10 citations · 45 across the 11 of their papers we have counts for
11 papers
Progenitor age-bias-corrected Type Ia supernovae favor a logarithmic luminosity-distance relation
Hoang Ky Nguyen
Type Ia supernovae provide one of the principal observational probes of late-time cosmic acceleration. Recently, Son et al. [MNRAS 544, 975 (2025)] proposed that correlations betwe…
An intrinsic kinematic relation inferred from Type Ia supernovae
Hoang Ky Nguyen
Based on the Hubble diagram of SNeIa, we present empirical evidence for a kinematic relation between the speed of light and the late-time cosmic expansion rate. To infer this relat…
New analysis of SNeIa Pantheon Catalog: Variable speed of light as an alternative to dark energy
Hoang Ky Nguyen
In A&A 412, 35 (2003) Blanchard, Douspis, Rowan-Robinson, and Sarkar (BDRS) slightly modified the primordial fluctuation spectrum and produced an excellent fit to WMAP's CMB power…
Dilaton-induced variations in Planck constant and speed of light: An alternative to Dark Energy
Hoang Ky Nguyen
We reveal a novel aspect of scale-invariant actions that allow matter to couple with a dilaton field: The dynamics of the dilaton can induce variations in the Planck constant $…
A mechanism to generate varying speed of light via Higgs-dilaton coupling: Theory and cosmological applications
Hoang Ky Nguyen
We allow the Higgs field to interact with a dilaton field of the background spacetime via the coupling . Upon spontaneous gauge symmetry breaking, the Higg…
Time-reversed information flow through a wormhole in scalar-tensor gravity
Hoang Ky Nguyen, Francisco S. N. Lobo
This Letter aims to advance unexplored properties of a new class of Closed Timelike Curves recently discovered in scalar-tensor gravity, reported in Universe 9, 467 (2023) and Eur.…
Observational test of spacetimes with the S2 star in the Milky Way galactic center
Jian-Ming Yan, Tao Zhu, Mustapha Azreg-Aïnou +2
A novel class of vacuum metrics expressible in analytical form was recently found for pure gravity, based on a groundwork put forth by Buchdahl in 1962. These Buchda…
Observational tests of asymptotically flat spacetimes
Tao Zhu, Hoang Ky Nguyen, Mustapha Azreg-Aïnou +1
A novel class of Buchdahl-inspired metrics with closed-form expressions was recently obtained based on Buchdahl's seminal work on searching for static, spherically symmetric metric…
Closed Timelike Curves Induced by a Buchdahl-inspired Vacuum Spacetime in Gravity
Hoang Ky Nguyen, Francisco S. N. Lobo
The recently obtained Buchdahl-inspired metric [Phys. Rev. D 107, 104008 (2023)] describes asymptotically flat spacetimes in pure Ricci-squared gravity. The metr…
Non-triviality of asymptotically flat Buchdahl-inspired metrics in pure gravity
Hoang Ky Nguyen
In Phys. Rev. D , 104008 (2023) we reported a novel exact closed-form solution which describes asymptotically flat spacetimes in pure gravity. The solution is R…
A stationary axisymmetric vacuum solution for pure gravity
Mustapha Azreg-Aïnou, Hoang Ky Nguyen
The closed-form expression for pure vacuum solution obtained in Phys. Rev. D \textbf{107}, 104008 (2023) lends itself to a generalization to axisymmetric setup vi…