The Accretion History of AGN: The Spectral Energy Distributions of X-Ray-luminous Active Galactic Nuclei

Spectral energy distributions (SEDs) from X-ray to far-infrared (FIR) wavelengths are presented for a sample of 1246 X-ray-luminous active galactic nuclei (AGNs; L (0.5-10 )keV > 10(43) erg s(-1)), with z (spec) < 1.2, selected from Stripe 82X, COSMOS, and GOODS-N/S. The rest-frame SEDs show a wide spread (similar to 2.5 dex) in the relative strengths of broad continuum features at X-ray, ultraviolet (UV), mid-infrared (MIR), and FIR wavelengths. A linear correlation (log-log slope of 0.7 +/- 0.04) is found between L (MIR) and L (X). There is significant scatter in the relation between the L (UV) and L (X) owing to heavy obscuration; however, the most luminous and unobscured AGNs show a linear correlation (log-log slope of 0.8 +/- 0.06) in the relation above this scatter. The relation between L (FIR) and L- X is predominantly flat, but with decreasing dispersion at L- X > 10(44) erg s(-1). The ratio between the galaxy-subtracted bolometric luminosity and the intrinsic L (X )increases from a factor of similar to 10 to 70 from log L (bol)/(erg s(-1)) = 44.5 to 46.5. Characteristic SED shapes have been determined by grouping AGNs based on relative strengths of the UV and MIR emission. The average L (1 mu m) is constant for the majority of these SED shapes, while AGNs with the strongest UV and MIR emission have elevated L (1 mu m), consistent with the AGN emission dominating their SEDs at optical and near-infrared wavelengths. A strong correlation is found between the SED shape and both the L- X and L- bol, such that L (bol)/L (X) = 20.4 +/- 1.8, independent of the SED shape. This is consistent with an evolutionary scenario of increasing L (bol) with decreasing obscuration as the AGN blows away circumnuclear gas.

Automated summary

This study presents spectral energy distributions of X-ray-luminous active galactic nuclei (AGNs) in different wavelengths and explores the correlation between different features. The results suggest that the strengths of UV and MIR emission play a significant role in determining the shape of the SEDs, and propose an evolutionary scenario for AGNs.