Searching for Black Hole Candidates in Quiescence by Using Multiband Observations in Globular Cluster M22 (NGC 6656)
4 affiliations
- 1Xiamen University
- 2Shanghai Astronomical Observatory
- 3Nanjing Normal University
- 4University of Science and Technology of China
Abstract
We present a multiwavelength investigation of radio sources in the globular cluster M22 (NGC 6656) using the Karl G. Jansky Very Large Array, Chandra, and Hubble Space Telescope. By crossmatching the radio and X-ray source catalogs, we identify eight radio/X-ray counterparts, of which VLA22 is the most promising stellar-mass black hole (BH) candidate. Its radio and X-ray luminosities are consistent with the established L X − L R correlation for BH low-mass X-ray binaries. The observed X-ray variability supports an accreting nature. One possible optical counterpart ( M ₈₁₄ ≈ 16.695 ± 0.011 mag) is identified. Based on its inferred stellar parameters, the estimated orbital period of P orb ∼ 16 ± 6 h places the proposed counterpart predominantly in the BH region rather than in the neutron star (NS) region in the L X − P orb plane. These results demonstrate the effectiveness of joint radio, X-ray, and optical observations in identifying quiescent BH candidates in globular clusters.
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BibTeX
@article{徐2026searching,
title = {{Searching for Black Hole Candidates in Quiescence by Using Multiband Observations in Globular Cluster M22 (NGC 6656)}},
author = {Yu-Jing 雨婧 Xu 徐 and Wei-Min 为民 Gu 顾 and Yuanqi 媛琪 Liu 刘 and Xin-Yu 欣雨 Fang 方 and Shan-Shan 山杉 Weng 翁 and Tao 涛 An 安},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea795},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea795},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Searching for Black Hole Candidates in Quiescence by Using Multiband Observations in Globular Cluster M22 (NGC 6656)
AU - Yu-Jing 雨婧 Xu 徐
AU - Wei-Min 为民 Gu 顾
AU - Yuanqi 媛琪 Liu 刘
AU - Xin-Yu 欣雨 Fang 方
AU - Shan-Shan 山杉 Weng 翁
AU - Tao 涛 An 安
PY - 2026
DA - 2026/10/19
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea795
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea795
AB - We present a multiwavelength investigation of radio sources in the globular cluster M22 (NGC 6656) using the Karl G. Jansky Very Large Array, Chandra, and Hubble Space Telescope. By crossmatching the radio and X-ray source catalogs, we identify eight radio/X-ray counterparts, of which VLA22 is the most promising stellar-mass black hole (BH) candidate. Its radio and X-ray luminosities are consistent with the established L X − L R correlation for BH low-mass X-ray binaries. The observed X-ray variability supports an accreting nature. One possible optical counterpart ( M ₈₁₄ ≈ 16.695 ± 0.011 mag) is identified. Based on its inferred stellar parameters, the estimated orbital period of P orb ∼ 16 ± 6 h places the proposed counterpart predominantly in the BH region rather than in the neutron star (NS) region in the L X − P orb plane. These results demonstrate the effectiveness of joint radio, X-ray, and optical observations in identifying quiescent BH candidates in globular clusters.
SN - 0004-637X
SN - 1538-4357
ER -