The strong gravitational lensing properties of black holes surrounded by dark matter halos of two types—a self-interacting scalar field and an NFW profile—are studied. The metric is reconstructed numerically using the Einstein cluster formalism. The photon sphere radius, critical impact parameter, and observable quantities for M87* and Sgr A* are calculated: Einstein rings, image positions, magnification, and time delays. Deviations from the Schwarzschild solution turn out to be extremely small (less than 0.1%), so the models are nearly indistinguishable in images. However, in the time delays between relativistic rings, the halo's influence is more pronounced, especially for the most massive black holes. This points to the potential of temporal analysis for probing dark matter in the vicinity of black holes.
The gravity of a black hole creates a curvature of spacetime, acting like a lens: light from a distant galaxy splits in two, stretching into arcs. Dark matter around the hole barely changes the picture—as if a transparent curtain was added to a window pane. But light from the different images arrives with a delay—from minutes to years. And it's this interval that slightly shifts due to the invisible substance.
Calculations show: even for giant holes, the image distortion is less than a thousandth of a percent. However, the arrival time difference of the 'twins' shifts by fractions of a second—atomic clocks can notice such a thing.
Time becomes the key to the invisible halo. And although image distortions are negligible, future telescopes will catch microsecond shifts. Paradox: the delay from the hole itself can be so gigantic that the light set off before the first humans appeared on Earth.
🎯 In 1912, [scientist:Albert Einstein]Albert Einstein[/scientist] predicted that gravity bends light; the first mirage ring was found only in 1979 with the help of radio telescopes.
🎬 In 'Interstellar', the heroes study the black hole Gargantua by the distorted light of stars—the scene almost exactly mirrors the calculations for the real M87*.