Alpha Band - Tick Tock

We propose 3 orbits of optical+UV spectroscopy to test the nature of the "Tick Tock" binary supermassive black hole candidate. J143016+230344 (hereafter J1430) was recently selected based on a rapidly evolving periodicity in its multi-band photometric light curve and is predicted to coalesce within the next 3 years. J1430 is an active galactic nucleus (AGN) and its broad H-alpha line has changed from single peaked with a -2400 km/s velocity offset to double peaked at the systemic velocity. In the binary scenario, this could indicate that the broad line initially traced bulk orbital motion of the secondary and now the newly formed circumbinary broad-line region. We will test the alternative scenario that J1430 is actually a variable single AGN with a perturbed accretion disk. By nearly-simultaneously observing the Ly-alpha, CIV, H-beta, and H-alpha broad emission lines and comparing the shapes of their profiles we can discriminate between (i) bulk orbital motion of the secondary in a binary, (ii) a newly formed circumbinary broad-line region, and (iii) a single black hole with dramatic photometric variability and an emissivity enhancement like a spiral arm in the outer disk where broad lines are produced. This test will arbitrate on the binary nature of J1430.

Alpha Band - Tick Tock

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