Cool (T∼104~K) gas is commonly observed around z>2 quasars as traced by extended Lyα emission. These large-scale nebulae are usually studied using circularly averaged surface brightness profiles, which suppress information on morphological differences. Here, we revisit the Lyα nebulae around 78 z∼2−3 quasars to obtain a novel estimate of their area and asymmetry using a common redshift-corrected surface-brightness threshold. We find a luminosity-area relation of the form log(LLyαNeb)=a1log(AreaNeb)+a0. Most nebulae are symmetric and bright, the most lopsided ones being the faintest and the less extended. The Enormous Lyman-Alpha Nebulae, asymmetric due to the presence of active companions, are the exceptions to this trend. By using simulations able to reproduce z∼6 quasar's nebulae, we show that the observed relation should not vary with redshift. Finally, we discuss possible mechanisms that drive the relation and future work needed to constrain them.
@article{arxiv.2306.14334,
title = {The luminosity-area relation of $z>2$ quasars' Ly$\alpha$ nebulae},
author = {Fabrizio Arrigoni Battaia and Aura Obreja and Tiago Costa and Emanuele P. Farina and Zheng Cai},
journal= {arXiv preprint arXiv:2306.14334},
year = {2023}
}