Testing for gravitational preferred directions with galaxy and lensing surveys. (arXiv:1907.12285v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Resco_M/0/1/0/all/0/1">Miguel Aparicio Resco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maroto_A/0/1/0/all/0/1">Antonio L. Maroto</a>
We analyze the sensitivity of galaxy and weak-lensing surveys to detect
preferred directions in the gravitational interaction. We consider general
theories of gravity involving additional vector degrees of freedom with
non-vanishing spatial components in the background. We use a model-independent
parametrization of the perturbations equations in terms of four effective
parameters, namely, the standard effective Newton constant $G_{eff}$ and slip
parameter $gamma$ for scalar modes and two new parameters $mu_Q$ and $mu_h$
for vector and tensor modes respectively, which are required when preferred
directions are present. We obtain the expressions for the multipole galaxy
power spectrum in redshift space and for the weak-lensing shear, convergence
and rotation spectra in the presence of preferred directions. By performing a
Fisher matrix forecast analysis, we estimate the sensitivity of a future
Euclid-like survey to detect this kind of modification of gravity. We finally
compare with the effects induced by violations of statistical isotropy in the
primordial power spectrum and identify the observables which could discriminate
between them.
We analyze the sensitivity of galaxy and weak-lensing surveys to detect
preferred directions in the gravitational interaction. We consider general
theories of gravity involving additional vector degrees of freedom with
non-vanishing spatial components in the background. We use a model-independent
parametrization of the perturbations equations in terms of four effective
parameters, namely, the standard effective Newton constant $G_{eff}$ and slip
parameter $gamma$ for scalar modes and two new parameters $mu_Q$ and $mu_h$
for vector and tensor modes respectively, which are required when preferred
directions are present. We obtain the expressions for the multipole galaxy
power spectrum in redshift space and for the weak-lensing shear, convergence
and rotation spectra in the presence of preferred directions. By performing a
Fisher matrix forecast analysis, we estimate the sensitivity of a future
Euclid-like survey to detect this kind of modification of gravity. We finally
compare with the effects induced by violations of statistical isotropy in the
primordial power spectrum and identify the observables which could discriminate
between them.
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