Poisson spot and wave scattering of scalar fields by conformal anomaly black holes: probing the near-horizon geometry
Abstract
We investigate the scattering and diffraction of scalar plane waves by static conformal anomaly black holes. We determine the truncation requirements for the partial-wave series (PWS) method at finite distances and compute the full waveforms, which display a clear diffraction pattern: on the negative z-axis the field reduces to the incident plane wave, while on the positive z-axis a distorted plane wave coexists with a scattered spherical wave, and a bright Poisson spot appears at θ=0 surrounded by concentric diffraction rings. We obtain the on-axis intensity of the Poisson spot as a function of the radial coordinate. The intensity is most sensitive to the near-horizon geometry: close to the horizon it differs markedly from that of the RN black hole, whereas in the far field the two curves converge. We trace this to the metric functions, where different values of f'(r+) produce different phase increments that compress and shift the interference fringes, while the conformal anomaly correction falls off as O(α̃M2/r4). By analyzing the potential barrier we study the absorption cross section, and use the series reduction method to accelerate the PWS convergence for the differential scattering cross section. The low- and high-frequency absorption cross sections are strongly correlated with the ℓ=0 and ℓ-dependent parts of the potential barrier, respectively. The differential cross section and glory scattering arise mainly from scattering in a finite region excluding a small neighborhood of the outer horizon. Charge and α̃ have opposite effects on the width of the glory peak but the same effect on its height.
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BibTeX
@misc{zhuang2026poisson,
title = {{Poisson spot and wave scattering of scalar fields by conformal anomaly black holes: probing the near-horizon geometry}},
author = {Zeming Zhuang and Hongsheng Zhang and Zong-Kuan Guo and Rong-Gen Cai},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.39672},
eprint = {2609.39672},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.39672},
}
RIS
TY - UNPB
TI - Poisson spot and wave scattering of scalar fields by conformal anomaly black holes: probing the near-horizon geometry
AU - Zeming Zhuang
AU - Hongsheng Zhang
AU - Zong-Kuan Guo
AU - Rong-Gen Cai
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.39672
UR - https://arxiv.org/abs/2609.39672
AB - We investigate the scattering and diffraction of scalar plane waves by static conformal anomaly black holes. We determine the truncation requirements for the partial-wave series (PWS) method at finite distances and compute the full waveforms, which display a clear diffraction pattern: on the negative z-axis the field reduces to the incident plane wave, while on the positive z-axis a distorted plane wave coexists with a scattered spherical wave, and a bright Poisson spot appears at θ=0 surrounded by concentric diffraction rings. We obtain the on-axis intensity of the Poisson spot as a function of the radial coordinate. The intensity is most sensitive to the near-horizon geometry: close to the horizon it differs markedly from that of the RN black hole, whereas in the far field the two curves converge. We trace this to the metric functions, where different values of f'(r_+) produce different phase increments that compress and shift the interference fringes, while the conformal anomaly correction falls off as O(α̃M^2/r^4). By analyzing the potential barrier we study the absorption cross section, and use the series reduction method to accelerate the PWS convergence for the differential scattering cross section. The low- and high-frequency absorption cross sections are strongly correlated with the ℓ=0 and ℓ-dependent parts of the potential barrier, respectively. The differential cross section and glory scattering arise mainly from scattering in a finite region excluding a small neighborhood of the outer horizon. Charge and α̃ have opposite effects on the width of the glory peak but the same effect on its height.
ER -