Fig. 6: A small Lyman-α nebula, possibly associated to W0410-0913.

a We show an optimally extracted map of the spatial distribution of the narrow and spectrally-offset Lyman-α emission emitted at the same location of the Hot DOG (see Fig. 5). We measure a spatial extension, defined as the maximum projected linear size, of about 30 kpc (see white line). The white contours represent the [3, 5, 10]σ levels of significance, where the noise is estimated by propagating the variance and taking into account the number of layers contributing to each pixel in the 3D mask. The last contour at 3σ defines the spatial projection of the 3D mask. For display purposes, we have added to the map of the projected 3D-mask one wavelength layer of the cube corresponding to the central wavelength of the nebula. b We show the 3σ contour of the nebula overlaid onto the HST WFC3 F160W image. Black contours are located around galaxies in the cutout that are detected in MUSE continuum (obtained collapsing the full datacube) and are defined as the regions in which 80% of the flux is contained.