Simultaneous Measurements of Star Formation and Supermassive Black Hole Growth in Galaxies

TL;DR

This paper discusses the potential of a large, cold infrared telescope combined with next-generation radio interferometers to simultaneously measure star formation and supermassive black hole growth in galaxies across cosmic time, filling current observational gaps.

Contribution

Proposes a new observational approach using thermal infrared and radio telescopes to study galaxy evolution and black hole growth from high redshift to the present.

Findings

Infrared and radio observations can measure star formation and black hole accretion simultaneously.

Current gaps exist between JWST and ALMA in wavelength coverage.

Future telescopes can enable unbiased, large-scale studies of galaxy evolution.

Abstract

Galaxies grow their supermassive black holes in concert with their stars, although the relationship between these major galactic components is poorly understood. Observations of the cosmic growth of stars and black holes in galaxies suffer from disjoint samples and the strong effects of dust attenuation. The thermal infrared holds incredible potential for simultaneously measuring both the star formation and black hole accretion rates in large samples of galaxies covering a wide range of physical conditions. Spitzer demonstrated this potential at low redshift, and by observing some of the most luminous galaxies at z~2. JWST will apply these methods to normal galaxies at these epochs, but will not be able to generate large spectroscopic samples or access the thermal infrared at high-redshift. An order of magnitude gap in our wavelength coverage will persist between JWST and ALMA. A large, cold infrared telescope can fill this gap to determine when (in cosmic time), and where (within the cosmic web), stars and black holes co-evolve, by measuring these processes simultaneously in statistically complete and unbiased samples of galaxies to z>8. A next-generation radio interferometer will have the resolution and sensitivity to measure star-formation and nuclear accretion in even the dustiest galaxies. Together, the thermal infrared and radio can uniquely determine how stars and supermassive blackholes co-evolve in galaxies over cosmic time.