Astrophys. J., Suppl. Ser., 226, 23-23 (2016/October-0)
Lyα emitter galaxies at z∼ 2.8 in the Extended Chandra Deep Field South. I. Tracing the large-scale structure via Lyα imaging.
ZHENG Z.-Y., MALHOTRA S., RHOADS J.E., FINKELSTEIN S.L., WANG J.-X., JIANG C.-Y. and CAI Z.
Abstract (from CDS):
We present a narrowband survey with three adjacent filters for z = 2.8-2.9 Lyman alpha (Lyα) emitter (LAE) galaxies in the Extended Chandra Deep Field South (ECDFS), along with spectroscopic follow-up. With a complete sample of 96 LAE candidates in the narrowband NB466, we confirm the large-scale structure at z ∼ 2.8 suggested by previous spectroscopic surveys. Compared to the blank field detected with the other two narrowband filters NB470 and NB475, the LAE-density excess in NB466 (900 arcmin2) is ∼ 6.0 ± 0.8 times the standard deviation expected at z ∼ 2.8, assuming a linear bias of 2. The overdense large-scale structure in NB466 can be decomposed into four protoclusters, whose overdensities (each within an equivalent comoving volume 153 Mpc3) relative to the blank field (NB470+NB475) are in the range of 4.6-6.6. These four protoclusters are expected to evolve into a Coma-like cluster (M >= 1015 M☉) at z ∼ 0. We also investigate the various properties of LAEs at z = 2.8-2.9 and their dependence on the environment. The average star formation rates derived from the Lyα, rest-frame UV, and X-ray bands are ∼4, 10, and <16 M☉ yr–1, respectively, implying a Lyα escape fraction of 25% <= fESCLyα <= 40% and a UV continuum escape fraction of fESCUV,cont >= 62% for LAEs at z ∼ 2.8. The Lyα photon density calculated from the integrated Lyα luminosity function in the overdense field (NB466) is ∼50% higher than that in the blank field (NB470+NB475), and more bright LAEs are found in the overdense field. The three brightest LAEs, including a quasar at z = 2.81, are all detected in the X-ray band and in NB466. These three LAE-active galactic nuclei contribute an extra 20%-30% Lyα photon density compared to other LAE galaxies. Furthermore, we find that LAEs in overdense regions have larger equivalent width values, bluer U - B and V - R (∼2-3σ) colors compared with those in lower density regions, indicating that LAEs in overdense regions are younger and possible less dusty. We conclude that the structure at z ∼ 2.8 in the ECDFS field is a very significant and rare density peak similar to the SSA22 protocluster, and narrowband imaging is an efficient method of detecting and studying such structures in the high-z universe.
© 2016. The American Astronomical Society. All rights reserved.
galaxies: evolution - galaxies: high-redshift - galaxies: luminosity function - galaxies: structure - mass function - mass function
Tables 2-4: [ZMR2016] NNNN NNN N=50+28+34.
Status in Simbad:
waiting for electronic table
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