Tag: quasars

Scientists: Quasar data shows time running five times slower in the early universe

8:53 am

The uncertainty of science: According to new research using data from almost 200 quasars collected over the two decades, scientists now believe they have detected the difference between the rate of time now and as we see it in the early universe.

“Looking back to a time when the universe was just over a billion years old, we see time appearing to flow five times slower,” said lead author of the study, Professor Geraint Lewis from the School of Physics and Sydney Institute for Astronomy at the University of Sydney. “If you were there, in this infant universe, one second would seem like one second – but from our position, more than 12 billion years into the future, that early time appears to drag.”

…Professor Lewis worked with astro-statistician Dr Brewer to examine details of 190 quasars observed over two decades. Combining the observations taken at different colours (or wavelengths) – green light, red light and into the infrared – they were able to standardise the ‘ticking’ of each quasar. Through the application of Bayesian analysis, they found the expansion of the universe imprinted on each quasar’s ticking.

“With these exquisite data, we were able to chart the tick of the quasar clocks, revealing the influence of expanding space,” Professor Lewis said.

These results further confirm Einstein’s picture of an expanding universe but contrast earlier studies that had failed to identify the time dilation of distant quasars. [emphasis mine]

I have highlighted the word “exquisite” because it is a favorite buzzword of scientists when they are trying to oversell conclusions that carry many uncertainties. As good as this data might be, it is still incredibly sparse, and the interpretation of it requires many assumptions.

Nonetheless, these results are likely correct, in some manner, because they match well with Einstein’s predictions. It is also most likely that there are many errors and incorrect aspects to those results that the scientists do not yet understand. Above all, confirmation bias remains a concern.

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First binary quasar found

9:48 am

Double quasar as seen by the Hubble Space Telescope
Double quasar as seen by the Hubble Space Telescope

Using a suite of telescopes on the ground and in orbit, astronomers have found the first galaxy made up of two quasars, supermassive black holes that are very active in eating material from around them.

ESA’s (European Space Agency) Gaia space observatory first detected the unresolved double quasar, capturing images that indicate two closely aligned beacons of light in the young universe. Chen and his team then used NASA’s Hubble Space Telescope to verify the points of light were in fact coming from a pair of supermassive black holes.

Multi-wavelength observations followed; using Keck Observatory’s second generation Near-Infrared Camera (NIRC2) paired with its adaptive optics system, as well as Gemini North, NASA’s Chandra X-ray Observatory, and the Very Large Array network of radio telescopes in New Mexico, the researchers confirmed the double quasar was not two images of the same quasar created by gravitational lensing.

The two quasars are estimated to be only about 10,000 light years apart. Scientists estimate that this galaxy is about ten billion light years away, and exists in this state only about three billion years after the Big Bang.

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Astronomers discover three merging supermassive black holes

9:03 am

Using telescopes on Mauna Kea in Hawaii, astronomers have discovered three different galaxies that have pairs of supermassive black holes at their center, with all three likely to merge at some point in the future.

First the scientists used the Subaru Telescope to survey more than 34,000 known quasars, high energy supermassive black holes.

The team identified 421 promising cases. However, there was still the chance many of these were not bona-fide dual quasars but rather chance projections such as starlight from our own galaxy. Confirmation required detailed analysis of the light from the candidates to search for definitive signs of two distinct quasars.

Using Keck Observatory’s Low Resolution Imaging Spectrometer (LRIS) and Gemini Observatory’s Near-Infrared Integral Field Spectrometer, Silverman and his team identified three dual quasars, two of which were previously unknown. Each object in the pair showed the signature of gas moving at thousands of kilometers per second under the influence of a supermassive black hole.

From this survey work they now tentatively estimate that only 0.3% of all known quasars are likely made up of a binary, which in turn gives them a rough estimate of how often galaxies with such supermassive black holes collide and merge. This in turn helps them develop theories on galaxy formation.

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Quasars that shut off

8:37 am

The uncertainty of science: Astronomers have discovered a class of quasars that suddenly turn off, something that no theory had predicted possible.

LaMassa, an astronomer now at the Space Telescope Science Institute, was mystified. Until that moment in 2014, she, like so many others, had expected quasars to be relatively stagnant. “Then you see these drastic changes within a human lifetime, and it’s pretty cool,” she said.

Confusion turned into excitement, and a hunt began to find more of these oddities. Although less luminous examples had already been seen, astronomers wanted to know if changes as dramatic as the one LaMassa discovered were common. It was no straightforward task, given that surveys tend not to go back and look at objects they have previously observed. But astronomers searched through archived data and discovered 50 to 100 more of what became known as “changing-look quasars.” Some of these have dimmed substantially more than LaMassa’s first example. Others have transitioned in the space of a month or two. And others, after disappearing, have reappeared again.

“It’s clear that the reason we weren’t finding these objects before is that we weren’t looking for them,” said Eric Morganson, an astronomer at the University of Illinois.

The article does a fine job of explaining the whole problem, including outlining the theories now being posited to explain these events. Bottom line: the universe is always more complicated that expected by initial observations.

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Combined Earth-Space radio array discovers superhot quasar interior

11:01 am

The uncertainty of science: Data obtained by combining four ground-based radio telescopes with the Russian orbiting RadioAstron 10-meter radio telescope have detected temperatures of 10 trillion degrees in the quasar 3C 273, a hundred times hotter than predicted possible by theory.

Supermassive black holes, containing millions to billions times the mass of our Sun, reside at the centers of all massive galaxies. These black holes can drive powerful jets that emit prodigiously, often outshining all the stars in their host galaxies. But there is a limit to how bright these jets can be – when electrons get hotter than about 100 billion degrees, they interact with their own emission to produce X-rays and Gamma-rays and quickly cool down.

Astronomers have just reported a startling violation of this long-standing theoretical limit in the quasar 3C 273. “We measure the effective temperature of the quasar core to be hotter than 10 trillion degrees!” comments Yuri Kovalev (Astro Space Center, Lebedev Physical Institute, Moscow, Russia), the RadioAstron project scientist. “This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate.”

In addition, the higher resolution of the radio images produced by this space/ground-based array was good enough to see the effect produced by the structure of the interstellar material between here and the quasar.

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A quasar shuts down

10:19 am

Astronomers have identified the first quasar to change its energy output.

Quasars are massive, luminous objects that draw their energy from black holes. Until now, scientists have been unable to study both the bright and dim phases of a quasar in a single source. As described in an upcoming edition of the Astrophysical Journal, Yale-led researchers spotted a quasar that had dimmed by a factor of six or seven, compared with observations from a few years earlier.

It is also believed that quasars are the central supermassive black holes at the center of these very distant and ancient galaxies. Knowing how these black holes change can tell us something about the behavior of Sagittarius A*, the generally quiet central black hole in the Milky Way.

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Two newly discovered supermassive black holes weigh in as the heaviest known

11:48 am

Two newly discovered supermassive black holes weigh in as the heaviest known.

One of the newly discovered black holes is 9.7 billion solar masses and is located in the elliptical galaxy NGC 3842, which is the brightest galaxy in the Leo cluster of galaxies that sits 320 million light years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, which is the brightest galaxy in the Coma cluster about 336 million light years from Earth in the direction of the constellation Coma Berenices.

It is believed that these heavy supermassive black holes are the kind that produced quasars in the early universe.

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The most distant quasar ever found

9:04 am

Astronomers have found the most distant quasar ever, and are baffled by its existence.

The light from the quasar started its journey toward us when the universe was only 6% of its present age, a mere 770 million years after the Big Bang, at a redshift of about 7.1 [3]. “This gives astronomers a headache,” says lead author Daniel Mortlock, from Imperial College London. “It’s difficult to understand how a black hole a billion times more massive than the Sun can have grown so early in the history of the universe. It’s like rolling a snowball down the hill and suddenly you find that it’s 20 feet across!”

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