Speaker
Description
The densest structures of the Universe formed at the knots of the cosmic
web at high redshifts and constitute the present-day clusters of galaxies. The
early stages of these structures are called protoclusters. In this work, we use the
submm source J1000+0234, representative of a population of dusty and distant
starburst galaxies expected to inhabit peaks of matter density, as a target for a
potential protocluster region. We use combined wide-band and narrow-band op-
tical photometry to identify Lyα emitters (LAEs) within a 21cMpc radius from
the submm source J1000+0234, at z = 4.54 ± 0.03, to identify typical star-
forming galaxies that may trace the underlying structure containing our target
source. Our approach selects line emitters as narrow-band excess objects and
we use the COSMOS2020 photometric redshift catalog to eliminate potential
low-redshift interlopers whose line emission (e.g. [OIII] at z ∼ 0.3) might be
responsible for the observed excess in the narrow band. In comparison with
the LAE density in the field, our results point to a mean LAE number overdensity
of δ = 3, spanning a region of 27 x 20 x 36 cMpc^3, probably evolving
into a moderate-mass cluster (3 − 10 × 10^14 M⊙) at z ∼ 0. This structure likely
forms an extension at z ∼ 4.5, a few comoving Mpc away from the recently iden-
tified Taralay protocluster. This work supports the idea that submm sources,
although offset from the major overdensity peaks, serve as traces of moderately
massive, potentially infalling structures.
