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arXiv · 1003.4849

VLBI detection of an AGN pair in the binary black hole candidate SDSS J1536+0441

M. Bondi·M-A. Perez-Torres
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Abstract

We present first pc-scale radio imaging of the radio-quiet candidate binary black hole system SDSS J1536+0441. The observations were carried out by the European VLBI Network at the frequency of 5 GHz and allowed to image SDSS J1536+0441 with a resolution of about 10 mas (50 pc). Two compact radio cores are detected at the position of the kpc-scale components VLA-A and VLA-B, proving the presence of two compact active nuclei with radio luminosity about 10^{40} erg/s, thus ruling out the possibility that the two radio sources are both powered by one 0.1 pc binary black hole. From a comparison with published 8.5 GHz flux densities we derived an estimate of the radio spectral index of the two pc-scale cores. Both cores have flat or inverted spectral index and, at least for the case of VLA-A, we can rule out the possibility that synchrotron self-absorption is responsible for the inverted radio spectrum. We suggest that thermal free-free emission from an X-ray heated disk wind may be powering the radio emission in VLA-A.

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M. Bondi, M-A. Perez-Torres. 2010-04-09. VLBI detection of an AGN pair in the binary black hole candidate SDSS J1536+0441. https://doi.org/10.1088/2041-8205%2F714%2F2%2Fl271

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