Speaker
Description
We report the discovery of the Cosmic Himalayas, hosting 11 luminous Type-1 SDSS quasars at redshift z=2.2, initially identified through the MAMMOTH-Subaru survey with strong Intergalactic absorbers. These quasars, with bolometric luminosities L_bol ≳ 10^45.5 erg s^-1, reside in a (40 cMpc)^3 volume, exhibiting a quasar overdensity 30 times the cosmic average as the 17σ outlier over the 10,000 deg^2 SDSS sky (Liang et al. 2024, arXiv:2404.15963). This structure provides a rare opportunity to study the role of quasars in shaping galaxy evolution and cosmic environments during one of the most active phases of the Universe. Subaru/HSC NB387 observations revealed the spatial distribution of z=2.2 Lyman-alpha emitters (LAEs), uncovering a surprising pattern: quasars align perpendicular to a ~100 cMpc filament but do not coincide with LAE overdensities. Filament nodes exhibit distinct galaxy properties, while quasars occupy intermediate regions, suggesting a pivotal role in influencing their surroundings. The 3D intergalactic medium (IGM) tomography using SDSS/eBOSS background quasars reveals significant ionization variations along the filament, indicating quasars as key drivers of ionizing feedback. Furthermore, luminous submillimeter galaxies (SMGs) with flux densities >2 mJy at 850 µm are identified by JCMT/SCUBA-2, which are spatially offset from the LAEs with bright continuum, with quasars situated in transitional regions. This configuration suggests an evolutionary sequence within the LSS, progressing from dusty galaxies undergoing mergers to the quasar phase, and ultimately to massive galaxies with inactive AGNs. This unique and extreme testbed provides critical insights into galaxy formation and evolution, bridging the influence of small-scale active nuclei with large-scale cosmic environments.