In this work, we study cosmological and astrophysical applications of the recently proposed generalized hybrid metric-Palatini gravity theory, which combines features of both the metric and the Palatini approaches to the variational method in $f\left(R\right)$ gravity. This theory arises as a natural generalization of the hybrid metric-Palatini gravity which has been proven to be the first theory to unify the cosmic acceleration with the solar system constraints, without resource to the chameleon mechanism. In the cosmological point of view, we show using reconstruction methods that the usual power-law and exponential scale factor behaviors in FLRW universes exist for various different distributions of matter, along with solutions for collapsing universes. Using the dynamical system approach, we also show that no global attractors can exist in the cosmological phase space and that stable universes can either be described by scale factors that diverge in finite time or asymptotically approach constant values. In the area of astrophysics, we show that using the junction conditions of the theory it is possible to obtain solutions for compact objects supported by thin-shells, such as self-gravitating shells with and without perfect fluids on their exteriors, and also traversable wormhole solutions which satisfy the null energy condition for the whole spacetime, thus not needing the support of exotic matter. Furthermore, we show that there exist specific forms of the action for which the massive scalar degree of freedom of the theory is stable in the scope of rotating black-holes described by the Kerr metric.

# Hybrid metric-Palatini gravity: applications to cosmology and astrophysics

## Next Seminar

## Echoes of quantum black holes from Kerr/CFT

## Next Journal Club

## Discussion of the paper "Gravitational Radiation from Colliding Black Holes" by S. W. Hawking

## Black Hole Workshops

Next workshop:

XIII Black Holes Workshop, Lisbon,

21-22 December 2020

Previous workshops in the series:

I Black Holes Workshop, Porto, 2008

II Black Holes Workshop, Lisbon, 2009

III Black Holes Workshop, Minho, 2010

IV Black Holes Workshop, Aveiro, 2011

V Black Holes Workshop, Lisbon, 2012

VI Black Holes Workshop, Minho 2013

VII Black Holes Workshop, Aveiro 2014

VIII Black Holes Workshop, Lisbon 2015

IX Black Holes Workshop, Minho 2016

X Black Holes Workshop, Aveiro 2017

XI Black Holes Workshop, Lisbon, 2018

XII Black Holes Workshop, Minho, 2019

## Numerical data

## FunFiCO Network

Our group coordinates the Marie Curie RISE FunFiCO network (Dec 2017- Dec 2021)

More info here

## GWVerse COST

## StronGrHEP Network

Our group is part of the RISE StronGrHEP network (2016-2019)

Meetings:

Paris, 12-13 May 2016

Azores, 3-8 July 2017

Osaka, 4-8 September 2017

## NRHEP Network Meetings

Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:

First Meeting:

9-13 July 2012, Aveiro, Portugal

Second Meeting:

11-14 March 2013, Lisbon, Portugal

Third Meeting:

6-10 January 2014, Mississippi, USA

Fourth Meeting:

7-10 July 2015, Rome, Italy

Fifth Meeting:

28 Sep-2 Oct 2015, Belém, Brazil

## Ph.D. and Post-doctoral opportunities

Contact us If you are interested in pursuing graduate studies/research in our group.