About me

Hello everyone, I am a Postdoctoral Researcher in Theoretical Physics at the University of Trento. I am also affiliated with the Trento Institute for Fundamental Physics and Applications (TIFPA) of the National Institute for Nuclear Physics (INFN).

My work focuses mainly on fundamental topics in cosmology, including cosmic inflation, dark energy, and the large-scale structure of the universe. I am driven by a strong passion for exploring complex cosmological models and analyzing data from the Cosmic Microwave Background radiation in conjunction with large-scale structures, using statistical tools in Python and Fortran languages (such as CAMB, CLASS, CosmoMC, MontePython, and MultiNest codes). My goal is to find the most effective compromise to accurately describe our universe.

My journey in Physics/Astronomy/Cosmology

Vereda Grande

I am originally from Brazil and grew up in the small village of Vereda Grande (the countryside of Barra de Santana, Paraíba), with just over 200 inhabitants.

Campina Grande

My academic journey began with a degree in Physics, followed by a master's in the same field. During my undergraduate studies, I lived with my grandparents in Puxinanã (a town with around 15,000 inhabitants). During my master's, I moved to Campina Grande, a city of about 400,000 inhabitants.

Rio de Janeiro

Then, I continued my academic path in Rio de Janeiro—nearly 2,900 km away from my hometown, where I did a PhD in Astronomy at National Observatory under the supervision of Prof. Jailson Alcaniz.

Observatório Nacional

After completing my PhD, I did a postdoc at National Observatory from 2019 to 2022. Note that part of this time was during the COVID pandemic when I had the opportunity to do home office and be close to my family back in Paraíba.

Pisa

When the borders were finally free, I moved to Italy, where I spent two years in Tuscany, living in the historic city of Pisa. There, I worked as a postdoctoral researcher at the National Institute for Nuclear Physics (INFN) with Prof. Giovanni Marozzi, through a prestigious fellowship for foreigners (or Italians who have been abroad long enough).

View from Frangarto

More recently, I relocated to the stunning Alpine region, where I do a postdoc at the University of Trento. This opportunity was possible thanks to a CARITRO fellowship, which I won after an extensive application procedure. Now I have the chance to work with Prof. Sunny Vagnozzi and Prof. Massimiliano Rinaldi to further expand my research and academic experience.

View from Bolzano

Beyond my work in physics and astronomy, I have always been fascinated by the natural world. Living in the Alps allows me to indulge in my passion for hiking and cycling, exploring breathtaking landscapes in every season. I also enjoy practicing Pilates and yoga, activities that help me maintain balance and focus. In my free time, I love solving puzzles and working on scrapbooking projects, finding joy in creativity and intricate details.

Cinque Terre - Liguria

My journey has been one of curiosity and exploration, both in science and in life. Whether studying the cosmos or discovering new trails in the mountains, I am always seeking to learn, grow, and appreciate the beauty of the world around me.

Research

Publications

CV (PDF)

Here, I outline the core research topics I investigate

Inflation

Back to my Ph.D., I explored different inflationary models (also in the context of modified gravity theories), examining their effects on the large-scale structure of the universe and assessing their observational viability using current data from Cosmic Microwave Background (CMB) temperature anisotropies and Baryon Acoustic Oscillations (BAO).

My works span over models with features in the primordial power spectrum motivated by the early universe physics, α -attractor inflationary models with a Higgs-like potential, brane inflation, non-minimally coupled β-exponential inflation, warm inflation, backreaction in axion inflation models, and more recently, I also investigated the impact of DESI BAO data on the inflationary parameters.

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Dark Energy and Modified Gravity

I am also interested in investigate the dark sector of the Universe, i.e. Dark Matter (DM) and Dark Energy (DE), which nature is unknown. The DM component is known mainly by its clustering feature playing a crucial role in driving large-scale structure formation on cosmological scales. The DE component instead is responsible for driving the accelerated expansion of the Universe. Only 5% of the Universe’s energy content is composed of ordinary matter (or baryons).

In particular, I have explored models considering a geometric approach to dark energy in the framework of modified theories of gravity, such as f(R,G), f(R,T)−Λ(ϕ) gravity, and a cuscuton-like model.

Image Credit: D’arcy Kenworthy

Cosmological tensions

Cosmological tensions, particularly the H₀ and S₈ tensions, are topics that warrant attention in the whole Cosmology community nowadays. In a recent study, my collaborators and I demonstrated that resolving the H₀ tension requires an increase in the physical dark matter density ωm, which in turn worsens the S₈ tension.

In addition, I also consider the impact of non-thermal dark matter production as a potential explanation for the discrepancy between local and global measurements of the Hubble constant.

Most significant projects and collaborations

The one-dimensional marginalized posterior distribution considering the baseline dataset combination CMB+SDSS+PP for the ΛCDM model (black dotted line), and the dataset combination CMB+DESI+PP for the ΛCDM model (red solid line), the ΛCDM with free curvature (blue solid line), CPL parametrization with (magenta line) and without (green line) the w(z) > −1 constrain, and lastly the sign-switching cosmological constant (cyan line). Source: Santos da Costa Phys.Dark Univ. 47 (2025) 101791

Impact of DESI BAO Data on Inflationary Parameters: Stability against late-time new physics

In this work, I investigate the impact of Dark Energy Spectroscopic Instrument (DESI) Baryonic Acoustic Oscillations (BAO) data on inflationary parameters. By examining different models of late-time new physics, the inflationary parameters were revealed to be stable when compared with the baseline dataset that used the earlier BAO data from the SDSS collaboration. When combined with Cosmic Microwave Background (CMB) and type Ia supernovae (SNeIa), DESI BAO data leads to a slight reduction in ωm (less than 2%) and modest changes in As and ns, if compared with the same combination but using SDSS BAO data instead, suggesting a subtle shift in matter clustering. These effects may be attributed to a higher expansion rate from dynamical dark energy, changes in the recombination period, or modifications to the matter-radiation equality time. Further analyses of models with dynamical dark energy and free curvature show a consistent trend of reduced ωm, accompanied by slight increases in both ns and H0. The results emphasize the importance of the DESI BAO data in refining cosmological parameter estimates and highlight the stability of inflationary parameters across different late-time cosmological models.

Multidimensionality of the Hubble tension: The roles of Ωm and ωc

The Hubble tension is inherently multidimensional and bears important implications for parameters beyond H0. In this work, we discuss the key role of the matter density parameter Ωm and the physical cold dark matter density ωc. We argue that once Ωm and the physical baryon density ωb are calibrated, through BAO and/or SNeIa for Ωm, and via big bang nucleosynthesis for ωb, any model raising H0 requires raising ωc and, under minimal assumptions, also the clustering parameter S8. We explicitly verify that this behavior holds when analyzing recent BAO and SNeIa data. We argue that a calibration of Ωm as reliable and model-independent as possible should be a priority in the Hubble tension discussion, and an interesting possibility in this sense could be represented by galaxy cluster gas mass fraction measurements.

Triangular plot showing 2D joint and 1D marginalized posterior probability distributions for the fractional matter density parameter Ωm, the physical cold dark matter density ωc, the reduced Hubble constant h, and the clustering parameter S8, in light of the BBN +PP+BAO (red contours and curves) and BBN +PP+BAO+SH0ES (blue contours and curves) dataset combinations. We clearly see that h, ωc, and S8 increase hand-in-hand. Source: Pedrotti et al. Phys.Rev.D 111 (2025) 2, 023506.

Time evolution for the ξ parameter, considering g = 60/MPl and f = 5MPl. We show the results of solving the Friedmann and Klein-Gordon equations in the absence of backreaction (blue dotted lines), the case when only the gauge fields production is taken into account (red dot-dashed lines), and the current work in solid black lines, where we consider also metric and field scalar perturbations to calculate the effective expansion rate. Source: Campanella Galanti et al. Phys.Rev.D 110 (2024) 12, 123510.

Gauge invariant quantum backreaction in U(1) axion inflation

We evaluate the quantum backreaction due to a gauge field coupled to a pseudoscalar field driving a slow-roll inflationary stage, the so-called axion inflation. The backreaction is evaluated for the first time using a gauge invariant approach, going to second order in perturbation theory, and taking into consideration inflaton fluctuations as well as scalar perturbations of the metric. Within our gauge-invariant, but observer-dependent approach, we naturally consider as physical observers the ones comoving with the inflaton field. Considering the effective expansion rate consequent to the gauge field’s backreaction, we observe that the backreaction effect becomes significant quite rapidly, moving the system out of the perturbative regime and into what is often referred to as the strong backreaction regime. This behavior also applies to the parameter that dictates the production of the gauge fields. The spacetime backreaction is mainly due to the helicity contribution within the region of validity of the perturbative regime. As a final result, we see that the evaluated backreaction prolongs the inflationary period more than the scenarios previously studied.

Cuscuton-like contribution to dark energy evolution

This work deals with the presence of the cuscuton term in the otherwise standard dark energy evolution under the usual FLRW background. We disclose a first-order framework similar to the solutions. We explore several possibilities, concentrating mainly on how the cuscuton-like contribution works to modify cosmic evolution. Some results are of current interest since they describe scenarios capable of changing the evolution, adding or excluding possible distinct phases during the Universe’s expansion history. Additionally, we present interesting constraints on the cuscuton-like contribution for the dark energy evolution using a set of homogeneous geometrical observational probes. Finally, based on the Akaike Information Criterion (AIC), we perform a statistical comparison of the cuscuton-like model with ΛCDM, and find strong support for our model.

One-dimensional posterior distributions and two-dimensional joint contours for the parameter space {Ωm, h, B} for different dataset combinations. We display also the ΛCDM model, using the full dataset HD+SN+BAO+CMB, for comparison purposes. Source: Bazeia et al. Eur.Phys.J.C 85 (2025) 196.

Allowed regions of parameters that connect the decay mechanism and the value of Hubble constant in phantom-like cases. The contour regions correspond to cases where χ′ lifetime is 102s, 103s, or 104s, with 95% of C.L. (the huge and lighter regions) and 68% of C.L. (the small and darker regions). It is a cosmology with no curvature, where exists a phantom-like quintessence and non-zero ∆Nef f . The bounds use Planck 2018 CMB data, BAO, and type Ia data from the Pantheon sample. Source: Santos da Costa et al. JCAP 04 (2024) 035.

The H0 trouble: confronting non-thermal dark matter and phantom cosmology with the CMB, BAO, and Type Ia supernovae data

The trouble with the Hubble constant is often treated as a cosmological problem. However, the Hubble constant can be a laboratory to probe cosmology and particle physics models. In our work, we investigated if the possibility of explaining the H0 trouble using non-thermal dark matter production aided by phantom-like cosmology is consistent with the CMB and BAO data. We performed a full Monte Carlo simulation using CMB and BAO datasets keeping the cosmological parameters Ωbh2, Ωch2, 100θ, τopt, and w as priors and concluded that a non-thermal dark matter production aided by phantom-like cosmology yields at most H0 = 70.5 km s−1 Mpc−1 which is consistent with some late-time measurements. However, if H0 > 72 km s−1 Mpc−1 as many late-time observations indicate, an alternative solution to the Hubble trouble is needed. Lastly, we limited the fraction of relativistic dark matter at the matter-radiation equality to be at most 1%

Observational constraints on α -attractor inflationary models with a Higgs-like potential

The ns − r plane for the Higgs-like potential, considering different values of the parameter α (solid colored lines and magenta dashed line) and two values for the number of e-folds, N=50 and N=60 (black dotted lines). The contours are the 68% and 95% confidence level regions obtained from Planck (2018) CMB data using the pivot scale k∗ = 0.05Mpc−1. Source: Rodrigues, et al. Phys.Lett.B 815 (2021) 136156.

68% and 95% confidence regions for the primary and derived parameters of the Higgs-like model. Source: Rodrigues, et al. Phys.Lett.B 815 (2021) 136156.

We investigate the observational viability of a class of α-attractors inflationary models in light of the most recent CMB and Large-Scale Structure (LSS) data. By considering a double-well potential we perform a slow-roll analysis to study the behavior of this class of models, which is a continuous interpolation between the chaotic inflation for large values of α and the universal attractor, i.e., ns=1−2/N and r=α12/N2 for small α, where ns is the scalar spectral index, r is the tensor-to-scalar ratio, and N is the e-fold number. In order to explore the parameter space of the model, we also perform a MCMC analysis and find α=7.56±5.15 (1σ).

Community

One of my strong beliefs is that Science is collaborative and must be accessible to everyone. In particular, I am passionate about scientific outreach. Thus, beyond my research, I am deeply committed to public science communication. I have organized and led outreach programs at various institutions in Brazil and in Italy, aiming to make complex scientific concepts more accessible to a broader audience. I have given numerous public talks and workshops, helping to increase awareness of scientific research in cosmology and its implications for our understanding of the universe.

I also have been actively involved in mentoring and teaching undergraduate students. These experiences have reinforced my commitment to developing the next generation of researchers and contributing to the educational mission of the institutions I have been part of.‍

In the following, you can find some SELECTED activities I developed over the years:

Mentoring:‍

Supervisor of Ana Clara da Rocha e Silva (Universidade Federal do Rio de Janeiro) - Bachelor's thesis.
Supervisor of Ester Costa Nascimento (Universidade de Brasília) in the Science initiation program at Observatório Nacional. [Next position: Master student at Observatório Nacional.]
Supervisor of Maria Eduarda Gomes Lopes (Instituto Federal do Sertão de Pernambuco) in the Science initiation program at Observatório Nacional. [Next position: Master student at Observatório Nacional.]

Teaching:‍

Taught course of 9 hours on "Alternative cosmological models'' for Undergraduate and Graduate students, Universidade Estadual do Rio Grande do Norte, Mossoró (RN), Brazil.
Taught course of 2 hours on "CAMB (Code for Anisotropies in the Microwave Background)" for Undergraduate and Graduate students at International Institute of Physics - IIP, Natal, RN, Brazil.
Taught course of 3 hours on "Observational Cosmology" for Undergraduate and Graduate students at Universidade Federal de Góias - UFG, Goiânia (GO), Brazil.‍

Outreach:

Invited talk "Onde a Física me levou" in Laboratório de Ensino e Estudos em Astronomia - Departamento de Física - Universidade Estadual do Ceará, Iguatu (CE), Brazil.
Invited talk "Una breve storia dell'Universo" in Istituto Arcivescovile di Trento, as part of the activities on the "Assemblea comune delle scuole secondarie di Trento - 2030 Odissea nel futuro”.
Invited e-talk: "Universo: planetas estrelas e tudo mais'' in I Encontro de Física - Instituto Federal do Sertão de Pernambuco, Ouricuri (PE), Brazil.
Invited e-talk: "Mistérios do Universo: da Radiação Cósmica de Fundo à Energia Escura" in 16ª Quinta Científica e Cultural (QCC) - Departamento de Física da UFS. Sergipe, Brazil.
Exhibition: "Sky Observation with Luneta 46'' at Observatório Nacional - Luneta Equatorial 46, Rio de Janeiro, Brazil.
Exhibition: "Pelo Céu de Sobral'' in celebration of the 100 years of the Solar Eclipse that confirmed Einstein's General Relativity Theory in Sobral (CE), Brazil.
Exhibition: "LNA's open day" presenting General Relativity Experiments at Observatório Pico dos Dias, Itajubá (MG), Brazil.

In the media:

Radio Interview: "Gravidade Modificada e Cosmologia'' for Radio MEC AM, Rio de Janeiro, Brazil.
AstroMulheres || AstroFísica ft. Simony Costa. Youtube channel: Física e Afins.
General Relativity Theory and the Solar Eclipse in Sobral. Video for Observatório Nacional's social media.
Interview: Perseverança | Simony Costa: As mulheres podem ser o que quiserem.
Radio Interview: Universo: a fronteira final for Radio MEC AM, Rio de Janeiro, Brazil.
Interview: "Mulheres na Astronomia'' for "Programa Mulheres na Astronomia da LAOBA".