A Combined Optical and X-ray Study of Unobscured Type 1 AGN. I. Optical Spectra and SED Modeling

By C. Jin, Martin P. Ward, C. Done, J. Gelbord. 2011

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We present modeling and interpretation of the continuum and emission lines for a sample of 51 unobscured Type 1 active galactic nuclei (AGN). All of these AGNs have high quality spectra from both XMM-Newton and Sloan Digital Sky Survey (SDSS). We extend the wavelength coverage where possible by adding simultaneous UV data from the OM onboard XMM-Newton. Our sample is selected based on low reddening in the optical and low gas columns implied by their X-ray spectra. They also lack clear signatures for the presence of a warm absorber. Therefore the observed characteristics of this sample are likely to be directly related to the intrinsic properties of the central engine. We perform multi-component spectral fitting for strong optical emission lines and the whole optical spectra. We fit the combined optical, UV and X-ray data by applying a new broadband SED model which comprises the accretion disc emission, low temperature optically thick Comptonisation and a hard X-ray tail by introducing the a corona radius (Done et al. 2011). We find that in order to fit the data, the model often requires an additional long wavelength optical continuum component, whose origin is discussed in this paper. We also find that the Photo-recombination edge of Balmer continuum shifts and broadens beyond the standard limit of 3646{\AA}, implying an electron number density which is far higher than that in the broad line region clouds. Our results indicate that the Narrow Line Seyfert 1s in this sample tend to have lower black hole masses, higher Eddington ratios, softer 2-10 keV band spectra, lower 2-10 keV luminosities and higher \alpha_{ox}, compared with typical broad line Seyfert 1s (BLS1), although their bolometric luminosities are similar. We illustrate these differences in properties by forming an average SED for three subsamples, based on the FWHM velocity width of the H{\beta} emission line.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6fea1f7149efd06a79698916a35947657696c1ff

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Citations in the corpus

Black Hole Growth to z = 2 - I: Improved Virial Methods for Measuring M_BH and L/L_Edd (2012, methodology): “Jin et al. (2012) used an accretion disk fitting method that results in a much higher (unobserved) far-UV luminosity for a given optical and/or near-UV luminosity.”
A physical model of the broad-band continuum of AGN and its implications for the UV/X relation and optical variability (2018, methodology): “…emission, which can extend into the soft X-ray bandpass for the lowest mass, Narrow Line Seyfert-1 (NLS1) galaxies, but these still have a small fraction of their bolometric power emitted in a soft X-ray excess component (Jin et al. 2012a,b; Done et al. 2012; Jin et al. 2013; Matzeu et al. 2017).”