Discovery of "cold quasars" ̵
1; galaxies with an abundance of cold gas that can still produce new stars despite a quasar in the center – a breakthrough that abandons the assumptions about the maturation of galaxies and possibly represents one phase of each unknown life cycle of the galaxy.
Her newscast, entitled "A New Population of Cold Quasars," will take place on Wednesday, June 12, at 3:00 pm CDT on the 2nd floor of the St. Louis Union Station Hotel. It will be streamed live at https: / / aas. org / Media Press / aas press conference webcasts
A quasar or "quasi-stellar radio source" is essentially a supermassive black hole on steroids. Gas that falls in the direction of a quasar in the center of a galaxy forms an "accretion disk" that can emit an amazing amount of electromagnetic energy, often hundreds of times higher than a typical galaxy. Typically, the formation of a quasar is similar to galactic retirement, and has long been thought to signal the end of a galaxy's ability to produce new stars.
"All the gas that accumulates on the black hole is heated and emitted X-rays," Kirkpatrick said, "the wavelength of light you give depends directly on how hot you are. For example, you and I will emit infrared light. But something that gives off x-rays is one of the hottest things in the universe. This gas begins to accumulate on the black hole and begins to move at a relativistic speed, in addition there is a magnetic field around this gas and it can twist. As with solar flares, this magnetic field can cause material jets to rise. These jets essentially throttle the galaxy's gas supply so that gas can no longer fall on the galaxy and form new stars. After a galaxy has stopped forming stars, we say that it is passive dead galaxy. "
But in Kirkpatrick's survey, about 10 percent of the supermassive black hole galaxies still had a supply of cold gas after entering this phase and still formed new stars.
" That in itself surprised. "She said," This whole population is a whole bunch of different objects. Some of the galaxies have very obvious fusion signatures; some are very similar to the Milky Way and have very obvious spiral arms. Some of them are very compact. Out of this diverse population We then have another 10 percent, which is really unique and unexpected. These are very compact, blue, luminous sources. They look exactly as if one expects a supermassive black hole to appear in the final state after it has erased the entire star forming in a galaxy. This evolves into a passive elliptical galaxy, but we've also found a lot of cold gas in it. This is the population I'm cold Quasars & # 39; call.
KU astrophysicist suspects The "cold quasars" in their survey represented a short period of time that was not recognized in the final stages of a galaxy's lifetime – the fleeting "cold quasar" could be used in a human life.
"These galaxies are rare because they are in a transitional phase – we caught them just before the star formation in the galaxy went out, and this transitional period should be very short," she said. 19659005] Kirkpatrick first identified the objects of interest in a section of the Sloan Digital Sky Survey, the most detailed digital map available in the Universe, in an area called "Stripe 82" that allowed Kirkpatrick and her colleagues to visually identify Quasare.
"Then went We examined the area with the XMM Newton telescope and examined it on the X-ray, "she said These are the key signature for growing black holes. From there we examined them with the Herschel Space Telescope, a far-infrared telescope that can detect dust and gas in the host galaxy. We have selected the galaxies we could be in both the X-ray and the infrared.
The KU researcher said that their findings gave scientists a new understanding and more information on how to quench star formation in galaxies and supersedes quasars.
"We already knew it Quasars go through one Dust-masked phase, "said Kirkpatrick," We knew they were going through a heavily fogged phase where dust surrounds the supermassive black hole. We call this the red quasar phase. But now we have found this unique transitional regime that we did not know before. Before, if you told someone that you found a luminous quasar that has a blue optical color – but still contains a lot of dust and gas and much star formation – people would say, "No, that's not how it should be watch.
Next, Kirkpatrick hopes to determine if the "cold quasar" phase belongs to a particular class of galaxy or galaxy.
"It is surrounded by dust and gas and begins to blow out the material," she said. "Then it becomes a bright blue object. We assumed that if it blew its own gas, it would also blow out its host gas. But with these objects that does not seem to be the case. They have their own dust blown out – so we see it as a blue object – but they have not yet blown off all the dust and gas in the host galaxies. This is a transitional phase, say 10 million years. In universal timescales that's really short. – and it's hard to catch this thing. We do a so-called blind survey to find objects that we did not look for. And if we find these objects, it could mean that this happens to every galaxy. "
Kirkpatrick collected data using the XMM Newton Telescope, a high-throughput X-ray telescope operated by the European Space Agency, by 2015. Her work is part of a collaboration entitled Accretion History of AGN (under the guidance of the astrophysicist Meg Urry of Yale University), which collects archival data and conducts a multi-wavelength analysis.
Kirkpatrick's colleagues in this and related work include Brandon Coleman and Michael of KU Estrada, Urry and Tonima Ananna of Yale University, Dave Sanders of The Department 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, are NASA's No. 80NSSC18K0418 Yale University and National Science Foundation under the award no. AST-1715512.