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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731530.0, MPI für Astronomie / Publikationen_mpia
Shadow of a colossus: A z = 2.44 galaxy protocluster detected in 3D Ly forest tomographic mapping of the COSMOS field
Authors:Lee, K.-G.; Hennawi, J. F.; White, M.; Prochaska, J. X.; Font-Ribera, A.; Schlegel, D. J.; Rich, R. M.; Suzuki, N.; Stark, C. W.; Le Fèvre, O.; Nugent, P. E.; Salvato, M.; Zamorani, G.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 160 (16 pp)
Audience:Not Specified
Abstract / Description:Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at z∼ 2.3{{{--}}}3 within a 11.‧5 × 13.‧5 area of the COSMOS field (∼ 1200 {{deg}}-2 projected area density or ∼ 2.4 {h}-1\text{} {Mpc} mean transverse separation), we reconstruct a 3D tomographic map of the foreground Lyα forest absorption at 2.2 < z < 2.5 with an effective smoothing scale of {ε }{{3D}}≈ 2.5 {h}-1\text{} {Mpc} comoving. Comparing with 61 coeval galaxies with spectroscopic redshifts in the same volume, we find that the galaxy positions are clearly biased toward regions with enhanced intergalactic medium (IGM) absorption in the tomographic map. We find an extended IGM overdensity with deep absorption troughs at z = 2.45 associated with a recently discovered galaxy protocluster at the same redshift. Based on simulations matched to our data, we estimate the enclosed dark matter mass within this IGM overdensity to be {M}{{dm}}(z=2.45)=(1.1+/- 0.6)× {10}14 {h}-1\text{}{M}ȯ , and argue based on this mass and absorption strength that it will form at least one z ∼ 0 galaxy cluster with M(z=0)=(3+/- 1.5)× {10}14 {h}-1\text{}{M}ȯ , although its elongated nature suggests that it will likely collapse into two separate clusters. We also point out a compact overdensity of six MOSDEF galaxies at z = 2.30 within a r∼ 1 {h}-1\text{} {Mpc} radius and Δz ∼ 0.006, which does not appear to have a large associated IGM overdensity. These results demonstrate the potential of Lyα forest tomography on larger volumes to study galaxy properties as a function of environment, as well as revealing the large-scale IGM overdensities associated with protoclusters or other features of large-scale structure.
Free Keywords:cosmology: observations; galaxies: clusters: general; galaxies: high-redshift; intergalactic medium; quasars: absorption lines; techniques: spectroscopic
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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