2022 Fiscal Year Annual Research Report
Hunting physics beyond General Relativity with gravitational waves
| Project/Area Number |
21F21318
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| Allocation Type | Single-year Grants |
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| Research Institution | Kyoto University |
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Principal Investigator |
向山 信治 京都大学, 基礎物理学研究所, 教授 (40396809)
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| Co-Investigator(Kenkyū-buntansha) |
DI FILIPPO FRANCESCO 京都大学, 基礎物理学研究所, 外国人特別研究員
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| Project Period (FY) |
2021-11-18 – 2024-03-31
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| Keywords | gravitation / cosmology / gravitational waves |
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| Outline of Annual Research Achievements |
I worked on several aspects of black holes physics.
I published one paper regarding aspects of nonsingular black holes in theories that violate Lorentz invariance. In this paper, we studied different frameworks and classified the possible geometries based on modified dispersion relations. We demonstrated the robustness of a classification that we introduced in a previous paper showing its applicability to multi-metric frameworks. Our results contribute to understanding geodesically complete black hole solutions in Lorentz-violating gravity and their potential implications for non-singular solutions.
In that period, I also uploaded on arXiv (and published afterward) a paper on the instability of the inner horizon of non-singular black holes. In this paper, we clarify some of the doubts present in the literature about the nature of the instability and we show the universality of the phenomenon.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Currently, my research encompasses three main areas. Firstly, I am working on a paper examining the phenomenology of horizonless ultracompact objects. These objects can mimic the phenomenology of black holes without a well-defined event horizon and a singular core. However, if compact objects surrounded by an accretion disk had a reflective surface, we would observe an outgoing thermal flux of energy. In a previous paper, we have shown that the outgoing flux of energy gets considerably weakened if even a tiny amount of energy is absorbed by the compact object and is permanently lost. I am currently working on reifying the analysis to get a better understanding of the physics at play.
Secondly, I am collaborating with master students and my host Prof. Mukohyama to finalize a paper on black holes with soft hairs. In this paper, we introduce a formalism and we show its relevance by using it to reproduce some known results in the literature in a simplified way. In the future, this formalism might be used to address the information loss paradox. Lastly, with Prof. Mukohyama and other collaborators, I am working on a project regarding black holes in semiclassical gravity. The motivation to consider this problem is because semiclassical effects are very well justified as they are obtained simply considering quantum field theory on a classical curved spacetime and they become relevant close to horizon formation if the matter is far from free falling.
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| Strategy for Future Research Activity |
In the future, I plan to continue investigating the physics of black holes. In particular, I plan to continue the investigation of the information loss paradox and continue studying the growing field of comparing the black hole paradigm with non-singular alternatives, focusing both on theoretical and phenomenological issues to be able to distinguish them in the forthcoming observations.
Regarding the information loss paradox, I plan to investigate the impact that the formalism described in the previous section might have on the study of black holes soft hairs.
Regarding the study of non-singular alternatives to black holes, my future work will follow three different lines. The first line consists in the identification and in the study of spacetimes that can mimic properties and phenomenology of black holes. The second investigation line will aim to understand whether the classes identified are viable alternatives and to address eventual self-consistency issues. The final line of investigation will study the phenomenology of the viable classes without self-consistency issues.
This research will be extremely timely as the LIGO/VIRGO/KAGRA detectors, as well as the next generation of earth and space-based interferometers, will collect plenty of data in future years. This leads to a growing necessity for theoretical studies beyond general relativity to understand if this data will contain imprints of new physics that could revolutionize our understanding of the fundamental laws of nature.
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Research Products
(11 results)
