What powers Hyperluminous Infrared galaxies at z~1-2?

TL;DR

This study analyzes the power sources of hyperluminous infrared galaxies at redshifts 1-2, revealing that active galactic nuclei (AGN) dominate their infrared emission at the brightest luminosities, shaping the galaxy luminosity function.

Contribution

It provides new insights into the dominant energy sources of HyLIRGs at z~1-2, showing AGN's increasing role with luminosity and their dominance at the brightest end.

Findings

AGN luminosity function converges with galaxy luminosity function at high luminosities.

AGN can account for all infrared emission in HyLIRGs with LIR >10^13.5 Lsun.

The bright end of the infrared galaxy luminosity function is shaped by AGN activity.

Abstract

We investigate what powers hyperluminous infrared galaxies (HyLIRGs; LIR(8-1000um)>10^13 Lsun) at z~1-2, by examining the behaviour of the infrared AGN luminosity function in relation to the infrared galaxy luminosity function. The former corresponds to emission from AGN-heated dust only, whereas the latter includes emission from dust heated by stars and AGN. Our results show that the two luminosity functions are substantially different below 10^13 Lsun but converge in the HyLIRG regime. We find that the fraction of AGN dominated sources increases with total infrared luminosity and at LIR >10^13.5 Lsun AGN can account for the entire infrared emission. We conclude that the bright end of the 1<z<2 infrared galaxy luminosity function is shaped by AGN rather than star-forming galaxies.