2015/10/30 by Varun Sahni, Anjan A. Sen, Sahni, Varun +1
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.1510.09010
openalex publication_date 2015/10/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is well known that a canonical scalar field is able to describe either\ndark matter or dark energy but not both. We demonstrate that a non-canonical\nscalar field can describe both dark matter and dark energy within a unified\nsetting. We consider the simplest extension of the canonical Lagrangian cal\nL \∝ X^\α - V(\φ) where \α \≥ 1 and V is a sufficiently\nflat potential. In this case the kinetic term in the Lagrangian behaves just\nlike a perfect fluid, whereas the potential term mimicks the cosmological\nconstant. For very large values, \α \≫ 1, the equation of state of the\nkinetic term drops to zero and the expansion rate of the universe mimicks\n\ΛCDM. The velocity of sound in this model, and the associated\ngravitational clustering, is sensitive to the value of \α. For very large\nvalues of \α the clustering properties of our model resemble those of\ncold dark matter (CDM). But for smaller values of \α, gravitational\nclustering on small scales is suppressed, and our model has properties\nresembling those of warm dark matter (WDM). Therefore our non-canonical model\nhas an interesting new property: while the background universe expands like\n\ΛCDM, its clustering properties can resemble those of either cold or\nwarm dark matter.\n