AGN Triality of Triple Mergers: Detection of Faint X-ray Point Sources
  We present results from our X-ray analysis of the first systematic search for
triple AGN in nearby (z<0.077) triple galaxy mergers. We analyze archival
Chandra observations of 7 triple galaxy mergers with BAYMAX (Bayesian Analysis
of Multiple AGN in X-rays), fitting each observation with single, dual, and
triple X-ray point source models. In doing so, we conclude that 1 triple merger
has one X-ray point source (SDSS J0858+1822, although it's unlikely to be an
AGN); 5 triple mergers are likely composed of two X-ray point sources (NGC
3341, SDSS J1027+1749, SDSS J1631+2352, SDSS J1708+2153, and SDSS
J2356$-$1016); and one system is composed of three X-ray point sources (SDSS
J0849+1114). By fitting the individual X-ray spectra of each point source, we
analyze the 2-7 keV luminosities as well as the levels of obscuration
associated with each potential AGN. We find that 4/5 dual X-ray point source
systems have primary and secondary point sources with bright X-ray luminosities
(L_2-7 kev >10^40 erg s^-1), possibly associated with 4 new undetected dual
AGN. The dual and triple point source systems are found to have physical
separations between 3-9 kpc and flux ratios between 2x10^-3 - 0.84. A
multi-wavelength analysis to determine the origin of the X-ray point sources
discovered in this work is presented in our companion paper (Foord et al.
2020c).
