科研之友
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摘要
Dual active galactic nuclei (AGNs) at kpc scales that originated from galaxy mergers have been found, but the dynamics of the mergers are insufficiently understood, especially the relevant observational consequences. We present evolutionary models of dual AGNs in two cases driven by different friction laws with their surroundings, which are characterized by forces with F proportional to V-* and F proportional to V-*(-2) . The evolutionary behaviours show that there is a minimum time-scale of similar to 10(8) yr to accomplish a merger. Since the total friction and moment acting on dual AGNs with unequal masses do not vanish, the centre of mass moves with a velocity of V-c similar to a few ten km s(-1) and makes an offset of Delta S similar to sub-kpc of the merged AGNs with respect to the centre of their host galaxies. The relative motion of the two cores along the line joining the centre of mass is of V-R similar to a few ten km s(-1), which determines the merger time-scales. Dissipation of the orbital kinetic energy of dual AGNs either enhances stellar velocity dispersion or heats up the interstellar medium in its revirialization to form a soft X-ray cocoon enshrouding them with a typical luminosity of similar to 10(42) erg s(-1). We predict that galaxies with offset AGNs are likely to host binary supermassive black holes at sub-kpc scales, shedding light on searching candidates from AGNs.
- 出版日期2012-11
- 单位中国科学技术大学
