Mergers drive a powerful dusty quasar

A galaxy merger provided the raw materials to form a bright and powerful dust-obscured quasar in the early Universe, according to a new imaging analysis. This analysis, which focused on the most luminous galaxy known, also reveals how very luminous galaxies may simultaneously feed the super-massive black holes at their center, and also obscure them with dust. The most luminous galaxies in the early Universe host supermassive black holes at their centers. When material falls towards the central black holes in these young galaxies, the material releases energy and is observed as a quasar. Astronomers have previously identified a population of powerful distant quasars that are obscured by dust, but it has been unclear how they formed. These extremely bright objects are quite uncommon and pose a challenge to current galaxy formation and evolution models. Here, Tanio Diaz Santos et al. analyzed one such dust-obscured quasar using the Atacama Large Millimeter/Sub-millimeter Array (ALMA) telescope. Using ALMA, they observed the dust-obscured quasar known as WISE J224607.57?052635.0 at submillimeter wavelengths. Their analyses, including of dust emissions, revealed three small companion galaxies connected to the quasar by bridges of gas and dust. Further studies revealed dynamical interactions between the companion galaxies and the bright central quasar. From their findings, the researchers infer that merger-driven accretion of neighbor galaxies is a catalytic mechanism that can not only provide the raw material to power a hyper-luminous quasar; it can also provide large quantities of dust to obscure it.

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http://dx.doi.org/10.1126/science.aap7605

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