arXiv subjects

Oğuzhan K. Yamak

Publications and source records attributed to Oğuzhan K. Yamak.

2 recordsLinked to original sources

arXiv2026

Novel Observable Signals from First-Order Gravitational Phase Transitions

Spontaneous scalarization is a well-known phenomenon in scalar-tensor theories, featuring large deviations from general relativity. However, some of its signatures are hard to detect, because it is generally studied as a continuous phase transition. We show that scalarization occurs in a discontinuous (first-order) manner in many astrophysically relevant scenarios. This leads to loud signals that provide new tests of gravity. We demonstrate this in the case of gravitational wave breathing modes from a neutron star that scalarizes due to accretion, and discuss other possibilities.

gr-qc↗

arXiv2025

Nature of phase transitions and metastability in scalar-tensor theories

Compact stars above a critical stellar mass develop large scalar fields in some scalar-tensor theories. This scenario, called spontaneous scalarization, has been an intense topic of study since it passes weak-field gravity tests naturally while providing clear observables in the strong-field regime. The underlying mechanism for the onset of scalarization is often depicted as a second-order phase transition. Here, we show that a first-order phase transition is in fact the most common mechanism. This means metastability and transitions between locally stable compact object configurations are much more likely than previously believed, opening vast new avenues for observational prospects.

gr-qc↗