Quasars slowed star formation: First observed evidence of galactic-wind phenomenon

March 23, 2016
New research shows quasars slowed star formation
In an artist's conception, heated galactic wind shown in the hazy portion of the picture emanates from the bright quasar at the edge of a black hole, scattering dust and gas. If allowed to cool and condense, that dust and gas would instead begin to form stars. Credit: Johns Hopkins University

Research led by Johns Hopkins University scientists has found new persuasive evidence that could help solve a longstanding mystery in astrophysics: Why did the pace of star formation in the universe slow down some 11 billion years ago?

A paper published in the Monthly Notices of the Royal Astronomical Society finds evidence supporting the argument that the answer was energy feedback from quasars within the galaxies where stars are born. That is, intense radiation and galaxy-scale winds emitted by the quasars - the most luminous objects in the universe - heats up clouds of dust and gas. The heat prevents that material from cooling and forming more dense clouds, and eventually stars.

"I would argue that this is the first convincing observational evidence of the presence of quasar feedback when the universe was only a quarter of its present age, when the cosmic was most vigorous," said Tobias Marriage, an assistant professor in the university's Henry A. Rowland Department of Physics and Astronomy. While the findings appearing in the journal published by the Oxford University Press are not conclusive, Marriage said, the evidence is very compelling and has scientists excited.

"It's like finding a smoking gun with fingerprints near the body, but not finding the bullet to match the gun," Marriage said.

Specifically, investigators looked at information on 17,468 galaxies and found a tracer of energy known as the Sunyaev-Zel'dovich Effect. The phenomenon, named for two Russian physicists who predicted it nearly 50 years ago, appears when high-energy electrons disturb the Cosmic Microwave Background. The CMB is a pervasive sea of microwave radiation, a remnant from the superheated birth of the universe some 13.7 billion years ago.

Devin Crichton, a Johns Hopkins graduate student and the paper's lead author, said the thermal energy levels were analyzed to see if they rise above predictions for what it would take to stop star formation. A large number of galaxies were studied to give the study statistical heft, he said.

"For feedback to turn off star formation, it must be occurring broadly," said Crichton, one of five Johns Hopkins scientists who led the work conducted by a total of 23 investigators from 18 institutions. Most of the scientists are members of the Atacama Cosmology Telescope collaboration, named for one of the three instruments used in the study.

To take the faint temperature measurements that would show the Sunyaev-Zel'dovich Effect, the scientists used information gathered by two ground-based telescopes and one receiver mounted on a space observatory. Using several instruments with different strengths in search of the SZ Effect is relatively new, Marriage said.

"It's a pretty wild sort of thermometer," he said.

Information gathered in the Sloan Digital Sky Survey by an optical telescope at the Apache Point Observatory in New Mexico was used to find the quasars. Thermal energy and evidence of the SZ Effect were found using information from the Atacama Cosmology Telescope, an instrument designed to study the CMB that stands in the Atacama Desert in northern Chile. To focus on the dust, investigators used data from the SPIRE, or Spectral and Photometric Imaging Receiver, on the Herschel Space Observatory.

Galaxies reached their busiest star-making pace about 11 billion years ago, then slowed down. A team of astronomers more than three years ago estimated that the pace of star formation is one-thirtieth as fast as when it peaked. Scientists have puzzled for years over the question of what happened. The chief suspect has been the feedback process, Marriage said.

Nadia L. Zakamska, an assistant professor in the Department of Physics and Astronomy at Johns Hopkins and one of the report's co-authors, said it is only in the last few years that evidence of this phenomenon from direct observation has been compiled. The SZ Effect, she said, is a novel approach to the subject, making clearer the full effect of galactic wind on the surrounding galaxy.

"Unlike all other methods that are probing small clumps within the wind, the Sunyaev-Zeldovich Effect is sensitive to the bulk of the wind, the extremely hot plasma that's filling the volume of the wind and is completely undetectable using any other technique," she said.

Explore further: Big black holes can block new stars

More information: Devin Crichton et al. Evidence for the Thermal Sunyaev-Zel'dovich Effect Associated with Quasar Feedback, Monthly Notices of the Royal Astronomical Society (2016). DOI: 10.1093/mnras/stw344

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12 comments

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Tuxford
1.7 / 5 (6) Mar 23, 2016
Galaxies reached their busiest star-making pace about 11 billion years ago, then slowed down. A team of astronomers more than three years ago estimated that the pace of star formation is one-thirtieth as fast as when it peaked.


And why is it simply not due to observational bias based on instrumentation limits combined with varying data sets based on distance? Merger maniacs have already proven to be not very smart. I don't trust much from them now.

Feedback? Talk to some control systems engineers. Yes, of coarse the bigger the core star, the more it blasts winds, which shut down formation rates, except that the core is ejecting new matter like crazy, maybe up to one sun's worth an hour!

http://phys.org/n...ies.html

wduckss
1.8 / 5 (5) Mar 23, 2016
Correct is say .. closer than 11 billion light-years and further from ..
Speed of the body in belt away of 13.8 billion ly is 270,000 km / sec, in belt about 11 billion ly over 200,000 km / sec.
Observation quasars must take and the fact that it is rapidly rotating elliptical galaxy.
Of observation are wrong without these data and the results are lost time.
Da Schneib
4 / 5 (4) Mar 23, 2016
If this turns out to be correct it's a major advance in our understanding. There's been a lot of data to connect the quasar era to the slowdown in star production, but nothing definitive about what the actual mechanism is. Fascinating.
Da Schneib
4 / 5 (4) Mar 23, 2016
Oh, and I should also mention that there's another article on here, somewhat older, about ultra-fast winds around a supermassive black hole, that has some consilience with this result. It's definitely worth a read, and these two findings seem to validate one another.
Phys1
4.2 / 5 (5) Mar 24, 2016
@Tuxford
Merger maniacs have already proven to be not very smart.

You are so funny.
Hat1208
3.7 / 5 (3) Mar 24, 2016
And why is it simply not due to observational bias based on instrumentation limits combined with varying data sets based on distance? Merger maniacs have already proven to be not very smart. I don't trust much from them now.

Feedback? Talk to some control systems engineers. Yes, of coarse the bigger the core star, the more it blasts winds, which shut down formation rates, except that the core is ejecting new matter like crazy, maybe up to one sun's worth an hour!

Control systems engineers are the most unintelligent people on the planet. They make up stories and present them as facts with no supporting evidence at all and with no regard for the scientific method. The core of galaxies do not eject matter like crazy, ever end of story and that is the absolute truth about it.

Da Schneib
4 / 5 (4) Mar 24, 2016
@Tuxford
Merger maniacs have already proven to be not very smart.

You are so funny.
"Merger maniacs?"

Let's start here:

https://upload.wi...ild!.jpg

@Hat, are you being sarcastic? Or do I need to post pictures of AGNs from Hubble here?
Steelwolf
3 / 5 (4) Mar 26, 2016
I happen to particularly like this last statement where:
"Unlike all other methods that are probing small clumps within the wind, the Sunyaev-Zeldovich Effect is sensitive to the bulk of the wind, the extremely hot plasma that's filling the volume of the wind and is COMPLETELY UNDETECTABLE using any other technique," she said." (Emphasis by way of Caps mine; Dark Matter/Energy anyone?)

So, not only are we talking extremely large amounts of plasma, we know that even more is produced by way of the Quasar's jets and so we have an intergalactic medium upon which to carry an electric charge, electric current and magnetic fields. Since cooling and the precipitation to normal atomic material at the cooling edges of the plasma field would allow gravity to interact within the precipitates allowing for local infall at magnetic vorticies giving rise to the creation of new stars and planetary systems, perhaps globular clusters and larger at the edges of these quasars shock boundaries?

obama_socks
1 / 5 (3) Mar 26, 2016
@Tuxford
Merger maniacs have already proven to be not very smart.

You are so funny.
- Piss1

Wow....that's ALL you had to offer? Nothing pertinent to the topic with any sort of substance? Pissy, you don't belong commenting in a science website...go back to Clown College where you belong.
obama_socks
1 / 5 (3) Mar 26, 2016
"While the findings appearing in the journal published by the Oxford University Press are not conclusive, Marriage said, the evidence is very compelling and has scientists excited.
"It's like finding a smoking gun with fingerprints near the body, but not finding the bullet to match the gun,"

Not conclusive. I think I'll wait until they FIND the bullet to get excited about it.
Skepticism 101
Tuxford
1 / 5 (4) Mar 27, 2016
@Tuxford
Merger maniacs have already proven to be not very smart.

You are so funny.
"Merger maniacs?"

Let's start here:

https://upload.wi...ild!.jpg

Da, clearly you side with the maniacs. Yes, some galaxies collide. However, many of these examples are easily interpreted as diverging. Nothing conclusive here. Enjoy the fantasy! Want some tickets to Disney??
Phys1
5 / 5 (3) Mar 28, 2016
@ Tuxford
you side with the maniacs

You are on your own.

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