Astronomers from Japan, Taiwan, and Princeton University discovered 83 quasars in a distant universe propelled by supermassive black holes when the universe was less than 1
"It is notable that such massive, dense objects could form so rapidly after the Big Bang," said Michael Strauss, professor of astrophysical sciences at Princeton University, one of the co-authors of the study. "Understanding how and how often black holes can form in the early universe is a challenge to our cosmological models."
This finding significantly increases the number of black holes known in this epoch and shows that this is the case. For the first time, how common they are at the beginning of the history of the universe. In addition, there are new insights into the effects of black holes on the physical state of gas in the early universe in the first billion years. The research appears in a series of five articles published in The Astrophysical Journal and publications of the Astronomical Observatory of Japan .
Supermassive black holes found in the centers of galaxies. can be millions or even billions of times more massive than the sun. While they are prevalent today, it is not clear when they formed and how many existed in the distant early universe. A supermassive black hole becomes visible when gas accumulates on it and shines as a "quasar". Previous studies were sensitive only to the very rare, brightest quasars and thus to the most massive black holes. The new discoveries examine the population of weaker quasars driven by black holes whose masses are comparable to most black holes in the universe today.
The research team used data acquired with an innovative instrument, "Hyper Suprime-Cam" (HSC), mounted on the Subaru telescope of the National Astronomical Observatory in Japan at the summit of Maunakea, Hawaii. HSC has a gigantic field of view – 1.77 degrees across, or seven times the area of the full moon – mounted on one of the largest telescopes in the world. The HSC team misses the sky over 300 nights of telescope time over five years.
The team selected quasic candidates from the sensitive HSC survey data. Subsequently, they conducted an intensive observation campaign to obtain spectra of these candidates with three telescopes: the Subaru telescope; the Gran Telescopio Canarias on the island of La Palma in the Canary Islands, Spain; and the Gemini South Telescope in Chile. The survey revealed 83 previously unknown, distant quasars. Together with 17 quasars already known in the study area, the researchers found that there is approximately one supermassive black hole per cubic Giga-light year – in other words, if you divide the universe into imaginary cubes with a billion light years one side, each would be a supermassive one keep black hole.
The sample of quasars in this study is about 13 billion light-years from Earth; In other words, we see them as they existed 13 billion years ago. When the Big Bang took place 13.8 billion years ago, we effectively look back into the past and see these quasars and supermassive black holes when they first appeared 800 million years after the creation of the (known) Universe.
It is widely accepted that the hydrogen in the Universe was once neutral, but was "reionized" – split into its protons and electrons – by the time when the first generation of stars, galaxies and supermassive black holes in the first was born a hundred million years after the big bang. This is a milestone in cosmic history, but astronomers still do not know what was needed for the incredible amount of energy needed for reionization. A compelling hypothesis suggests that there were many more quasars in the early universe than it was before, and it is their integrated radiation that re-ionizes the universe.
"The number of observed quasars, however, shows that this is not the case," said Robert Lupton, Princeton Ph.D. Alumnus, senior scientist in astrophysical sciences. "The number of quasars seen is much smaller than required to explain the reionization." The reionization was therefore caused by another source of energy, most likely by numerous galaxies formed in the young universe.
This study was made possible by the world-leading survey capability of Subaru and HSC. "The quasars we've discovered will be an interesting topic for further observations on current and future facilities," said Yoshiki Matsuoka, a former Princeton postdoctoral fellow at Ehime University in Japan, who led the study. "We will also learn about the formation and early development of supermassive black holes by comparing the measured number density and brightness distribution with predictions from theoretical models."
Based on the results so far, the team looks forward to finding out even more black holes and discovering when the first supermassive black hole appeared in the universe.
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The results of the present study are published in the following five papers, especially in the second paper.
Yoshiki Matsuoka et al., Discovery of the First Quasar with Low Luminosity at z> 7, The Astrophysical Journal (2019). DOI: 10.3847 / 2041-8213 / ab0216
Yoshiki Matsuoka et al., Subaru exploration of high-z quasars (SHELLQs). V. Quasar Luminosity Function and Contribution to Cosmic Reionization at z = 6, The Astrophysical Journal (2018). DOI: 10.3847 / 1538-4357 / aaee7a
Yoshiki Matsuoka et al. Subaru high-z exploration of low light intensity quasars (SHELLQs). IV. Discovery of 41 quasars and luminescent galaxies at 5.7 ≤ z ≤ 6.9 The Astrophysical Journal Supplement Series (2018). DOI: 10.3847 / 1538-4365 / aac724
Yoshiki Matsuoka et al. Subaru High-z exploration of low light intensity quasars (SHELLQs). II. Discovery of 32 quasars and luminous galaxies at 5.7 <z ≤ 6.8, Publications of the Astronomical Society of Japan (2017). DOI: 10.1093 / pasj / psx046
Yoshiki Matsuoka et al. SUBARU HIGH EXPLORATION OF QUASARS WITH LOW LIGHT (SHELLQs). I. DISCOVERY OF 15 QUASAR AND LIGHT GALAXIES AT 5.7 (19459024) The Astrophysical Journal (2016). DOI: 10.3847 / 0004-637X / 828/1/26