In 2009, NASA launched its Wide-field Infrared Survey Explorer (WISE) telescope, an Earth-orbiting infrared observatory designed to map the entire sky in unprecedented detail. WISE surveyed the sky for less than two years, but in that time collected vast quantities of information: It's been eighteen months since the observatory was decommissioned, and astronomers are still sifting through the data.
Today, during a live teleconference scheduled to begin at 13:00 ET, WISE scientists announced their latest findings. The subject: "the distant universe... supermassive black holes, rare galaxies" and "extreme objects."
Here's our liveblog of what they said.
Update | 12:55 ET
Today's briefing participants are:
— Daniel Stern, astronomer, NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.
— Peter Eisenhardt, WISE project scientist, JPL
— Jingwen Wu, astronomer, JPL
— Rachel Somerville, Downsbrough Chair in Astrophysics, Rutgers University
Update | 13:00 ET
Still no teleconference audio from the Ustream feed, though we are picking up some peppy Jazz. HAS WISE DETECTED SPACE MUSIC? Kidding. Only kind of.
Update | 13:05 ET
Looks like things are getting underway here. NASA Has posted a slew of graphics here. All images, video and captions posted here courtesy of ESA/NASA/JPL-Caltech/UCLA/STScI.
Daniel Stern: "WISE has found a bonanza of black holes, more than had been found by any previous survey."
According to Stern, every orange circle you see in this image is a black hole.
From NASA: With its all-sky infrared survey, NASA's Wide-field Infrared Survey Explorer, or WISE, has identified millions of quasar candidates. Quasars are supermassive black holes with masses millions to billions times greater than our sun. The black holes "feed" off surrounding gas and dust, pulling the material onto them. As the material falls in on the black hole, it becomes extremely hot and extremely bright. This image zooms in on one small region of the WISE sky, covering an area about three times larger than the moon. The WISE quasar candidates are highlighted with yellow circles.
WISE has spotted about 2.5 million actively feeding supermassive black holes. According to NASA, "About two-thirds of these objects never had been detected before because dust blocks their visible light. WISE easily sees these monsters because their powerful, accreting black holes warm the dust, causing it to glow in infrared light."
The image featured here is an artist's conception of what these "donut-shaped" quasars look like.
Sez NASA: This artist's concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below. X-rays emerge from the very central region, while thermal infrared radiation is emitted by dust throughout most of the torus. While this figure shows the quasar's torus approximately edge-on, the torus around APM 08279+5255 is likely positioned face-on from our point of view.
This is a closeup of the "Bonanza of black holes" graphic featured above. The inset grey images show images from Hubble Telescope. ON the bottom right, the black hole looks like a point of light because we're "looking down the throat of the [quasar] donut."
According to NASA: This zoomed-in view of a portion of the all-sky survey from NASA's Wide-field Infrared Survey Explorer shows a collection of quasar candidates. Quasars are supermassive black holes feeding off gas and dust. The larger yellow circles show WISE quasar candidates; the smaller blue-green circles show quasars found in the previous visible-light Sloan Digital Sky Survey. WISE finds three times as many quasar candidates with a comparable brightness. Thanks to WISE's infrared vision, it picks up previously known bright quasars as well as large numbers of hidden, dusty quasars.
The circular inset images, obtained with NASA's Hubble Space Telescope, show how the new WISE quasars differ from the quasars identified in visible light. Quasars selected in visible light look like stars, as shown in the lower right inset; the cross is a diffraction pattern caused by the bright point source of light. Quasars found by WISE often have more complex appearances, as seen in the Hubble inset near the center. This is because the quasars found by WISE are often obscured or hidden by dust, which blocks their visible light and allows the fainter host galaxy surrounding the black hole to be seen.
Daniel Stern: "WISE has identified about 2.5 million quasars across the sky, this is a vast increase of the number known before." (About two thirds of these had never been spotted before WISE.)
Via NASA: NASA's Wide-field Infrared Survey Explorer (WISE) has identified about 1,000 extremely obscured objects over the sky, as marked by the magenta symbols. These hot dust-obscured galaxies, or "hot DOGs," are turning out to be among the most luminous, or intrinsically bright objects known, in some cases putting out over 1,000 times more energy than our Milky Way galaxy.
"Hot dogs are much, much rarer than the quasars Dan Stern just talked about," says Eisenhart. This image features the first hot DOG discovered by WISE.
NASA: This image zooms in on the region around the first "hot DOG" (red object in magenta circle), discovered by NASA's Wide-field Infrared Survey Explorer, or WISE. Hot DOGs are hot dust-obscured galaxies. Follow-up observations with the W.M. Keck Observatory on Mauna Kea, Hawaii, show this source is over 10 billion light-years away. It puts out at least 37 trillion times as much energy as the sun. [Emphasis added, because holy CRAP]
WISE has identified 1,000 similar candidate objects over the entire sky (magenta dots). These extremely dusty, brilliant objects are much more rare than the millions of active supermassive black holes also found by WISE (yellow circles).
Via NASA: This image is a portion of the all-sky survey from NASA's Wide-field Infrared Survey Explorer, or WISE. It highlights the first of about 1,000 "hot DOGs" found by the mission (magenta circle). Hot DOGs are hot dust-obscured galaxies and are among the most powerful galaxies known. Yellow circles are active supermassive black holes found by WISE, which are much more common.
The panels at right show the "Hot DOG" as seen in the four individual infrared bands obtained by WISE. These images are at wavelengths from 5 to 30 times redder than what our eyes can see, with the shortest wavelengths at top, and longest at bottom.
Jingwen Wu, astronomer, JPL says these hot DOGS are much, much hotter and brighter than normal galaxies.
Rachel Somerville, Downsbrough Chair in Astrophysics, Rutgers University thinks we may be seeing these hot DOG galaxies at a "crucial transformational stage" that could tell us a lot about how galaxies and the black holes at their centers grow and evolve together.
Featured here is a neighboring spiral galaxy, very similar to our own Milky Way (on the left), on the right is the central region of a nearby cluster of elliptical galaxies.
Since discovering these types of galaxies decades ago using Hubble, astronomers have been arguing about why we see different kinds of galaxies, and why we see differences and correlations in their properties. Can spiral galaxies like the Milky Way be transformed into elliptical galaxies like the one on the right? Somerville says the model above, which shows two large disc galaxies colliding, could provide some clues. The animation demonstrates how gravity can rearrange the gas and stars in galaxies during these mergers "destroying the disc of stars," and "expelling the gas from the galaxy, so no more stars can be born," says Somerville.
Update, 13:25 | Question and Answer Session
You can ask questions over twitter at #NASA — Select questions and answers have been transcribed here in real time and have therefore been summarized
Question: Do we think all elliptical galaxies went through this kind of collision at one point?
Somerville says: this is a hotly debated topic. Mergers are probably a good way to create elliptical galaxies, but it may not be the only way. There are other processes, for example one is: if you try to cram too much gas into a galaxy, that gas can become spontaneously unstable, and collapse to form something like an elliptical galaxy.
The whole merger process lasts a hundred million years. The hot DOG phase is likely even shorter.
Question: The discovery of hot DOGs is a first for WISE, correct?
Answer, Peter Eisenhardt: Yes, these objects are different from others we've seen before. There are dust-obscured galaxies, and there are infrared luminous galaxies, but they tend to peak at temps. much much colder than these hot DOGs. They also seem to be, as far as we can tell, really dominated by supermassive black hooles, and not by star formation. That's not something that is so clearly seen in other infrared luminous galaxies, so in that way, they're definitely different from what we've seen before.
The reason we could find these with WISE is its sensitivity and its ability to survey the entire sky... 1000 may seem like a lot, but remember we've found only 1000 of these hot DOGS in THE ENTIRE SKY.
Question: So why are these only visible at such great distances?
Answer, Eisenhardt: Most of these are being found at 10 billion light years away or greater. Some objects ahve much closer distances, but they might actually be different kinds of objects. They're not as bright, but they're closer, so they appear equally bright to WISE. I might have to disagree with [Somerville] here: it does seem to me that the phenomena we're talking about here is much more common in the earlier stages of the Universe... so while we may become a hot DOG, I think it's a relatively unusal event today, based on the distribution of distances that we're finding.
Question: What were the hot DOGs before they were hot DOGs?
Answer, Somerville: To wind up with these supermassive black holes we need to start out with what are called "seed" black holes. One way to end up with a seed black hole is by collapsing a massive star. We think in the early universe, stars were significantly more massive than our Sun, and that when they collapsed they could turn into these supermassive black holes.
Question: What are we measuring when we measure temperature of the hot DOGs, what are we measuring the temperature of?
Answer, Jingwen Wu: we're measureing the average temp of the whole galaxy, we measure that from the galaxy's spectral energy distribution, and from that we can estimate the temperature of this type of object. In future research, we'll need to go into greater detail with more resolution, but for now, we're looking at the temperature of the whole galaxy.
Question: Could the Milky Way possibly go through this process [colliding with the Andromeda galaxy to become an elliptical galaxy]? Where might Earth be during this process?
Answer, Somerville: IT's tough to determine that, because many things start to happen on a similar time scale. The sun will go red giant around the same time that we'll probably merge with Andromeda. There's even evidence that earth could become tidally unbound during this process. So the real answer is: we really don't know; I think it's just quite uncertain.
How important is the WISE Satellite to the advancement of Astronomy?
Answer, Eisenhardt: The primary objective of WISE is to gain a sensitive map of the Universe in the infrared. This is hundreds of times more sensitive that previous maps have been in the infrared. We released our data in March, and we've got about 175 published papers based on WISE data, and that number is climbing rapidly. That rate hsould continue to climb for several years.
The catalogue from the wise survey contains over five hundred million sources, where previous surveys contained only a few million, at most. I'm sure there are a number of discoveries to be made in the future.
In summary, I'd say it's quite a major advance, and an affordable one for the field, at that (Wise observatory was $320 million, pretty affordable for a NASA project that has contributed as much data as it has).
Question: How big can black holes be?
Answer, Somerville: The biggest black holes we know about are in neighboring elliptical galaxies, and they can approach 10 billion times the mass of our sun... That said, we don't know of any absolute limit, so in the future there could be even bigger black holes that form, but those are the biggest we know about.
Question: Where do things stand in the WISE mission?
Answer, Eisenhardt: WISE was launched in December, 2009. We started surveying a month later, and in six months we covered the whole sky once. We continued for a few months before cryo ran out, but we managed to continue collecting enough data to survey the sky a second time. WISE has been hibernation mode, passively orbiting the Earth, since February of 2011. We could, in theory, bring it out of hibernation, but we lack the funding to do so yet. We haven't really released data from the second survey yet. That's something we're starting to release now. About a year from now, we'll be releasing the fully processed, grand combination of all the WISE Data [i.e. both sky surveys].
Question: What do hot DOGs tell us about galaxy classification in general?
Answer, Somerville: There's this idea that most galaxies started their lives as discs, but something may have happened [be it a collision, collapse, etc] that converted them into elliptical galaxies, and maybe they went through this hot DOG phase during their transition.