On the Origin of Very Wide Ly$\alpha$-Absorption-Lines in Quasar Spectra

We present a new explanation for the very wide absorption features in quasar spectra. In our model, a very wide absorption feature will originate, when the line of sight crosses a bubble wall tangentially. We demonstrate this on the quasar pair (2138-4427), (2139-4434). Both show two very wide absorption lines in their spectra at the same redshift. The bubble wall model can explain these observations in low density Friedmann-Lemaitre models with spherical metric. It contradicts models with euclidian or hyperbolic metric.