SDSS J125417.98+274004.6: An X-ray Detected Minor Merger Dual AGN

Abstract

In this paper, we present the discovery of a dual AGN in a $\sim$11:1 minor merger between the galaxy SDSS J125417.98+274004.6 and its unnamed dwarf satellite. We calculated stellar masses of the primary and secondary galaxy to be 2.5$\times$10$^{10}$M$_{\odot}$ and 2.2$\times$10$^{9}$M$_{\odot}$, respectively. We used archival Chandra X-ray observations to assess the presence of AGN. We found that both AGN have comparable luminosities of $\sim$2$\times$10$^{42}$ erg s$^{-1}$, with the secondary AGN being more likely to be the dominant one. The galaxies are in the early stages of the merger and are connected by a tidal bridge. Previous works suggest that the secondary AGN should experience a brief but intensive period of Eddington-limit approaching accretion during the early stages of the merger. During the merger, the secondary black hole can increase its mass by a factor of ten. SDSS J125417.98+274004.6 is the first known dual AGN in an early-stage minor merger with a comparably or more luminous secondary AGN. As such, it will be of great value for future studies of merger-triggered accretion and black hole growth mechanisms.