article published yes Daniel J. D'Orazio author Zoltán Haiman author 7c006e8c-cc0d-11ee-8322-cb904ef76f36 Andrew MacFadyen author A near-equal-mass binary black hole (BH) can clear a central cavity in a circumbinary accretion disc; however, previous works have revealed accretion streams entering this cavity. Here we use 2D hydrodynamical simulations to study the accretion streams and their periodic behaviour. In particular, we perform a suite of simulations, covering different binary mass ratios q = M2/M1 in the range 0.003 ≤ q ≤ 1. In each case, we follow the system for several thousand binary orbits, until it relaxes to a stable accretion pattern. We find the following results: (i) the binary is efficient in maintaining a low-density cavity. However, the time-averaged mass accretion rate into the cavity, through narrow coherent accretion streams, is suppressed by at most a factor of a few compared to a disc with a single BH with the same mass; (ii) for q ≳ 0.05, the accretion rate is strongly modulated by the binary, and depending on the precise value of q, the power spectrum of the accretion rate shows either one, two or three distinct periods; and (iii) for q ≲ 0.05, the accretion rate becomes steady, with no time variations. Most binaries produced in galactic mergers are expected to have q ≳ 0.05. If the luminosity of these binaries tracks their accretion rate, then a periodogram of their light curve could help in their identification, and to constrain their mass ratio and disc properties. Oxford University Press2013 eng 1365-2966 0035-8711 1210.053610.1093/mnras/stt1787 43642997-3020 yes D.J. D’Orazio, Z. Haiman, A. MacFadyen, Monthly Notices of the Royal Astronomical Society 436 (2013) 2997–3020. D’Orazio, D. J., Haiman, Z., &#38; MacFadyen, A. (2013). Accretion into the central cavity of a circumbinary disc. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href="https://doi.org/10.1093/mnras/stt1787">https://doi.org/10.1093/mnras/stt1787</a> D’Orazio, Daniel J., et al. “Accretion into the Central Cavity of a Circumbinary Disc.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 436, no. 4, Oxford University Press, 2013, pp. 2997–3020, doi:<a href="https://doi.org/10.1093/mnras/stt1787">10.1093/mnras/stt1787</a>. D’Orazio DJ, Haiman Z, MacFadyen A. Accretion into the central cavity of a circumbinary disc. <i>Monthly Notices of the Royal Astronomical Society</i>. 2013;436(4):2997-3020. doi:<a href="https://doi.org/10.1093/mnras/stt1787">10.1093/mnras/stt1787</a> D’Orazio, Daniel J., Zoltán Haiman, and Andrew MacFadyen. “Accretion into the Central Cavity of a Circumbinary Disc.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2013. <a href="https://doi.org/10.1093/mnras/stt1787">https://doi.org/10.1093/mnras/stt1787</a>. D. J. D’Orazio, Z. Haiman, and A. MacFadyen, “Accretion into the central cavity of a circumbinary disc,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 436, no. 4. Oxford University Press, pp. 2997–3020, 2013. D’Orazio DJ, Haiman Z, MacFadyen A. 2013. Accretion into the central cavity of a circumbinary disc. Monthly Notices of the Royal Astronomical Society. 436(4), 2997–3020. 176242024-09-05T13:53:11Z2024-09-24T08:47:58Z