A study of distant Ly-alpha emitters in overdense regions
Bram Venemas
In this talk I will present the results of a VLT large program to search
for overdensities of Ly-alpha emitters near high redshift radio galaxies.
During the last decade, evidence has mounted that the most powerful high
redshift radio galaxies are progenitors of brightest cluster galaxies and
are located in dense environments. To search for direct evidence of the
association of a (forming) cluster with radio galaxies, a large program
at the VLT was conducted, aimed at finding an excess of Ly-alpha emitting
galaxies around radio galaxies at 2 < z < 5.
The program was very successful. Seven overdensities are discovered near
radio galaxies. In total nearly 300 good candidate Ly-alpha emitters are
found in these fields. Roughly 150 emitters are spectroscopically
confirmed to be at high redshift, allowing a detailed study of these
galaxies. The Ly-alpha emitters are found to be faint, blue and small, as
compared to Lyman break galaxies at the same redshift. These properties of
the emitters are consistent with young star forming galaxies which are
still nearly dust free.
I will also discuss the macro properties of the Ly-alpha emitters and show
that they are in line with models of structure formation.