An overdensity of red galaxies around the hyperluminous dust-obscured quasar W1835$+$4355 at $z=2.3$

TL;DR

This study finds a significant overdensity of red galaxies around the Hot DOG W1835+4355 at z=2.3, suggesting Hot DOGs are good tracers of dense high-redshift regions, but the specific galaxy is not in the densest part.

Contribution

First near-infrared observations of a Hot DOG at z=2.3 reveal galaxy overdensities, indicating Hot DOGs as markers of dense environments at high redshift.

Findings

Significant excess of Distant Red Galaxies around W1835+4355

Overdensity factor of about 2 compared to control fields

W1835+4355 is not in the densest environment, possibly due to merging activity

Abstract

\emph{Wide-field Infrared Survey Explorer} all-sky survey has discovered a new population of hot dust-obscured galaxies (Hot DOGs), which has been confirmed to be dusty quasars. Previous statistical studies have found significant overdensities of sub-millimeter and mid-IR selected galaxies around Hot DOGs, indicating they may reside in dense regions. Here we present the near-infrared ($J$ and $K_s$ bands) observations over a $7.5'\times 7.5'$ field centered on a Hot DOG W1835$+$4355 at $z \sim 2.3$ using the wide-field infrared camera on the Palomar 200-inch telescope. We use the color criterion $J-K_s>2.3$ for objects with $K_s<20$, to select Distant Red Galaxies (DRGs). We find a significant excess of number density of DRGs in W1835$+$4355 field compared to three control fields, by a factor of about 2. The overdensity of red galaxies around W1835$+$4355 are consistent with the multi-wavelength environment of Hot DOGs, suggesting that Hot DOGs may be a good tracer for dense regions at high redshift. We find that W1835$+$4355 do not reside in the densest region of the dense environment traced by itself. A possible scenario is that W1835$+$4355 is undergoing merging process, which lowers the local number density of galaxies in its surrounding region.