A powerful vacuum cleaner sucks in not only dust but also its own collection bag. That's roughly how a black hole behaves at the center of a 'red dot'—a distant galaxy where the glow comes not from the hole itself but from its dense gas shroud. This shroud is so thick it resembles a puffed-up cool star. And, like many stars, it has a magnetic field.
Gas falls onto the black hole from all sides. But before disappearing beyond the horizon, it gets twisted by the envelope's magnetic field. Individual clumps of plasma rotate with it, and their motion smears the spectral lines. It's like an ambulance siren: the pitch changes as the vehicle zooms past. Add light scattering off electrons, and the line profile becomes a hill with a gentle tail: a smooth rise and a sharp drop. This shape explains velocities of thousands of kilometers per second without extra hypotheses.
The model also explains why 'red dots' barely shine in X-rays. The two possible sources of such emission, the shock wave from infalling gas and a heated magnetic corona, turn out to be too weak. For any black hole mass from one hundred thousand to ten million solar masses and any accretion rate, the X-ray luminosity does not exceed 10⁴¹ erg/s. This matches observations. The magnetic cocoon muffles high-energy glow, leaving only visible and infrared light.
So a vacuum cleaner that has sucked in its own bag changes our view of what's inside. Red dots may not be what they seem at first glance.
Gas speeds in the envelope can reach several thousand kilometers per second — hundreds of times faster than a bullet.
In Stanislaw Lem's novel 'Solaris', the planet's ocean behaves like a living magnetic structure — somewhat similar to the black hole envelope in this model, only on a cosmic scale.