A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields
Abstract Self-gravitating horizonless ultra-compact objects that possess light rings have attracted the attention of physicists and mathematicians in recent years. In the present compact paper we raise the following physically interesting question: Is there a lower bound on the global compactness pa...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-02-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-13866-y |
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| author | Shahar Hod |
| author_facet | Shahar Hod |
| author_sort | Shahar Hod |
| collection | DOAJ |
| description | Abstract Self-gravitating horizonless ultra-compact objects that possess light rings have attracted the attention of physicists and mathematicians in recent years. In the present compact paper we raise the following physically interesting question: Is there a lower bound on the global compactness parameters $$\mathcal{C}\equiv \text {max}_r\{2m(r)/r\}$$ C ≡ max r { 2 m ( r ) / r } of spherically symmetric ultra-compact objects? Using the non-linearly coupled Einstein-matter field equations we explicitly prove that spatially regular ultra-compact objects with monotonically decreasing density functions (or monotonically decreasing radial pressure functions) are characterized by the lower bound $$\mathcal{C}\ge 1/3$$ C ≥ 1 / 3 on their dimensionless compactness parameters. |
| format | Article |
| id | doaj-art-b35d015fc2da41d18fc1a6514737a83b |
| institution | Kabale University |
| issn | 1434-6052 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj-art-b35d015fc2da41d18fc1a6514737a83b2025-02-09T12:51:33ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-02-018521410.1140/epjc/s10052-025-13866-yA compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fieldsShahar Hod0The Ruppin Academic CenterAbstract Self-gravitating horizonless ultra-compact objects that possess light rings have attracted the attention of physicists and mathematicians in recent years. In the present compact paper we raise the following physically interesting question: Is there a lower bound on the global compactness parameters $$\mathcal{C}\equiv \text {max}_r\{2m(r)/r\}$$ C ≡ max r { 2 m ( r ) / r } of spherically symmetric ultra-compact objects? Using the non-linearly coupled Einstein-matter field equations we explicitly prove that spatially regular ultra-compact objects with monotonically decreasing density functions (or monotonically decreasing radial pressure functions) are characterized by the lower bound $$\mathcal{C}\ge 1/3$$ C ≥ 1 / 3 on their dimensionless compactness parameters.https://doi.org/10.1140/epjc/s10052-025-13866-y |
| spellingShingle | Shahar Hod A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields European Physical Journal C: Particles and Fields |
| title | A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields |
| title_full | A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields |
| title_fullStr | A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields |
| title_full_unstemmed | A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields |
| title_short | A compact theorem on the compactness of ultra-compact objects with monotonically decreasing matter fields |
| title_sort | compact theorem on the compactness of ultra compact objects with monotonically decreasing matter fields |
| url | https://doi.org/10.1140/epjc/s10052-025-13866-y |
| work_keys_str_mv | AT shaharhod acompacttheoremonthecompactnessofultracompactobjectswithmonotonicallydecreasingmatterfields AT shaharhod compacttheoremonthecompactnessofultracompactobjectswithmonotonicallydecreasingmatterfields |