Weak cosmic growth in coupled dark energy with a Lagrangian formulation
We investigate a dark energy scenario in which a canonical scalar field ϕ is coupled to the four velocity ucμ of cold dark matter (CDM) through a derivative interaction ucμ∂μϕ. The coupling is described by an interacting Lagrangian f(X,Z), where f depends on X=−∂μϕ∂μϕ/2 and Z=ucμ∂μϕ. We derive stabi...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2020-05-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269320302045 |
| _version_ | 1818305882846396416 |
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| author | Ryotaro Kase Shinji Tsujikawa |
| author_facet | Ryotaro Kase Shinji Tsujikawa |
| author_sort | Ryotaro Kase |
| collection | DOAJ |
| description | We investigate a dark energy scenario in which a canonical scalar field ϕ is coupled to the four velocity ucμ of cold dark matter (CDM) through a derivative interaction ucμ∂μϕ. The coupling is described by an interacting Lagrangian f(X,Z), where f depends on X=−∂μϕ∂μϕ/2 and Z=ucμ∂μϕ. We derive stability conditions of linear scalar perturbations for the wavelength deep inside the Hubble radius and show that the effective CDM sound speed is close to 0 as in the standard uncoupled case, while the scalar-field propagation speed is affected by the interacting term f. Under a quasi-static approximation, we also obtain a general expression of the effective gravitational coupling felt by the CDM perturbation. We study the late-time cosmological dynamics for the coupling f∝X(2−m)/2Zm and show that the gravitational coupling weaker than the Newton constant can be naturally realized for m>0 on scales relevant to the growth of large-scale structures. This allows the possibility for alleviating the tension of σ8 between low- and high-redshift measurements. |
| first_indexed | 2024-12-13T06:33:39Z |
| format | Article |
| id | doaj.art-cd2b93c684e549bc9cf49e945d18980b |
| institution | Directory Open Access Journal |
| issn | 0370-2693 |
| language | English |
| last_indexed | 2024-12-13T06:33:39Z |
| publishDate | 2020-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj.art-cd2b93c684e549bc9cf49e945d18980b2022-12-21T23:56:34ZengElsevierPhysics Letters B0370-26932020-05-01804Weak cosmic growth in coupled dark energy with a Lagrangian formulationRyotaro Kase0Shinji Tsujikawa1Corresponding author.; Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, JapanDepartment of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, JapanWe investigate a dark energy scenario in which a canonical scalar field ϕ is coupled to the four velocity ucμ of cold dark matter (CDM) through a derivative interaction ucμ∂μϕ. The coupling is described by an interacting Lagrangian f(X,Z), where f depends on X=−∂μϕ∂μϕ/2 and Z=ucμ∂μϕ. We derive stability conditions of linear scalar perturbations for the wavelength deep inside the Hubble radius and show that the effective CDM sound speed is close to 0 as in the standard uncoupled case, while the scalar-field propagation speed is affected by the interacting term f. Under a quasi-static approximation, we also obtain a general expression of the effective gravitational coupling felt by the CDM perturbation. We study the late-time cosmological dynamics for the coupling f∝X(2−m)/2Zm and show that the gravitational coupling weaker than the Newton constant can be naturally realized for m>0 on scales relevant to the growth of large-scale structures. This allows the possibility for alleviating the tension of σ8 between low- and high-redshift measurements.http://www.sciencedirect.com/science/article/pii/S0370269320302045 |
| spellingShingle | Ryotaro Kase Shinji Tsujikawa Weak cosmic growth in coupled dark energy with a Lagrangian formulation Physics Letters B |
| title | Weak cosmic growth in coupled dark energy with a Lagrangian formulation |
| title_full | Weak cosmic growth in coupled dark energy with a Lagrangian formulation |
| title_fullStr | Weak cosmic growth in coupled dark energy with a Lagrangian formulation |
| title_full_unstemmed | Weak cosmic growth in coupled dark energy with a Lagrangian formulation |
| title_short | Weak cosmic growth in coupled dark energy with a Lagrangian formulation |
| title_sort | weak cosmic growth in coupled dark energy with a lagrangian formulation |
| url | http://www.sciencedirect.com/science/article/pii/S0370269320302045 |
| work_keys_str_mv | AT ryotarokase weakcosmicgrowthincoupleddarkenergywithalagrangianformulation AT shinjitsujikawa weakcosmicgrowthincoupleddarkenergywithalagrangianformulation |