A team of astronomers has bolstered the evidence for the existence of one of the most remarkable, yet elusive, phenomena in the universe: pairs of supermassive black holes (SMBH) in orbit around each other in the centres of galaxies.<\/p>\n
Their research, recently published in the journal Astronomy & Astrophysics, describes the discovery \u2014 as well as the \u201cfingerprint\u201d they used to identify the SMBH pairs and how it paves the way for finding more.<\/p>\n
\u201cWe looked at two objects previously thought to be SMBH binary candidates,\u201d says cosmologist Adam Hincks. \u201cOur work using data from the Atacama Cosmology Telescope<\/a> has helped confirm that these are very likely what we thought they were.<\/p>\n \u201cAs well, we\u2019ve found this potential path to discovering more of these systems using telescopes like the Simons Observatory<\/a> in northern Chile.\u201d<\/p>\n Hincks is an assistant professor in the Faculty of Arts & Science\u2019s David A. Dunlap Department of Astronomy & Astrophysics<\/a> and St. Michael\u2019s College,<\/a> and lead author of the paper, The Atacama Cosmology Telescope: Observations of supermassive black hole binary candidates<\/a>.<\/p>\n SMBHs contain the mass of hundreds of thousands to billions of suns. They are thought to reside at the centres of most large galaxies and many emit great jets of material at nearly the speed of light.<\/p>\n The existence of two solitary galactic SMBHs has been confirmed \u2014 including one at the centre of our own Milky Way Galaxy<\/a>. However, there is little evidence that these giants form binary systems.<\/p>\n The binary candidates studied by Hincks and his collaborators \u2014 within galaxies prosaically named PKS 2131\u2013021 and PKS J0805\u20130111 \u2014 feature jets of charged particles from the disk of material around the black holes, channeled by intense magnetic fields. These energetic streams can be millions of light years long and are known as \u2018relativistic jets\u2019 because the particles in them are travelling at a significant fraction of the speed of light.<\/p>\n One jet points roughly at the Earth. The SMBH from which the jet originates is moving in a circular orbit which drags the base of the jet in a circle.<\/p>\n \u201cAs a result, the jet is helix-shaped,\u201d says Hincks, \u201clike the ribbon in rhythmic gymnastics, where the gymnast moves their hand in a circle and the ribbon makes a helix.\u201d<\/p>\n As a result of the structure and its motion, Hincks and his collaborators observed a periodic signal that varies in intensity by the same magnitude over a broad range of frequencies. This distinctive fingerprint can be used in the future to identify new objects.<\/p>\n In addition to advancing our ability to identify these binaries, the research may help answer two major questions in astronomy today.<\/p>\n Firstly, there is tentative evidence that the cosmos is awash with a background of gravitational waves \u2014 ripples in spacetime generated when two SMBHs merge. A team, including astronomers from U of T,<\/a> had already detected gravitational waves from stellar black holes with masses equivalent to tens of our sun but these waves are akin to the wake of a boat on a lake; on the other hand, the waves from merging SMBHs is more like tiny ripples covering the entire surface of the lake.<\/p>\n \u201cIf recent evidence is correct that the surface of the cosmos is rippling,\u201d says Hincks, \u201cthe best explanation we have for that is countless SMBH binaries throughout the universe sending out gravitational waves.\u201d<\/p>\n Secondly, astronomers hope the study of SMBH binaries will shed light on the evolution and growth of these cosmic giants.<\/p>\n \u201cHow SMBHs grow so big is still a major question in astronomy, so learning more about these pairs could help unlock this mystery,\u201d says Hincks.<\/p>\n With the James Webb Space Telescope, astronomers have seen very massive black holes very early in the universe but don\u2019t think they emerged from the Big Bang at that size. Astronomers therefore ask: how then did they get so big so fast? One theory is that they grow by accreting more and more mass as black holes merge into new, more massive objects.<\/p>\n \u201cThat seems to be part of how nature makes galaxies,\u201d says Hincks. \u201cBut what we know less about is binaries.<\/p>\n \u201cWhen two galaxies merge, what happens to their black holes? Can they remain in orbit around each other or does their gravity bring them together until they merge? There are many questions that we hope our research helps answer.\u201d<\/p>\n Other U of T co-authors include postdoctoral fellow Aretaios Lalakos and Professor Richard Bond<\/a>, both with the Canadian Institute for Theoretical Astrophysics (CITA); and Yilun Guan<\/a>, a Schmidt AI in Science fellow with the Dunlap Institute for Astronomy & Astrophysics.<\/a> U of T alum Xiaoyi Ma, now with Peking University, is a second author.<\/p>\n \u201cThe thing that excites me and all my co-authors is that this is a new way to identify SMBH binaries,\u201d says Hincks. \u201cIn the future, we\u2019re going to observe a large area of the sky, every night or two, with the Simons Observatory. That means we can monitor thousands of these galaxies and start searching for the telltale signal.<\/p>\n \u201cOur hope is to discover a few dozen binaries, a few score, or more. It will just depend on how generous nature is.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"A team of astronomers has bolstered the evidence for the existence of one of the most remarkable, yet…\n","protected":false},"author":2,"featured_media":565131,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[49,48,66],"class_list":["post-565130","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ca","tag-canada","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/565130","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=565130"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/565130\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/565131"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=565130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=565130"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=565130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}