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Centro de Astrofísica da Universidade do Porto

Ubiquitous Giant Lyα Nebulae around the Brightest Quasars at z~3.5 Revealed with MUSE

E. Borisova, S. Cantalupo, S. Lilly, R. A. Marino, S. G. Gallego, R. Bacon, J. Blaizot, N. Bouché, J. Brinchmann, C. M. Carollo, J. Caruana, H. Finley, E. C. Herenz, J. Richard, J. Schaye, L. A. Straka, M. L. Turner, T. Urrutia, A. Verhamme, L. Wisotzki

Abstract
Direct Lyα imaging of intergalactic gas at z̃ 2 has recently revealed giant cosmological structures around quasars, e.g., the Slug Nebula. Despite their high luminosity, the detection rate of such systems in narrow-band and spectroscopic surveys is less than 10%, possibly encoding crucial information on the distribution of gas around quasars and the quasar emission properties. In this study, we use the MUSE integral-field instrument to perform a blind survey for giant {Ly}α nebulae around 17 bright radio-quiet quasars at 3lt zlt 4 that does not suffer from most of the limitations of previous surveys. After data reduction and analysis performed with specifically developed tools, we found that each quasar is surrounded by giant {Ly}α nebulae with projected sizes larger than 100 physical kiloparsecs and, in some cases, extending up to 320 kpc. The circularly averaged surface brightness profiles of the nebulae appear to be very similar to each other despite their different morphologies and are consistent with power laws with slopes ≈ -1.8. The similarity between the properties of all these nebulae and the Slug Nebula suggests a similar origin for all systems and that a large fraction of gas around bright quasars could be in a relatively “cold” (T ̃ 104 K) and dense phase. In addition, our results imply that such gas is ubiquitous within at least 50 kpc from bright quasars at 3lt zlt 4 independently of the quasar emission opening angle, or extending up to 200 kpc for quasar isotropic emission.Based on observations made with ESO Telescopes at the Paranal Observatory under programs 094.A-0396, 095.A-0708, 096.A-0345, 094.A-0131, 095.A-0200, and 096.A-0222.

Keywords
cosmology: observations, galaxies: high-redshift, intergalactic medium, quasars: emission lines, quasars: general

The Astrophysical Journal
Volume 831
October 2016

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