A systematic search for massive black hole binaries in the Sloan Digital Sky Survey spectroscopic sample

P. Tsalmantza, R. Decarli, M. Dotti, David W. Hogg

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We present the results of a systematic search for massive black hole binaries in the Sloan Digital Sky Survey (SDSS) spectroscopic database. We focus on bound binaries, under the assumption that one of the black holes is active. In this framework, the broad lines associated with the accreting black hole are expected to show systematic velocity shifts with respect to the narrow lines, which trace the rest frame of the galaxy. For a sample of 54,586 quasars and 3929 galaxies at redshifts 0.1 < z < 1.5, we brute-force model each spectrum as a mixture of two quasars at two different redshifts. The spectral model is a data-driven dimensionality reduction of the SDSS quasar spectra based on a matrix factorization. We identified 32 objects with peculiar spectra. Nine of them can be interpreted as black hole binaries. This doubles the number of known black hole binary candidates. We also report on the discovery of a new class of extreme double-peaked emitters with exceptionally broad and faint Balmer lines. For all the interesting sources, we present detailed analysis of the spectra and discuss possible interpretations.

    Original languageEnglish (US)
    Article number20
    JournalAstrophysical Journal
    Volume738
    Issue number1
    DOIs
    StatePublished - Sep 1 2011

    Keywords

    • methods: data analysis
    • methods: statistical
    • quasars: emission lines
    • quasars: general

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

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