Optical Signatures of Sgr A* and M87* with Dark Matter Halos
Abstract
The event horizon telescope (EHT) has opened a new window onto the strong-field regime by imaging the shadows of the supermassive black holes (SMBHs) Sgr A* and M87*. These observations provide a unique laboratory for probing the dark matter (DM) distribution around black holes. In this work we systematically investigate the imprints of two distinct DM halo models, the cold DM (CDM), and the cored scalar field DM (SFDM) profiles on the gravitational lensing signatures of Sgr A* and M87*. We compute the photon spheres, shadows, weak and strong lensing observables, and caustic structures for both models. We then compared the obtained values of the shadow diameters with the EHT data, using χ2 statistics. We found that all the models are within 1.2σ of the measured shadow diameters with the small χ2 differences, Δχ2 ≲ 1.2. The caustic analysis reveals distinct topological regimes, Sgr A* retains both tangential and radial critical curves, while M87* may show only tangential critical curves due to its larger mass. This topological difference provides a clear observational signature for future observations.
Related
- Searching for signatures of self-interacting dark matter in halos from full physics simulations: From 3D structure to projected observables
- Testing the Isothermal Jeans Model for Self-interacting Dark Matter Halos in the Collapse Phase
- Core-collapse universality for inelastic self-interacting dark matter halos
- Dynamics of self-gravitating halos with decaying dark matter
- Radial stress in rotating ACKN/KSZ continuations of Einstein-cluster dark matter halos
BibTeX
@misc{tahir2026optical,
title = {{Optical Signatures of Sgr A* and M87* with Dark Matter Halos}},
author = {Noraiz Tahir and Muhammad Ali Paracha and Mubasher Jamil},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2608.06924},
eprint = {2608.06924},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.06924},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Optical Signatures of Sgr A* and M87* with Dark Matter Halos
AU - Noraiz Tahir
AU - Muhammad Ali Paracha
AU - Mubasher Jamil
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2608.06924
UR - https://arxiv.org/abs/2608.06924
AB - The event horizon telescope (EHT) has opened a new window onto the strong-field regime by imaging the shadows of the supermassive black holes (SMBHs) Sgr A* and M87*. These observations provide a unique laboratory for probing the dark matter (DM) distribution around black holes. In this work we systematically investigate the imprints of two distinct DM halo models, the cold DM (CDM), and the cored scalar field DM (SFDM) profiles on the gravitational lensing signatures of Sgr A* and M87*. We compute the photon spheres, shadows, weak and strong lensing observables, and caustic structures for both models. We then compared the obtained values of the shadow diameters with the EHT data, using χ^2 statistics. We found that all the models are within 1.2σ of the measured shadow diameters with the small χ^2 differences, Δχ^2 ≲ 1.2. The caustic analysis reveals distinct topological regimes, Sgr A* retains both tangential and radial critical curves, while M87* may show only tangential critical curves due to its larger mass. This topological difference provides a clear observational signature for future observations.
ER -