299 citations · 882 across the 40 of their papers we have counts for
43 papers
Non-Gaussian timing residual skewness in pulsar timing arrays
Reginald Christian Bernardo, Rituparna Mandal, Kin-Wang Ng
Motivated by searches for weak primordial non-Gaussianity in the cosmic microwave background, we investigate perturbative departures from Gaussian stochastic gravitational wave bac…
Testing internal dynamics in neutron stars with radio pulsar timing
Reginald Christian Bernardo
Rotational variations in pulsars reflect either internal angular momentum exchange via equal and opposite torques (stationary spin noise) or independent torques causing diffusive c…
Intrinsic versus observation induced spin nonstationarity in pulsar timing
Reginald Christian Bernardo
Whether spin noise of a neutron star is stationary is, in two-component models, a question of whether stellar angular momentum is conserved internally or exchanged externally throu…
Stochastic problems in pulsar timing
Reginald Christian Bernardo
Langevin stochastic differential equations provide a dynamical description of pulsar timing noise and gravitational wave background (GWB) signals. They are also central to state sp…
Cosmo-Learn: code for learning cosmology using different methods and mock data
Reginald Christian Bernardo, Daniela Grandón, Jackson Levi Said +3
We present cosmo_learn, an open-source python-based software package designed to simulate cosmological data and perform data-driven inference using a range of modern statistical an…
Simulating a Gaussian stochastic gravitational wave background signal in pulsar timing arrays
Reginald Christian Bernardo, Kin-Wang Ng
We revisit the theoretical modeling and simulation of a Gaussian stochastic gravitational wave background (SGWB) signal in a pulsar timing array (PTA). We show that the correlation…
Genetic algorithm demystified for cosmological parameter estimation
Reginald Christian Bernardo, Yun Chen
Genetic algorithm (GA) belongs to a class of nature-inspired evolutionary algorithms that leverage concepts from natural selection to perform optimization tasks. In cosmology, the…
Nature-inspired optimization, the Philippine Eagle, and cosmological parameter estimation
Reginald Christian Bernardo, Erika Antonette Enriquez, Renier Mendoza +2
Precise and accurate estimation of cosmological parameters is crucial for understanding the Universe's dynamics and addressing cosmological tensions. In this methods paper, we expl…
Implications of pulsar timing arrays for Gauss-Bonnet Inflation
Reginald Christian Bernardo, Seoktae Koh, Gansukh Tumurtushaa
Correlated time-of-arrival measurements by pulsar timing arrays (PTAs) have provided a new means of constraining astrophysical or cosmological models that produce a gravitational w…
The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
Eleonora Di Valentino, Jackson Levi Said, Adam Riess +533
The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades.…
The Topology of Rayleigh-Levy Flights in Two Dimensions
Reginald Christian Bernardo, Stephen Appleby, Francis Bernardeau +1
Rayleigh-Lévy flights are simplified cosmological tools which capture certain essential statistical properties of the cosmic density field, including hierarchical structures in hig…
Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
Reginald Christian Bernardo, Kin-Wang Ng
In the summer of 2023, the pulsar timing arrays (PTAs) announced a compelling evidence for the existence of a nanohertz stochastic gravitational wave background (SGWB). Despite thi…
Accurate pulsar timing array residual variances and correlation of the stochastic gravitational wave background
Reginald Christian Bernardo, Kin-Wang Ng
Pulsar timing arrays have reported a compelling evidence of a nanohertz stochastic gravitational wave background. However, the origin of the signal remains undetermined, largely be…
Toward a test of Gaussianity of a gravitational wave background
Reginald Christian Bernardo, Stephen Appleby, Kin-Wang Ng
The degree of Gaussianity of a field offers insights into its cosmological nature, and its statistical properties serve as indicators of its Gaussianity. In this work, we examine t…
Correlations for an anisotropic polarized stochastic gravitational wave background in pulsar timing arrays
Reginald Christian Bernardo, Guo-Chin Liu, Kin-Wang Ng
The recent compelling observation of the nanohertz stochastic gravitational wave background has brought to light a new galactic arena to test gravity. In this paper, we derive a fo…
Beyond the Hellings-Downs curve: Non-Einsteinian gravitational waves in pulsar timing array correlations
Reginald Christian Bernardo, Kin-Wang Ng
The recent astronomical milestone by the pulsar timing arrays (PTA) has revealed galactic-size gravitational waves (GW) in the form of a stochastic gravitational wave background (S…
Tadpole Cosmology: Milne Solution as a Cosmological Constant Hideout
Stephen Appleby, Reginald Christian Bernardo
Dynamical cancellation frameworks present a potential means of mitigating the effect of a large vacuum energy, that would otherwise ruin the late-time, low energy dynamics of the U…
Testing gravity with cosmic variance-limited pulsar timing array correlations
Reginald Christian Bernardo, Kin-Wang Ng
The nanohertz stochastic gravitational wave background (SGWB) is an excellent early universe laboratory for testing the fundamental properties of gravity. In this letter, we elucid…
Hunting the stochastic gravitational wave background in pulsar timing array cross correlations through theoretical uncertainty
Reginald Christian Bernardo, Kin-Wang Ng
Incredible progress on the theoretical uncertainty of the spatial correlations of the stochastic gravitational wave (GW) background were recently made. However, it remains to reali…
Constraining gravitational wave propagation using pulsar timing array correlations
Reginald Christian Bernardo, Kin-Wang Ng
Pulsar timing arrays (PTA) are a promising probe to the cosmologically novel nanohertz gravitational wave (GW) regime through the stochastic GW background. In this work, we conside…
Hubble constant by natural selection: Evolution chips in the Hubble tension
Reginald Christian Bernardo, You-Ru Lee
The Approximate Bayesian Computation (ABC) algorithm considers natural selection in biology as a guiding principle for statistical model selection and parameter estimation. We take…
Dark energy by natural evolution: Constraining dark energy using Approximate Bayesian Computation
Reginald Christian Bernardo, Daniela Grandón, Jackson Levi Said +1
We look at dark energy from a biology inspired viewpoint by means of the Approximate Bayesian Computation (ABC) and late time cosmological observations. We find that dynamical dark…
Pulsar and cosmic variances of pulsar timing-array correlation measurements of the stochastic gravitational wave background
Reginald Christian Bernardo, Kin-Wang Ng
Pulsar timing-array correlation measurements offer an exciting opportunity to test the nature of gravity in the cosmologically novel nanohertz gravitational wave regime. The stocha…
Stochastic gravitational wave background phenomenology in a pulsar timing array
Reginald Christian Bernardo, Kin-Wang Ng
Pulsar timing offers an independent avenue to test general relativity and alternative gravity theories. This requires an understanding of how metric polarizations beyond the famili…