Constraining the cosmic UV background at z > 3 with MUSE Lyman-α emission observations

Sofia G. Gallego et al.

A new and independent way to constrain the cosmic UV background: the faint Lyα glow of self-shielded gas clouds that it illuminates, detected by stacking MUSE data.

Paper ↗arXiv ↗ADS ↗Project page

What was found

• Instead of matching simulated Lyα-forest spectra, the method looks for the faint Lyα glow that self-shielded gas clouds emit when the UV background illuminates them.
• That glow is too faint to image directly, so MUSE data around Lyα emitters between z = 2.9 and 6.6 are stacked and compared with mock observations from the EAGLE simulation.
• The results agree with earlier measurements and favour a relatively low UV background intensity at z = 3.
• The background seems to fall in a non-monotonic way between z = 3 and z = 5, which could signal tension with some models. Deeper and wider data would test this.

This summary is written for a general audience. The paper has the full details.

@article{gallego2021,
  author = {Gallego, Sofia G. and others},
  title = {{Constraining the cosmic UV background at z > 3 with MUSE Lyman-α emission observations}},
  journal = {Monthly Notices of the Royal Astronomical Society},
  year = {2021},
  volume = {504},
  number = {1},
  pages = {16--32},
  doi = {10.1093/mnras/stab796},
  eprint = {2103.09250},
  archivePrefix = {arXiv}
}

Topics Cosmic web and UV background Circumgalactic and intergalactic gas