International Conference “Exploring the Energetic Universe 2017”

Permanent URI for this collection

https://testres.nu.edu.kz/handle/123456789/2541

Browse

Browsing International Conference “Exploring the Energetic Universe 2017” by Subject "gravity"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Cosmic Growth and Expansion Conjoined
    (International conference "ECL17: Exploring the Energetic Universe 2017", Nazarbayev University Energetic Cosmic Laboratory, 2016-10-17) Linder, Eric V.
    Cosmological measurements of both the expansion history and growth history have matured, and the two together provide an important test of general relativity. We consider their joint evolutionary track, showing that this has advantages in distinguishing cosmologies relative to considering them individually or at isolated redshifts. In particular, the joint comparison relaxes the shape degeneracy that makes f 8(z) curves difficult to separate from the overall growth amplitude. The conjoined method further helps visualization of which combinations of redshift ranges provide the clearest discrimination. We examine standard dark energy cosmologies, modified gravity, and “stuttering” growth, each showing distinct signatures.
  • Thumbnail Image
    ItemOpen Access
    Cosmic Growth Signatures of Modified Gravitational Strength
    (International conference "ECL17: Exploring the Energetic Universe 2017", Nazarbayev University Energetic Cosmic Laboratory, 2017-03-02) Denissenya, Mikhail; Linder, Eric V.
    Cosmic growth of large scale structure probes the entire history of cosmic expansion and gravitational coupling. To get a clear picture of the effects of modification of gravity we consider a deviation in the coupling strength (effective Newton’s constant) at different redshifts, with different durations and amplitudes. We derive, analytically and numerically, the impact on the growth rate and growth amplitude. Galaxy redshift surveys can measure a product of these through redshift space distortions and we connect the modified gravity to the observable in a way that may provide a useful parametrization of the ability of future surveys to test gravity. In particular, modifications during the matter dominated era can be treated by a single parameter, the “area” of the modification, to an accuracy of 0.3% in the observables. We project constraints on both early and late time gravity for the Dark Energy Spectroscopic Instrument and discuss what is needed for tightening tests of gravity to better than 5% uncertainty.