# A Potential Recoiling Supermassive Black Hole CXO J101527.2+625911

## TL;DR

This study identifies a candidate recoiling supermassive black hole with spatial and velocity offsets, using multi-wavelength data, suggesting it is in the final merger stage and not an active nucleus.

## Contribution

First systematic search for recoiling SMBHs combining Chandra and SDSS data, identifying a promising candidate with detailed analysis of its properties.

## Key findings

- Detected a potential recoiling SMBH at z=0.3504 with spatial and velocity offsets.
- Ruled out low-luminosity AGN as the source of offsets.
- Host galaxy is a bulge-dominated elliptical in late merger stage.

## Abstract

We have carried out a systematic search for recoiling supermassive black holes (rSMBH) using the Chandra Source and SDSS Cross Matched Catalog. From the survey, we have detected a potential rSMBH, 'CXO J101527.2+625911' at z=0.3504. The CXO J101527.2+625911 has a spatially offset (1.26$\pm$0.05 kpc) active SMBH and kinematically offset broad emission lines (175$\pm$25 km s$^{\rm -1}$ relative to systemic velocity). The observed spatial and velocity offsets suggest this galaxy could be a rSMBH, but we also have considered a possibility of dual SMBH scenario. The column density towards the galaxy center was found to be Compton thin, but no X-ray source was detected. The non-detection of the X-ray source in the nucleus suggests either there is no obscured actively accreting SMBH, or there exists an SMBH but has a low accretion rate (i.e. low-luminosity AGN (LLAGN)). The possibility of the LLAGN was investigated and found to be unlikely based on the H$\alpha$ luminosity, radio power, and kinematic arguments. This, along with the null detection of X-ray source in the nucleus supports our hypothesis that the CXO J101527.2+625911 is a rSMBH. Our GALFIT analysis shows the host galaxy to be a bulge-dominated elliptical. The weak morphological disturbance and small spatial and velocity offsets suggest that CXO J101527.2+625911 could be in the final stage of merging process and about to turn into a normal elliptical galaxy.