# Repeated Spectroscopy of Candidate Close Binary Massive Black Holes

## Contact

Yue Shen
Carnegie Observatories
yshen@obs.carnegiescience.edu

## Summary

Second-epoch spectroscopy of SDSS-I/II quasars that are candidate massive black hole binaries with separations less than one parsec, selected to improve our understanding of close black hole pairs

## Finding Targets

An object whose ANCILLARY_TARGET2 value includes one or more of the bitmasks in the following table was targeted for spectroscopy as part of this ancillary target program. See SDSS bitmasks to learn how to use these values to identify objects in this ancillary target program.

Program (bit name) Bit number Target Description Number of Fibers Number of Unique Primary Objects
DISKEMITTER_REPEAT 13 Candidate massive binary black hole pair 100 90

## Description

Second-epoch spectroscopy was obtained for SDSS-I/II quasars that are candidate massive black hole binaries with separations less than one parsec. The new BOSS ancillary spectrum is separated from the original first-epoch SDSS spectrum by multiple years, and thus provides a test of binarity by observing changes in emission line properties.

Spectra from this ancillary program will result in new constraints on the close massive black hole binary population in SDSS quasars, and will provide a better understanding of the nature of these peculiar broad line profiles.

## Target Selection

The quasars were selected from the DR7 quasar catalog (Schneider et al. 2010) based on having double-peaked broad Balmer lines or signi cant velocity o sets between broad and narrow line centroids. The new SDSS-III spectra selected in this ancillary target program are identified by the DISKEMITTER_REPEAT ancillary target class.

## REFERENCES

Schneider, D., et al. 2010, AJ, 139, 2360S