Properties of Lyα emitters around the radio galaxy MRC 0316 257

摘要: Observations of the radio galaxy MRC 0316–257 at $z = 3.13$ and surrounding field are presented. Using narrow- broad-band imaging obtained with VLT, 77 candidate Ly α  emitters a rest-frame equivalent width >15 A were selected in ∼ 7´$\,\times\,7$´ field around galaxy. Spectroscopy 40 emitters resulted discovery 33 emission line galaxies which 31 redshifts similar to that galaxy, while remaining two turned out be [$\ion{O}{ii}$] emitters. The  profiles have widths ( FWHM ) range 120–800 km s -1 , median 260 km s . Where signal-to-noise was large enough, found asymmetric, apparent absorption troughs blueward profile peaks, indicative along sight an $\ion{H}{i}$ mass least $2 \times 10^2 {-} 5 10^4$ M $_{\odot}$. Besides one is QSO, continuum faint, luminosities ranging from 1.3 L * colors confirmed are, on average, very blue. UV slope $\beta -1.76$, bluer than average LBGs  emission ($\beta \sim -1.09$). A fraction 2/3) consistent dust-free starburst galaxies. Advanced Camera for Surveys Hubble Space Telescope show detected ACS image different morphologies. Four 25%) unresolved upper limits their half light radii $r_{\rm h} 19%) multiple clumps emission, as does rest 56%) single, resolved objects smaller LBGs. star formation rate 2.6  $_{\odot}\;{\rm yr}^{-1}$ as measured by or continuum. properties  galaxies (faint, blue small) young forming still nearly dust free.
The volume density  emitting factor $3.3^{+0.5}_{-0.4}$ larger compared redshift. velocity distribution spectroscopically has dispersion 640 km s corresponding 1510 km s substantially narrow-band filter (${\it FWHM} 3500$ km s ). peak located within 200 km s  of redshift We conclude members protocluster 3.13$. size unconstrained $3.3 3.3$  Mpc 2 this structure estimated >$3{-}6 10^{14}$  $_{\odot}$ could progenitor cluster e.g. the Virgo cluster.