The spectrum of frequencies and characteristic times that compose the ringdown phase of gravitational waves emitted by neutron stars carries information about the matter content (the equation of state) and the underlying theory of gravity. Typically, modified theories of gravity introduce additional degrees of freedom/fields, such as scalars, which result in new families of modes composing the ringdown spectrum. Simple but physically promising candidates are scalar-tensor theories, which effectively introduce an additional massive scalar field ( i.e. , an ultra-light boson) that couples non-minimally to gravity, resulting in scalarized neutron stars. Here we present the first calculation of the full ringdown spectrum in such theories. We show that the ringdown spectrum of neutron stars with ultra-light bosons is much richer and fundamentally different from the spectrum in general relativity and that it possesses propagating ultra-long-lived modes.

中文翻译：

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标量张量引力下中子星的超长准准模式

构成中子星发出的引力波的衰荡相的频率频谱和特征时间频谱携带着有关物质含量（状态方程）和基本引力理论的信息。通常，修改后的重力理论会引入额外的自由度/场（例如标量），从而导致构成振铃光谱的新模式族。标量-张量理论是简单但在物理上很有前途的候选者，它有效地引入了额外的巨大标量场（即超轻玻色子），该场与引力非最小耦合，从而形成了标量中子星。在这里，我们介绍了这种理论中的完整振铃频谱的首次计算。