Black supernovae and black holes in non-local gravity

Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo

doi:10.1007/jhep04(2016)147

Cited by 34 publications

(33 citation statements)

References 83 publications

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“…In what concerns local models with more than four derivatives, the numerical calculations presented in [52] give evidence that the spherically symmetric solutions are regular. Similar discussions have been carried out for the non-local models [16,44,47,[53][54][55][56][57], which raises the interesting question of to which extent the relation between local and non-local models in the linear regime can be extended to the full non-linear one.…”

Section: Discussionsupporting

confidence: 53%

Effective delta sources and regularity in higher-derivative and ghost-free gravity

Giacchini

Netto

2019

J. Cosmol. Astropart. Phys.

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It is shown that polynomial gravity theories with more than four derivatives in each scalar and tensor sectors have a regular weak-field limit, without curvature singularities. This is achieved by proving that in these models the effect of the higher derivatives can be regarded as a complete regularization of the delta-source. We also show how this result implies that a wide class of non-local ghost-free gravities has a regular Newtonian limit too, and discuss the applicability of this approach to the case of weakly non-local models.1 We use the same sign conventions as [10]. Also, we set c = = 1. 2 That is, we shall consider non-local gravity models which are extensions of GR in the UV-limit, which means that for large momentum the propagator decays faster than in GR. Specifically, we require that f 0 (z) and f 2 (z) (defined in (3) and (4)) are constant or diverge at least linearly as z −→ ∞, and that f s (0) = 1. Owed to this improved behaviour in the UV, sometimes these models are called non-local HDG. The situation is quite different from non-local IR modifications of GR, such as those defined by form factors of the type F i ∝ ✷ −1 and F i ∝ ✷ −2 [24-26], or the logarithmic ones, F i ∝ ln ✷, which come from the integration of quantum matter fields in curved space-time [27][28][29][30][31].

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Section: Discussionsupporting

confidence: 53%

Effective delta sources and regularity in higher-derivative and ghost-free gravity

Giacchini

Netto

2019

J. Cosmol. Astropart. Phys.

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“…While this does not directly represent a problem for the model, it is surely not aesthetically appealing. Moreover, on the base of the present analysis, we cannot exclude an instability, similar to that discovered in [33], that turns the black hole spacetime structure in a trapped surface.…”

Section: Black Hole Solutionsmentioning

confidence: 62%

Lee–Wick black holes

2017

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We derive and study an approximate static vacuum solution generated by a point-like source in a higher derivative gravitational theory with a pair of complex conjugate ghosts. The gravitational theory is local and characterized by a high derivative operator compatible with Lee-Wick unitarity. In particular, the tree-level two-point function only shows a pair of complex conjugate poles besides the massless spin two graviton. We show that singularity-free black holes exist when the mass of the source M exceeds a critical value Mcrit. For M > Mcrit the spacetime structure is characterized by an outer event horizon and an inner Cauchy horizon, while for M = Mcrit we have an extremal black hole with vanishing Hawking temperature. The evaporation process leads to a remnant that approaches the zero-temperature extremal black hole state in an infinite amount of time. *

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“…This kind of bouncing behavior was first studied in [29][30][31][32], but has been independently proposed more recently in scenarios inspired by emergent gravity [33][34][35] and loop quantum gravity [36,37]. Regardless of the special details of each particular implementation of this idea, there are some aspects that are shared by different proposals (see however [38][39][40][41][42][43][44][45][46] for alternative bouncing scenarios):…”

Section: B Bouncing Geometriesmentioning

confidence: 99%

Phenomenological aspects of black holes beyond general relativity

et al. 2018

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While singularities are inevitable in the classical theory of general relativity, it is commonly believed that they will not be present when quantum gravity effects are taken into account in a consistent framework. In particular, the structure of black holes should be modified in frameworks beyond general relativity that aim at regularizing singularities. Being agnostic on the nature of such theory, in this paper we classify the possible alternatives to classical black holes and provide a minimal set of phenomenological parameters that describe their characteristic features. The introduction of these parameters allows us to study, in a largely model-independent manner and taking into account all the relevant physics, the phenomenology associated with these quantummodified black holes. We perform an extensive analysis of different observational channels and obtain the most accurate characterization of the viable constraints that can be placed using current data. Aside from facilitating a critical revision of previous work, this analysis also allows us to highlight how different channels are capable of probing certain features but are oblivious to others, and pinpoint the theoretical aspects that should be addressed in order to strengthen these tests.

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Black supernovae and black holes in non-local gravity

Cited by 34 publications

References 83 publications

Effective delta sources and regularity in higher-derivative and ghost-free gravity

Effective delta sources and regularity in higher-derivative and ghost-free gravity

Lee–Wick black holes

Phenomenological aspects of black holes beyond general relativity

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