2016/09/30 by Zheng Cai, Xiaohui Fan, Yujin Yang +12 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aa5d14
corrected a typo of a coordinate in the last published version; and also updated Fig.2
arxiv created 2020/10/07 · arxiv updated 2020/10/08
Enormous Lyα Nebulae (ELANe), unique tracers of galaxy density peaks, are predicted to lie at the nodes and intersections of cosmic filamentary structures. Previous successful searches for ELANe have focused on wide-field narrowband surveys, or have targeted known sources such as ultraluminous quasi-stellar-objects (QSOs) or radio galaxies. Utilizing groups of coherently strong Lyα absorptions (CoSLAs), we have developed a new method to identify high-redshift galaxy overdensities and have identified an extremely massive overdensity, BOSS1441, at z=2-3 (Cai et al. 2016a). In its density peak, we discover an ELAN that is associated with a relatively faint continuum. To date, this object has the highest diffuse Lyα nebular luminosity of L_\rmnebula=5.1±0.1×1044 erg s-1. Above the 2σ surface brightness limit of SB_\rmLyα= 4.8×10-18 erg s-1 cm-2 arcsec-2, this nebula has an end-to-end spatial extent of 442 kpc. This radio-quiet source also has extended \civ λ1549 and \heii λ1640 emission on \gtrsim30 kpc scales. Note that the Lyα, \heii and \civ emission all have double-peaked line profiles. Each velocity component has a full-width-half-maximum (FWHM) of ≈700 - 1000 km s-1. We argue that this Lyα nebula could be powered by shocks due to an AGN-driven outflow or/and photoionization by a strongly obscured source.