Cosmological perturbations in mimetic Horndeski gravity

被引：42

作者：

Arroja, Frederico ^{[1
]}

Bartolo, Nicola ^{[2
,3
,4
]}

Karmakar, Purnendu ^{[2
,3
,5
]}

Matarrese, Sabino ^{[2
,3
,4
,6
]}

机构：

[1] Natl Taiwan Univ, Leung Ctr Cosmol & Particle Astrophys, 1,Sec 4,Roosevelt Rd, Taipei 10617, Taiwan

[2] Univ Padua, Dipartimento Fis & Astron G Galilei, Via Marzolo 8, I-35131 Padua, Italy

[3] Ist Nazl Fis Nucl, Sez Padova, Via Marzolo 8, I-35131 Padua, Italy

[4] Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy

[5] Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway

[6] Ist Nazl Fis Nucl, Gran Sasso Sci Inst, Viale F Crispi 7, I-67100 Laquila, Italy

来源：

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS | 2016年 / 04期

关键词：

cosmological perturbation theory; gravity; modified gravity; FIELD; INFLATION;

D O I：

10.1088/1475-7516/2016/04/042

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity. In the absence of matter, we show that the Newtonian potential satisfies a second-order differential equation with no spatial derivatives. This implies that the sound speed for scalar perturbations is exactly zero on this background. We also show that in mimetic G(3) theories the sound speed is equally zero. We obtain the equation of motion for the comoving curvature perturbation (first order differential equation) and solve it to find that the comoving curvature perturbation is constant on all scales in mimetic Horndeski gravity. We find solutions for the Newtonian potential evolution equation in two simple models. Finally we show that the sound speed is zero on all backgrounds and therefore the system does not have any wave-like scalar degrees of freedom.

引用

页数：23

共 35 条

[1]

[Anonymous], 2008, COSMOLOGY

[2] The two faces of mimetic Horndeski gravity: disformal transformations and Lagrange multiplier [J].