1 / 12

Dark energy and dust matter phases form an exact f(R)-cosmology model

Dark energy and dust matter phases form an exact f(R)-cosmology model. Prado Martín Moruno IFF (CSIC) ERE2008. S. Capozziello, P. Martín-Moruno and C. Rubano Phys. Lett. B664:12-15,2008. Why f(R)? Point-like Lagrangian and the equations of motion. Noether Symmetry Approach.

wfitting
Télécharger la présentation

Dark energy and dust matter phases form an exact f(R)-cosmology model

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dark energy and dust matter phases form an exact f(R)-cosmology model Prado Martín Moruno IFF (CSIC) ERE2008 S. Capozziello, P. Martín-Moruno and C. Rubano Phys. Lett. B664:12-15,2008

  2. Why f(R)? • Point-like Lagrangian and the equations of motion. • Noether Symmetry Approach. • A particular case. • Contrast with some observational data. • Conclusions and further comments.

  3. Cosmic acceleration and dark matter could be nothing else but signals of a breakdown of GR. The simpler extension is f(R) 1. Why f(R)? • The validity of GR on large astrophysical and cosmological scales has never been tested • Higher order theories Of course, a new theory of gravitation must reproduce the low energy limits where GR has been tested.

  4. +Lagrange multiplier 2. Point-like Lagrangian (Metric formalism) 4th order differential equations • Homogenity and isotropy FRW metric

  5. Point-like Lagrangian: Energy function: Vacuum Matter D: standard amount of dust fluid

  6. 3. Noether symmetry • We ask for the existence of a Noether symmetry One solution is: Noether symmetry Constant of the motion • Change of variables:

  7. It is possible to solve the equations of motion Integration constants

  8. 4. A particular case A possible choice of the parameters: • Time units such that The dimensionless quantity must be • For simplicity, we take

  9. If an observer living in this universe is unaware of the fact that the function which appears in the Lagrangian is and not , he would then perform the calculations taking into account , obtaining ! 4. Contrast with some observational data In this model, it seems that the consideration of dark matter is only a consequence of the assumption of GR as the physical theory.

  10. The percentage difference of the two scale factors is less than 3% for the range

  11. The concordance between the distance modulus of our model and of the CDM model with, , seems to be perfect. z

  12. 5. Conclusions and further comments • The Noether symmetry approach allows us to obtain an analytic solution. • Our solution interpolates between the qualitative behaviour of a Friedman radiation-like universe, at small t, and an accelerated expansion, at large t. It must be an intermediate Friedman dust-like behaviour. • A first attempt in the selection of the values of the parameters allows us to fulfill some observational prescription. • A more accurate study and selection of the parameters is required.

More Related