# Can the WISE telescope detect black holes?

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Black holes are hot, aren't they? With its infrared scan, could the WISE telescope also detect a black hole? The hypothetical planet beyond the Kuiper belt could actually be a primordial black hole. The WISE telescope might already have imaged the object but could it have done it also if it is a black hole?

Black holes are black. They are only observed directly by telescopes if they are accreting matter. Any radiation observed comes from the matter surrounding the black hole. Generally speaking, the smaller the black hole, the hotter the accreted material becomes. For something of planetary mass, one might expect X-rays and Gamma rays from accreting material.

A non-accreting black hole would produce no signature at any wavelength and there is very little material to be accreted in the outer solar system, except perhaps a small possibility of seeing X-rays if something like an Oort cloud object interacts with the black hole.

It is possible that such a black hole could be detected via its lensing effect on light coming from distant stars, but since the black hole would be very small as seen from Earth, this is unlikely, and WISE would not be the instrument to do that.

EDIT: Just to prevent any confusion. "Naked" black holes are hypothesisd (but not yet observed) to produce Hawking radiation. Planet X, if it exists, is thought to be about ten times the mass of the Earth. Such a black hole would have an event horizon about 20 cm in diameter and would emit Hawking radiation with a luminosity of $$10^{-20}$$ Watts at a blackbody temperature of around 0.002 K. This is not going to emit any detectable infrared radiation.

## Here's How Scientists Turned the World Into a Telescope (to See a Black Hole)

It took eight telescopes across the planet a week of observations to produce the black hole image that stunned the world last week, but it took scientists much longer to teach those instruments to work together.

And in the two years since the data behind that image was gathered, the Event Horizon Telescope partnership behind the groundbreaking observations has already expanded, with more telescopes looking to join the fray soon. Each new instrument will sharpen scientists' images of their quarry, but each will also need to be outfitted carefully before it can join the collaboration.

Fortunately, the hardest work is already done, Dan Marrone, an astronomer at the University of Arizona and a member of the Event Horizon Telescope science team, told Space.com. "For the most part, the sites we're adding now are just reimplementing the basic hardware that we know how to do well," he said.

But the more telescopes the team can bring on board, the sharper the final image is. The challenge in doing this comes from the fact that none of these telescopes were custom-built for the Event Horizon Telescope project. They're just instruments that happen to be what scientists call submillimeter telescopes, which can sense the wavelength range the Event Horizon team members needed to tune to for their black hole hunt.

For the South Pole Telescope, then, the team needed to adapt a telescope designed to study the remnants of the Big Bang, installing a special detector and an optics package. All of which, of course, needed to withstand the extreme cold of Antarctica.

And the instruments involved in the observations included both single-dish telescopes and multidish arrays. That posed a particular challenge at the Atacama Large Millimeter/submillimeter Array (ALMA) high in the Chilean desert, where information from the different dishes needed to be compiled perfectly.

Then, each of the instruments needed to be armed with an atomic clock so precise that it loses just 1 second every 100 million years. The clock's time must be imprinted on all the telescope's observations so that when scientists combine data gathered by different telescopes, the observations aren't blurred.

The other crucial equipment the team needed to install at each instrument was a system that could keep up with the massive stream of data being produced — 16 gigabits every second of the observation period, significantly more than other astronomy projects, Marrone said. That required recording systems custom-built from commercial components.

The Event Horizon Telescope team has already outfitted one newcomer this way: the Greenland Telescope, which came online for the program's 2018 observation campaign. The addition posed its own challenges: The telescope was originally built as a prototype for the dishes of ALMA, then outfitted to withstand the cold, shipped up to Greenland and set up as part of the Event Horizon Telescope.

That addition improved the team's observations of the northern part of M87, stretching the array's coverage northward. Another upcoming addition, of the Kitt Peak Telescope in Arizona, will strengthen the array in the opposite way, partnering with the nearby Submillimeter Telescope to offer scientists some redundancy, helping the team calibrate the observations. "If we could choose our array, we would have two telescopes at every site," Marrone said.

While there are plenty of schemas for how to arrange a collection of networked instruments, the team isn't really all that picky — more telescopes will always help their resolution, no matter where they are. "The Earth's terrain does a good job of randomizing where we can put them," Marrone said.

But there's no reason the Event Horizon Telescope will always need to be Earth-bound. Currently, there are no submillimeter telescopes in orbit, but some team members are looking into proposing just such an instrument. "You don't need that much of a telescope," Marrone said. "It's not quite cubesat scale, but it ain't JWST," he added, referencing the massive, over-budget and behind-schedule James Webb Space Telescope currently scheduled to launch in 2021.

And perhaps a space-based contributor would address some of the mundane challenges that haunt Marrone and his colleagues during their quest to see what can't be seen. That's because the process requires gathering data, multiplying it thousands of times, and then clarifying a perfect sine wave, rhythmic and symmetrical, from it.

"The number of days I've spent just trying to figure out what was making my sine wave wiggle, it can be really painful," Marrone said. The culprits can range from someone stepping on a cable or jumping near an atomic clock, to the wind blowing too strongly or two pieces of metal touching each other when they shouldn't.

"Doing this is a really weird job," Marrone said. "It's all these stupid little issues that we always have to sort out to get this to work." But when it works, it's worth it.

## NASA’s Hubble telescope detects supermassive black hole that defies theoretical models

NASA’s Hubble telescope has recently discovered a supermassive black hole that defies existing theories about the universe, a report said.

The black hole, which is about 250 million times heavier than the sun, lies at the heart of the spiral galaxy NGC 3147 and is 140 million light-years from Earth.

The Hubble telescope has detected a supermassive black hole that technically shouldn't exist, according to new findings. (nasa.gov)

Spotted around the black hole was a thin “accretion disk” containing debris and gas rapidly pacing around the edge, according to findings published Thursday in the journal Monthly Notices of the Royal Astronomical Society.

The black hole was unusual in that its gravitational pull was not capturing the disk of material, which was moving at 10 percent the speed of light, according to the journal.

Lead author Stefano Bianchi said it’s “the same type of disk we see in objects that are 1,000 or even 100,000 times more luminous.”

“The predictions of current models for gas dynamics in very faint active galaxies clearly failed,” Bianchi added.

By observing the disk through blocking out starlight, researchers were able to better study processes happening close to the black hole’s edge. The team said they plan to study more galaxies with the Hubble Space Telescope in the future to find similar disks of material.

Astronomers used to think spirals and ellipticals were two wholly separate classes of galaxy, but now researchers are coming to believe they are just two different stages of life. A merger between two colliding galaxies, or some other dynamic process, may transform a spiral into an elliptical.

And that halfway point between the two could perhaps be embodied by hot DOGs, scientists speculate.

"We think we may be seeing these galaxies at a crucial transformational stage," said Rachel Somerville, an astrophysicist at Rutgers University. The Milky Way itself could someday become a hot DOG, she said, after it collides with our neighbor Andromeda, which it is expected to do in about 2 billion years.

Hot DOGs are even more luminous intrinsically than the average quasar, scientists said.

"They may be hosting an extremely powerful supermassive black hole at their center which can heat the dust to high temperatures," said Jingwen Wu, also of JPL. "We may be seeing a rare phase of galactic evolution where dust and gas are heated and ejected by supermassive black holes. This may be a missing link of galaxy evolution."

WISE has now completed its mission and run out of coolant to keep its electronics cold. The telescope's operations were shut down in February 2011, but scientists anticipate many more discoveries are still to come from its observations.

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Copyright 2012 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

## How to detect black holes

Black holes are some of the most impressive and strangest astronomical oddities in existence. But, complex as they are, it was Albert Einstein who first predicted their presence back in 1916 with his theory of General Relativity. However, it wasn’t until 1967 that astronomer John Wheeler coined the name ‘black holes’, a rather precise moniker given that not even light can escape one.

#### Galactic giants

Born from the death of a star, stellar black holes are created by the collapsing of a star’s mass and are the smallest form of black hole. Just as our Sun does, stars convert hydrogen into helium during nuclear fusion at their core. The radiation caused by this reaction pushes against the star’s gravitational forces, which push inwards. As long as there is a balance between the radiation and gravity, the star will remain as it is. However, as that radiation reduces over time, the fight against gravity also decreases. Eventually the gravity of the star forces its mass to fold in on itself, creating a stellar black hole, the resulting singularity around 30 or more times the mass of our Sun. Though stellar black holes are pretty big, there are others that make them look tiny.

At the heart of galaxies are supermassive black holes. With the mass of more than 1 million Suns, these black holes are true galactic giants. While their origins are unclear, some suggest they are the result of the collapse of massive clouds of gas during the formation of the galaxy.

What is particularly interesting about supermassive black holes, and something scientist are keen to study, is its event horizon. The point at which nothing can escape the gravitation pull of a black hole, this border casts a ‘shadow’ over the black hole. For example, using a pen, draw a circle on a piece of paper. How do you see the circle on the page? The ink is revealing a circle, the same way as the event horizon reveals a black hole. At this point of descending infinite gravity, time itself is effected by the black hole’s gravity. Black holes, however, don’t act like a vacuum cleaner sucking up stardust but more a deep well into which objects irretrievably fall.

Currently, the existence of a black hole as we know it is theoretical. The reason we know these masses exist is because of the way stars and light act when one is nearby. Monitoring stars’ positions in the universe, scientists can record the way they orbit a potential black hole. Observing X-ray emissions from black holes has also proven to pinpoint these holes, but it can only get you so far without actually seeing them directly. So how do you catch a glimpse of one?

#### Peering into the unknown

Three projects have come together to form the world’s biggest array of radio telescopes and hopefully produce the required image resolution. The Event Horizon Telescope (EHT), sister project Global mm-VLBI Array (GMVA) and The Atacama Large Millimeter/submillimeter Array (ALMA) have turned the Earth into a planet-sized telescope. They will focus their attention on the compact radio source at the centre of the Milky Way. Known as Sagittarius A*, this is thought to be the location of a supermassive black hole, with the equal mass of around
4 million Suns.

Using a technique called very-long-baseline interferometry (VLBI), the array of telescopes are linked together in order to pickup the astronomical radio sources in space. Objects in space emit different radio waves and radiation, including black holes. The radiation can help produce an image: not of the black hole itself, as that would be impossible, but of its event horizon and the accretion disc that encircles it.

As a star, planet, or any matter in any form, crosses the path of a black hole, the sheer magnitude of the hole’s gravitational pull will devour it. A meal eaten so aggressively will only leave small bits of debris behind. The dust, gas and plasma that remain are held orbiting a black hole in what is known as the accretion disc and fire vertically to form relativistic jets. This is where the production of electromagnetic radiation and light is generated and shot out of the black hole. When the collision with a star produces a vast amount of energy and light it is known as a quasar. This enormous event allows the array of radio telescopes to detect the radiation, locate the event horizon and finally form a picture of a black hole’s shadow.

This planetary collaboration started collecting data in April of this year, and with the last results coming from the South Pole at the end of the year, we could finally see the first image of a black hole at the beginning of 2018.

#### A picture is worth a thousand words

Taking an image of a black hole will do more than simply show us what a black hole looks like: it could solidify the theories surrounding the phenomenon.

Einstein’s theory of General Relativity describes gravity not as a force but as a curvature of space-time. As a result of his theories, Einstein concludes the shape of a black hole is spherical, while others have suggested the shape to be ‘squashed’. It may seem strange to be concerned with the shape of a black hole, but the shape directly correlates to the way the black hole works and how we view space-time.

Imagine a tightly stretched piece of lycra, pinned at each end, with a weighted ball in the middle. This is how we currently view the workings of black holes and space-time by way of general relativity. The denser the mass of the black hole (in this case the ball) the more it affects the lycra (representing space-time). By knowing the shape and mass of a black hole we can better understand the space-time around it.

Theoretical physicist Stephen Hawking also proposed the idea that black holes emit radiation from their mass, sinking the hole and eventually leading to its total evaporation. By imaging Sagittarius A* the EHT can determine its shape and size and the decreasing factors of a black hole. This could cement or adjust these theories and allow us to gain a better understanding of the universe we live in.

It appears that alongside the remains of stars, a multitude of unanswered questions circle black holes, but by catching a glimpse of one scientists could start answering them.

## NASA's NuSTAR Space Telescope Discovers 10 Monster Black Holes

A powerful NASA space telescope has found not one, but 10 monster black holes lurking in the hearts of distant galaxies — the first major finds for the X-ray space observatory, scientists say.

The discoveries, which scientists say occurred "serendipitously," were made as astronomers reviewed images from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), an X-ray space telescope designed specifically to hunt black holes.

"We were looking at known targets and spotted the black holes in the background of the images," David Alexander, a professor with Durham University's physics department, said in a statement.

Then the team confirmed what they saw with observations from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite, which also can look at low-energy light.

The 10 black holes discovered are just the beginning of hundreds of expected finds, the scientists added. With every supermassive black hole catalogued, scientists are hoping to better understand the population.

Surrounded by galaxies

According to NASA, discovering the supermassive black holes were a key piece of a puzzle first uncovered in 1962. Astronomers found a glow of X-rays in the background of the universe, but didn't know where the glow came from.

Today, scientists know the glow (also called the cosmic X-ray background) comes from very distant supermassive black holes, some of which are as large as 17 billion times the mass of the sun. But how these black holes form is still under investigation.

"Our early results show that the more distant supermassive black holes are encased in bigger galaxies," stated Daniel Stern, a co-author of the study and the project scientist for NuSTAR at NASA's Jet Propulsion Laboratory. "This is to be expected. Back when the universe was younger, there was a lot more action with bigger galaxies colliding, merging and growing."

While NuSTAR can detect these big black holes, other measurements (such as mass) come from agency observatories including the Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope.

## How NASA’s Roman Space Telescope Will Uncover Lonesome Black Holes

NASA&rsquos Nancy Grace Roman Space Telescope will provide an unprecedented window into the infrared universe when it launches in the mid-2020s. One of the mission&rsquos planned surveys will use a quirk of gravity to reveal thousands of new planets beyond our solar system. The same survey will also provide the best opportunity yet to definitively detect solitary small black holes for the first time. Formed when a star with more than 20 solar masses exhausts the nuclear fuel in its core and collapses under its own weight, these objects are known as stellar-mass black holes.

Black holes have such powerful gravity that not even light can escape their clutches. Since they&rsquore invisible, we can only find black holes indirectly, by seeing how they affect their surroundings. The supermassive black holes found at the centers of galaxies, which contain millions of times the mass of the Sun, disrupt the orbits of nearby stars and occasionally tear them apart with visible consequences.

But astronomers think the vast majority of stellar-mass black holes, which are much lighter, have nothing around them that can tip us off to their presence. Roman will find planets throughout our galaxy by observing how their gravity distorts distant starlight, and because stellar-mass black holes produce the same effects, the mission should be able to find them too.

This animation illustrates the concept of gravitational microlensing with a black hole. When the black hole appears to pass nearly in front of a background star, the light rays of the star become bent as they travel through the warped space-time around the black hole. It becomes a virtual magnifying glass, amplifying the brightness of the distant background star. Unlike when a less massive star or planet is the lensing object, black holes warp space-time so much that it noticeably alters the distant star&rsquos apparent location in the sky. Credits: NASA's Goddard Space Flight Center/Conceptual Image Lab

&ldquoAstronomers have identified about 20 stellar-mass black holes so far in the Milky Way, but all of them have a companion that we can see,&rdquo said Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore. &ldquoMany scientists, myself included, have spent years trying to find black holes on their own using other telescopes. It&rsquos exciting that with Roman, it will finally be possible.&rdquo

Making a black hole
Stars seem like eternal beacons, but each is born with a limited supply of fuel. Stars spend the majority of their lives turning hydrogen in their centers into helium, which creates an enormous amount of energy. This process, called nuclear fusion, is like a controlled explosion &ndash a finely balanced game of tug-of-war between outward pressure and gravity.

But as a star&rsquos fuel runs low and fusion slows, gravity takes over and the star&rsquos core contracts. This inward pressure heats up the core and sparks a new round of fusion, which produces so much energy that the star&rsquos outer layers expand. The star swells in size, its surface cools, and it becomes a red giant or supergiant.

The type of stellar corpse that&rsquos ultimately left behind depends on the star&rsquos mass. When a Sun-like star runs out of fuel, it eventually ejects its outer layers, and only a small, hot core called a white dwarf remains. The white dwarf will fade out over time, like the dying embers of a once-roaring fire. Our Sun has about five billion years of fuel remaining.

More massive stars run hotter, so they use up their fuel faster. Above about eight times the mass of the Sun, most stars are doomed to die in cataclysmic explosions called supernovae before becoming black holes. At the highest masses, stars may skip the explosion and collapse directly into black holes.

The cores of these massive stars collapse until their protons and electrons crush together to form neutrons. If the leftover core weighs less than about three solar masses, the collapse stops there, leaving behind a neutron star. For larger leftover cores, even the neutrons cannot support the pressure and the collapse continues to form a black hole.

Millions of massive stars have undergone this process and now lurk throughout the galaxy as black holes. Astronomers think there should be about 100 million stellar-mass black holes in our galaxy, but we&rsquove only been able to find them when they noticeably affect their surroundings. Astronomers can infer the presence of a black hole when hot, glowing accretion disks form around them, or when they spot stars orbiting a massive but invisible object.

&ldquoRoman will revolutionize our search for black holes because it will help us find them even when there&rsquos nothing nearby,&rdquo Sahu said. &ldquoThe galaxy should be littered with these objects.&rdquo

###### Seeing the invisible

Roman will primarily use a technique called gravitational microlensing to discover planets beyond our solar system. When a massive object, such as a star, crosses in front of a more distant star from our vantage point, light from the farther star will bend as it travels through the curved space-time around the nearer one.

The result is that the closer star acts as a natural lens, magnifying light from the background star. Planets orbiting the lens star can produce a similar effect on a smaller scale.

In addition to causing a background star to brighten, a more massive lensing object can warp space-time so much that it noticeably alters the distant star&rsquos apparent location in the sky. This change in position, called astrometric microlensing, is extremely small &ndash only about one milliarcsecond. That&rsquos like distinguishing movement as small as about the width of a quarter on top of the Empire State Building in New York all the way from Los Angeles. Using Roman&rsquos exquisite spatial resolution to detect such a tiny apparent movement &ndash the telltale sign of a massive black hole &ndash astronomers will be able to constrain the black hole&rsquos mass, distance, and motion through the galaxy.

Microlensing signals are so rare that astronomers need to monitor hundreds of millions of stars for long periods to catch them. Observatories must be able to track the position and brightness of the background star extremely precisely &ndash something that can only be done from above Earth&rsquos atmosphere. Roman&rsquos location in space and enormous field of view will provide us with the best opportunity yet to probe our galaxy&rsquos black hole population.

&ldquoThe stellar-mass black holes we&rsquove discovered in binary systems have strange properties compared to what we expect,&rdquo Sahu said. &ldquoThey&rsquore all about 10 times more massive than the Sun, but we think they should span a much wider range of between three and 80 solar masses. By conducting a census of these objects, Roman will help us understand more about stars&rsquo death throes.&rdquo

The Nancy Grace Roman Space Telescope is managed at NASA&rsquos Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA's Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are Ball Aerospace and Technologies Corporation in Boulder, Colorado, L3Harris Technologies in Melbourne, Florida, and Teledyne Scientific & Imaging in Thousand Oaks, California.

Banner: This illustration shows the concept of gravitational microlensing with a black hole. When a black hole passes nearly in front of a more distant star, it can lens light from the star. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab​

By Ashley Balzer
NASA&rsquos Goddard Space Flight Center, Greenbelt, Md.

Claire Andreoli
NASA&rsquos Goddard Space Flight Center, Greenbelt, Md.
301-286-1940

## NASA Space Telescope Discovers 10 Monster Black Holes

A powerful NASA space telescope has found not one, but 10 monster black holes lurking in the hearts of distant galaxies — the first major finds for the X-ray space observatory, scientists say.

The discoveries, which scientists say occurred “serendipitously,” were made as astronomers reviewed images from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), an X-ray space telescope designed specifically to hunt black holes.

“We were looking at known targets and spotted the black holes in the background of the images,” David Alexander, a professor with Durham University’s physics department, said in a statement.

Then the team confirmed what they saw with observations from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton satellite, which also can look at low-energy light.

(MORE: Supermassive Black Hole Spins Super Fast)

The 10 black holes discovered are just the beginning of hundreds of expected finds, the scientists added. With every supermassive black hole catalogued, scientists are hoping to better understand the population.

Surrounded by galaxies
According to NASA, discovering the supermassive black holes were a key piece of a puzzle first uncovered in 1962. Astronomers found a glow of X-rays in the background of the universe, but didn’t know where the glow came from.

Today, scientists know the glow (also called the cosmic X-ray background) comes from very distant supermassive black holes, some of which are as large as 17 billion times the mass of the sun. But how these black holes form is still under investigation.

“Our early results show that the more distant supermassive black holes are encased in bigger galaxies,” stated Daniel Stern, a co-author of the study and the project scientist for NuSTAR at NASA’s Jet Propulsion Laboratory. “This is to be expected. Back when the universe was younger, there was a lot more action with bigger galaxies colliding, merging and growing.”

While NuSTAR can detect these big black holes, other measurements (such as mass) come from agency observatories including the Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope.

## Black Hole 'Bonanza': Millions Found by NASA Space Telescope

A jackpot of previously unknown black holes across the universe has been discovered by the infrared eyes of a prolific NASA sky-mapping telescope.

The cosmic find comes from data collected by NASA's Wide-field Infrared Survey (WISE) telescope, which scanned the entire sky in infrared light from December 2009 to February 2011. The full catalog of observations by WISE during its mission was publicly released in March, and astronomers are still poring through this celestrial trove for discoveries.

"WISE has found a bonanza of black holes in the universe," astronomer Daniel Stern of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said during a news briefing today (Aug. 29). WISE turned up about three times as many black holes as have been found by comparable surveys in visible light, offering up a total of 2.5 million new sources across the sky.

These black holes aren't the average tiny, dense objects created by the collapse of dead stars, but rather humongous "supermassive" black holes that have been caught feasting on matter falling into them. Such active black holes are known as quasars, and are some of the brightest objects in the universe, because of light released by the infalling matter. [Photos: Millions of Black Holes Seen by WISE Telescope]

"We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky," Stern said. "We think these quasars are really important for shaping how galaxies look today."

Cosmic Hot DOGs

In addition to this haul of gorging black holes, WISE has turned up a smaller population of rarer objects researchers are dubbing "hot DOGs," for hot, dust-obscured galaxies.

These galaxies are thought to be extremely bright, but appear very faint to us because their light is shrouded by dust.

"It is actually the most obscured objects in the WISE sky that are among the brightest objects in the universe," said Peter Eisenhardt, a WISE project scientist at JPL. "They're definitely a different type of beast than we&rsquove seen before."

The hot DOGs observed by WISE number about 1,000, and are mostly spotted from very far away, meaning they existed in the early days of the universe, because their light has taken billions of years to travel to Earth.

Scientists suspect these weird objects may represent a missing link in galaxy evolution, capturing a brief phase in the life of a galaxy that is transitioning from being a spiral disk galaxy like our milky way to what's called an elliptical galaxy.

Astronomers used to think spirals and ellipticals were two wholly separate classes of galaxy, but now researchers are coming to believe they are just two different stages of life. A merger between two colliding galaxies, or some other dynamic process, may transform a spiral into an elliptical.

And that halfway point between the two could perhaps be embodied by hot DOGs, scientists speculate.

"We think we may be seeing these galaxies at a crucial transformational stage," said Rachel Somerville, an astrophysicist at Rutgers University. The Milky Way itself could someday become a hot DOG, she said, after it collides with our neighbor Andromeda, which it is expected to do in about 2 billion years.

Hot DOGs are even more luminous intrinsically than the average quasar, scientists said.

"They may be hosting an extremely powerful supermassive black hole at their center which can heat the dust to high temperatures," said Jingwen Wu, also of JPL. "We may be seeing a rare phase of galactic evolution where dust and gas are heated and ejected by supermassive black holes. This may be a missing link of galaxy evolution."

WISE has now completed its mission and run out of coolant to keep its electronics cold. The telescope's operations were shut down in February 2011, but scientists anticipate many more discoveries are still to come from its observations.

## Black Holes: Millions Revealed By NASA's WISE Space Telescope

A jackpot of previously unknown black holes across the universe has been discovered by the infrared eyes of a prolific NASA sky-mapping telescope.

The cosmic find comes from data collected by NASA's Wide-field Infrared Survey (WISE) telescope, which scanned the entire sky in infrared light from December 2009 to February 2011. The full catalog of observations by WISE during its mission was publicly released in March, and astronomers are still poring through this celestrial trove for discoveries.

"WISE has found a bonanza of black holes in the universe," astronomer Daniel Stern of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said during a news briefing today (Aug. 29). WISE turned up about three times as many black holes as have been found by comparable surveys in visible light, offering up a total of 2.5 million new sources across the sky.

These black holes aren't the average tiny, dense objects created by the collapse of dead stars, but rather humongous "supermassive" black holes that have been caught feasting on matter falling into them. Such active black holes are known as quasars, and are some of the brightest objects in the universe, because of light released by the infalling matter. [Photos: Millions of Black Holes Seen by WISE Telescope]

"We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky," Stern said. "We think these quasars are really important for shaping how galaxies look today."

This zoomed-in view of a portion of the all-sky survey from WISE shows a collection of quasar candidates.

Cosmic Hot DOGs

In addition to this haul of gorging black holes, WISE has turned up a smaller population of rarer objects researchers are dubbing "hot DOGs," for hot, dust-obscured galaxies.

These galaxies are thought to be extremely bright, but appear very faint to us because their light is shrouded by dust.

"It is actually the most obscured objects in the WISE sky that are among the brightest objects in the universe," said Peter Eisenhardt, a WISE project scientist at JPL. "They're definitely a different type of beast than we’ve seen before."

The hot DOGs observed by WISE number about 1,000, and are mostly spotted from very far away, meaning they existed in the early days of the universe, because their light has taken billions of years to travel to Earth.

Scientists suspect these weird objects may represent a missing link in galaxy evolution, capturing a brief phase in the life of a galaxy that is transitioning from being a spiral disk galaxy like our milky way to what's called an elliptical galaxy.

Astronomers used to think spirals and ellipticals were two wholly separate classes of galaxy, but now researchers are coming to believe they are just two different stages of life. A merger between two colliding galaxies, or some other dynamic process, may transform a spiral into an elliptical.

And that halfway point between the two could perhaps be embodied by hot DOGs, scientists speculate.

"We think we may be seeing these galaxies at a crucial transformational stage," said Rachel Somerville, an astrophysicist at Rutgers University. The Milky Way itself could someday become a hot DOG, she said, after it collides with our neighbor Andromeda, which it is expected to do in about 2 billion years.

Hot DOGs are even more luminous intrinsically than the average quasar, scientists said.

"They may be hosting an extremely powerful supermassive black hole at their center which can heat the dust to high temperatures," said Jingwen Wu, also of JPL. "We may be seeing a rare phase of galactic evolution where dust and gas are heated and ejected by supermassive black holes. This may be a missing link of galaxy evolution."

WISE has now completed its mission and run out of coolant to keep its electronics cold. The telescope's operations were shut down in February 2011, but scientists anticipate many more discoveries are still to come from its observations.

## Black Hole 'Bonanza': Millions Found by NASA Space Telescope

A jackpot of previously unknown black holes across the universe has been discovered by the infrared eyes of a prolific NASA sky-mapping telescope.

The cosmic find comes from data collected by NASA's Wide-field Infrared Survey (WISE) telescope, which scanned the entire sky in infrared light from December 2009 to February 2011. The full catalog of observations by WISE during its mission was publicly released in March, and astronomers are still poring through this celestrial trove for discoveries.

"WISE has found a bonanza of black holes in the universe," astronomer Daniel Stern of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said during a news briefing today (Aug. 29). WISE turned up about three times as many black holes as have been found by comparable surveys in visible light, offering up a total of 2.5 million new sources across the sky.

These black holes aren't the average tiny, dense objects created by the collapse of dead stars, but rather humongous "supermassive" black holes that have been caught feasting on matter falling into them. Such active black holes are known as quasars, and are some of the brightest objects in the universe, because of light released by the infalling matter. [Photos: Millions of Black Holes Seen by WISE Telescope]

"We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky," Stern said. "We think these quasars are really important for shaping how galaxies look today."

Cosmic Hot DOGs

In addition to this haul of gorging black holes, WISE has turned up a smaller population of rarer objects researchers are dubbing "hot DOGs," for hot, dust-obscured galaxies.

These galaxies are thought to be extremely bright, but appear very faint to us because their light is shrouded by dust.

"It is actually the most obscured objects in the WISE sky that are among the brightest objects in the universe," said Peter Eisenhardt, a WISE project scientist at JPL. "They're definitely a different type of beast than we’ve seen before."

The hot DOGs observed by WISE number about 1,000, and are mostly spotted from very far away, meaning they existed in the early days of the universe, because their light has taken billions of years to travel to Earth.

Scientists suspect these weird objects may represent a missing link in galaxy evolution, capturing a brief phase in the life of a galaxy that is transitioning from being a spiral disk galaxy like our milky way to what's called an elliptical galaxy.

Astronomers used to think spirals and ellipticals were two wholly separate classes of galaxy, but now researchers are coming to believe they are just two different stages of life. A merger between two colliding galaxies, or some other dynamic process, may transform a spiral into an elliptical.

And that halfway point between the two could perhaps be embodied by hot DOGs, scientists speculate.

"We think we may be seeing these galaxies at a crucial transformational stage," said Rachel Somerville, an astrophysicist at Rutgers University. The Milky Way itself could someday become a hot DOG, she said, after it collides with our neighbor Andromeda, which it is expected to do in about 2 billion years.

Hot DOGs are even more luminous intrinsically than the average quasar, scientists said.

"They may be hosting an extremely powerful supermassive black hole at their center which can heat the dust to high temperatures," said Jingwen Wu, also of JPL. "We may be seeing a rare phase of galactic evolution where dust and gas are heated and ejected by supermassive black holes. This may be a missing link of galaxy evolution."

WISE has now completed its mission and run out of coolant to keep its electronics cold. The telescope's operations were shut down in February 2011, but scientists anticipate many more discoveries are still to come from its observations.