Galaxy Zoo: bulgeless galaxies with growing black holes

The growth of supermassive black holes appears to be driven by galaxy mergers, violent merger-free processes and/or 'secular' processes. In order to quantify the effects of secular evolution on black hole growth, we study a sample of active galactic nuclei (AGN) in galaxies with a calm formation history free of significant mergers, a population that heretofore has been difficult to locate. Here we present an initial sample of 13 AGN in massive (M * 10 10 M ) bulgeless galaxies -which lack the classical bulges believed inevitably to result from mergers -selected from the Sloan Digital Sky Survey using visual classifications from Galaxy Zoo. Parametric morphological fitting confirms that the host galaxies lack classical bulges; any contributions from pseudo-bulges are very small (typically <5 per cent). We compute black hole masses for the two broad-line objects in the sample (4.2 10 6 and 1.2 10 7 M ) and place lower limits on black hole masses for the remaining sample (typically M BH 10 6 M ), showing that significant black hole growth must be possible in the absence of mergers or violent disc instabilities.