Study Reveals Extended Lyα Emission in Quasar Pairs

A recent study titled "QSO MUSEUM II: Search for extended Lyα emission around 8 z ∼ 3 quasar pairs" by Eileen Herwig and colleagues investigates the presence of extended Lyα emission in the circumgalactic medium (CGM) surrounding quasar pairs. The research focuses on eight pairs of quasars at redshift z ∼ 3, utilizing VLT/MUSE observations to analyze the characteristics of the Lyα nebulae associated with these quasars.

The study found that extended Lyα emission was detected around 12 out of the 14 targeted quasars. The average size of these nebulae is approximately 90 kiloparsecs, with a luminosity of about 2.8 × 10^43 erg s^−1. Notably, around 45% of the nebulae exhibited an extension toward the other quasar in the pair, indicating a potential interaction between the two.

The authors concluded that the cool gas in the CGM aligns with the large-scale structure of the universe, tracing the direction of cosmic web filaments. The radial profile of the Lyα surface brightness showed a shallower slope compared to single quasars, suggesting increased densities in the CGM and a significant contribution from the intergalactic medium (IGM).

This research provides valuable insights into the behavior of gas in the vicinity of quasars and highlights the importance of studying quasar pairs to understand the cosmic environment better. The findings may serve as a foundation for future ultra-deep observations aimed at exploring filamentary IGM structures in emission. The full paper can be accessed at arXiv:2408.16826.