Black hole growth and stellar assembly at high-z - AstrophysicsReport as inadecuate

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Abstract: Context. Observations indicate a strong link between star formation and blackhole BH growth, but some questions remain unanswered: whether both activitiesare coeval or whether one precedes the other, what their characteristictimescales are, and what kinds of physical processes are responsible for thisinterplay.Aims. We examine stellar and BH masses M star and M BH in z~2 activesystems at the peak of their AGN or star formation activity to investigate howthey are linked and whether AGN radiative or else radio power provides afeedback mechanism that regulates the stellar growth in these systems.Methods. We analyze the infrared IR spectral energy distributions of radio,sub-millimeter and mid-IR selected AGNs at z~1-3 and constrain their stellarand AGN luminosities using AGN and host-galaxy templates.Results. We find evidence of increasing stellar light, thereby decreasing theAGN mid-IR power going from mid-IR selected AGNs, to radio galaxies, and tosub-millimeter AGNs. This trend can be explained by either decreasing Eddingtonratios or increasing offsets from the local M BH-M star relation. All systemsare characterized by high star formation rates regardless of their differentAGN powers, thus neither AGN radiative power nor AGN-driven radio activityseems to influence the star formation rate in the selected AGNs. We discuss twopossible evolutionary scenarios that might link these three AGN classes.

Author: M. Polletta IAP, France and INAF-IASF Milano, Italy



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