# Intrinsic AGN SED & black hole growth in the Palomar--Green quasars

## TL;DR

This study analyzes the intrinsic spectral energy distributions of PG quasars using Spitzer and Herschel data, revealing differences from previous models and exploring black hole and star formation growth patterns.

## Contribution

It provides new median intrinsic AGN SEDs based on PAH-based star formation estimates, accounting for FIR-luminous quasars, and investigates black hole and stellar mass growth in relation to star formation activity.

## Key findings

- Median AGN SEDs are hotter and less luminous than previous models.
- Star formation luminosity correlates with AGN luminosity on the star formation main sequence.
- Different duty cycles suggest distinct evolutionary pathways for luminous AGN populations.

## Abstract

We present a new analysis of the PG quasar sample based on Spitzer and Herschel observations. (I) Assuming PAH-based star formation luminosities (L_SF) similar to Symeonidis et al. (2016, S16), we find mean and median intrinsic AGN spectral energy distributions (SEDs). These, in the FIR, appear hotter and significantly less luminous than the S16 mean intrinsic AGN SED. The differences are mostly due to our normalization of the individual SEDs, that properly accounts for a small number of very FIR-luminous quasars. Our median, PAH-based SED represents ~ 6% increase on the 1-243 micron luminosity of the extended Mor & Netzer (2012, EM12) torus SED, while S16 find a significantly larger difference. It requires large-scale dust with T ~ 20 -- 30 K which, if optically thin and heated by the AGN, would be outside the host galaxy. (II) We also explore the black hole and stellar mass growths, using L_SF estimates from fitting Herschel/PACS observations after subtracting the EM12 torus contribution. We use rough estimates of stellar mass, based on scaling relations, to divide our sample into groups: on, below and above the star formation main sequence (SFMS). Objects on the SFMS show a strong correlation between star formation luminosity and AGN bolometric luminosity, with a logarithmic slope of ~ 0.7. Finally we derive the relative duty cycles of this and another sample of very luminous AGN at z = 2 -- 3.5. Large differences in this quantity indicate different evolutionary pathways for these two populations characterised by significantly different black hole masses.