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2022 年度 実績報告書

重力波による一般相対論を超える物理の探索

研究課題

研究課題/領域番号 21F21318
配分区分補助金
研究機関京都大学

研究代表者

向山 信治  京都大学, 基礎物理学研究所, 教授 (40396809)

研究分担者 DI FILIPPO FRANCESCO  京都大学, 基礎物理学研究所, 外国人特別研究員
研究期間 (年度) 2021-11-18 – 2024-03-31
キーワードgravitation / cosmology / gravitational waves
研究実績の概要

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.

現在までの達成度 (区分)
現在までの達成度 (区分)

2: おおむね順調に進展している

理由

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.

今後の研究の推進方策

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.

  • 研究成果

    (11件)

すべて 2023 2022 その他

すべて 国際共同研究 (5件) 雑誌論文 (4件) (うち国際共著 4件、 査読あり 4件) 学会発表 (2件) (うち国際学会 2件、 招待講演 2件)

  • [国際共同研究] Southern Denmark U(デンマーク)

    • 国名
      デンマーク
    • 外国機関名
      Southern Denmark U
  • [国際共同研究] SISSA(イタリア)

    • 国名
      イタリア
    • 外国機関名
      SISSA
  • [国際共同研究] CENTRA(ポルトガル)

    • 国名
      ポルトガル
    • 外国機関名
      CENTRA
  • [国際共同研究] Johns Hopkins U(米国)

    • 国名
      米国
    • 外国機関名
      Johns Hopkins U
  • [国際共同研究] Victoria U(ニュージーランド)

    • 国名
      ニュージーランド
    • 外国機関名
      Victoria U
  • [雑誌論文] Constraints on horizonless objects after the EHT observation of Sagittarius?A*2022

    • 著者名/発表者名
      Carballo-Rubio Raul、Di Filippo Francesco、Liberati Stefano、Visser Matt
    • 雑誌名

      Journal of Cosmology and Astroparticle Physics

      巻: 2022 ページ: 055~055

    • DOI

      10.1088/1475-7516/2022/08/055

    • 査読あり / 国際共著
  • [雑誌論文] Regular black holes without mass inflation instability2022

    • 著者名/発表者名
      Carballo-Rubio Raul、Di Filippo Francesco、Liberati Stefano、Pacilio Costantino、Visser Matt
    • 雑誌名

      Journal of High Energy Physics

      巻: 2022

    • DOI

      10.1007/JHEP09(2022)118

    • 査読あり / 国際共著
  • [雑誌論文] Stability of the fundamental quasinormal mode in time-domain observations against small perturbations2022

    • 著者名/発表者名
      Berti Emanuele、Cardoso Vitor、Cheung Mark Ho-Yeuk、Di Filippo Francesco、Duque Francisco、Martens Paul、Mukohyama Shinji
    • 雑誌名

      Physical Review D

      巻: 106

    • DOI

      10.1103/PhysRevD.106.084011

    • 査読あり / 国際共著
  • [雑誌論文] On the Inner Horizon Instability of Non-Singular Black Holes2022

    • 著者名/発表者名
      Di Filippo Francesco、Carballo-Rubio Ra?l、Liberati Stefano、Pacilio Costantino、Visser Matt
    • 雑誌名

      Universe

      巻: 8 ページ: 204~204

    • DOI

      10.3390/universe8040204

    • 査読あり / 国際共著
  • [学会発表] Hearts of Darkness: theory and phenomenology of non-singular black holes2023

    • 著者名/発表者名
      Francesco Di Filippo
    • 学会等名
      Seminar series “Quantum Gravity and All of That”, Online
    • 国際学会 / 招待講演
  • [学会発表] Viable regular black holes2022

    • 著者名/発表者名
      Francesco Di Filippo
    • 学会等名
      Spanish and Portuguese relativity meeting (EREP) 2022”, Salamanca, Spain
    • 国際学会 / 招待講演

URL: 

公開日: 2023-12-25  

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