Ly-alpha emission reveals two satellite halos around massive groups at z ~ 3: The puzzling case of a quiescent central galaxy
MUSE follow-up of four giant Lyα nebulae at z ≈ 3 revealed two smaller satellite nebulae, each about 300 kpc from its main nebula and at nearly the same velocity.
What was found
- Two Lyα nebulae lie about 300 physical kpc from giant nebulae at z ≈ 2.9–3.1, with velocities that differ by only about 100–300 km/s, which hints at a shared large-scale structure.
- The halos weigh roughly 1013 and 1012.8 solar masses, and the number of such satellites matches what simulations predict.
- The brightest galaxy of one halo is a quiescent elliptical aligned with the peak of the nebula. It shows no star formation, probably because of radio-mode feedback from its black hole. The other halo is centred on a dusty star-forming spiral.
- A tentative Lyα filament may connect one of the pairs.
This summary is written for a general audience. The paper has the full details.
Cite this paper
Guo, S., et al. 2025, A&A, 704, A340, doi:10.1051/0004-6361/202555793
@article{guo2025,
author = {Guo, Sicen and others},
title = {{Ly-alpha emission reveals two satellite halos around massive groups at z ~ 3: The puzzling case of a quiescent central galaxy}},
journal = {Astronomy & Astrophysics},
year = {2025},
volume = {704},
pages = {A340},
doi = {10.1051/0004-6361/202555793},
eprint = {2510.01421},
archivePrefix = {arXiv}
}Topics Circumgalactic and intergalactic gas Clusters and protoclusters