The supernova remnant G352.7-0.1 in a composite image with X-rays from the Chandra X-Ray Telescope (blue), radio waves from the Very Large Array (pink), infrared information from the Spitzer Space Telescope (orange) and optical data from the Digital Sky Survey (white). Credit: X-ray: NASA/CXC/Morehead State Univ/T.Pannuti et al.; Optical: DSS; Infrared: NASA/JPL-Caltech; Radio: NRAO/VLA/Argentinian Institute of Radioastronomy/G.Dubner
Shining 24,000 light-years from Earth is an expanding leftover of a supernova that is doing a great cleanup job in its neighborhood. As this new composite image from NASA reveals, G352.7-0.1 (G352 for short) is more efficient than expected, picking up debris equivalent to about 45 times the mass of the Sun.
“A recent study suggests that, surprisingly, the X-ray emission in G352 is dominated by the hotter (about 30 million degrees Celsius) debris from the explosion, rather than cooler (about 2 million degrees) emission from surrounding material that has been swept up by the expanding shock wave,” the Chandra X-Ray Observatory’s website stated.
“This is curious because astronomers estimate that G352 exploded about 2,200 years ago, and supernova remnants of this age usually produce X-rays that are dominated by swept-up material. Scientists are still trying to come up with an explanation for this behavior.”
A grouping of galaxies, known as J0717 (center) is visible in this Spitzer Space Telescope image. Credit: NASA/JPL-Caltech/P. Capak (Caltech)
Talk about turning back time. Three NASA observatories — the Hubble Space Telescope, the Chandra X-Ray Observatory and the Spitzer Space Telescope — are all working together to look for the universe’s first galaxies. The project is called “Frontier Fields” and aims to examine these galaxies through a technique called gravitational lensing, which allows astronomers to peer at more distant objects when massive objects in front bend their light.
“Our overall science goal with the Frontier Fields is to understand how the first galaxies in the universe assembled,” stated Peter Capak, a research scientist with the NASA/JPL Spitzer Science Center at the California Institute of Technology and the Spitzer lead for the Frontier Fields.
“This pursuit is made possible by how massive galaxy clusters warp space around them, kind of like when you look through the bottom of a wine glass.”
Using the three observatories allows investigators to peer at the galaxies in different light wavelengths (namely, infrared for Spitzer, shorter infrared and optical for Hubble, and X-rays for Chandra). The teams also plan to learn more about how the foreground clusters influence the “warping” of the galaxies behind.
The Hubble and Spitzer telescopes are designed to locate where the galaxies are (and if they are indeed early galaxies) while Chandra can map out the X-ray emissions to better determine the galaxies’ masses. An early example of this project at work was examination of Abell 2744, which yielded a distant find: Abell2744 Y1, one of the earliest known galaxies, which was born about 650 million years after the Big Bang.
Hubble Space Telescope deep image of galaxy cluster Abell 2744. Credit: NASA, ESA, J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI), and N. Laporte (Instituto de Astrofisica de Canarias)
Peering deep into the universe with the Hubble Space Telescope, a team of researchers have found an extremely distant galaxy. It was discovered in Abell 2744, a galaxy cluster. The galaxy (called Abell2744_Y1) was spotted at a time when it was just 650 million years after the universe-forming Big Bang (which makes it more than 13 billion years old).
This demonstrates the potential of a relatively new project, researchers said, called “Hubble Frontier Fields.” It’s part of an effort where Hubble and fellow NASA space telescopes Spitzer and the Chandra X-ray Observatory will examine six galaxy clusters that bend the light from more distant objects in the background. By doing this, researchers hope to learn more about galaxies formed in the universe’s first billion years.
“We expected to find very distant galaxies close to the cluster core, where the light amplification is maximum. However, this galaxy is very close to the edge of the Hubble image where the light is not strongly amplified,” stated Nicolas Laporte, a post-doctoral researcher at the Institute of Astrophysics of the Canary Islands (Instituto de Astrofisica de Canarias) who led the study.
“We are really lucky that we could find it in the small field of view of Hubble. In a related study led by Hakim Atek … more galaxies are analyzed but none is more distant than Abell2744_Y1.”
A composite image (X-ray and optical wavelengths) showing galaxy cluster RX J1532.9+3021 and the black hole at its center. Credit: X-ray: NASA/CXC/Stanford/J.Hlavacek-Larrondo et al, Optical: NASA/ESA/STScI/M.Postman & CLASH team
Got gas? The black hole in galaxy cluster RX J1532.9+3021 is keeping it all for itself and stopping trillions of stars from coming to be, according to new research. You can see data above from NASA’s Chandra X-ray Observatory (purple) and the Hubble Space Telescope (yellow).
The drama is taking place about 3.9 billion light-years from Earth, showing an extreme phenomenon that has been noted in other galaxies on smaller scales, Chandra officials stated.
“The large amount of hot gas near the center of the cluster presents a puzzle,” a statement read. “Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.”
Black hole with disc and jets visualization courtesy of ESA
What’s blocking the stars (according to data from Chandra and the National Science Foundation’s Karl G. Jansky Very Large Array) could be supersonic jets blasting from the black hole and shoving the gas in the area away, forming cavities on either side of the galaxy. These cavities, by the way, are immense — at 100,000 light-years across each, this makes them about as wide as our home galaxy, the Milky Way.
The big question is where that power came from. Perhaps the black hole is “ultramassive” (10 billion times of the sun) and has ample mass to shoot out those jets without eating itself up and producing radiation. Or, the black hole could be smaller (a billion times that of the sun) but spinning quickly, which would allow it to send out those jets.
A composite image in X-ray and radio showing a likely candidate for a jet emanating from the supermassive black hole at the center of the Milky Way. X-ray: NASA/CXC/UCLA/Z.Li et al; Radio: NRAO/VLA
Jets of high energy particles emanating from a black hole have been detected plenty of times before, but in other galaxies, that is — not from the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*). Previous studies and other evidence suggested that perhaps there were jets – or ghosts of past jets – but many findings and studies often contradicted each other, and none were considered definitive.
Now, astronomers using Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope have found strong evidence Sgr A* is producing a jet of high-energy particles.
“For decades astronomers have looked for a jet associated with the Milky Way’s black hole. Our new observations make the strongest case yet for such a jet,” said Zhiyuan Li of Nanjing University in China, lead author of a study in The Astrophysical Journal.
The supermassive black hole at the center of the Milky Way is about four million times more massive than our Sun and lies about 26,000 light-years from Earth.
While the common notion is that black holes inhale and ingest everything that comes their way, that’s not always true. Sometimes they reject small portions of incoming mass, pushing it away in the form of a powerful jet, and many times a pair of jets. These jets also feed the surroundings, releasing both mass and energy and likely play important roles in regulating the rate of formation of new stars.
Sgr A* is presently known to be consuming very little material, and so the jet is weak, making it difficult to detect. Astronomers don’t see another jet “shooting” in the opposite direction but that may be because of gas or dust blocking the line of sight from Earth or a lack of material to fuel the jet. Or there may be just a single jet.
“We were very eager to find a jet from Sgr A* because it tells us the direction of the black hole’s spin axis. This gives us important clues about the growth history of the black hole,” said Mark Morris of the University of California at Los Angeles, a co-author of the study.
The study shows the spin axis of Sgr A* is pointing in one direction, parallel to the rotation axis of the Milky Way, which indicates to astronomers that gas and dust have migrated steadily into Sgr A* over the past 10 billion years. If the Milky Way had collided with large galaxies in the recent past and their central black holes had merged with Sgr A*, the jet could point in any direction.
The jet appears to be running into gas near Sgr A*, producing X-rays detected by Chandra and radio emission observed by the VLA. The two key pieces of evidence for the jet are a straight line of X-ray emitting gas that points toward Sgr A* and a shock front — similar to a sonic boom — seen in radio data, where the jet appears to be striking the gas. Additionally, the energy signature, or spectrum, in X-rays of Sgr A* resembles that of jets coming from supermassive black holes in other galaxies.
The Chandra observations in this study were taken between September 1999 and March 2011, with a total exposure of about 17 days.
X-ray emissions from the supermassive black hole in the center of the Milky Way galazy, about 26,000 light years from Earth. Credit: NASA/CXC/APC/Université Paris Diderot/M.Clavel et al
How’s that for a beacon? NASA’s Chandra X-ray Observatory has tracked down evidence of at least a couple of past luminous outbursts near the Milky Way’s huge black hole. These flare-ups took place sometime in the past few hundred years, which is very recently in astronomical terms.
“The echoes from Sagittarius A were likely produced when large clumps of material, possibly from a disrupted star or planet, fell into the black hole,” the Chandra website stated.
“Some of the X-rays produced by these episodes then bounced off gas clouds about 30 to 100 light years away from the black hole, similar to how the sound from a person’s voice can bounce off canyon walls. Just as echoes of sound reverberate long after the original noise was created, so too do light echoes in space replay the original event.”
The astronomers saw evidence of “rapid variations” in how X-rays are emitted from gas clouds circling the hole, revealing clues that the area likely got a million times brighter at times.
This graphic depicts HD 189733b, the first exoplanet caught passing in front of its parent star in X-rays. Credit: X-ray: NASA/CXC/SAO/K.Poppenhaeger et al; Illustration: NASA/CXC/M.Weiss.
In the medical field, X-rays are used for finding and diagnosing all sorts of ailments hidden inside the body; in astronomy X-rays can also be used to study obscured objects like pulsars and black holes. Now, for the first time, X-rays have been used to study another object in space that tends to be difficult to spot: an extra solar planet. The Chandra X-ray Observatory and the XMM Newton Observatory combined their X-ray super powers to look at an exoplanet passing in front of its parent star.
This is not a new detection of an exoplanet – this same exoplanet, named HD 189733b has been one of the most-observed planets orbiting another star, and was recently in the news for Hubble confirming the planet’s ocean-blue atmosphere and the likelihood of having glass raining down on the planet.
But being able to see the exoplanet in X-rays is good news for future studies and perhaps even detections of planets around other stars.
“Thousands of planet candidates have been seen to transit in only optical light,” said Katja Poppenhaeger of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study, which will be published in the Aug. 10 edition of The Astrophysical Journal. “Finally being able to study one in X-rays is important because it reveals new information about the properties of an exoplanet.”
Artist’s impression of the deep blue planet HD 189733b, based on observations from the Hubble Space Telescope. Credit: NASA/ESA.
HD 189733b is a Jupiter-sized extrasolar planet orbiting a yellow dwarf star that is in a binary system called HD 189733 in the constellation of Vulpecula, near the Dumbell Nebula, approximately 62 light years from Earth.
This huge gas giant orbits very close to its host star and gets blasted with X-rays from its star — tens of thousands of times stronger than the Earth receives from the Sun — and endures wild temperature swings, reaching scorching temperatures of over 1,000 degrees Celsius. Astronomers say it likely rains glass (silicates) – sideways — in howling 7,000 kilometer-per-hour winds.
But it is relatively close to Earth, and so it has been oft-studied by many other space and ground-based telescopes.
In a blog post, Poppenhaeger said she was inspired by the launch of the Kepler telescope, and wondered if exoplanets could be seen in X-rays. She was excited when she found archived data from XMM Newton showing a fifteen hour long observation of the star HD 189733 and the “Hot Jupiter” HD 189733b was crossing in front of the star during that observation.
But the light curve was disappointing, she said. “The star is magnetically active, meaning that its corona is bright and flickering, so its X-ray light curve showed lots of scatter. Looking for a transit signal in this light curve was like trying to hear a whisper in a noisy pub,” Poppenhaeger wrote.
She knew with more data, the transit signal would be clearer, so she applied for – and got – time on Chandra to observe this exoplanet.
She combined the data from all the observations and was finally successful. “I could detect the transit of the planet in X-rays,” Poppenhaeger said. “What surprised me was how deep the transit was: The planet swallowed about 6-8% of the X-ray light from the star, while it only blocked 2.4% of the starlight at optical wavelengths. That means that the planet’s atmosphere blocks X-rays at altitudes of more than 60,000 km above its optical radius – a 75% larger radius in X-rays!”
That means that the outer atmosphere has to be heated up to about 20,000 K to sustain itself at such high altitudes. Additionally, the planet loses its atmosphere about 40% faster than thought before.
Poppenhaeger said she and her colleagues will test more X-ray observations of other similar planets such as CoRoT-2b to learn more about how stars can affect a planet’s atmosphere.
G1.9+0.3 in an image by the Chandra X-ray Observatory. Credit: X-ray (NASA/CXC/NCSU/K.Borkowski et al.); Optical (DSS)
In 2008, astronomers discovered a star relatively nearby Earth went kablooie some 28,000 light-years away from us. Sharp-eyed astronomers, as they will do, trained their telescopes on it to snap pictures and take observations. Now, fresh observations from the orbiting Chandra X-ray Observatory suggest that supernova was actually a double-barrelled explosion.
This composite picture of G1.9+0.3, coupled with models by astronomers, suggest that this star had a “delayed detonation,” NASA stated.
“First, nuclear reactions occur in a slowly expanding wavefront, producing iron and similar elements. The energy from these reactions causes the star to expand, changing its density and allowing a much faster-moving detonation front of nuclear reactions to occur.”
To explain a bit better what’s going on with this star, there are two main types of supernovas:
In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to collapse and then explosion. Credit: NASA
– Type Ia: When a white dwarf merges with another white dwarf, or picks up matter from a close star companion. When enough mass accretes on the white dwarf, it reaches a critical density where carbon and oxygen fuse, then explodes.
– Type II: When a massive star reaches the end of its life, runs out of nuclear fuel and sees its iron core collapse.
NASA said this was a Type Ia supernova that “ejected stellar debris at high velocities, creating the supernova remnant that is seen today by Chandra and other telescopes.”
In this artist’s conception, a supernova explosion is about to obliterate an orbiting Saturn-like planet. Credit: David A. Aguilar (CfA)
You can actually see the different energies from the explosion in this picture, with red low-energy X-rays, green intermediate energies and blue high-energies.
“The Chandra data show that most of the X-ray emission is “synchrotron radiation,” produced by extremely energetic electrons accelerated in the rapidly expanding blast wave of the supernova. This emission gives information about the origin of cosmic rays — energetic particles that constantly strike the Earth’s atmosphere — but not much information about Type Ia supernovas,” NASA stated.
Also, unusually, this is an assymetrical explosion. There could have been variations in how it expanded, but astronomers are looking to map this out with future observations with Chandra and the National Science Foundation’s Karl G. Jansky Very Large Array.
Check out more information about this supernova in the scientific paper led by North Carolina State University.
A new analysis of data from the Chandra space telescope revealed 26 black hole candidates in the Andromeda Galaxy. This is the largest collection of possible black holes found in another galaxy besides that of the Milky Way, Earth's home galaxy. Credit: X-ray (NASA/CXC/SAO/R.Barnard, Z.Lee et al.), Optical (NOAO/AURA/NSF/REU Prog./B.Schoening, V.Harvey; Descubre Fndn./CAHA/OAUV/DSA/V.Peris)
More than two DOZEN potential black holes have been found in the nearest galaxy to our own. As if that find wasn’t enough, another research group is teaching us why extremely high-energy X-rays are present in black holes.
The Andromeda Galaxy (M31) is home to 26 newly found black hole candidates that were produced from the collapse of stars that are five to 10 times as massive as the sun.
Using 13 years of observations from NASA’s Chandra X-Ray Observatory, a research team pinpointed the locations. They also corroborated the information with X-ray spectra (distribution of X-rays with energy) from the European Space Agency’s XMM-Newton X-ray observatory.
“When it comes to finding black holes in the central region of a galaxy, it is indeed the case where bigger is better,” stated co-author Stephen Murray, an astronomer at Johns Hopkins University and the Harvard-Smithsonian Center for Astrophysics.
A close-up of the candidate black holes in Andromeda, as seen by the Chandra X-Ray Observatory. Credit: X-ray (NASA/CXC/SAO/R.Barnard, Z.Lee et al.), Optical (NOAO/AURA/NSF/REU Prog./B.Schoening, V.Harvey; Descubre Fndn./CAHA/OAUV/DSA/V.Peris
“In the case of Andromeda, we have a bigger bulge and a bigger supermassive black hole than in the Milky Way, so we expect more smaller black holes are made there as well,” Murray added.
The total number of candidates in M31 now stands at 35, since the researchers previously identified nine black holes in the area. All told, it’s the largest number of black hole candidates identified outside of the Milky Way.
Meanwhile, a study led by the NASA Goddard Space Flight Center examined the high-radiation environment inside a black hole — by simulation, of course. The researchers performed a supercomputer modelling of gas moving into a black hole, and found that their work helps explain some mysterious X-ray observations of recent decades.
Researchers distinguish between “soft” and “hard” X-rays, or those X-rays that have low and high energy. Both types have been observed around black holes, but the hard ones puzzled astronomers a bit.
Here’s what happens inside a black hole, as best as we can figure:
– Gas falls towards the singularity, orbits the black hole, and gradually becomes a flattened disk;
– As gas piles up in the center of the disk, it compresses and heats up;
– At a temperature of about 20 million degrees Fahrenheit (12 million degrees Celsius), the gas emits “soft” X-rays.
So where did the hard X-rays — that with energy tens or even hundreds of times greater than soft X-rays — come from? The new study showed that magnetic fields are amplified in this environment that then “exerts additional influence” on the gas, NASA stated.
Artist’s conception of the Chandra X-Ray Observatory. Credit: NASA
“The result is a turbulent froth orbiting the black hole at speeds approaching the speed of light. The calculations simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein’s theory of relativity,” NASA stated.
One key limitation of the study was it modelled a non-rotating black hole. Future work aims to model one that is rotating, NASA added.
You can check out more information about these two studies below:
This all-sky Fermi view includes only sources with energies greater than 10 GeV. From some of these sources, Fermi's LAT detects only one gamma-ray photon every four months. Brighter colors indicate brighter gamma-ray sources. Credit: NASA/DOE/Fermi LAT Collaboration
The universe, most cosmologists tell us, began with a bang. At some point, the lights turned on. How much light has the universe produced since it was born, 13.8 billion years ago?
It seems a difficult answer at first glance. Turn on a light bulb, turn it off and the photons appear to vanish. In space, however, we can track them down. Every light particle ever radiated by galaxies and stars is still travelling, which is why we can peer so far back in time with our telescopes.
A new paper in the Astrophysical Journal explores the nature of this extragalactic background light, or EBL. Measuring the EBL, the team states, “is as fundamental to cosmology as measuring the heat radiation left over from the Big Bang (the cosmic microwave background) at radio wavelengths.”
Turns out that several NASA spacecraft have helped us understand the answer. They peered at the universe in every wavelength of light, ranging from long radio waves to short, energy-filled gamma rays. While their work doesn’t go back to the origin of the universe, it does give good measurements for the last five billion years or so. (About the age of the solar system, coincidentally.)
Artist’s conception of how gamma rays (dashed lines) bump against photons of electromagnetic background light, producing electrons and positrons. Credit: Nina McCurdy and Joel R. Primack/UC-HiPACC; Blazar: Frame from a conceptual animation of 3C 120 created by Wolfgang Steffen/UNAM
It’s hard to see this faint background light against the powerful glow of stars and galaxies today, about as hard as it is to see the Milky Way from downtown Manhattan, the astronomers said.
The solution involves gamma rays and blazars, which are huge black holes in the heart of a galaxy that produce jets of material that point towards Earth. Just like a flashlight.
These blazars emit gamma rays, but not all of them reach Earth. Some, astronomers said, “strike a hapless EBL photon along the way.”
When this happens, the gamma ray and photon each zap out and produce a negatively charged electron and a positively charged positron.
More interestingly, blazars produce gamma rays at slightly different energies, which are in turn stopped by EBL photons at different energies themselves.
So, by figuring out how many gamma rays with different energies are stopped by the photons, we can see how many EBL photons are between us and the distant blazars.
Scientists have now just announced they could see how the EBL changed over time. Peering further back in the universe, as we said earlier, serves as a sort of time machine. So, the further back we see the gamma rays zap out, the better we can map out the EBL’s changes in earlier eras.
The Fermi Gamma-ray Space Telescope (formerly called GLAST). Credit: NASA
To get technical, this is how the astronomers did it:
– Compared the gamma-ray findings of the Fermi Gamma-ray Space Telescope to the intensity of X-rays measured by several X-ray observatories, including the Chandra X-Ray Observatory, the Swift Gamma-Ray Burst Mission, the Rossi X-ray Timing Explorer, and XMM/Newton. This let astronomers figure out what the blazars’ brightnesses were at different energies.
– Comparing those measurements to those taken by special telscopes on the ground that can look at the actual “gamma-ray flux” Earth receives from those blazars. (Gamma rays are annihilated in our atmosphere and produce a shower of subatomic particles, sort of like a “sonic boom”, called Cherenkov radiation.)
The measurements we have in this paper are about as far back as we can see right now, the astronomers added.
“Five billion years ago is the maximum distance we are able to probe with our current technology,” stated the paper’s lead author, Alberto Dominguez.
“Sure, there are blazars farther away, but we are not able to detect them because the high-energy gamma rays they are emitting are too attenuated by EBL when they get to us—so weakened that our instruments are not sensitive enough to detect them.”
