It Takes Two Black Holes to Tango

The supermassive black holes from the Milky-Way and Andromeda are predicted to sink to the center of Milkomeda, each dressed up with a dense cluster of stars. Dynamical friction on surrounding stars and gas is expected to bring the black holes closer down to a distance smaller than the size of the solar system, where the emission of gravitational radiation will cause them to merge. The spacetime ripples by the two black holes are inevitable, akin to the waves stirred on the surface of a pond by two sticks in a circular motion. Mergers are not only found locally but also in the infant universe. Last week, a new <a href="https://arxiv.org/pdf/2312.03589.pdf" rel="noopener ugc nofollow" target="_blank">preprint</a> announced the Webb telescope’s discovery of an offset quasar, likely a member of a merging black-hole pair, 740 million years after the Big Bang. As I demonstrated in <a href="https://ui.adsabs.harvard.edu/search/fq=%7B!type%3Daqp%20v%3D%24fq_database%7D&fq_database=database%3A%20astronomy&q=author%3A(%22Blecha%22%20%22Loeb%22)&sort=date%20desc%2C%20bibcode%20desc&p_=0" rel="noopener ugc nofollow" target="_blank">17 papers</a> with my former graduate student, Laura Blecha, one expects an abundant population of black hole pairs as a result of galaxy mergers throughout cosmic history. <a href="https://avi-loeb.medium.com/it-takes-two-black-holes-to-tango-6ea04ca2553e">Visit Now</a>