NGC 3628: Ejection activity associated with quasars

Abstract

NGC 3628 is a well-studied starburst/low level AGN galaxy in the Leo Triplet noted for its extensive outgassed plumes of neutral hydrogen. QSOs are shown to be concentrated around NGC 3628 and aligned with the HI plumes. The closest high redshift quasar has z = 2.15 and is at the tip of an X-ray filament emerging along the minor axis HI plume. Location at this point has an accidental probability of ∼ 2 × 10-4. In addition a coincident chain of optical objects coming out along the minor axis ends on this quasar. More recent measures on a pair of strong X-ray sources situated at 3.2 and 5.4 arcmin on either side of NGC 3628 along its minor axis, reveal that they have nearly identical redshifts of z = 0.995 and 0.981. The closer quasar lies directly in the same X-ray filament which extends from the nucleus out 4.1 arcmin to end on the quasar of z = 2.15. The chain of objects SW along the minor axis of NGC 3628 has been imaged in four colours with the VLT. Images and spectra of individual objects within the filament are reported. It is suggested that material in various physical states and differing intrinsic redshifts is ejected out along the minor axis of this active, disturbed galaxy.