English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present new spectroscopic observations that are part of our continuingmonitoring campaign of 88 quasars at z<0.7 whose broad H$\beta$ lines areoffset from their systemic redshifts by a few thousand km/s. These quasars havebeen considered candidates for hosting supermassive black hole binaries (SBHBs)by analogy with single-lined spectroscopic binary stars. We present the dataand describe our improved analysis techniques, which include an extensiveevaluation of uncertainties. We also present a variety of measurements from thespectra that are of general interest and will be useful in later stages of ouranalysis. Additionally, we take this opportunity to study the variability ofthe optical continuum and integrated flux of the broad H$\beta$ line. Wecompare the variability properties of the SBHB candidates to those of a sampleof typical quasars with similar redshifts and luminosities observed multipletimes during the Sloan Digital Sky Survey. We find that the variabilityproperties of the two samples are similar (variability amplitudes of 10-30% ontime scales of approximately 1-7 years) and that their structure functions canbe described by a common model with parameters characteristic of typicalquasars. These results suggest that the broad-line regions of SBHB candidateshave a similar extent as those of typical quasars. We discuss the implicationsof this result for the SBHB scenario and ensuing constraints on the orbitalparameters.

the astrophysical journal. supplement series/astrophysical journal. supplement series

A Large Systematic Search for Close Supermassive Binary and Rapidly  Recoiling Black Holes - II. Continued Spectroscopic Monitoring and Optical  Flux Variability