Updating quasar bolometric luminosity corrections

TL;DR

This paper derives and evaluates bolometric luminosity corrections for quasars using spectral energy distributions, addressing practical challenges and proposing adjustments for viewing angle and emission anisotropy.

Contribution

It provides new bolometric correction formulas based on detailed SEDs for quasars, including adjustments for viewing angle and emission anisotropy, with analysis of radio-loud and radio-quiet sources.

Findings

Bolometric corrections vary with wavelength and can be improved by optical slope adjustments.

Radio-loud and radio-quiet quasars have consistent corrections in optical/UV but differ in X-ray.

Large scatter exists in X-ray bolometric corrections, especially for radio-loud sources.

Abstract

Bolometric corrections are used in quasar studies to quantify total energy output based on a measurement of a monochromatic luminosity. First, we enumerate and discuss the practical difficulties of determining such corrections, then we present bolometric luminosities between 1 \mu m and 8 keV rest frame and corrections derived from the detailed spectral energy distributions of 63 bright quasars of low to moderate redshift (z = 0.03-1.4). Exploring several mathematical fittings, we provide practical bolometric corrections of the forms L_iso=\zeta \lambda L_{\lambda} and log(L_iso)=A+B log(\lambda L_{\lambda}) for \lambda= 1450, 3000, and 5100 \AA, where L_iso is the bolometric luminosity calculated under the assumption of isotropy. The significant scatter in the 5100 \AA\ bolometric correction can be reduced by adding a first order correction using the optical slope, \alpha_\lambda,opt. We recommend an adjustment to the bolometric correction to account for viewing angle and the anisotropic emission expected from accretion discs. For optical/UV monochromatic luminosities, radio-loud and radio-quiet bolometric corrections are consistent within 95% confidence intervals so we do not make separate radio-loud and radio-quiet corrections. In addition, we provide several bolometric corrections to the 2-10 keV X-ray luminosity, which are shown to have very large scatter. Separate radio-loud and radio-quiet corrections are warranted by the X-ray data.