QSO MUSEUM

III. The circumgalactic medium in the Lyα emission around 120 z ∼ 3 quasars covering the SDSS parameter space. Witnessing the instantaneous active galactic nucleus feedback on halo scales

¹ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str 1, 85748 Garching bei München, Germany
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Universität Heidelberg, Im Neuenheimer Feld 205, D-69120 Heidelberg, Germany
⁴ Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Straße 2, D-69120 Heidelberg, Germany
⁵ International Gemini Observatory/NSF NOIRLab, 670 N A’ohoku Place, Hilo, Hawai’i 96720, USA
⁶ School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 6 February 2025
Accepted: 27 November 2025

Abstract

Recent surveys have shown that z ≳ 2 quasars are surrounded by hydrogen Lyman-α (Lyα) glows with diverse emission levels and extents. These characteristics seem to depend on the activity of embedded quasars, on the number of active galactic nucleus (AGN) photons that are able to reach the halo gas or circumgalactic medium (CGM), and on the physical properties of the CGM. In this framework, we present VLT/MUSE snapshot observations (45 minutes/source) of 59 z ∼ 3 quasars extending the long-term QSO MUSEUM campaign to the fainter SDSS sources. The whole survey is homogeneously reduced and analyzed here and now targets 120 quasars with a median redshift z = 3.13 and bolometric luminosities, black hole masses, and Eddington ratios in the ranges 45.1 < log(L_bol/[erg s⁻¹]) < 48.7, 7.9 < log(M_BH/[M_⊙]) < 10.3, and 0.01 < λ_Edd < 1.8. We detected extended Lyα emission in 110 of the 120 systems, with all the nondetections in the newly added fainter sample. The surface brightness of the CGM Lyα emission (SB_Lyα) increases with quasar luminosity. Stacking of the nondetections unveiled emission just below our individual field detection limit. Moreover, the Lyα line width increases in the central regions (projected radius R < 40 kpc or ∼40% R_vir) of the CGM around quasars with stronger radiation. The variation in surface brightness and the velocity dispersion as a function of quasar luminosity indicate that we witness the instantaneous AGN feedback in action on CGM scales. Assuming that all targeted quasars sit in halos of M_DM ∼ 10^12.5 M_⊙ independent of luminosity, as suggested by clustering studies, we explain the trend in SB_Lyα naturally by a larger fraction of cool gas mass that is illuminated, which implies that brighter quasars have larger ionization cone opening angles. Similarly, brighter AGN seem to perturb the cool (T ∼ 10⁴ K) gas more strongly. We show that QSO MUSEUM starts to have enough statistics to study this instantaneous AGN feedback while controlling for black hole properties (e.g., mass), which will be key to constraining AGN models.