We characterize the incidence and intensity of low-level super-massive black hole activity within the Fornax cluster , through X-ray observations of the nuclei of 29 quiescent early-type galaxies .
Using the Chandra X-ray Telescope , we target 17 galaxies from the Hubble Space Telescope Fornax Cluster Survey , down to a uniform ( 3 \sigma ) limiting X-ray luminosity threshold of 5 \cdot 10 ^ { 38 } ergs ^ { -1 } , which we combine with deeper , archival observations for an additional 12 galaxies .
A nuclear X-ray point-source is detected in 11 out of 29 targets .
After accounting for the low mass X-ray binary contamination to the nuclear X-ray signal , the X-ray active fraction is measured at 26.6 \% \pm 9.6 \% .
The results from this analysis are compared to similar investigations targeting quiescent early types in the Virgo cluster , as well as the field .
After correcting for the different mass distributions , the measured Fornax active fraction is less than the field fraction , at more than 3 \sigma , confirming that the funneling of gas to the nuclear regions of cluster members is inhibited compared to those galaxies in the field .
At the same time , we find no statistically significant difference between Fornax and Virgo galaxies , with only marginal evidence for a lower active fraction in Fornax ( 1 \sigma ) ; if real , owing to Fornax ’ s higher galaxy number density , this could indicate that galaxy-galaxy interactions are more effective at gas removal than galaxy-gas effects .