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AR 13922 (Archival Research)

Sat Nov 2 20:57:13 GMT 2024

Principal Investigator: Andrew Robinson
PI Institution: Rochester Institute of Technology
Investigators (xml)

Title: Do Supermassive Black Holes really reside at the centers of their host galaxies?
Cycle: 22

Abstract
It is generally assumed in studies of active galactic nuclei {AGN} and galactic dynamics that supermassive black holes {SMBH} reside at rest at the dynamical centers of their host galaxies. However, SMBH can be significantly displaced by gravitational recoil kicks generated during the coalescence of an SMBH binary which itself formed in the aftermath of a galaxy merger. Such events have profound implications for gravitational wave astronomy and galaxy evolution and therefore determining the frequency with which they occur is of great interest. Gravitational recoils are capable of producing persistent {oscillating} displacements ~ 10 pc to ~ 100 pc or more and are likely to operate most commonly in early type galaxies, which are partly assembled via mergers. Here we propose to build on a recently completed pilot study and undertake a systematic search for SMBH displacements in a large sample of active early type galaxies, by measuring the position of the AGN {as a proxy for the SMBH} relative to the photocenter of its host galaxy. Our pilot study demonstrates that offsets ~0.05" are recoverable with high significance from HST data, allowing detection of projected displacements of ~10 - 100 pc, for the redshift range {z<0.3} covered by our sample. Theoretical models for both the distribution of recoil velocities and the subsequent dynamical evolution of the kicked SMBH in the host galaxy potential are sufficiently well developed that predictions can be tested statistically by measuring displacements {or upper limits} in a large sample.