Jittering Jets by Negative Angular Momentum Feedback in Cooling Flows

Abstract

I apply the jittering jets in a cooling flow scenario to explain the two pairs of bubbles in the cooling flow galaxy cluster RBS 797 which are perpendicular to each other and almost coeval, and conclude that the interaction of the jets with the cold dense clumps that feed the supermassive black hole (SMBH) takes place in the zone where the gravitational influence of the SMBH and that of the cluster are about equal. According to the jittering jets in a cooling flow scenario, jets uplift and entrain cold and dense clumps, impart the clumps’ velocity perpendicular to the original jets’ direction, and ‘drop’ them closer to the jets’ axis. The angular momentum of these clumps is at a very high angle compared to the original jets’ axis. When these clumps feed the SMBH in the next outburst (jet-launching episode) the new jets’ axis might be at a high angle to the axis of the first pair of jets. I apply this scenario to recent observations that show the two perpendicular pairs of bubbles in RBS 797 have a small age difference of Myr, and conclude that the jets–clumps interaction takes place at a distance of about ≈10–100 pc from the SMBH. Interestingly, in this zone, the escape velocity from the SMBH is about equal to the sound speed of the intracluster medium (ICM). I mention two other clusters of galaxies and discuss the implications of this finding.

Keywords

• galaxies: clusters: individual: RBS 797
• galaxies: clusters: intracluster medium
• galaxies: jets