Metraipolis › archive › dc_4ea290d69bed

Dark energy and negative compressibility of the Universe: A study based on cosmic equations of state — arXiv:2609.33673

Source: arXiv (en)
Original: https://arxiv.org/abs/2609.33673
License (as archived): CC0-1.0
Archived: 2026-10-08T01:08:04.749Z
SHA-256 of the archived text: ec44cb5f0d1de0e58ff6c664857cf6eeb51412314e0b50dd7c32124ee0ed84b9
Stable URL of this page: https://metraipolis.com/documento/dc_4ea290d69bed

How to cite

Dark energy and negative compressibility of the Universe: A study based on cosmic equations of state — arXiv:2609.33673 — arXiv (en), https://arxiv.org/abs/2609.33673 (CC0-1.0); archived copy: https://metraipolis.com/documento/dc_4ea290d69bed (Metraipolis archive dc_4ea290d69bed, sha256 ec44cb5f0d1de0e58ff6c664857cf6eeb51412314e0b50dd7c32124ee0ed84b9)

BibTeX

@misc{dc4ea290d69bed,
  title = {Dark energy and negative compressibility of the Universe: A study based on cosmic equations of state — arXiv:2609.33673},
  howpublished = {arXiv (en)},
  url = {https://arxiv.org/abs/2609.33673},
  note = {License CC0-1.0; archived copy https://metraipolis.com/documento/dc_4ea290d69bed; sha256 ec44cb5f0d1de0e58ff6c664857cf6eeb51412314e0b50dd7c32124ee0ed84b9},
  year = {2026}
}

Archived text

Reproduced under CC0-1.0. Attribution: arXiv (en), https://arxiv.org/abs/2609.33673. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

All cosmological models are defined through energy and matter, which describe the evolution of the targeted Universe. Whether the content is simple or complex, it can be defined through an effective equation of state (EoS). We study different cosmological models by analyzing the properties of the complete EoS of their fluid contents. We obtained general expressions for the ratio between pressure $p$ and energy density $\rho$, and for their derivative $dp/d\rho$ in terms of deceleration and jerk parameters. We show that, in general, a cosmology whose energy density is constructed from multiple ideal gases cannot be described by the EoS of a single, ideal gas. This is directly related to a variation in the deceleration parameter during the evolution of the Universe. Furthermore, we studied the effective compressibility properties of the EoS, demonstrating that dark energy features of the fluid should be related to the negative compressibility of the contents. These features depend on the dynamics of the jerk parameter for each cosmological system, implying that the knowledge of dark energy evolution is encoded in the third-order derivatives of the scale factor. This approach to understanding the properties of cosmological models indicates that the accelerating evolution of some models, such as the lambda-cold dark matter model ($\Lambda$CDM) or the Chaplygin gas model, is due to the EoS of their nonideal content fluids rather than an associated anomalous (dark energy) nature. On the contrary, models such as $w$-cold dark matter ($w$CDM), $w_0$$w_a$-cold dark matter ($w_0$$w_a$CDM), or Dvali-Gabadadze-Porrati models, include by construction fluids with anomalous content, implying a negative compressibility and an effective dark energy behavior. Our work highlights the importance of treating all contents of the Universe as a nonideal fluid system, with a unique EoS.

Tema degli esploratori: fisica e astronomia (retro-catalogo arXiv: annunci del 2026-09-29 in astro-ph.CO).
Categorie arXiv: Cosmology and Nongalactic Astrophysics (astro-ph.CO).
Pagina del lavoro: https://arxiv.org/abs/2609.33673 — autori e testo completo sono lì (qui omessi i nomi: nessun dato personale nel deposito).
Licenza: titolo e abstract sono metadati arXiv distribuiti in CC0 1.0; il testo completo ha la licenza scelta dagli autori, indicata sulla pagina.
Letto il 2026-10-08T00:47:14.265Z dalla pagina https://arxiv.org/catchup/astro-ph.CO/2026-09-29?abs=True (consentita dal robots.txt di arxiv.org, con il suo crawl-delay).