatible with the Riess et al. measurement in the case of power-law f(T) model. Moreover, the free parameters are constrained at non-zero values in more than 3-σ, showing a preference of the observations for extended gravity models.

Neutrino nonstandard interactions via light scalars in the Earth, Sun, supernovae, and the early Universe

Non-standard interactions (NSI) of neutrinos with matter mediated by a scalar field would induce medium-dependent neutrino masses which can modify oscillation probabilities. Generating observable effects requires an ultra-light scalar mediator. We derive general expressions for the scalar NSI using techniques of quantum field theory at finite density and temperature, including the long-range force effects, and discuss various limiting cases applicable to the neutrino propagation in different media, such as the Earth, Sun, supernovae and early Universe. We also analyze various terrestrial and space-based experimental constraints, as well as astrophysical and cosmological constraints on these NSI parameters, applicable to either Dirac or Majorana neutrinos. By combining all these constraints, we show that observable scalar NSI effects, although precluded in terrestrial experiments, are still possible in future solar and supernovae neutrino data, and in cosmological observations such as cosmic microwave background and big bang nucleosynthesis data.

The BAO+BBN take on the Hubble tension

Many attempts to solve the Hubble tension with extended cosmological models combine an enhanced relic radiation density, acting at the level of background cosmology, with new physical ingredients affecting the evolution of cosmological perturbations. Several authors have pointed out the ability of combined Baryon Acoustic Oscillation (BAO) and Big Bang Nucleosynthesis (BBN) data to probe the background cosmological history independently of both CMB maps and supernovae data. Using state-of-the-art assumptions on BBN, we confirm that combined BAO, deuterium, and helium data are in tension with the SH0ES measurements under the ΛCDM assumption at the 3.2σ level, while being in close agreement with the CMB value. We subsequently show that floating the radiation density parameter Neff only reduces the tension down to the 2.6σ level. This conclusion, totally independent of any CMB data, shows that a high Neff accounting for extra relics (either free-streaming or self-interacting) does not provide an obvious solution to the crisis, not even at the level of background cosmology. To circumvent this strong bound, (i) the extra radiation has to be generated after BBN to avoid helium bounds, and (ii) additional ingredients have to be invoked at the level of perturbations to reconcile this extra radiation with CMB and LSS data.

Methods for cluster cosmology and application to the SDSS in preparation for DES Year 1 release

ABSTRACT We implement the first blind analysis of cluster abundance data to derive cosmological constraints from the abundance and weak lensing signal of redMaPPer clusters in the Sloan Digital Sky Survey (SDSS). We simultaneously fit for cosmological parameters and the richness–mass relation of the clusters. For a flat Λ cold dark matter cosmological model with massive neutrinos, we find $S_8 \equiv \sigma _{8}(\Omega _\mathrm{ m}/0.3)^{0.5}=0.79^{+0.05}_{-0.04}$. This value is both consistent and competitive with that derived from cluster catalogues selected in different wavelengths. Our result is also consistent with the combined probes analyses by the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS), and with the cosmic microwave background (CMB) anisotropies as measured by Planck. We demonstrate that the cosmological posteriors are robust against variation of the richness–mass relation model and to systematics associated with the calibration of the selection function. In combination with baryon acoustic oscillation data and big bang nucleosynthesis data (Cooke et al.), we constrain the Hubble rate to be h = 0.66 ± 0.02, independent of the CMB. Future work aimed at improving our understanding of the scatter of the richness–mass relation has the potential to significantly improve the precision of our cosmological posteriors. The methods described in this work were developed for use in the forthcoming analysis of cluster abundances in the DES. Our SDSS analysis constitutes the first part of a staged-unblinding analysis of the full DES data set.

Nucleosynthesis Constraints on the Explosion Mechanism for Type Ia Supernovae

Abstract Observations of type Ia supernovae (SNe Ia) include information about the characteristic nucleosynthesis associated with these thermonuclear explosions. We consider observational constraints from iron-group elemental and isotopic ratios, to compare with various models obtained with the most realistic recent treatment of electron captures (ECs). The nucleosynthesis is sensitive to the highest white-dwarf central densities. Hence, nucleosynthesis yields can distinguish high-density Chandrasekhar-mass models from lower-density burning models such as white-dwarf mergers. We discuss new results of post-processing nucleosynthesis for two spherical models (deflagration and/or delayed-detonation models) based upon new EC rates. We also consider cylindrical and 3D explosion models (including deflagration, delayed-detonation, or a violent merger model). Although there are uncertainties in the observational constraints, we identify some trends in the observations and the models. We make a new comparison of the models with elemental and isotopic ratios from five observed supernovae and three supernova remnants. We find that the models and data tend to fall into two groups. In one group, low-density cores such as in a 3D merger model are slightly more consistent with the nucleosynthesis data, while the other group is slightly better identified with higher-density cores such as in single-degenerate 1D–3D deflagration models. Hence, we postulate that both types of environments appear to contribute nearly equally to observed SN Ia. We also note that observational constraints on the yields of 54Cr and 54Fe, if available, might be used as a means to clarify the degree of geometrical symmetry of SN Ia explosions.

The production of proton-rich isotopes beyond iron: The γ-process in stars

Beyond iron, a small fraction of the total abundances in the Solar System is made of proton-rich isotopes, the [Formula: see text]-nuclei. The clear understanding of their production is a fundamental challenge for nuclear astrophysics. The [Formula: see text]-nuclei constrain the nucleosynthesis in core-collapse and thermonuclear supernovae. The [Formula: see text]-process is the most established scenario for the production of the [Formula: see text]-nuclei, which are produced via different photodisintegration paths starting on heavier nuclei. A large effort from nuclear physics is needed to access the relevant nuclear reaction rates far from the valley of stability. This review describes the production of the heavy proton-rich isotopes by the [Formula: see text]-process in stars, and explores the state of the art of experimental nuclear physics to provide nuclear data for stellar nucleosynthesis.

Atomic Data for Stellar Nucleosynthesis

AbstractStellar chemical composition analyses can only yield reliable abundances if the atomic transition parameters are accurately determined. During the last couple of decades a renewed emphasis on laboratory spectroscopy has produced large sets of useful atomic transition probabilities for species of interest to stellar spectroscopists. In many cases the transition data are of such high quality that they play little part in the abundance uncertainties. We summarize the current state of atomic parameters, highlighting the areas of satisfactory progress and noting places, where further laboratory progress will be welcome.

Another look at leptonic photon couplings

It may be that additional gauge bosons exist that are associated with unbroken U(1) symmetries; such bosons might couple to some combination of lepton number, and have thus been coined leptonic photons. It can be shown that such gauge forces are restricted to coupling to tau minus muon number Nτ−Nμ. Such gauge bosons can be produced in quantity in the early Universe shortly after the Big Bang. Constraints arising from primordial nucleosynthesis data limit the coupling to α′⩽5×10−18, a significant improvement over previous estimates.

From Cavendish to PLANCK: Constraining Newton’s gravitational constant with CMB temperature and polarization anisotropy

We present new constraints on cosmic variations of Newton's gravitational constant by making use of the latest CMB data from WMAP, BOOMERANG, CBI and ACBAR experiments and independent constraints coming from big bang nucleosynthesis. We found that current CMB data provide constraints at the $\ensuremath{\sim}10%$ level, that can be improved to $\ensuremath{\sim}3%$ by including big bang nucleosynthesis data. We show that future data expected from the Planck satellite could constrain $G$ at the $\ensuremath{\sim}1.5%$ level while an ultimate, cosmic variance limited, CMB experiment could reach a precision of about 0.4%, competitive with current laboratory measurements.

Cosmic microwave anisotropies from BPS semilocal strings

We present the first ever calculation of cosmic microwave background (CMB) anisotropypower spectra from semilocal cosmic strings, obtained via simulations of a classical fieldtheory. Semilocal strings are a type of non-topological defect arising in some models ofinflation motivated by fundamental physics, and are thought to relax the constraints on thesymmetry breaking scale as compared to models with (topological) cosmic strings. Wederive constraints on the model parameters, including the string tension parameterμ,from fits to cosmological data, and find that in this regard Bogomol’nyi–Prasad–Sommerfield (BPS)semilocal strings resemble global textures more than topological strings. The observedmicrowave anisotropy at is reproduced if Gμ = 5.3 × 10−6 (G is Newton’s constant). However as with other defects the spectral shape does not matchobservations, and in models with inflationary perturbations plus semilocal strings the95% confidence levelupper bound is Gμ<2.0 × 10−6 when CMB, Hubble key project and big bang nucleosynthesis data are used(cf Gμ<0.9 × 10−6 for cosmic strings). We additionally carry out a Bayesian model comparison of severalmodels with and without defects, showing that models with defects are neither conclusivelyfavoured nor disfavoured at present.

F(R)-theories of gravity and gravitational baryogenesis

The mechanism for generating the baryon asymmetry in the Universe is discussed in the framework of f(R)-theories of gravity. The gravitational baryogenesis, based on the coupling between the Ricci scalar curvature R and the baryon current, allows to determine the form of gravity Lagrangian, i.e. \U0001d50f(R) ∼ Rn. The current bound on the observed matter-antimatter asymmetry and Big Bang Nucleosynthesis data lead to n = 0.97.

Primordial nucleosynthesis as a test of the Friedmann equation in the early Universe

In the standard hot big bang model, the expansion of the early universe is given by the Friedmann equation with an energy density dominated by relativistic particles. Since in a variety of models this equation is altered, we introduce modifications in the Friedmann equation and show that we can constrain them using big bang nucleosynthesis data. When there is no neutrino/antineutrino asymmetry these modifications are tightly bounded but in presence of an asymmetry the bounds become much looser. As an illustration, we apply our results to a model where the second and third families couple to gravity differently than the first family (non-universal gravity).

Interacting quintessence solution to the coincidence problem

We show that a suitable interaction between a scalar field and a matter fluid in a spatially homogeneous and isotropic spacetime can drive the transition from a matter dominated era to an accelerated expansion phase and simultaneously solve the coincidence problem of our present Universe. For this purpose we study the evolution of the energy density ratio of these two components. We demonstrate that a stationary attractor solution is compatible with an accelerated expansion of the Universe. We extend this study to account for dissipation effects due to interactions in the dark matter fluid. Finally, type Ia supernovae and primordial nucleosynthesis data are used to constrain the parameters of the model.

Current status of models with hot and cold dark matter

An analysis of a five-parameter family of cosmological models in a spatially flat Friedmann Universe with a zero Λ term is presented. The five parameters are (1) σ8, the dispersion of the mass fluctuations in a sphere with radius 8h −1 Mpc, where h=H 0/100 km s−1 Mpc−1 and H 0 is the Hubble constant; (2) n, the slope of the density-perturbation spectrum; (3) Ωv, the normalized energy density of hot dark matter; (4) Ωb, the baryon density; and (5) h, the normalized Hubble constant. The density of cold dark matter is determined from the condition Ω cdm >1−Ωv−Ω b . Analysis of the models is based on comparison of computational results with observational data for: (1) the number density and mass function of galaxy clusters (a so-called Press-Schechter formalism) and (2) the cosmic microwave background anisotropy. The first method enabled us to determine the value σ8=0.52±0.01 with high accuracy. Using the resulting normalization of the density-perturbation spectrum, we calculated a model for the anisotropy of the cosmic microwave background radiation on large scales (l⋍10, where l is the harmonic number) and the required contribution of cosmological gravitational waves, characterized by the parameter T/S. The restrictions on T/S become weaker as Ωv increases. Nevertheless, even when Ωv≤0.4, models with h+n≥1.5 require a considerable contribution from gravitational waves: T/S≳0.3. On the other hand, in models with Ωv≤0.4 and a scale-invariant density-perturbation spectrum (n=1), we find T/S ≳10(h−0.47). The minimization of T/S is possible only for the family of models with red spectra (n<1) and small h (<0.6). The value of Ωv is determined most accurately by the data onΔT/T near the first acoustic peak (l⋍200). By imposing a general restriction on the amplitude of gravitational waves T/S∈[0, 3] and taking into account the available observational data on the amplitude of the acoustic peak of Sakharov oscillations, ranges of possible values n and Ωv are derived. If the baryon number is constrained by nucleosynthesis data, the models under consideration can have both moderately red and blue power spectra n∈[0.9, 1.2] with a rather high concentration of hot particles Ωv∈[0.2,0.4]. The conditions that n<0.9 and/or Ωv<0.2 decrease the relative amplitude of the acoustic peak by over 30% compared to its value in the standard cold-dark-matter (CDM) model normalized using COBE data.