Spatially resolved metal gas clouds

Abstract

We now have mounting evidences that the circumgalactic medium (CGM) of galaxies is polluted with metals processed through stars. The fate of these metals is however still an open question and several findings indicate that they remain poorly mixed. A powerful tool to study the low-density gas of the CGM is offered by absorption lines in quasar spectra, although the information retrieved is limited to 1D along the sightline. We report the serendipitous discovery of two close-by bright zgal = 1.148 extended galaxies with a fortuitous intervening zabs = 1.067 foreground absorber. MUSE IFU observations spatially probes kpc-scales in absorption in the plane of the sky over a total area spanning ~30 kpc-2.We identify two [O II] emitters at zabs down to 21 kpc with SFR ~2M⊙ yr-1.We measure small fractional variations (< 30 per cent) in the equivalent widths of Fe II and MgII cold gas absorbers on coherence scales of 8 kpc but stronger variation on larger scales (25 kpc).We compute the corresponding cloud gas mass < 2 × 109M⊙. Our results indicate a good efficiency of the metal mixing on kpc-scales in the CGM of a typical z ~ 1 galaxy. This study show-cases new prospects for mapping the distribution and sizes of metal clouds observed in absorption against extended background sources with 3D spectroscopy.