. | . |
Early Black Holes May Have Grown in Fits and Spurts by Staff Writers Boston MA (SPX) Jun 01, 2017
A long-standing question in astrophysics is: how and when did supermassive black holes appear and grow in the early universe? New research using NASA's Chandra X-ray Observatory and the Sloan Digital Sky Survey (SDSS) suggests that an answer to this question lies with the intermittent way giant black holes may consume material in the first billion years after the Big Bang. Astronomers have determined the Big Bang occurred about 13.8 billion years ago and have evidence from the SDSS that supermassive black holes with masses of about a billion times that of the Sun existed by about 12.8 billion years ago. This implies that supermassive black holes grew rapidly in the first billion years after the Big Bang. Yet, scientists have struggled to find signs of these growing giant black holes. "Supermassive black holes are not spontaneously born - they need to ingest vast amounts of material and that takes time," said lead author Edwige Pezzulli, PhD student of the University of Rome in Italy and member of the project "FIRST," funded by the European Research Council. "We are trying to figure out how they have done this without giving off many telltale signs of this growth." When material is falling toward a black hole, it becomes heated, and produces large amounts of electromagnetic radiation, including copious X-ray emission. Rapidly growing black holes in the very early universe should be detectable with Chandra. However, these growing supermassive black holes have proved to be elusive, with only a few, yet-to-be-confirmed candidates found in very long Chandra observations such as the Chandra Deep Field-South, the deepest X-ray image ever taken. To address this conundrum, Pezzulli and her colleagues examined different theoretical models and tested them against optical data from the SDSS and X-ray data from Chandra. Their findings indicate that black hole feeding during this era may turn on abruptly and last for short periods of time, which means this growth may be difficult to spot. "In our model only about a third of black holes were actively consuming material and growing 13 billion years ago" said co-author Rosa Valiante of the National Institute for Astrophysics (INAF) in Italy and member of the FIRST team. "About 200 million years earlier only 3% of the black holes were actively eating. Timing, it appears, may be everything." The researchers reached their conclusions after testing multiple hypotheses, all of which assumed that the black hole growth could exceed the so-called Eddington limit, where the outward pressure of radiation from the hot gas balances the inward pull of the gravity of the black hole. The authors' results argued against the possibility that only a small fraction of galaxies during the first billion years after the Big Bang contain supermassive black holes. Also, although these early black holes were likely obscured by thick clouds of material, the authors found that most of the X-rays would have been able to penetrate these clouds. The study is based on the idea that when they were born, the first black holes weighed only about a hundred Suns. "These "light" black holes seeds could be the remnants of the first generation of massive stars formed only a few hundred million years after the Big Bang," said co-author Maria Orofino, PhD student of the Scuola Normale Superiore in Italy. The researchers, a team of female scientists, including Simona Gallerani of Scuola Normale Superiore in Pisa and Tullia Sbarrato of Bicocca University of Milan, in Italy, found that black holes can bulk up so much in their relatively rare bursts of intense growth that light seeds can reach a billion times the mass of the Sun when the universe is only a billion years old. "In order to know if we are ultimately correct, we will need to look at larger swaths of the sky in X-rays to see if we can find the early, feasting black holes that our models have predicted," said Raffaella Schneider, of Sapienza University in Italy and leader of the ERC project FIRST. "Our results certainly show promise." Research paper: "Faint Progenitors of Luminous z~6 Quasars: Why Don't We See Them?" Edwige Pezzulli et al., 2017 April, Monthly Notices of the Royal Astronomical Society
Austin TX (SPX) May 31, 2017 Astronomers at The University of Texas at Austin and Harvard University have put a basic principle of black holes to the test, showing that matter completely vanishes when pulled in. Their results constitute another successful test for Albert Einstein's General Theory of Relativity. Most scientists agree that black holes, cosmic entities of such great gravity that nothing can escape their ... read more Related Links Chandra X-Ray Center Understanding Time and Space
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |