Exploring Changes in Quasar Spectral Energy Distributions across C iv Parameter Space
| Autor: | Rivera, AB, Richards, GT, Gallagher, SC, McCaffrey, TV, Rankine, AL, Hewett, PC, Shemmer, O |
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| Přispěvatelé: | Rivera, AB [0000-0001-8125-1669], Richards, GT [0000-0002-1061-1804], Gallagher, SC [0000-0001-6217-8101], McCaffrey, TV [0000-0002-9321-9559], Rankine, AL [0000-0002-2091-1966], Hewett, PC [0000-0002-6528-1937], Shemmer, O [0000-0003-4327-1460], Apollo - University of Cambridge Repository |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Rivera, A B, Richards, G T, Gallagher, S C, McCaffrey, T V, Rankine, A L, Hewett, P C & Shemmer, O 2022, ' Exploring Changes in Quasar Spectral Energy Distributions across C iv Parameter Space ', Astrophysical Journal, vol. 931, no. 2, 154, pp. 1-19 . https://doi.org/10.3847/1538-4357/ac6a5d Physics and Astronomy Publications |
| DOI: | 10.3847/1538-4357/ac6a5d |
| Popis: | We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when (1) using C iv broad emission line equivalent width (EQW) and blueshift (relative to systemic) values calculated from high signal-to-noise ratio reconstructions of optical/UV spectra and (2) removing quasars expected to be absorbed based on their UV/X-ray spectral slopes. In addition to using the traditional C iv parameter space measures of C iv EQW and blueshift, we define a “C iv ∥ distance” along a best-fit polynomial curve that incorporates information from both C iv parameters. We find that the C iv ∥ distance is linearly correlated with both the optical-to-X-ray slope, α ox, and broad-line He ii EQW, which are known spectral energy distribution indicators, but does not require X-ray or high spectral resolution UV observations to compute. The C iv ∥ distance may be a better indicator of the mass-weighted accretion rate, parameterized by L/L Edd, than the C iv EQW or blueshift alone, as those relationships are known to break down at the extrema. Conversely, there is only a weak correlation with the X-ray energy index (Γ), an alternate L/L Edd indicator. We find no X-ray or optical trends in the direction perpendicular to the C iv distance that could be used to reveal differences in accretion disk, wind, or corona structure that could be widening the C iv EQW–blueshift distribution. A different parameter (such as metallicity) not traced by these data must come into play. |
| Databáze: | OpenAIRE |
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