arXiv subjects

Florencia Anabella Teppa Pannia

Publications and source records attributed to Florencia Anabella Teppa Pannia.

6 recordsLinked to original sources

arXiv2026

Dark matter-baryons elastic coupling

We consider a cosmological model where dark matter and baryons interact via a pure momentum transfer. We present the foundations of the interaction and derive its main equations. In this framework, only the Euler equations for the two interacting components differ from those in the standard scenario. We also explain how this interaction relates with the common Tight-Coupling Approximation schemes typically used in many Boltzmann solver. After that, we implement the model in CLASS and CAMB Boltzmann solvers, which relay on those Tight-Coupling Approximation schemes and in SymBoltz, which is free from any approximation scheme. We demonstrate full consistency among all the implementations in the difference codes. We demonstrate how this type of interactions are useful regarding the $σ_8$ tension by producing a reduced clustering on smaller scales. Using cosmic microwave background, baryon acoustic oscillations, supernovae type Ia data and low-redshift constraints from Sunyaev-Zeldovich cluster counts and from DES year 6 results, we show the interacting scenario is mildly preferred when those low-redshift datasets are included.

astro-ph.CO↗

arXiv2026

Revisiting observational constraints on coupled exponential quintessence with energy and momentum transfers: degeneracy with massive neutrinos

We investigate the impact of massive neutrinos on cosmological models in which dark energy, described by a quintessence scalar field $ϕ$ with an exponential potential, interacts with dark matter through both energy and momentum transfers. Previous analyses have shown that the inclusion of low-redshift data tends to favour the detection of a pure momentum transfer between the dark sectors, consistent with the fact that such a transfer generically suppresses the growth of cosmic structures. Since massive neutrinos also reduce matter clustering, a potential degeneracy between the interaction parameters and the neutrino mass may arise. After updating the observational constraints on the model parameters obtained in earlier studies, we investigate the effect of allowing the neutrino mass to vary. We find that the detection of momentum transfer degrades once massive neutrinos are included. This occurs because a new degeneracy emerges between the neutrino mass and the parameter governing the energy exchange between dark energy and dark matter. Our findings differ from previous results in the literature, where the detection of momentum transfer was reported to be robust against varying neutrino masses. This suggests that the robustness of such detections depends on the underlying model and should therefore be carefully reassessed for each specific interacting scenario.

astro-ph.CO↗

arXiv2024

On the (non-)degeneracy of massive neutrinos and elastic interactions in the dark sector

Cosmological models featuring an elastic interaction in the dark sector at linear order has been shown to provide a promising scenario for alleviating the $σ_8$ tension. A natural question for these scenarios is whether there could be a degeneracy between the interaction and massive neutrinos that also contribute to erasing structures at late times. In this work we investigate the presence of such a degeneracy and show that the two effects do not exhibit strong correlations.

astro-ph.CO↗

arXiv2021

Particle Production in Accelerated Thin Bubbles

We investigate the creation of scalar particles inside a region delimited by a bubble which is expanding with non-zero acceleration. The bubble is modelled as a thin shell and plays the role of a moving boundary, thus influencing the fluctuations of the test scalar field inside it. Bubbles expanding in Minkowski spacetime as well as those dividing two de Sitter spacetimes are explored in a unified way. Our results for the Bogoliubov coefficient $β_k$ in the adiabatic approximation show that in all cases the creation of scalar particles decreases with the mass, and is much more significant in the case of nonzero curvature. They also show that the dynamics of the bubble and its size are relevant for particle creation, but in the dS-dS case the combination of both effects leads to a behaviour different from that of Minkowski space-time, due to the presence of a length scale (the Hubble radius of the internal geometry).

gr-qc↗

arXiv2021

Probing elastic interactions in the dark sector and the role of $S_8$

We place observational constraints on two models within a class of scenarios featuring an elastic interaction between dark energy and dark matter that only produces momentum exchange up to first order in cosmological perturbations. The first one corresponds to a perfect-fluid model of the dark components with an explicit interacting Lagrangian, where dark energy acts as a dark radiation at early times and behaves as a cosmological constant at late times. The second one is a dynamical dark energy model with a dark radiation component, where the momentum exchange covariantly modifies the conservation equations in the dark sector. Using Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO), and Supernovae type Ia (SnIa) data, we show that the Hubble tension can be alleviated due to the additional radiation, while the $σ_8$ tension present in the $Λ$-Cold-Dark-Matter model can be eased by the weaker galaxy clustering that occurs in these interacting models. Furthermore, we show that, while CMB+BAO+SnIa data put only upper bounds on the coupling strength, adding low-redshift data in the form of a constraint on the parameter $S_8$ strongly favours nonvanishing values of the interaction parameters. Our findings are in line with other results in the literature that could signal a universal trend of the momentum exchange among the dark sector.

astro-ph.CO↗

arXiv2013

Structure of neutron stars in R-squared gravity

The effects implied for the structure of compact objects by the modification of General Relativity produced by the generalization of the Lagrangian density to the form f(R)=R+αR^2, where R is the Ricci curvature scalar, have been recently explored. It seems likely that this squared-gravity may allow heavier Neutron Stars (NSs) than GR. In addition, these objects can be useful to constrain free parameters of modified-gravity theories. The differences between alternative gravity theories is enhanced in the strong gravitational regime. In this regime, because of the complexity of the field equations, perturbative methods become a good choice to treat the problem. Following previous works in the field, we performed a numerical integration of the structure equations that describe NSs in f(R)-gravity, recovering their mass-radius relations, but focusing on particular features that arise from this approach in the profiles of the NS interior. We show that these profiles run in correlation with the second-order derivative of the analytic approximation to the Equation of State (EoS), which leads to regions where the enclosed mass decreases with the radius in a counter-intuitive way. We reproduce all computations with a simple polytropic EoS to separate zeroth-order modified gravity effects.

astro-ph.CO↗