The Unusual Weak-Line Quasar PG1407+265 and its Foreground z~0.7 X-ray Cluster

TL;DR

This study investigates the peculiar weak-line quasar PG1407+265, revealing its variability, powerful accretion activity, and the presence of a foreground galaxy cluster, providing insights into its environment and properties.

Contribution

It reports the discovery of a foreground z~0.7 X-ray cluster and analyzes the quasar's variability and accretion features, offering new understanding of its environment and activity.

Findings

PG1407+265 shows significant variability over years.

A foreground z=0.68 cluster contributes to X-ray emission.

The cluster has a mass of (0.6-5.5)×10^{14} solar masses.

Abstract

We present new observations of the odd $z=0.96$ weak-line quasar PG1407+265, and report the discovery of CXOU J140927.9+261813, a $z=0.68$ X-ray cluster. Archival X-ray photometry spanning nearly four decades reveals that PG1407+265 is variable at the 1 dex level on a timescale of years. V-band variability is present with an amplitude less than 0.1 mag. The emission-line properties of PG1407+265 also reveal clear evidence for a powerful inflow or outflow due to near- or super-Eddington accretion, having a mechanical luminosity of order $10^{48}$ erg s$^{-1}$. Our follow-up {\sl Chandra} exposure centered on this object reveal a foreground $z=0.68$ cluster roughly 1' x 1'.5 in extent, offset to the east of PG1407+265, roughly coincident with the $z=0.68$ radio galaxy FIRST J140927.8+261818. This non-cool-core cluster contributes about 10\% of the X-ray flux of PG1407+265, has a mass of $(0.6- 5.5)\times10^{14} M_\odot$, and an X-ray gas temperature of ($2.2-4.3$) keV. Because the projected position of the quasar lies at about twice that of the cluster's inferred Einstein radius, lensing by the cluster is unlikely to explain the quasar's unusual properties. We also discuss the evidence for a second cluster centered on and at the redshift of the quasar.