The near-simultaneous multi-messenger detection of the gravitational wave (GW) event GW170817 and its optical counterpart, the short γ-ray burst GRB170817A, implies that deviations of the GW speed from the speed of light are restricted to being of O(10^-15). In this note, we study the implications of this bound for mimetic gravity and confirm that in the original setting of the theory, GWs propagate at the speed of light, hence ensuring agreement with the recent multi-messenger detection. A higher-order extension of the original mimetic theory, appearing in the low-energy limit of projectable Hořava–Lifshitz gravity, is then considered. Performing a Bayesian statistical analysis where we compare the predictions of the higher-order mimetic model for the speed of GWs against the observational bound from GW170817/GRB170817A, we derive constraints on the three free parameters of the theory. Imposing the absence of both ghost instabilities and superluminal propagation of scalar and tensor perturbations, we find very stringent 95% confidence level upper limits of ∼7×10^-15 and ∼4×10^-15 on the coupling strengths of Lagrangian terms of the form ∇µ∇νφ∇µ∇νφ and (☐φ)^2 respectively, with φ the mimetic field. We discuss implications of the obtained bounds for mimetic theories. This work presents the first ever robust comparison of a mimetic theory to observational data.

Alive and Well: Mimetic Gravity and a Higher-order Extension in Light of GW170817 / Casalino, Alessandro; Rinaldi, Massimiliano; Sebastiani, Lorenzo; Vagnozzi, Sunny. - In: CLASSICAL AND QUANTUM GRAVITY. - ISSN 0264-9381. - 36:1(2019), p. 017001. [10.1088/1361-6382/aaf1fd]

Alive and Well: Mimetic Gravity and a Higher-order Extension in Light of GW170817

Alessandro Casalino;Massimiliano Rinaldi;Lorenzo Sebastiani;Sunny Vagnozzi
2019-01-01

Abstract

The near-simultaneous multi-messenger detection of the gravitational wave (GW) event GW170817 and its optical counterpart, the short γ-ray burst GRB170817A, implies that deviations of the GW speed from the speed of light are restricted to being of O(10^-15). In this note, we study the implications of this bound for mimetic gravity and confirm that in the original setting of the theory, GWs propagate at the speed of light, hence ensuring agreement with the recent multi-messenger detection. A higher-order extension of the original mimetic theory, appearing in the low-energy limit of projectable Hořava–Lifshitz gravity, is then considered. Performing a Bayesian statistical analysis where we compare the predictions of the higher-order mimetic model for the speed of GWs against the observational bound from GW170817/GRB170817A, we derive constraints on the three free parameters of the theory. Imposing the absence of both ghost instabilities and superluminal propagation of scalar and tensor perturbations, we find very stringent 95% confidence level upper limits of ∼7×10^-15 and ∼4×10^-15 on the coupling strengths of Lagrangian terms of the form ∇µ∇νφ∇µ∇νφ and (☐φ)^2 respectively, with φ the mimetic field. We discuss implications of the obtained bounds for mimetic theories. This work presents the first ever robust comparison of a mimetic theory to observational data.
2019
1
Casalino, Alessandro; Rinaldi, Massimiliano; Sebastiani, Lorenzo; Vagnozzi, Sunny
Alive and Well: Mimetic Gravity and a Higher-order Extension in Light of GW170817 / Casalino, Alessandro; Rinaldi, Massimiliano; Sebastiani, Lorenzo; Vagnozzi, Sunny. - In: CLASSICAL AND QUANTUM GRAVITY. - ISSN 0264-9381. - 36:1(2019), p. 017001. [10.1088/1361-6382/aaf1fd]
File in questo prodotto:
File Dimensione Formato  
Casalino_2019_Class._Quantum_Grav._36_017001.pdf

Solo gestori archivio

Tipologia: Versione editoriale (Publisher’s layout)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 1.24 MB
Formato Adobe PDF
1.24 MB Adobe PDF   Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/360120
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 66
  • ???jsp.display-item.citation.isi??? 68
social impact