Goal 1

At the center of all active galaxies lives a supermassive black hole, 1e6–1e10 times more massive than the Sun and spanning a space comparable to the orbit of the Earth. Surrounding the black hole is an accretion disk, itself a thousand times larger in diameter. Heated by friction, the disk creates light that outshines all the stars in the galaxy and drives a strong wind that both induces and inhibits star formation, shaping the very appearance of the galaxy. Light from the disk is scattered to X-ray energies by a mysterious plasma, and those X-rays are also seen in reflection off the relativistic disk. Surrounding material, up to lightyears from the black hole, can extinguish the low-energy X-rays while penetrating high-energy emission escapes.

Goal 1 investigates how black holes grow and drive galaxy evolution, highlighted as a key question by Astro2020. This goal motivates three science objectives.

• Objective 1: uncovers the dominant sources of cosmic X-ray emission by resolving the 25 keV peak of the X-ray background into individual sources and revealing the predicted large population of missing obscured sources.
• Objective 2: determines whether supermassive black holes grow primarily from accretion or mergers by measuring black hole spins for an ensemble of local AGN.
• Objective 3: will reveal the physics of the X-ray corona, the hot, shining plasma that exists just beyond the event horizon and produces most of the X-rays in the Universe. 

For more information about Goal 1, see: Civano et al. (FrASS, submitted; arXiv:2311.04832), Piotrowska et al. (FrASS, submitted; arXiv:2311.04752), Kammoun et al. (FrASS, submitted; arXiv:2311:04679), and Connors et al. (2024; FrASS, 10, 12926682)