Astrophysicists announce discovery that could rewrite story of how galaxies die

Astrophysicist announces her discovery that could rewrite story of how galaxies die
This artist conception depicts an energetic quasar which has cleared the center of the galaxy of gas and dust, and these winds are now propagating to the outskirts. Soon, there will be no gas and dust left, and only a luminous blue quasar will remain. Credit: Michelle Vigeant

At the annual meeting of the American Astronomical Society in St. Louis, Missouri, Allison Kirkpatrick, assistant professor of physics and astronomy at the University of Kansas, will announce her discovery of "cold quasars"—galaxies featuring an abundance of cold gas that still can produce new stars despite having a quasar at the center—a breakthrough finding that overturns assumptions about the maturation of galaxies and may represent a phase of every galaxy's lifecycle that was unknown until now.

Her news briefing, entitled "A New Population of Cold Quasars," takes place Wednesday, June 12, on the 2nd floor of the St. Louis Union Station Hotel.

A quasar, or "quasi-stellar radio source," is essentially a on steroids. Gas falling toward a quasar at the center of a galaxy forms an "accretion disk" which can cast off a mind-boggling amount of electromagnetic energy, often featuring luminosity hundreds of times greater than a typical galaxy. Typically, formation of a quasar is akin to galactic retirement, and it's long been thought to signal an end to a galaxy's ability to produce .

"All the gas that is accreting on the black hole is being heated and giving off X-rays," Kirkpatrick said. "The wavelength of light that you give off directly corresponds to how hot you are. For example, you and I give off infrared light. But something that's giving off X-rays is one of the hottest things in the universe. This gas starts accreting onto the black hole and starts moving at relativistic speeds; you also have a magnetic field around this gas, and it can get twisted up. In the same way that you get solar flares, you can have jets of material go up through these magnetic field lines and be shot away from the black hole. These jets essentially choke off the gas supply of the galaxy, so no more gas can fall on to the galaxy and form new stars. After a galaxy has stopped forming stars, we say it's a passive dead galaxy."

But in Kirkpatrick's survey, about 10 percent of hosting accreting supermassive had a supply of cold gas remaining after entering this phase, and still made new .

Astrophysicist announces her discovery that could rewrite story of how galaxies die
An optical blue quasar at a lookback time of 7 billion years (this is not a nearby galaxy). Normally, something like this would not have infrared emission. Credit: Dark Energy Camera Legacy Survey DR7/NOAO

"That in itself is surprising," she said. "This whole population is a whole bunch of different objects. Some of the galaxies have very obvious merger signatures; some of them look a lot like the Milky Way and have very obvious spiral arms. Some of them are very compact. From this diverse population, we then have a further 10 percent that is really unique and unexpected. These are very compact, blue, luminous sources. They look exactly like you would expect a supermassive black hole to look in the end stages after it has quenched all of the star formation in a galaxy. This is evolving into a passive elliptical galaxy, yet we have found a lot of cold gas in these as well. These are the population that I'm calling 'cold quasars.'"

The KU astrophysicist suspected the "cold quasars" in her survey represented a brief period yet to be recognized in the end-phases of a galaxy's lifespan—in terms of a human life, the fleeting "cold quasar" phase may something akin to a galaxy's retirement party.

"These galaxies are rare because they're in a transition phase—we've caught them right before star formation in the galaxy is quenched and this transition period should be very short," she said.

Kirkpatrick first identified the objects of interest in an area of the Sloan Digital Sky Survey, the most detailed digital map of the universe available. In an area dubbed "Stripe 82," Kirkpatrick and her colleagues were able to visually identify quasars.

"Then we went over this area with the XMM Newton telescope and surveyed it in the X-ray," she said. "X-rays are the key signature of growing black holes. From there, we surveyed it with the Herschel Space Telescope, a far infrared telescope, which can detect dust and gas in the host galaxy. We selected the galaxies that we could find in both the X-ray and in the infrared."

Astrophysicist announces her discovery that could rewrite story of how galaxies die
The dust emission of the same blue-quasar galaxy. It is surprisingly bright -- in fact, it's one of the brightest objects in the field, indicating a lot of dust. Due to the resolution of the telescope, we cannot see what that dust actually looks like. Credit: Herschel/ESA

The KU researcher said her findings give scientists new understanding and detail of how the quenching of star formation in galaxies proceeds, and overturns presumptions about quasars.

"We already knew quasars go through a dust-obscured phase," Kirkpatrick said. "We knew they go through a heavily shrouded phase where dust is surrounding the supermassive black hole. We call that the red quasar phase. But now, we've found this unique transition regime that we didn't know before. Before, if you told someone you had found a luminous quasar that had a blue optical color—but it still had a lot of dust and gas in it, and a lot of star formation—people would say, 'No, that's not the way these things should look.'"

Next, Kirkpatrick hopes to determine if the "cold quasar" phase happens to a specific class of galaxies or every galaxy.

"We thought the way these things proceed was you have a growing black hole, it's enshrouded by dust and gas, it begins to blow that material out," she said. "Then it becomes a luminous blue object. We assumed when it blew out its own gas, it would blow out its host gas as well. But it seems with these objects, that's not the case. These have blown out their own dust—so we see it as a blue object—but they haven't yet blown out all of the dust and gas in the host galaxies. This is a transition phase, let's say of 10 million years. In universal timescales, that's really short—and it's hard to catch this thing. We're doing what we call a blind survey to find objects we weren't looking for. And by finding these objects, yes, it could imply that this happens to every galaxy."


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Jun 12, 2019
Presented here are the ideas about the origin and evolution of galaxies based on the new paradigm about the real physical and elastonic spaces. The classical Big Bang model, where our world is suddenly born out of nothing, replaced by a model in which there is evolutionary change of the space leading to the emergence of metric and energy. Gradually formed elastonic space which then goes into a flat Euclidean space with the presence of particles and physical fields.
https://www.acade...ome_From
https://www.acade...ilky_Way

Jun 12, 2019
Typically, formation of a quasar is akin to galactic retirement, and it's long been thought to signal an end to a galaxy's ability to produce new stars.

As usual the plasma ignoramuses have it backwards, quasars are young galaxies according to simulations using real physical models.
https://plasmauni...PS-I.pdf
"...when the simulation parameters were scaled to galactic dimensions, the interaction between pinched filaments led to synchrotron radiation whose emission properties were found to share the following characteristics with double radio galaxies and quasars: power magnitude, isophotal morphology, spectra, brightness along source, polarization, and jets..."

Jun 13, 2019
@cantdrive85

You are saying that the simulations use real physical models of quasars, real physical models sounds like something you would rail against.

Jun 13, 2019
These have blown out their own dust—so we see it as a blue object—but they haven't yet blown out all of the dust and gas in the host galaxies.

Because the source of the gas is the quasar itself ! The core star has grown huge and therefore super-active, periodically ejecting massive amounts of newly formed gas from deep therein. Yes, this is not supposed to be, but yet it does be. Go figure, or go back to sleep.

Jun 13, 2019
It does seem as if Quasars were ten times more common in the early universe. To me that indicates Quasars happen early in galaxy evolution, not at the end stage.
The observations correlate to that view rather than the convoluted interpretation forcing facts to fit an idea based on thought alone.

Jun 13, 2019
@cantdrive85

You are saying that the simulations use real physical models of quasars, real physical models sounds like something you would rail against.

No, it is the wildly speculative maths based guesswork that the darkists propagate with which I have a problem.

Jun 15, 2019
Interesting. But also a test that supports the current models.

It does seem as if Quasars were ten times more common in the early universe.


Source? By the way, how can someone be "forcing facts" since they are what they are?

Jun 15, 2019

No, it is the wildly speculative maths based guesswork that the darkists propagate with which I have a problem.


Who cares what you have a problem with? You are a clueless clown, who follows a cult that believes Earth used to orbit Saturn!

Jun 17, 2019
in my own inconsiderate opinion
a key reason for much of the confusion expressed in the preceding comments
that the terminology the scientists are using
does not match the intent
of most commentators usage.

it is meaningless this early in the Universal existence since the Big Bang
to use terms such as "new" or "old" galaxies
old galaxies could have new star
new galaxies could have old stars.
this one moment of time during which we make our observations
is a single photograph of an infant cosmos

it would be more accurate to use terms such as:
a forming galaxy
an assembling galaxy
a dispersing galaxy
a dissipating galaxy
a rejuvenating galaxy

none of these dependent on the age of included stars
but rather on the overall mass of material gravitationaly bound to it

different galaxies of similar mass could be categorized, temporarily
as energetic or passive or accumulating or dispersing

depending on temporary & local energetic phenomena we can observe

right now, was here, now gone

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