Todd A. Boroson

The emission-line properties of low-redshift quasi-stellar objects

Spectra covering the region λλ4300-5700 have been obtained of all 87 QSOs in the BQS catalog having redshifts less than 0.5. An empirical technique which allows the measurement and subtraction of the many Fe II lines in this region has been developed and applied to these spectra. Measurements of the strengths of Hβ, [O III] λ5007, and He II λ4686, and a four-dimensional parameterization of the Hβ profile have been combined with optical, radio, and X-ray continuum information from the literature to try to understand how these properties are related

Black Hole Mass and Eddington Ratio as Drivers for the Observable Properties of Radio-loud and Radio-quiet QSOs

Recent studies of black holes in the nuclei of both active and normal galaxies have yielded relationships that permit a physical interpretation of the principal components of the spectra of QSOs. It is shown that principal component (or eigenvector) 1 (PC1) is driven predominantly by L/LEdd, and principal component 2 (PC2) is driven by accretion rate. This results in a PC2 versus PC1 diagram in which lines of constant black hole mass are diagonal. Using a sample consisting of the low-redshift PG objects supplemented by 75 radio-loud QSOs, it is shown that such a diagram effectively distinguishes radio-loud from radio-quiet objects and demonstrates that both narrow-line Seyfert 1 galaxies and broad absorption line QSOs lie at the high L/LEdd extreme, although these two types of objects are well separated in the PC2 direction. A simple picture that ties together physical parameters (black hole mass and Eddington ratio) and classification of active galactic nuclei is presented. Based on the location of core-dominated and lobe-dominated radio-loud QSOs, orientation can be modeled as a third parameter in this scheme, implying an enhancement in the radio flux of core-dominated objects.

A candidate sub-parsec supermassive binary black hole system

The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black holes in their nuclei, implies that binary supermassive black hole systems should be common. Here we report that the quasar SDSS J153636.22+044127.0 is a plausible example of such a system. This quasar shows two broad-line emission systems, separated in velocity by 3,500 km s-1. A third system of unresolved absorption lines has an intermediate velocity. These characteristics are unique among known quasars. We interpret this object as a binary system of two black holes, having masses of 107.3 and 108.9 solar masses separated by ∼0.1 parsec with an orbital period of ∼100 years.

The optical properties of IR-selected and MG II broad absorption line quasars

Spectra covering the rest frame region λλ5000-6800 are presented for 19 IR-selected AGNs. This sample is of particular interest because it contains four low-ionization broad absorption line QSOs (BALQSOs) out of 38 objects. Measurements of emission lines in the observed region, including Hα, [O III] λ5007, the Fe II emission, He I λ5876, and the Na I D doublet are tabulated, together with a four-parameter description of the Hα line profile. A variety of statistical tests show no strong differences in emission-line properties between these IR-selected AGNs and a well-studied sample of optically selected QSOs

Optical imaging and long-slit spectroscopy of Markarian galaxies with multiple nuclei. I - Basic data

Optical CCD images and long-slit spectroscopic data are presented for over 100 Markarian (UV-excess) galaxies reported in early studies to possess multiple optical nuclei or extreme morphological peculiarities suggestive of galaxy collisions and mergers. Stacked broad-band images are presented with histogram equalization in order to show simultaneously the nuclei and features at very low surface-brightness levels. Morphological properties, luminosities and colors of the integral systems are given. Photometric and image properties of over 200 individual nuclei and giant H II regions have been measured with respect to the local backgrounds in the galaxies using an objective image finding algorithm. Labeled contour plots identify the measured subcomponents. Two-dimensional spectral data are presented, in addition to intensity profiles along the slit in the light of H-alpha + forbidden N II emission lines and adjacent continuum. Nuclear emission-line measurements, reddening estimates, monochromatic continuum magnitudes, and colors are given.

Blueshifted [O III] Emission: Indications of a Dynamic Narrow-Line Region

The [O III] λ5007 line is commonly used as an indicator of the systemic redshift of active galactic nuclei (AGNs). Also, recent studies have used the width of this emission line as a proxy for the stellar velocity dispersion in the host galaxy. This paper calls both of these assumptions into question by analyzing a sample of approximately 400 AGN spectra from the first data release of the Sloan Digital Sky Survey. These spectra show that the low-ionization forbidden lines ([O II], [N II], and [S II]) define a consistent redshift but that the peak of the [O III] line is blueshifted in approximately half of the AGNs with respect to that redshift. For the sample studied here, the average shift is 40 km s-1, with the largest shift being more than 400 km s-1. The magnitude of this shift is found to be correlated with a number of properties, including the width of the [O III] line and the Eddington ratio (L/LEdd), derived from the luminosity and width of Hβ.

More spectroscopy of the fuzz around QSOs: additional evidence for two types of QSO

Spectroscopic observations of the nebulosity around a sample of optically selected, UV excess QSOs are reported. The spectra of QSOs observed by Boroson, Oke, and Green (1982) are also presented. These sets of objects strengthen the case that there are fundamental properties that distinguish two groups of objects which are both called QSOs. These differences include the equivalent width of the nuclear forbidden O III 5007 A emission, the width and shape of the nuclear broad lines, the equivalent width of the nuclear Fe II emission, and the radio morphology or the spectral index. Measurements of these properties are presented and the correlations and statistical significances are discussed. These distinctions are discussed in terms of a model in which the accretion rate onto a black hole is varied. 25 references.

Does the Narrow [O III] λ5007 Line Reflect the Stellar Velocity Dispersion in Active Galactic Nuclei?

It has been proposed that the width of the narrow [O III] λ5007 emission line can be used as a surrogate for the stellar velocity dispersion in active galaxies. This proposition is tested using the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) spectra of 107 low-redshift radio-quiet QSOs and Seyfert 1 galaxies by investigating the correlation between black hole mass, as determined from Hβ FWHM and optical luminosity, and [O III] FWHM. The correlation is real, but the scatter is large. Without additional information or selection criteria, the [O III] width can predict the black hole mass to a factor of 5.

SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. III. OPTICAL CONTINUUM EMISSION AND BROADBAND TIME DELAYS IN NGC 5548

The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia; The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University. This paper used data obtained with the MODS spectrographs built with funding from National Science Foundation (NSF) grant AST-9987045 and the NSF Telescope System Instrumentation Program (TSIP), with additional funds from the Ohio Board of Regents and the Ohio State University Office of Research. This paper made use of the modsIDL spectral data reduction pipeline developed in part with funds provided by NSF Grant AST - 1108693. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. KAIT and its ongoing operation were made possible by donations from Sun Microsystems, Inc., the Hewlett-Packard Company, AutoScope Corporation, Lick Observatory, the NSF, the University of California, the Sylvia and Jim Katzman Foundation, and the TABASGO Foundation. Research at Lick Observatory is partially supported by a generous gift from Google. Support for HST program number GO-13330 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. M.M.F., G.D.R., B.M.P., C.J.G., and R.W.P. are grateful for the support of the NSF through grant AST- 1008882 to The Ohio State University. A.J.B. and L.P. have been supported by NSF grant AST-1412693. A.V.F. and W.- K.Z. are grateful for financial assistance from NSF grant AST- 1211916, the TABASGO Foundation, and the Christopher R. Redlich Fund. M.C. Bentz gratefully acknowledges support through NSF CAREER grant AST-1253702 to Georgia State University. M.C. Bottorff acknowledges HHMI for support through an undergraduate science education grant to Southwestern University. K.D.D. is supported by an NSF Fellowship awarded under grant AST-1302093. R.E. gratefully acknowledges support from NASA under awards NNX13AC26G, NNX13AC63G, and NNX13AE99G. J.M.G. gratefully acknowledges support from NASA under award NNH13CH61C. P.B.H. is supported by NSERC. M.I. acknowledges support from the Creative Initiative program, No. 2008-0060544, of the National Research Foundation of Korea (NRFK) funded by the Korean government (MSIP). M.D.J. acknowledges NSF grant AST-0618209 used for obtaining the 0.91 m telescope at WMO. SRON is financially supported by NWO, the Netherlands Organization for Scientific Research. B.C.K. is partially supported by the UC Center for Galaxy Evolution. C.S.K. acknowledges the support of NSF grant AST-1009756. D.C.L. acknowledges support from NSF grants AST-1009571 and AST-1210311, under which part of this research (photometric observations collected at MLO) was carried out. We thank Nhieu Duong, Harish Khandrika, Richard Mellinger, J. Chuck Horst, Steven Armen, and Eddie Garcia for assistance with the MLO observations. P.L. acknowledges support from Fondecyt grant #1120328. A.P. acknowledges support from a NSF graduate fellowship, a UCSB Dean’s Fellowship, and a NASA Einstein Fellowship. J.S.S. acknowledges CNPq, National Council for Scientific and Technological Development (Brazil) for partial support and The Ohio State University for warm hospitality. T.T. has been supported by NSF grant AST-1412315. T.T. and B.C.K. acknowledge support from the Packard Foundation in the form of a Packard Research Fellowship to T.T.; also, T.T. thanks the American Academy in Rome and the Observatory of Monteporzio Catone for kind hospitality. The Dark Cosmology Centre is funded by the Danish National Research Foundation. M.V. gratefully acknowledges support from the Danish Council for Independent Research via grant no. DFF–4002-00275. J.-H.W. acknowledges support by the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. 2010-0027910). E.D.B. is supported by Padua University through grants 60A02-5857/13, 60A02-5833/14, 60A02-4434/15, and CPDA133894. K.H. acknowledges support from STFC grant ST/M001296/1. S.A.K. thanks Dr. I. A. Rakhimov, the Director of Svetloe Observatory, for his support and hospitality. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. IV - Intensity variations of the optical emission lines of NGC 5548

Measurements of optical emission-line flux variations based on spectra of the Seyfert galaxy NGC 5548 obtained between December 1988 and October 1989 are reported. All of the measured optical emission lines, H-alpha, H-beta, H-gamma, He I 5876, and He II 4686, exhibit the same qualitative behavior as the UV and optical continua, but with short time delays, or lags, which are different for the various lines. Cross-correlation analysis is applied to measure the lags between the various lines and the continuum. Similar lags are found with respect to the UV continuum for H-alpha and H-beta, 17 and 19 d, respectively. The lag for H-gamma is shorter (13 d), only somewhat larger than the lag measured for Ly-alpha (about 10 d). The helium lines respond to continuum variations more rapidly than the hydrogen lines, with lags of about 7 d for He II 4686 and 11 d for He I 5876.