Generating ultra compact boson stars with modified scalar potentials
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866910291554467840 |
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| author | Pitz, Sarah Louisa Schaffner-Bielich, Jürgen |
| author_facet | Pitz, Sarah Louisa Schaffner-Bielich, Jürgen |
| contents | The properties of selfinteracting boson stars with different scalar potentials going beyond the commonly used $ϕ^4$ ansatz are studied. The scalar potential is extended to different values of the exponent $n$ of the form $V \propto ϕ^n$. Two stability mechanism for boson stars are introduced, the first being a mass term and the second one a vacuum term. We present analytic scale-invariant expressions for these two classes of equations of state. The resulting properties of the boson star configurations differ considerably from previous calculations. We find three different categories of mass-radius relation: the first category resembles the mass-radius curve of selfbound stars, the second one those of neutron stars and the third one is the well known constant radius case from the standard $ϕ^4$ potential. We demonstrate that the maximal compactness can reach extremely high values going to the limit of causality $C_\text{max} = 0.354$ asymptotically for $n\to\infty$. The maximal compactnesses exceed previously calculated values of $C_\text{max}=0.16$ for the standard $ϕ^4$-theory and $C_\text{max}=0.21$ for vector-like interactions and is in line with previous results for solitonic boson stars. Hence, boson stars even described by a simple modified scalar potential in the form of $V \propto ϕ^n$ can be ultra compact black hole mimickers where the photon ring is located outside the radius of the star. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2308_01254 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Generating ultra compact boson stars with modified scalar potentials Pitz, Sarah Louisa Schaffner-Bielich, Jürgen High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology The properties of selfinteracting boson stars with different scalar potentials going beyond the commonly used $ϕ^4$ ansatz are studied. The scalar potential is extended to different values of the exponent $n$ of the form $V \propto ϕ^n$. Two stability mechanism for boson stars are introduced, the first being a mass term and the second one a vacuum term. We present analytic scale-invariant expressions for these two classes of equations of state. The resulting properties of the boson star configurations differ considerably from previous calculations. We find three different categories of mass-radius relation: the first category resembles the mass-radius curve of selfbound stars, the second one those of neutron stars and the third one is the well known constant radius case from the standard $ϕ^4$ potential. We demonstrate that the maximal compactness can reach extremely high values going to the limit of causality $C_\text{max} = 0.354$ asymptotically for $n\to\infty$. The maximal compactnesses exceed previously calculated values of $C_\text{max}=0.16$ for the standard $ϕ^4$-theory and $C_\text{max}=0.21$ for vector-like interactions and is in line with previous results for solitonic boson stars. Hence, boson stars even described by a simple modified scalar potential in the form of $V \propto ϕ^n$ can be ultra compact black hole mimickers where the photon ring is located outside the radius of the star. |
| title | Generating ultra compact boson stars with modified scalar potentials |
| topic | High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2308.01254 |