Relativistic boost as the cause of periodicity in a massive black-hole binary candidate

Article

关键词: ACTIVE GALACTIC NUCLEI;    ACCRETION DISKS;    CENTRAL CAVITY;    QUASAR;    VARIABILITY;    SIMULATION;    DYNAMICS;    SYSTEMS;    MODELS;    DRIVEN;   

DOI  :  10.1038/nature15262

来源: SCIE

【 摘 要 】

Because most large galaxies contain a central black hole, and galaxies often merge(1), black-hole binaries are expected to be common in galactic nuclei(2). Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries(3-5), most recently in PG 1302-102, which has a short rest-frame optical period of four years (ref. 6). If the orbital period of the black-hole binary matches this value, then for the range of estimated black-hole masses, the components would be separated by 0.007-0.017 parsecs, implying relativistic orbital speeds. There has been much debate over whether black-hole orbits could be smaller than one parsec (ref. 7). Here we report that the amplitude and the sinusoid-like shape of the variability of the light curve of PG 1302-102 can be fitted by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a two to three times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival ultraviolet data. Follow-up ultraviolet and optical observations in the next few years can further test this prediction and confirm the existence of a binary black hole in the relativistic regime.

【 授权许可】

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