A Super-Eddington, Lensing-Magnified Quasar at $z=5.07$ observed with JWST

TL;DR

This study uses JWST imaging to analyze a high-redshift quasar, confirming it is not multiply imaged and revealing it has an extremely high Eddington ratio, supporting super-Eddington black hole growth in the early universe.

Contribution

First JWST-based analysis confirming a single-image lensing of a $z=5.07$ quasar and revealing its super-Eddington accretion state.

Findings

Quasar is not multiply imaged, consistent with single lensing.

Estimated magnification is up to 3.2, indicating intrinsic super-Eddington accretion.

Quasar's Eddington ratio exceeds 4.9, one of the highest at $z>5$.

Abstract

We present JWST/NIRCam F070W and F480M imaging for a quasar at $z = 5.07$, J0025-0145, which is magnified by a foreground lensing galaxy. Existing Hubble Space Telescope (HST) imaging does not have sufficient spatial resolution to determine whether the background quasar is multiply imaged. Exploiting the sharp PSF of the F070W band, we confirm that the background quasar can be well-described by a single point spread function (PSF), essentially ruling out the existence of multiple lensed images. We do not detect the quasar host galaxy in either the F070W or the F480M band. Using the HST and JWST photometry, we fit the Spectral Energy Distribution (SED) of the foreground galaxy. The estimated mass ($\log(M_{*} / M_{\odot}) = 11.15 \pm 0.16$) and redshift ($z_{\text{phot}} = 3.62_{-0.04}^{+0.06}$) of the foreground galaxy are consistent with a single-image lensing model. We estimate the maximum possible magnification of the quasar to be $\mu_{\text{max}} = 3.2$, which implies that the intrinsic Eddington ratio of the quasar is at least $\lambda_{\text{Edd}}^{\text{intrinsic}} > 4.9$. Therefore, J0025-0145 has one of the highest Eddington ratios among $z>5$ supermassive black holes known so far, suggesting the viability of super-Eddington growth for supermassive black holes in the early universe.