Salvato in:
| Autori principali: | , , |
|---|---|
| Natura: | Preprint |
| Pubblicazione: |
2025
|
| Soggetti: | |
| Accesso online: | https://arxiv.org/abs/2509.14826 |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1866915504475602944 |
|---|---|
| author | Wu, Yi-Syuan Li, Chuan-Jui Kao, W. F. |
| author_facet | Wu, Yi-Syuan Li, Chuan-Jui Kao, W. F. |
| contents | We present a scalar-field formulation of the generalized Chaplygin gas (GCG) and modified Chaplygin gas (MCG) models, in which the cosmic fluid dynamics are reproduced by canonical Lagrangians with analytically derived energy density $ρ(ϕ)$, pressure $p(ϕ)$, and scalar potential $V(ϕ)$. This framework provides a unified description of dark matter and dark energy, transitioning naturally from a matter-dominated phase at early times to a negative-pressure dark-energy phase at late times. In this scalar-field formulation, the GCG and MCG models are naturally applicable to both theoretical analyses and numerical simulations. Extending this approach, we develop a systematic method to obtain a class of integrable scalar-field cosmological models. In this study, we use this method to construct a new scalar-field altered Chaplygin gas (ACG) model. To investigate the viability of Chaplygin-type models, we perform a likelihood analysis using the Pantheon+ Type Ia supernova compilation together with Cepheid-calibrated distances. We examine four models, $Λ$CDM, GCG, MCG, and ACG, obtaining posterior constraints on the Hubble constant $H_0$, the present-day effective equation of state $ω_0$, the transition redshift $z^\star$, and the cosmic age $t_0$. With the Cepheid calibration fixing the absolute distance scale, the inferred $H_{0}$ remains nearly model-independent. The Chaplygin-type models predict an earlier onset of cosmic acceleration than $Λ$CDM and give a broader range for the inferred age of the Universe, reflecting their greater flexibility in late-time expansion histories. Among them, the ACG model provides tighter parameter constraints, while the GCG and MCG models produce broader posteriors due to parameter degeneracies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_14826 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Altered Chaplygin Model as a Model for Dark Energy Wu, Yi-Syuan Li, Chuan-Jui Kao, W. F. Cosmology and Nongalactic Astrophysics We present a scalar-field formulation of the generalized Chaplygin gas (GCG) and modified Chaplygin gas (MCG) models, in which the cosmic fluid dynamics are reproduced by canonical Lagrangians with analytically derived energy density $ρ(ϕ)$, pressure $p(ϕ)$, and scalar potential $V(ϕ)$. This framework provides a unified description of dark matter and dark energy, transitioning naturally from a matter-dominated phase at early times to a negative-pressure dark-energy phase at late times. In this scalar-field formulation, the GCG and MCG models are naturally applicable to both theoretical analyses and numerical simulations. Extending this approach, we develop a systematic method to obtain a class of integrable scalar-field cosmological models. In this study, we use this method to construct a new scalar-field altered Chaplygin gas (ACG) model. To investigate the viability of Chaplygin-type models, we perform a likelihood analysis using the Pantheon+ Type Ia supernova compilation together with Cepheid-calibrated distances. We examine four models, $Λ$CDM, GCG, MCG, and ACG, obtaining posterior constraints on the Hubble constant $H_0$, the present-day effective equation of state $ω_0$, the transition redshift $z^\star$, and the cosmic age $t_0$. With the Cepheid calibration fixing the absolute distance scale, the inferred $H_{0}$ remains nearly model-independent. The Chaplygin-type models predict an earlier onset of cosmic acceleration than $Λ$CDM and give a broader range for the inferred age of the Universe, reflecting their greater flexibility in late-time expansion histories. Among them, the ACG model provides tighter parameter constraints, while the GCG and MCG models produce broader posteriors due to parameter degeneracies. |
| title | The Altered Chaplygin Model as a Model for Dark Energy |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2509.14826 |