First DAMPE data promises insights into the nature of dark matter

[Khafee]

First DAMPE data promises insights into the nature of dark matter
According to the Chinese Academy of Sciences, anomalies in the DAMPE data could be the "result of nearby cosmic ray sources or exotic physical processes."
By Brooks Hays
Nov. 30, 2017

China launched the Dark Matter Particle Explorer satellite in 2015. Photo by Qu Jingliang/European Pressphoto Agency

Scientists working on the Dark Matter Particle Explorer mission may have found hints -- but not direct evidence -- of dark matter.

The DAMPE mission involves the collaboration of dozens of scientists, all searching for insight into the nature of dark matter. This week, the group published their first paper -- in the journal Nature -- using data collected by the DAMPE satellite.

The DAMPE satellite is designed to look for evidence of decaying WIMPs, or weakly interacting massive particles, a dark matter candidate. The space observatory features a stack of interwoven detector strips capable of measuring high energy gamma rays, electrons and cosmic ray ions.

Researchers have yet to directly confirm the existence of dark matter, but scientists hypothesize the collision of dark matter particles like WIMPs yield ordinary particles and antiparticles.

Now, for the first time, scientists may have proof that dark matter collisions indeed produce odd particle pairs, electrons and positrons.

Positrons are the antimatter counterpart of the electron. Together the duo form cosmic rays. So far, DAMPE has measured 1.5 million pairs of cosmic ray-forming
electrons and positrons above a specific energy threshold. However, when researchers plotted the number of pairs against their energy, they failed to produce a smooth curve as expected.

According to the Chinese Academy of Sciences, the break in the curve could be the "result of nearby cosmic ray sources or exotic physical processes" -- like the collision of dark matter particles.

"It may be evidence of dark matter," said Chang Jin, CAS researcher and leader of the DAMPE mission.

DAMPE researchers say more evidence is needed to explore the unusual spectral blip revealed by the latest data. Even if the break in the curve isn't evidence of dark matter, the data anomalies could help scientists better understand other phenomena responsible for the production of cosmic, including black holes, pulsars and galactic collisions.

https://www.upi.com/Science_News/20...he-nature-of-dark-matter/9221511988997/?nll=1

 

[UAE]

I have always been interested to find out how does darkness form exactly. I have asked this question to many many people all the answers I got are the same; the absence of light. I do agree but forget about the light for a second and answer the question. What makes it dark? How does it form exactly? Just like answer to how does light form. What makes a light light.



Composite image showing the galaxy cluster. Isn't amazing.

 

[Khafee]

April 19, 2017


The Arrhythmic Beating of a Black Hole Heart

At the center of the Centaurus galaxy cluster, there is a large elliptical galaxy called NGC 4696. Deeper still, there is a supermassive black hole buried within the core of this galaxy.

New data from NASA’s Chandra X-ray Observatory and other telescopes has revealed details about this giant black hole, located some 145 million light years from Earth. Although the black hole itself is undetected, astronomers are learning about the impact it has on the galaxy it inhabits and the larger cluster around it.

In some ways, this black hole resembles a beating heart that pumps blood outward into the body via the arteries. Likewise, a black hole can inject material and energy into its host galaxy and beyond.

By examining the details of the X-ray data from Chandra, scientists have found evidence for repeated bursts of energetic particles in jets generated by the supermassive black hole at the center of NGC 4696. These bursts create vast cavities in the hot gas that fills the space between the galaxies in the cluster. The bursts also create shock waves, akin to sonic booms produced by high-speed airplanes, which travel tens of thousands of light years across the cluster.

This composite image contains X-ray data from Chandra (red) that reveals the hot gas in the cluster, and radio data from the NSF's Karl G. Jansky Very Large Array (blue) that shows high-energy particles produced by the black hole-powered jets. Visible light data from the Hubble Space Telescope (green) show galaxies in the cluster as well as galaxies and stars outside the cluster.

Astronomers employed special processing to the X-ray data to emphasize nine cavities visible in the hot gas. These cavities are labeled A through I in an additional image, and the location of the black hole is labeled with a cross. The cavities that formed most recently are located nearest to the black hole, in particular the ones labeled A and B.

The researchers estimate that these black hole bursts, or “beats”, have occurred every five to ten million years. Besides the vastly differing time scales, these beats also differ from typical human heartbeats in not occurring at particularly regular intervals.

A different type of processing of the X-ray data reveals a sequence of curved and approximately equally spaced features in the hot gas. These may be caused by sound waves generated by the black hole’s repeated bursts. In a galaxy cluster, the hot gas that fills the cluster enables sound waves – albeit at frequencies far too low for the human hear to detect – to propagate.

The features in the Centaurus Cluster are similar to the ripples seen in the Perseus cluster of galaxies. The pitch of the sound in Centaurus is extremely deep, corresponding to a discordant sound about 56 octaves below the notes near middle C. This corresponds to a slightly higher (by about one octave) pitch than the sound in Perseus. Alternative explanations for these curved features include the effects of turbulence or magnetic fields.

The black hole bursts also appear to have lifted up gas that has been enriched in elements generated in supernova explosions. The authors of the study of the Centaurus cluster created a map showing the density of elements heavier than hydrogen and helium. The brighter colors in the map show regions with the highest density of heavy elements and the darker colors show regions with a lower density of heavy elements. Therefore, regions with the highest density of heavy elements are located to the right of the black hole. A lower density of heavy elements near the black hole is consistent with the idea that enriched gas has been lifted out of the cluster’s center by bursting activity associated with the black hole. The energy produced by the black hole is also able to prevent the huge reservoir of hot gas from cooling. This has prevented large numbers of stars from forming in the gas.

A paper describing these results was published in the March 21st 2016 issue of the Monthly Notices of the Royal Astronomical Society and is available online. The first author is Jeremy Sanders from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.
Image credit: X-ray: NASA/CXC/MPE/J. Sanders et al.; Optical: NASA/STScI; Radio: NSF/NRAO/VLA

Read More from NASA's Chandra X-ray Observatory.

For more Chandra images, multimedia and related materials, visit:

http://www.nasa.gov/chandra

https://www.nasa.gov/mission_pages/chandra/the-arrhythmic-beating-of-a-black-hole-heart.html​

 

[Khafee]

Astronomers just discovered a supermassive black hole from the dawn of the universe
And it's much bigger than we expected.
By Mary Beth Griggs
December 08, 2017

An artist's image of a black hole with an accretion disk and a quasar shooting away from it.
Robin Dienel, courtesy of the Carnegie Institution for Science

There was a bang. A big one. It was the beginning of everything, but for several hundred million years, all was darkness. Then, lights started flickering to life, stars and gases and galaxies all coming online.

One of the brightest lights during that dawn had a dark and hungry hole at its heart. More massive than 800 million suns, the black hole existed just 690 million years after the Big Bang, when the universe was still an infant.

Researchers, including Eduardo Bañados, reported the existence of the black hole and its accompanying bright quasar in a paper in Nature this week. The astronomers were looking for evidence of black holes in these early days of the universe, but they were still surprised at the sheer size of this one, named J1342+0928.

Black holes are points in the universe where gravity is so intense that nothing can escape. Not rocks, not gas, not even light. Near large black holes, surrounding material swirls around to form something called an accretion disk. Material in the disk spins at thousands of miles per second, heating up as it moves and slams into other bits of dusts and gas, all riding the same frantic carousel toward doom.
The material itself spins down into the black hole, never to be seen again, but its jostling releases energy that heads out into the universe in the form of immensely bright heat and light. That light made the quasar that Bañados and his co-authors were able to detect, which they used to estimate J1342+0928's surprising mass.

Bañados says that a typical black hole, forming as a star collapses, might have the mass of 50 to 100 suns. “If you make it grow, feed it material like gas from its surroundings and let it grow for 690 million years, you wouldn’t be able to reach the size of this supermassive black hole,” Bañados says.

To figure out how this black hole could have gotten so large so quickly, observational astronomers like Bañados must team up with theoretical astronomers and astrophysicists. In the process, they’re also looking into ever-so-slightly broader questions, like the evolution of everything. “This object is so distant and so luminous that it provides a laboratory to study the early universe,” Bañados says.

Bañados has discovered about half of the most distant quasars on record, but this one—while not the most massive—is the furthest of them all. Because light takes time to travel, the more distant an object is, the earlier back in history we're peering when we look at it. So this object comes from earlier in the universe's lifespan than any of the others scientists have observed.

“This record is nice, but we’re not doing this for the record,” Bañados says. “This is so mature that I would be very surprised if this is the first quasar ever formed. I hope we or someone else will break this record soon.”

This particular quasar is so bright that it outshines the galaxy where it’s located—it’s 1000 times more luminous. And it’s not like that galaxy is a slouch either, even though the quasar at its heart drowns it out in both the optical and ultraviolet wavelengths of light.

Fortunately, if you look at the galaxy in longer wavelengths, you can start to see some details. Bañados is a co-author on another paper that came out this week in The Astrophysical Journal Letters that focuses on the galaxy around the black hole. They the galaxy was positively choked with interstellar dust, producing somewhere around 100 new solar masses (the mass of our star) per year. Our galaxy only makes about one solar mass per year.

They were also able to detect something about the neighborhood of space around the black hole, finding that about half of the area had un-ionized hydrogen (which would have blocked out light, leading to those first few hundreds of millions of years of darkness in the universe) and half had ionized hydrogen, indicating that this black hole could have existed at the time when the universe switched from being dominated by the former to the latter.

“How this happened and when this happened have fundamental implications for the evolution of the universe later on,” Bañados says. “But we need to find and keep searching for more objects even further away and try to repeat that experiment.”

Luckily, there are now more opportunities to look into those universal origins. In 2018, Bañados and other researchers around the world will use a variety of telescopes to explore this object more thoroughly and look for others in the night sky.

“We’re a very fortunate generation,” Bañados says. “We’re the first human beings to have the technology to study and characterize in detail some of the first galaxies and black holes that formed in the universe. If that's not fascinating, I don’t know what is.”

https://www.popsci.com/supermassive...1181172041&spReportId=MTE4MTE3MjA0MQS2#page-2