The HectoMAP Cluster Survey - II. X-ray Clusters

TL;DR

This paper presents a new catalog of 15 X-ray clusters identified in the HectoMAP survey, including 7 new discoveries, and analyzes their properties and scaling relations, contributing to understanding large-scale structure.

Contribution

It introduces a flux-limited X-ray cluster catalog from HectoMAP with 15 clusters, including 7 new ones, and provides detailed redshifts and scaling relations.

Findings

The catalog is complete to a flux of ~3x10^-13 erg s^-1 cm^-2.

HectoMAP clusters follow known Lx-σ scaling relations.

Predicted ~12,000 X-ray clusters detectable in RASS.

Abstract

We apply a friends-of-friends algorithm to the HectoMAP redshift survey and cross-identify associated X-ray emission in the ROSAT All-Sky Survey data (RASS). The resulting flux limited catalog of X-ray cluster survey is complete to a limiting flux of $\sim3 \times10^{-13}$ erg s$^{-1}$ cm$^{-2}$ and includes 15 clusters (7 newly discovered) with redshift $z \leq 0.4$. HectoMAP is a dense survey ($\sim1200$ galaxies deg$^{-2}$) that provides $\sim50$ members (median) in each X-ray cluster. We provide redshifts for the 1036 cluster members. Subaru/Hyper Suprime-Cam imaging covers three of the X-ray systems and confirms that they are impressive clusters. The HectoMAP X-ray clusters have an $L_{X} - {\sigma}_{cl}$ scaling relation similar to that of known massive X-ray clusters. The HectoMAP X-ray cluster sample predicts $\sim 12000 \pm3000$ detectable X-ray clusters in the RASS to the limiting flux, comparable with previous estimates.