European Southern Observatory | Very Large Telescope | 2016 Oct 26
[img3="Bright halos around distant quasars - Credit: ESO/Borisova et al."]https://cdn.eso.org/images/large/eso1638a.jpg[/img3][hr][/hr]An international team of astronomers has discovered glowing gas clouds surrounding distant quasars. This new survey by the MUSE instrument on ESO’s Very Large Telescope indicates that halos around quasars are far more common than expected. The properties of the halos in this surprising find are also in striking disagreement with currently accepted theories of galaxy formation in the early Universe.
An international collaboration of astronomers, led by a group at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, has used the unrivalled observing power of MUSE on the Very Large Telescope (VLT) at ESO’s Paranal Observatory to study gas around distant active galaxies, less than two billion years after the Big Bang. These active galaxies, called quasars, contain supermassive black holes in their centres, which consume stars, gas, and other material at an extremely high rate. This, in turn, causes the galaxy centre to emit huge amounts of radiation, making quasars the most luminous and active objects in the Universe.
The study involved 19 quasars, selected from among the brightest that are observable with MUSE. Previous studies have shown that around 10% of all quasars examined were surrounded by halos, made from gas known as the intergalactic medium. These halos extend up to 300 000 light-years away from the centres of the quasars. This new study, however, has thrown up a surprise, with the detection of large halos around all 19 quasars observed — far more than the two halos that were expected statistically. The team suspects this is due to the vast increase in the observing power of MUSE over previous similar instruments, but further observations are needed to determine whether this is the case. ...
Ubiquitous giant Ly α nebulae around the brightest quasars at z∼3.5 revealed with MUSE - Elena Borisova et al
- arXiv.org > astro-ph > arXiv:1605.01422 > 04 May 2016 (v1), 08 Jul 2016 (v3)