Imaging a semi-classical horizonless compact object with strong redshift

Fuente: arXiv
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Auteurs principaux: Chen, Che-Yu, Yokokura, Yuki
Format: Preprint
Publié: 2024
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author Chen, Che-Yu
Yokokura, Yuki
author_facet Chen, Che-Yu
Yokokura, Yuki
contents The recent advancements in black hole imaging have opened a new era of probing horizon-scale physics with electromagnetic radiation. However, a feature of the observed images, a bright ring encircling a relatively dark region, has not sufficiently proved the existence of event horizons. It thus requires extreme care when studying the possibility of using such image features to examine quantum effects that may change the classical picture of black holes slightly or drastically. In this work, we investigate the image of a horizonless compact object, whose interior metric satisfies the 4D semi-classical Einstein equation non-perturbatively for the Planck constant, and whose entropy agrees with the Bekenstein-Hawking formula. Although the absence of an event horizon allows light rays to pass through the dense interior, the extremely strong redshift significantly darkens the image, making it almost identical to the classical black-hole image. In particular, if there is light emission a bit inside the surface of the object, the intensity around the inner shadow is slightly enhanced, which could be a future observable prediction to characterize the object. We also find through a phenomenological parameter that the image is further darkened due to interactions inside. Thus, the image is consistent with current observations, and the object could be a candidate for black holes in quantum theory.
format Preprint
id arxiv_https___arxiv_org_abs_2403_09388
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Imaging a semi-classical horizonless compact object with strong redshift
Chen, Che-Yu
Yokokura, Yuki
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
High Energy Physics - Theory
The recent advancements in black hole imaging have opened a new era of probing horizon-scale physics with electromagnetic radiation. However, a feature of the observed images, a bright ring encircling a relatively dark region, has not sufficiently proved the existence of event horizons. It thus requires extreme care when studying the possibility of using such image features to examine quantum effects that may change the classical picture of black holes slightly or drastically. In this work, we investigate the image of a horizonless compact object, whose interior metric satisfies the 4D semi-classical Einstein equation non-perturbatively for the Planck constant, and whose entropy agrees with the Bekenstein-Hawking formula. Although the absence of an event horizon allows light rays to pass through the dense interior, the extremely strong redshift significantly darkens the image, making it almost identical to the classical black-hole image. In particular, if there is light emission a bit inside the surface of the object, the intensity around the inner shadow is slightly enhanced, which could be a future observable prediction to characterize the object. We also find through a phenomenological parameter that the image is further darkened due to interactions inside. Thus, the image is consistent with current observations, and the object could be a candidate for black holes in quantum theory.
title Imaging a semi-classical horizonless compact object with strong redshift
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2403.09388