Survey of Bare Active Galactic Nuclei in the Local Universe (z < 0.2). I. On the Origin of Soft Excess
Prantik Nandi, Arka Chatterjee, Arghajit Jana, Sandip K. Chakrabarti, Sachindra Naik, Samar Safí-Harb, Hsiang‐Kuang Chang, Jeremy Heyl
Abstract
Abstract We analyze a sample of 21 “bare” Seyfert 1 active galactic nuclei, a subclass of Seyfert 1 galaxies, with intrinsic absorption N H ∼ 10 20 cm −2 , in the local Universe ( z < 0.2) using XMM-Newton and Swift/XRT observations. The luminosities of the primary continuum, the X-ray emission in the 3–10 keV energy range, and the soft excess—the excess emission that appears above the low-energy extrapolation of the power-law fit of 3–10 keV X-ray spectra—are calculated. Our spectral analysis reveals that the long-term intrinsic luminosities of the soft excess and the primary continuum are tightly correlated <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>PC</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>SE</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>1.1</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> </mml:math> . We also found that the luminosities are correlated for each source. This result suggests that both the primary continuum and soft excess emissions exhibit a dependency on the accretion rate in a similar way.