Sommaire:

General Relativity (GR) provides so far our best effective field theory of the gravitational field and its interaction with matter. However, provided some energy conditions, it is well known that the theory predicts that pathological singularities develop at sufficiently high energy, breaking the predictability of cosmological and gravitational collapse solutions of GR beyond these focusing points.

Bouncing cosmologies have provided useful models where the initial Big Bang singularity is removed and where the universe transits smoothly from a contraction phase to the current expanding one. Over the last decades, numerous scenarios motivated either by modified gravity theories or quantum gravity proposals have been investigated to resolve the singularity and the phenomenology of these bouncing cosmologies has been intensively studied to confront them to the data available for early cosmology (See: https://arxiv.org/abs/1406.2790).

More recently, the idea to import the techniques from bouncing cosmologies to build model of non-singular gravitational collapse has attracted a lot of efforts. This idea appears indeed a natural extension of bouncing cosmologies to astrophysical objects. The resulting models of bouncing compact objects provide a new platform for phenomenology and suggest a new potential astrophysical window to test quantum gravity proposals.

In this talk, I will review this line of research and present a model of bouncing compact object based which provides an effective quantum extension of the seminal Oppenheimer-Snyder collapse model. I will discuss the main challenge and argue that crucial information on the causal structure of such bouncing compact object can be extracted in a model independent manner. While I will focus on the theoretical construction of the model, I shall also discuss the potential observational signatures it suggests to further investigate the physics of such exotic astrophysical object.

This talk is based on the recent work:
1) Towards consistent black-to-white hole bounces from matter collapse, JCAP, 2020
J. Ben Achour, S. Brahma, S. Mukohyama, J-P. Uzan
(https://arxiv.org/abs/2004.12977)

See also:
1) Bouncing compact objects. II. Effective theory of a pulsating Planck star, PRD, 2020
J. Ben Achour, J-P. Uzan,
(https://arxiv.org/abs/2001.06153)
2) Bouncing compact objects. I. Quantum extension of the Oppenheimer-Snyder collapse, 2020, JCAP
J. Ben Achour, S. Brahma, J-P. Uzan
(https://arxiv.org/abs/2001.06148)

Pour plus d'informations, merci de contacter Lavalle J.