Measuring supermassive black hole masses with VLTI/GRAVITY: From the local Universe up to Cosmic Noon and beyond

Daryl Joe Santos^1*, Taro Shimizu², Richard Davies², Yixian Cao², Frank Eisenhauer², Reinhard Genzel², Eckhard Sturm², Dieter Lutz², Jinyi Shangguan³

¹Physics Department, De La Salle University, Manila, Philippines
²Max Planck Institute for Extraterrestrial Physics, Garching b. München, Germany
³Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, China

* Presenter:Daryl Joe Santos, email:daryl02santos@gmail.com

Supermassive black holes (SMBHs) have been proven to be an essential ingredient in galaxy formation and evolution, as their masses are shown to be tightly correlated with many host galaxy properties. There are several methods for measuring SMBH masses. Still, the two most common methods, reverberation mapping (RM) and the single-epoch (SE) method, have limitations that prevent reliable measurements of SMBHs in bright quasars at high redshifts. GRAVITY, the beam-combiner instrument at the Very Large Telescope Interferometer (VLTI), has introduced a new way to resolve the broad-line region (BLR) and, therefore, the sphere of influence of SMBHs, allowing researchers to study BLR kinematics and directly infer SMBH masses. A series of upgrades to GRAVITY and the VLTI, collectively known as GRAVITY+, is underway, significantly increasing the instrument’s sensitivity and sky coverage. GRAVITY+ will enable interferometric observations of quasars at cosmic noon and even beyond. In this talk, I will present our GRAVITY observations and results, spanning from low redshift up to cosmic noon (z ~ 2), and more recently, to z ~ 4, all showing a shallower slope of the radius-luminosity relation, which leads to smaller-than-expected SMBH masses at higher quasar luminosities.

Keywords: active galactic nuclei (AGNs), interferometry, broad-line region (BLR), supermassive black holes (SMBHs), cosmic noon