Jessie C. Runnoe

The Next Generation Atlas of Quasar Spectral Energy Distributions from Radio To X-Rays

We have produced the next generation of quasar spectral energy distributions (SEDs), essentially updating the work of Elvis et al. by using high-quality data obtained with several space- and ground-based telescopes, including NASAs Great Observatories. We present an atlas of SEDs of 85 optically bright, non-blazar quasars over the electromagnetic spectrum from radio to X-rays. The heterogeneous sample includes 27 radio-quiet and 58 radio-loud quasars. Most objects have quasi-simultaneous ultraviolet-optical spectroscopic data, supplemented with some far-ultraviolet spectra, and more than half also have Spitzer mid-infrared Infrared Spectrograph spectra. The X-ray spectral parameters are collected from the literature where available. The radio, far-infrared, and near-infrared photometric data are also obtained from either the literature or new observations. We construct composite SEDs for radio-loud and radio-quiet objects and compare these to those of Elvis et al., finding that ours have similar overall shapes, but our improved spectral resolution reveals more detailed features, especially in the mid- and near-infrared.

Updating quasar bolometric luminosity corrections

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 μm 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 Liso = ζλ Lλ and log (Liso) = A + Blog (λLλ )f orλ = 1450, 3000 and 5100 A, where Liso is the bolometric luminosity calculated under the assumption of isotropy. The significant scatter in the 5100 A bolometric correction can be reduced by adding a first-order correction using the optical slope, αλ,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 per cent 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.

TOWARD COMPLETE STATISTICS OF MASSIVE BINARY STARS: PENULTIMATE RESULTS FROM THE CYGNUS OB2 RADIAL VELOCITY SURVEY

We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 Association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P 45 d, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P<25 d are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P < 45 d. Completeness corrections imply a binary fraction near 55% for P < 5000 d. The observed distribution of mass ratios 0.2<q<1 is consistent with uniform, while the observed distribution of eccentricities 0.1<e<0.6 is consistent with uniform plus an excess of e ~ 0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ~30 km/s attributed to atmospheric fluctuations.

THE PROPERTIES OF POST-STARBURST QUASARS BASED ON OPTICAL SPECTROSCOPY

We present optical spectroscopy of a sample of 38 post-starburst quasars (PSQs) at z ~ 0.3, 29 of which have morphological classifications based on Hubble Space Telescope imaging. These broad-lined active galactic nuclei (AGNs) possess the spectral signatures of massive intermediate-aged stellar populations, making them potentially useful for studying connections between nuclear activity and host galaxy evolution. We model the spectra in order to determine the ages and masses of the host stellar populations, and the black hole masses and Eddington fractions of the AGNs. Our model components include an instantaneous starburst, a power law, and emission lines. We find that the PSQs have M BH ~ 108 M ☉ accreting at a few percent of Eddington luminosity and host ~1010.5 M ☉ stellar populations which are several hundred Myr to a few Gyr old. We investigate relationships among these derived properties, spectral properties, and morphologies. We find that PSQs hosted in spiral galaxies have significantly weaker AGN luminosities, older starburst ages, and narrow emission-line ratios diagnostic of ongoing star formation when compared to their early-type counterparts. We conclude that the early-type PSQs are likely the result of major mergers and were likely luminous infrared galaxies in the past, while spiral PSQs with more complex star formation histories are triggered by less dramatic events (e.g., harassment, bars). We provide diagnostics to distinguish the early-type and spiral hosts when high spatial resolution imaging is not available.

The orientation dependence of quasar single-epoch black hole mass scaling relationships

Black hole masses are estimated for radio-loud quasars using several self-consistent scaling relationships based on emission-line widths and continuum luminosities. The emission lines used, Hβ, Mgii λ2798, and Civ λ1549, have different dependencies on orientation as estimated by radio core dominance. We compare differences in the log of black hole masses estimated from different emission lines and show that they depend on radio core dominance in the sense that core-dominated, jet-on objects have systematically smaller Hβ and Mgii determined masses compared to those from Civ, while lobe-dominated edge-on objects have systematically larger Hβ and Mgii determined masses compared to those from Civ. The effect is consistent with the Hβ line width, and to a lesser extent that of Mgii, being dependent upon orientation in the sense of a axisymmetric velocity field plus a projection effect. The size of the effect is nearly an order of magnitude in black hole mass going from one extreme orientation to the other. We find that radio spectral index is a good proxy for radio core dominance and repeating this analysis with radio spectral index yields similar results. Accounting for orientation could in principle significantly reduce the scatter in black hole mass scaling relationships, and we quantify and offer a correction for this effect cast in terms of radio core dominance and radio spectral index.

A Fresh Catch of Massive Binaries in the Cygnus OB2 Association

Massive binary stars may constitute a substantial fraction of progenitors to supernovae and γ-ray bursts, and the distribution of their orbital characteristics holds clues to the formation process of massive stars. As a contribution to securing statistics on OB-type binaries, we report the discovery and orbital parameters for five new systems as part of the Cygnus OB2 Radial Velocity Survey. Four of the new systems (MT070, MT174, MT267, and MT734 ≡ VI Cygni #11) are single-lined spectroscopic binaries while one (MT103) is a double-lined system (B1V+B2V). MT070 is noteworthy as the longest period system yet measured in Cyg OB2, with P = 6.2 yr. The other four systems have periods ranging between 4 and 73 days. MT174 is noteworthy for having a probable mass ratio q < 0.1, making it a candidate progenitor to a low-mass X-ray binary. These measurements bring the total number of massive binaries in Cyg OB2 to 25, the most currently known in any single cluster or association.

THE OPTICAL AND ULTRAVIOLET EMISSION-LINE PROPERTIES OF BRIGHT QUASARS WITH DETAILED SPECTRAL ENERGY DISTRIBUTIONS

We present measurements and statistical properties of the optical and ultraviolet emission lines present in the spectra of 85 bright quasars which have detailed spectral energy distributions. This heterogeneous sample has redshifts up to z = 1.5 and is comprised of three subsamples that may be of particular utility: ultraviolet excess Palomar-Green quasars, quasars with far-ultraviolet coverage from FUSE, and radio-loud quasars selected to have similar extended radio luminosity originally selected for orientation studies. Most of the objects have quasi-simultaneous optical-ultraviolet spectra, with significant coverage in the radio to X-ray wavebands. The parameters of all strong emission lines are measured by detailed spectral fitting. Many significant correlations previously found among quasar emission-line properties are also present in this sample, e.g., the Baldwin effect, the optical correlations collectively known as eigenvector 1, and others. Finally, we use our measurements plus scaling relationships to estimate black hole masses and Eddington fractions. We show the mass estimates from different emission lines are usually in agreement within a factor of two, but nearly a third show larger differences. We suggest using multiple mass scaling relationships to estimate black hole masses when possible, and adopting a median of the estimates as the black hole mass for individual objects. Line measurements and derived active galactic nucleus properties will be used for future studies examining the relationships among quasar emission lines and their spectral energy distributions.

An Infrared Excess Identified in Radio-loud Broad Absorption Line Quasars

If broad absorption line (BAL) quasars represent a high-covering-fraction evolutionary state (even if this is not the sole factor governing the presence of BALs), it is expected that they should show an excess of mid-infrared radiation compared to normal quasars. Some previous studies have suggested that this is not the case. We perform the first analysis of the IR properties of radio-loud BAL quasars, using IR data from WISE and optical (rest-frame ultraviolet) data from SDSS, and compare the BAL quasar sample with a well-matched sample of unabsorbed quasars. We find a statistically significant excess in the mid- to near-infrared luminosities of BAL quasars, particularly at rest-frame wavelengths of 1.5 and 4 μm. Our sample was previously used to show that BALs are observed along many lines of sight toward quasars, but with an overabundance of more edge-on sources, suggesting that orientation factors into the appearance of BALs. The evidence here—of a difference in IR luminosities between BAL quasars and unabsorbed quasars—can be ascribed to evolution. This suggests that a merging of the current BAL paradigms is needed to fully describe the class.

Updating quasar bolometric luminosity corrections – II. Infrared bolometric corrections

We present infrared bolometric luminosity corrections derived from the detailed spectral energy distributions of 62 bright quasars of low to moderate redshift (z = 0.03–1.4). At 1.5, 2, 3, 7, 12, 15 and 24 μm we provide bolometric corrections of the mathematical forms Liso = ζ λLλ and log(Liso) = A + B log(λLλ). Bolometric corrections for radio-loud and radio-quiet objects are consistent within 95 per cent confidence intervals, so we do not separate them. Bolometric luminosities estimated using these corrections are typically smaller than those derived from some commonly used in the literature. We investigate the possibility of a luminosity-dependent bolometric correction and find that, while the data are consistent with such a correction, the dispersion is too large and the luminosity range too small to warrant such a detailed interpretation. Bolometric corrections at 1.5 μm are appropriate for objects with properties that fall in the range log(Lbol) = 45.4–47.3 and bolometric corrections at all other wavelengths are appropriate for objects with properties that fall in the range log(Lbol) = 45.1–47.0.

The rest‐frame ultraviolet properties of radio‐loud broad absorption line quasars

We recently presented radio observations of a large sample of radio-loud broad absorption line (BAL) quasars from the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at Twenty-cm surveys, as well as a well matched sample of unabsorbed quasars, primarily to measure their radio spectral indices and estimate ensemble orientations. Here, we analyse the SDSS spectra of these samples and compare the rest-frame ultraviolet properties of radio-loud BAL and non-BAL quasars. Ultraviolet properties include the continuum shape, emission-line measurements of C iv, Al iii, C iii], Fe ii and Mg ii, and BAL properties including the balnicity index, absorption index and minimum and maximum outflow velocities. We find that radio-loud BAL quasars have similar ultraviolet properties compared to radio-loud non-BAL sources, though they do appear to have redder continua and stronger Fe ii emission, which is consistent with what is found for radio-quiet BAL sources. No correlations exist between outflow properties and orientation (radio spectral index), suggesting that BAL winds along any line of sight are driven by the same mechanisms. There are also few correlations between spectral index and other properties. We conclude that BAL outflows occur along all lines of sight with similar strengths and velocities.