Structural Implications of the Chameleon Mechanism on White Dwarfs
We study the behaviour of the chameleon mechanism around white dwarfs and its impact on their structure. Using a shooting method of our own design, we solve the corresponding scalar–tensor equilibrium equations for a Chandrasekhar equation of state, exploring various energy scales and couplings of t...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
|
| Series: | Universe |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-1997/11/7/237 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849251880985690112 |
|---|---|
| author | Joan Bachs-Esteban Ilídio Lopes Javier Rubio |
| author_facet | Joan Bachs-Esteban Ilídio Lopes Javier Rubio |
| author_sort | Joan Bachs-Esteban |
| collection | DOAJ |
| description | We study the behaviour of the chameleon mechanism around white dwarfs and its impact on their structure. Using a shooting method of our own design, we solve the corresponding scalar–tensor equilibrium equations for a Chandrasekhar equation of state, exploring various energy scales and couplings of the chameleon field to matter. For the considered parameter ranges, we find the chameleon field to be in a thick-shell configuration, identifying for the first time in the literature a similarity relation of the theory for the radially normalised scalar field gradient. Our analysis reveals that the chameleon mechanism alters the pressure gradient of white dwarfs, leading to a reduction in the stellar radii and masses and shifting the mass–radius curves below those predicted by Newtonian gravity. This also lowers the specific heat of white dwarfs, accelerating their cooling process. Finally, we derive parametric expressions from our results to expedite future analyses of white dwarfs in scalar–tensor theories. |
| format | Article |
| id | doaj-art-a879ff4a6dca47f5870db386b1d91cfa |
| institution | Kabale University |
| issn | 2218-1997 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Universe |
| spelling | doaj-art-a879ff4a6dca47f5870db386b1d91cfa2025-08-20T03:56:47ZengMDPI AGUniverse2218-19972025-07-0111723710.3390/universe11070237Structural Implications of the Chameleon Mechanism on White DwarfsJoan Bachs-Esteban0Ilídio Lopes1Javier Rubio2Centro de Astrofísica e Gravitação—CENTRA, Departamento de Física, Instituto Superior Técnico—IST, Universidade de Lisboa—UL, Av. Rovisco Pais 1, 1049-001 Lisboa, PortugalCentro de Astrofísica e Gravitação—CENTRA, Departamento de Física, Instituto Superior Técnico—IST, Universidade de Lisboa—UL, Av. Rovisco Pais 1, 1049-001 Lisboa, PortugalDepartamento de Física Teórica and Instituto de Física de Partículas y del Cosmos (IPARCOS), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, SpainWe study the behaviour of the chameleon mechanism around white dwarfs and its impact on their structure. Using a shooting method of our own design, we solve the corresponding scalar–tensor equilibrium equations for a Chandrasekhar equation of state, exploring various energy scales and couplings of the chameleon field to matter. For the considered parameter ranges, we find the chameleon field to be in a thick-shell configuration, identifying for the first time in the literature a similarity relation of the theory for the radially normalised scalar field gradient. Our analysis reveals that the chameleon mechanism alters the pressure gradient of white dwarfs, leading to a reduction in the stellar radii and masses and shifting the mass–radius curves below those predicted by Newtonian gravity. This also lowers the specific heat of white dwarfs, accelerating their cooling process. Finally, we derive parametric expressions from our results to expedite future analyses of white dwarfs in scalar–tensor theories.https://www.mdpi.com/2218-1997/11/7/237scalar–tensor theoriesscreening mechanismswhite dwarfs |
| spellingShingle | Joan Bachs-Esteban Ilídio Lopes Javier Rubio Structural Implications of the Chameleon Mechanism on White Dwarfs Universe scalar–tensor theories screening mechanisms white dwarfs |
| title | Structural Implications of the Chameleon Mechanism on White Dwarfs |
| title_full | Structural Implications of the Chameleon Mechanism on White Dwarfs |
| title_fullStr | Structural Implications of the Chameleon Mechanism on White Dwarfs |
| title_full_unstemmed | Structural Implications of the Chameleon Mechanism on White Dwarfs |
| title_short | Structural Implications of the Chameleon Mechanism on White Dwarfs |
| title_sort | structural implications of the chameleon mechanism on white dwarfs |
| topic | scalar–tensor theories screening mechanisms white dwarfs |
| url | https://www.mdpi.com/2218-1997/11/7/237 |
| work_keys_str_mv | AT joanbachsesteban structuralimplicationsofthechameleonmechanismonwhitedwarfs AT ilidiolopes structuralimplicationsofthechameleonmechanismonwhitedwarfs AT javierrubio structuralimplicationsofthechameleonmechanismonwhitedwarfs |