Chandra Discovery of a Candidate Hyper-Luminous X-ray Source in MCG+11-11-032

TL;DR

This study uses Chandra X-ray observations to identify a candidate hyper-luminous X-ray source in MCG+11-11-032, revealing a potential off-nuclear source with properties similar to known hyper-luminous X-ray sources, highlighting the importance of high-resolution imaging.

Contribution

First high-resolution Chandra analysis of MCG+11-11-032 revealing a candidate hyper-luminous X-ray source, advancing understanding of off-nuclear X-ray sources in AGN host galaxies.

Findings

Detection of a luminous off-nuclear X-ray source (MCG+11-11-032 X2).

X-ray and radio properties similar to ESO 243-49 HLX-1.

No evidence of double-peaked Fe Kα lines in the spectrum.

Abstract

We present a multi-wavelength analysis of MCG+11-11-032, a nearby AGN with the unique classification of both a binary and a dual AGN candidate. With new Chandra observations we aim to resolve any dual AGN system via imaging data, and search for signs of a binary AGN via analysis of the X-ray spectrum. Analyzing the Chandra spectrum, we find no evidence of previously suggested double-peaked Fe K$\alpha$ lines; the spectrum is instead best fit by an absorbed powerlaw with a single Fe K$\alpha$ line, as well as an additional line centered at $\approx$7.5 keV. The Chandra observation reveals faint, soft, and extended X-ray emission, possibly linked to low-level nuclear outflows. Further analysis shows evidence for a compact, hard source -- MCG+11-11-032 X2 -- located 3.27'' from the primary AGN. Modeling MCG+11-11-032 X2 as a compact source, we find that it is relatively luminous ($L_{\text{2$-$10 keV}} = 1.52_{-0.48}^{+0.96}\times 10^{41}$ erg s$^{-1}$), and the location is coincident with an compact and off-nuclear source resolved in Hubble Space Telescope infrared (F105W) and ultraviolet (F621M, F547M) bands. Pairing our X-ray results with a 144 MHz radio detection at the host galaxy location, we observe X-ray and radio properties similar to those of ESO 243-49 HLX-1, suggesting that MCG+11-11-032 X2 may be a hyper-luminous X-ray source. This detection with Chandra highlights the importance of a high-resolution X-ray imager, and how previous binary AGN candidates detected with large-aperture instruments benefit from high-resolution follow-up. Future spatially resolved optical spectra, and deeper X-ray observations, can better constrain the origin of MCG+11-11-032 X2.