Calibrating black hole masses and their host galaxy scaling relations with cosmic time

• Applicant: Dr. Knud Jahnke, since 5/2022
• Subject Area: Astrophysics and Astronomy
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437672511

Super-massive black holes (BHs) exceeding a million times the mass of the sun are likely present in all massive galaxies including our Milky Way Galaxy. Using dynamical tracers for BH mass in nearby galaxies, a tight correlation has emerged between BH mass and host galaxy properties, like the stellar velocity dispersion and the stellar mass of the bulge. It is still debated whether these scaling relations are established through the feedback of active galactic nuclei (AGN) or the merging of galaxies and their associated BHs through cosmic time. Tracking the evolution of the scaling relations with cosmic time is of crucial importance to understand their origin. This can only be done with luminous unobscured AGN, which allow to estimate BH masses solely from their spectra. However, those mass estimates depend on the virial conversion factor (f) which has been empirically calibrated mainly for low-mass BHs so far. Since most AGN detected at high redshifts are high-mass BHs, the calibration and validation of f in this BH mass range is still a missing step. In the proposed project for a PhD student, we plan to tackle three different aspects of the BH mass-host galaxy relation: 1) we will use integral-field unit spectroscopy to accurately measure the stellar velocity dispersion in the host galaxies of luminous AGN from which we will determine a robust empirical calibration of f over the entire BH mass range, 2) we will study the feeding and feedback process in the super-Eddington accreting AGN Mrk1044 based on novel AO-assisted MUSE observation at 20pc resolution to probe the scaling relation at these extreme conditions, and 3) we will also explore if narrow emission-line ratios in AGN spectra can be used to estimate gas-phase metallicities as an indirect tracer for the host galaxy mass. All three aspects of the project are tightly linked together in terms of observational data sets and scientific aims. We want to provide significantly improved methods to study the evolution of the BH mass-host galaxy relations with a great potential to explore galaxies at cosmic dawn with the upcoming large spectroscopic surveys planned for the James Webb Space Telescope.

• DFG Programme: Research Grants
• International Connection: USA
• Cooperation Partner: Professorin Dr. Vardha Nicola Bennert
• Ehemaliger Antragsteller: Dr. Bernd Husemann, until 4/2022