Fri - 06/06/25

**Title:

      Dust shell in effective loop quantum black hole model**  - **Authors:** Hanno Sahlmann, Cong Zhang  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  In this work, the dynamics of a dust shell in an effective theory of spherically symmetric gravity containing quantum corrections from loop quantum gravity is investigated. To provide a consistent framework for including the dust, we go beyond the standard formulation of the effective theory by introducing an action that includes not only the effective Hamiltonian constraint, but also the diffeomorphism constraint, along with appropriate gauge-fixing and boundary terms. By adding the dust shell action and substituting vacuum solutions for the interior and exterior regions, we derive a reduced action in which only the shell radius $\mathfrak{x}$ and the exterior black hole mass appear as dynamical variables. Varying the reduced action yields the evolution equation for $\mathfrak{x}$, which is then solved numerically to explore the dynamical properties of the dust shell and the continuity properties of the metric. Finally, our approach is compared with previous studies to highlight key differences and improvements.

There is no new related paper today

Thu - 06/05/25

**Title:

      Could Planck Star Remnants be Dark Matter?**  - **Authors:** Oem Trivedi, Abraham Loeb  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  We explore the end state of gravitational collapse under quantum gravity effects and propose that Planck Star Remnants (PSR), formed via nonsingular bounces, could serve as viable dark matter candidates. Within the framework of Loop Quantum Cosmology, we model the collapse of a homogeneous matter distribution and show that the classical singularity is replaced by a quantum bounce at the Planck density. By analytically matching the Friedmann Lemaitre Robertson Walker (FLRW) interior to an exterior Schwarzschild spacetime using the Israel junction conditions, we demonstrate that the bounce remains causally hidden from external observers, avoiding any observable re-expansion. This naturally leads to the formation of stable, non-radiating PSR, whose radius coincides with the Schwarzschild radius when the black hole mass approaches the Planck mass as a result of Hawking evaporation. We suggest that such remnants may originate from evaporating primordial black holes in the early universe, and estimate the relic abundance needed for PSR to account for the observed dark matter density. We also discuss some crucial differences between PSR and previous proposals of Planck mass relics. The scenario is shown to be consistent with existing astrophysical and cosmological constraints, offering a unified framework connecting quantum gravitational collapse, and the nature of dark matter.

There is no new related paper today

Wed - 06/04/25

There is no new related paper today

There is no new related paper today

  1. [] - Title: A short overview on the Black Hole-Tower Correspondence and Species Thermodynamics - Alvaro Herráez, Dieter Lüst, Joaquin Masias, Carmine Montella

Tue - 06/03/25

There is no new related paper today

There is no new related paper today

  1. [] - Title: Covariant diffusion and drift of the stochastic GW background with LISA - Giorgio Mentasti, Arad Nasiri

Mon - 06/02/25

There is no new related paper today

There is no new related paper today

  1. [] - Title: Covariant diffusion and drift of the stochastic GW background with LISA - Giorgio Mentasti, Arad Nasiri

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