Her newsletter entitled "A New Population of Cold Quasars" takes place on Wednesday, June 12 at 3 pm CDT on the 2nd floor of St. Louis Union Station Hotel.
A quasar or "quasi-stellar radio source" is essentially a supermassive black hole on steroids. Gas falling to a quasar in the middle of a galaxy forms an "accretion disk" that can remove a frightening amount of electromagnetic energy, often with brightness hundreds of times greater than a typical galaxy. Typically, the formation of a quasar is also galactic retirement, and it has long been thought to signal an end to a galaxy's ability to produce new stars.
"All gas that accreting on the black hole is heated and emitted X-rays," Kirkpatrick said. "The wavelength of light that you give off directly corresponds to how warm you are. For example, you and I emit infrared light. But something that gives away X-ray is one of the hottest things in the universe. This gas starts accreting on the black hole and begins Moving at relativistic speeds, you also have a magnetic field around this gas and it can be turned up. Just as you get sunspots, you can get material jets going up through this magnetic field lines and pushed away from the black hole. Substantially attenuates the galaxy's gas supply, so no gas can fall on the galaxy and form new stars. When a galaxy has stopped forming stars, we say it's a passive death galaxy. "
But in Kirkpatrick's survey, about 10 percent of the galaxies were worth for acclimatizing supermassive black holes an inflow of cold gas left after entering this phase and still made new stars.
"It's in itself surprising," she said. "The whole population is a whole lot of different objects. Some of the galaxies have very obvious merging signatures, some of them look very much like the Milky Way and have very obvious spiral arms. Some of them are very compact. Then we have another 10 percent that are really unique. and unexpected, these are very compact, blue and light sources, they look like you expect a super-massive black hole to see in the final stage after it has extinguished the entire star formed in a galaxy, evolving into a passive elliptical galaxy, but we have also found very cold gas in them. This is the population I call "cold quasars". "
The KU astrophysician was suspected of the" cold quasas "in his investigation represented a short period not yet characterized by the galaxy longevity – in the case of a human life, the volatile "cold quasar" phase may resemble a galaxy's departure.
"These galaxies are rare because they are in a transitional phase – we have taken them just before the star formation in the galaxy was extinguished and this transitional period should be very short," she said.
Kirkpatrick first identified objects of interest for an area of Sloan Digital Sky Survey, the most detailed digital map of the universe available, in an area called "Stripe 82", Kirkpatrick and her colleagues could visually identify quasars.
"Then we went over this area with the XMM Newton telescope and examined it in the x-ray, "she said." X-rays are the key signature for growing black holes. From there, we examined it with the Herschel space telescope, a long-infrared telescope that can detect dust and gas in the host galaxy. We chose the galaxies that we could find in both X-ray and infrared. "
The KU researcher said that her discoveries give scientists a new understanding and detail of how the cleavage of star formation in galaxies continues and disappears assumptions about quasars."
"We already knew quasars are going through a dust-drenched phase," Kirkpatrick said. . "We knew that they are going through a strongly encapsulated phase where dust surrounds the supermassive black hole. We call it the red quasar phase. But now we have found this unique transition regime that we did not know before. Before, if you told someone you had found a brilliant 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 it's not like this." 19659006] Next, Kirkpatrick hopes to determine if the "cold quasar" phase happens to a certain class of galaxies or every galaxy.
"We thought how these things went on if you were a growing black hole, it is enrouded by dust and gas, It starts to blow that material, "she said." Then it becomes a light blue object. We assumed when it blew out its own gas, it would also blow out its host gas. But it works with these objects, that's not the case. They have blown out their own dust – so we see it as a blue object – but they have not yet blown all the dust and gas in the host galaxies. This is a transitional phase, let's say in 10 million years. In universal time frames, it's really short – and it's hard to catch this thing. We do what we call a blind search to find objects that we were not looking for. And by finding these objects, yes, it can mean that this happens to every galaxy. " ###
Kirkpatrick collected data by 2015 with the XMM Newton Telescope, a high-throughput X-ray telescope operated by the European Space Agency. Her work is part of a collaboration called Accentions History of AGN (under the leadership by Astrophysicist Meg Urry from Yale University) who collects archival data and performs a multi-wavelength analysis.
Kirkpatrick's colleagues in this and related work include KU Brandon Coleman and Michael Estrada, Urry and Tonima Ananna from Yale University, Dave Sanders of the Institute of Astronomy in Hawaii. , Jane Turner of the University of Maryland, Baltimore County, Stephanie LaMassa of the Space Telescope Science Institute and Eilat Glikman of Middlebury College.The work is supported by NASA under award No. 80NSSC18K0418 to Yale University and the National Science Foundation under grant No AST-1715512.
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