Program: GN-2024A-Q-327

Jetted active galactic nuclei (AGNs) are the principal extragalactic gamma-ray sources. Fermi-detected high-redshift (z>2.5) blazars are jetted AGNs thought to be powered by massive, rapidly spinning supermassive black holes (SMBHs) in the early universe (< 2 Gyr). They provide a laboratory to study early black hole (BH) growth and super-Eddington accretion – possibly responsible for the more rapid formation of jetted BHs. However, the existing virial BH masses of high-redshift blazars are based on CIV, which is known to be biased by strong outflows. We propose Gemini/GNIRS near-IR spectroscopy for 11 high-redshift Fermi-ray blazars with multiwavelength observations that maximally sample the spectral energy distributions (SEDs). Our goal is to obtain robust virial BH masses based on the better calibrated H-beta and/or MgII. We will compare the more robust virial BH masses against independent mass estimates from SED modeling. The program will establish robust virial BH masses and Eddington ratio estimates for high-redshift Fermi blazars. It will test if they indeed host overly massive SMBHs, which may pose a theoretical challenge for rapid early BH growth models.