A LARGE SYSTEMATIC SEARCH FOR CLOSE SUPERMASSIVE BINARY AND RAPIDLY RECOILING BLACK HOLES

By M. Eracleous, Todd Boroson, J. Halpern, Jia Liu. 2011

183 citations recorded by the source corpus.

We have carried out a systematic search for subparsec supermassive black hole (BH) binaries among z ≲ 0.7 Sloan Digital Sky Survey quasars. These are predicted by models of supermassive BH and host galaxy coevolution, therefore their census and population properties constitute an important test of these models. In our working hypothesis, one of the two BHs accretes at a much higher rate than the other and carries with it the only broad emission line region of the system, making the system analogous to a single-lined spectroscopic binary star. Accordingly, we used spectroscopic principal component analysis to search for broad Hβ emission lines that are displaced from the quasar rest frame by |Δ v| ≳ 1000 km s−1. This method also yields candidates for rapidly recoiling BHs. Of the 88 candidates, several were previously reported in the literature. We found a correlation between the peak offset and skewness of the broad Hβ profiles, suggesting a common physical explanation for these profiles. We carried out follow-up spectroscopic observations of 68 objects to search for changes in the peak velocities of the Hβ lines. We measured statistically significant changes in 14 objects, with implied accelerations between −120 and +120 km s−1 yr−1. Interpreting the offset broad emission lines as signatures of supermassive binaries is subject to many caveats. Many more follow-up observations over a long temporal baseline are needed to characterize the variability pattern of the broad lines and test that it is consistent with orbital motion. The possibility that some of the objects in this sample are rapidly recoiling BHs remains open.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/764184e5d16f9a9d190caff221a9ea362283918e

Citations in the corpus

• THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES (2015, unknown): “…(i.e.,|∆V | & 1000 km s−1 relative to the host galaxy), and then obtain follow-up spectroscopy to check whether the broad-line velocity drifts over time in a manner consistent with expectations for orbital motion (Eracleous et al. 2012; Decarli et al. 2013; Tsalmantza et al. 2011; Liu et al. 2014).”
• A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey (2015, unknown): “This can either be from dedicated follow-up spectroscopy of initial epoch candidates (e.g., Eracleous et al. 2012; Decarli et al. 2013) or more general searches using emerging collections of multi-epoch data, e.g., Shen et al, (2013); Liu et al. (2014); Ju et al. (2013).”