Talk detail

Participant	Lobo, Francisco
Institution	Centro de Astronomia e Astrofísica da Universidade de Lisboa - Campo Grande, Ed. C8 - Lisbon - Lisbon - Portugal

Session	AT3	Accepted	Yes	Order	9	Time	17:10 - 17:30	15' + 5'
Talk	Oral abstract	Title	Traversable wormholes supported by dark gravity
Co-authors
Abstract	A fundamental ingredient in wormhole physics is the presence of exotic matter, which involves the violation of the null energy condition. Although a plethora of wormhole solutions have been explored in the literature, it is useful to find geometries that minimize the usage of exotic matter. In the context of modified gravity, it has also been shown that the normal matter can be imposed to satisfy the null energy condition, and it is the higher order curvature terms, interpreted as a gravitational fluid, that sustain these non-standard wormhole geometries, fundamentally different from their counterparts in general relativity. In this paper, we review recent work in wormhole physics in the context of modified theories of gravity.

Session	AT2	Accepted	Yes	Order	13	Time		20'
Talk	Oral abstract	Title	Extended f(R,Lm) theories of gravity
Co-authors	Tiberiu Harko
Abstract	The late-time cosmic acceleration may be due to infra-red modifications of General Relativity. In particular, we consider a maximal extension of the Hilbert-Einstein action and analyze several interesting features of the theory. Generally, the motion is non-geodesic and takes place in the presence of an extra force, which is orthogonal to the four-velocity. These models could lead to some major differences, as compared to the predictions of General Relativity or other modified theories of gravity, in several problems of current interest, such as cosmology, gravitational collapse or the generation of gravitational waves. The study of these phenomena may also provide some specific signatures and effects, which could distinguish and discriminate between the various gravitational models.

Session	GT4	Accepted	Yes	Order	6	Time	16:30 - 17:00
Talk	Oral abstract	Title	Linearized stability analysis of generic thin-shells
Co-authors	Prado Martin-Moruno, Nadiezhda Montelongo Garcia, Matt Visser
Abstract	We construct generic spherically symmetric thin-shells by using the cut-and-paste procedure. We take considerable effort to make the analysis as general and unified as practicable; investigating both the internal physics of the transition layer and its interaction with "external forces" arising due to interactions between the transition layer and the bulk spacetime. Furthermore, we discuss both the dynamic and static situations. In particular, we consider "bounded excursion" dynamical configurations, and probe the stability of static configurations. Applications to gravastars and wormholes geometries are also explored.