Extended Data Fig. 3: Optical emission-line diagnostic diagrams.
From: Two separate outflows in the dual supermassive black hole system NGC 6240
The galaxy was observed at two position angles, PA1 = 22° and PA2 = 56° (see Extended Data Fig. 1). The positive values of angular distance (green to red in the colour bar) correspond to the direction north of the centre of the galaxy, at that position angle. Negative angular distance values (green to blue in the colour bar) correspond to the direction south of the centre of the galaxy, at that position angle. The BPT diagram is usually divided into three regions: AGN (or Seyfert), LINER (or LIER, low-ionization emission-line region; see also ref. 50) and H ii (or starburst region). In both panels, we plot the extreme starburst diagnostic line21 (curved dashed line) and the LIER/LINER diagnostic line49 (straight dashed line). Hβ emission was detected with a signal-to-noise ratio higher than 3 in 16 spatial elements at PA1 = 22° (from r = −6″ to r = 2″) and in 26 spatial elements at PA2 = 56° (from r = −5″ to r = 6″). There are 15 spatial elements inside the [O iii] cone (Fig. 3). The error bars correspond to the uncertainties of the flux ratios (one standard deviation) and were calculated via standard error propagation for the flux of each emission line.
