Astrophysicist announces that the galaxies rewrite the story

This artist's conception depicts energetic quasar which has become the center of the galaxy of gas and dust, and which are now propagating to the outskirts. Soon, there will be no blue and light left, and only a luminous blue quasar will stay. 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, wants to announce the discovery of "cold quasars" galaxies featuring an abundance of cold gas that still galaxy's 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 supermassive black hole on steroids. Gas falling toward a quasar at the center of a galaxy forms on "accretion disk" which can be a mind-bending amount of electromagnetic energy, often featuring luminosity hundreds of times greater than a typical galaxy. Typically, the formation of a quasi is akin to galactic retirement, and it's long been thought to signal to end a galaxy's ability to produce new stars.

X-rays, "said Kirkpatrick." All of the gas is acclaimed on the black hole. X-rays is one of the most fun things in the universe You can get solar flares, you can go through these magnetic field These jets essentially choke off the gas supply of the galaxy, so no more gas can happen on the galaxy and form new stars dead galaxy. "

But in Kirkpatrick's survey, about 10 percent of the galaxies have accreting supermassive black holes.

Astrophysicist announces that the galaxies rewrite the story

An optical blue quasar at 7 billion years (this is not a nearby galaxy). Normally, something like this would not have an infrared emission. Credit: Dark Energy Camera Legacy Survey DR7 / NOAO

"That in itself is surprising," she said. Some of the galaxies have very obvious merger signatures Some of them are very compact These are very compact, blue, luminous sources They look exactly like you would expect a supermassive black hole to look up 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 it has a lot of cold gas in it as well.

The KU astrophysicist suspects the "cold quasars" in a survey period in the end-phases of a galaxy's lifespan-in terms of a human life, the fleting "cold quasar" 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. 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's telescope and surveyed the X-ray," she said. From there, we surveyed it with the Herschel Space Telescope, a far infrared telescope, which can detect dust and gas in the galaxy both the X-ray and the infrared. "

Astrophysicist announces that the galaxies rewrite the story

The dust emission of the same blue-quasar galaxy. It is surprisingly bright – in fact, it is one of the brightest objects in the field, indicating a lot of dust. Due to the resolution of the telescope, we can not see what that looks like. Credit: Herschel / ESA

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

"We already knew we were going through a dust-obscured phase," Kirkpatrick said. "We knew they were going through a heavy shrouded phase where there is a problem with the supermassive black hole." But before, if you A lot of people say they had a good night's sleep in a lot of dust and gas in it, and a lot of them did not know how to do it . ' "

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

"We thought the things proceeded, what you have a growing black hole, it's been absorbed by dust and gas, it's starting to blow that out," she said. But it seems with these objects, that's not the case. "These have blown out their own dust-so This is a transitional phase, let's say 10 million years. "In universal timescales, it's really short-and-it's And by finding these objects, yes, it could just that this happens to every galaxy. "

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