The large-scale cross-correlation of Damped Lyman alpha systems with the Lyman alpha forest: first measurements from BOSS
- Institute of Theoretical Physics, University of Zurich, 8057 Zurich (Switzerland)
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Catalonia (Spain)
- Institut de Ciències del Cosmos (IEEC/UB), Barcelona, Catalonia (Spain)
- Lawrence Berkeley National Laboratory, University of California Berkeley, Berkeley, California 94720 (United States)
- Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany)
- Institut d'Astrophysique de Paris, Université Paris 6 et CNRS, 98bis blvd. Arago, 75014 Paris (France)
- CEA, Centre de Saclay, IRFU, 91191 Gif-sur-Yvette (France)
- Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
We present the first measurement of the large-scale cross-correlation of Lyα forest absorption and Damped Lyman α systems (DLA), using the 9th Data Release of the Baryon Oscillation Spectroscopic Survey (BOSS). The cross-correlation is clearly detected on scales up to 40h{sup −1}Mpc and is well fitted by the linear theory prediction of the standard Cold Dark Matter model of structure formation with the expected redshift distortions, confirming its origin in the gravitational evolution of structure. The amplitude of the DLA-Lyα cross-correlation depends on only one free parameter, the bias factor of the DLA systems, once the Lyα forest bias factors are known from independent Lyα forest correlation measurements. We measure the DLA bias factor to be b{sub D} = (2.17±0.20)β{sub F}{sup 0.22}, where the Lyα forest redshift distortion parameter β{sub F} is expected to be above unity. This bias factor implies a typical host halo mass for DLAs that is much larger than expected in present DLA models, and is reproduced if the DLA cross section scales with halo mass as M{sub h}{sup α}, with α = 1.1±0.1 for β{sub F} = 1. Matching the observed DLA bias factor and rate of incidence requires that atomic gas remains extended in massive halos over larger areas than predicted in present simulations of galaxy formation, with typical DLA proper sizes larger than 20 kpc in host halos of masses ∼ 10{sup 12}M{sub ☉}. We infer that typical galaxies at z ≅ 2 to 3 are surrounded by systems of atomic clouds that are much more extended than the luminous parts of galaxies and contain ∼ 10% of the baryons in the host halo.
- OSTI ID:
- 22279887
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2012, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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