Cosmological Consequences of Massive Gravity Tina Kahniashvili Carnegie

Cosmological Consequences of Massive Gravity Tina Kahniashvili Carnegie Mellon University PHENO 2014 May 5, 2014

Outline u u Motivations to consider beyond the standard cosmological model • Cosmological constant problem • CMB large scale anomalies Massive cosmologies • d. RGT • Quasi-dilaton Models u Cosmological signatures • CMB Temperature Anisotropies • CMB Polarization Based on: Kahniashvili, Kar, and Kosowsky 2014 in preparation

Precise Cosmology • Observations – 1% precision • Theory – unknown 96% (Dark Universe) The cosmological constant problem 120 10 times lighter than we can expect from theory Mpl 4 “Einstein’s Greatest Blunder” “The worst theoretical prediction in the history of physics!" Hobson, Efstathiou & Lasenby Observational Tests

Do We Need New Physics?

Do We See New Physics in CMB Sky? u Anomalies at Large Scales • North-South Asymmetries • Power Suppression • Multipole Alignments • Cold Spot Two Point Correlation Function Cope, . Huterer, Schwarz & Starkman, 2008 North-South Asymmetry Low Multipoles Alignments

BICEP 2 vs Planck Smith et al. 2014

Massive Gravity u Motivation: Alternative explanation of accelerated expansion of the Universe • Massive graviton spin 0 mode mimics the presence of Dark Energy Theory (d. RGT): de. Rham, Gabadadze, Tolley, 2010 (1011. 1232) u Massive Cosmologies D'Amico, de Rham, Dubovsky, Gabadadze, Pirtskhalava, Tolley, 2011 (1108. 5231) u m~H 0 Two limits of the Universe expansion high densities - isotropic FLRW low densities – anisotropic model

Massive Gravity u u u Vainstein 1972 Fierz & Pauli, 1939 • v. DVZ discontinuity • Non-zero graviton mass disappears if we take into account non-linear van Dam & Veltman, interactions of the scalar 1970; Zakharov, 1970 mode • v. DVZ discontinuity (GR is not recovered in u Boulware & Deser, m->0 limit) 1972 • Sixth degree of freedom - ghost

Massive Cosmologies u u d. RGT – 4 D covariant, nonlinear, ghost free at decoupling limit at all orders • m~H 0 u Quasi-Dilaton • D’Amico, Gabadadze, Hui, Pirtskhalava, 2012 (1206. 4253) • De Felice et al. 2013 (1305. 5502 ) Vainstein radius u Mass varying theory • Huang, Piao, Zhou, 2012 (1206. 5678)

Massive Gravity: Imprints on CMB? At high densities GR is recovered and perturbations look like as LCDM u Late time evolution –ISW u Suppression exp(-m. R)? u u Anisotropic Bianchi model(s) ONLY at large scales

Massive Gravity: Background u De Felice et al. 1306. 5502

Massive Gravity: Background u u De Felice et al. 1306. 5502 0

Massive Gravity: Background Kahniashvili, Kar, Kosowsky 2014

Massive Gravity: Background Kahniashvili, Kar, Kosowsky 2014

Gravitational Waves in Massive Gravity Gumrukcuoglu et al. 2012

CMB vs. Gravitational Waves u Analytical approach: Review by Pritchard and Kamionkoswki 2004

Cosmological Signatures u Temperature anisotropies u u Massive gravity ISW Polarization

Conclusions u Are large scale anomalies physical? • Cosmological origin? u If yes do we see new physics at large scales? • Early Universe • Late time u Massive gravity manifestation? • CMB fluctuations formation • CMB Polarization

Thank You My special thanks to: PHENO 2014 Organizeers & Nishant Agarwal (CMU) Gregory Gabadadze (NYU) Arjun Kar (CMU) Arthur Kosowsky (Pitt) George Lavrelashvili (TSU, Georgia)