Black Hole Has Major Flare -HOW?!

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This diagram shows how a shifting feature, called a corona, can create a flare of X-rays around a black hole.

Credit: NASA/JPL-Caltech

 http://www.sciencedaily.com/releases/2015/10/151028071414.htm

 

The baffling and strange behaviors of black holes have become somewhat less mysterious recently, with new observations from NASA's Explorer missions Swift and the Nuclear Spectroscopic Telescope Array, or NuSTAR. The two space telescopes caught a supermassive black hole in the midst of a giant eruption of X-ray light, helping astronomers address an ongoing puzzle: How do supermassive black holes flare?

The results suggest that supermassive black holes send out beams of X-rays when their surrounding coronas -- sources of extremely energetic particles -- shoot, or launch, away from the black holes.
"This is the first time we have been able to link the launching of the corona to a flare," said Dan Wilkins of Saint Mary's University in Halifax, Canada, lead author of a new paper on the results appearing in the Monthly Notices of the Royal Astronomical Society. "This will help us understand how supermassive black holes power some of the brightest objects in the universe."


Supermassive black holes don't give off any light themselves, but they are often encircled by disks of hot, glowing material. The gravity of a black hole pulls swirling gas into it, heating this material and causing it to shine with different types of light. Another source of radiation near a black hole is the corona. Coronas are made up of highly energetic particles that generate X-ray light, but details about their appearance, and how they form, are unclear.


Astronomers think coronas have one of two likely configurations. The "lamppost" model says they are compact sources of light, similar to light bulbs, that sit above and below the black hole, along its rotation axis. The other model proposes that the coronas are spread out more diffusely, either as a larger cloud around the black hole, or as a "sandwich" that envelops the surrounding disk of material like slices of bread. In fact, it's possible that coronas switch between both the lamppost and sandwich configurations.
The new data support the "lamppost" model -- and demonstrate, in the finest detail yet, how the light-bulb-like coronas move. The observations began when Swift, which monitors the sky for cosmic outbursts of X-rays and gamma rays, caught a large flare coming from the supermassive black hole called Markarian 335, or Mrk 335, located 324 million light-years away in the direction of the constellation Pegasus. This supermassive black hole, which sits at the center of a galaxy, was once one of the brightest X-ray sources in the sky.


"Something very strange happened in 2007, when Mrk 335 faded by a factor of 30. What we have found is that it continues to erupt in flares but has not reached the brightness levels and stability seen before," said Luigi Gallo, the principal investigator for the project at Saint Mary's University. Another co-author, Dirk Grupe of Morehead State University in Kentucky, has been using Swift to regularly monitor the black hole since 2007.


In September 2014, Swift caught Mrk 335 in a huge flare. Once Gallo found out, he sent a request to the NuSTAR team to quickly follow up on the object as part of a "target of opportunity" program, where the observatory's previously planned observing schedule is interrupted for important events. Eight days later, NuSTAR set its X-ray eyes on the target, witnessing the final half of the flare event.


After careful scrutiny of the data, the astronomers realized they were seeing the ejection, and eventual collapse, of the black hole's corona.


"The corona gathered inward at first and then launched upwards like a jet," said Wilkins. "We still don't know how jets in black holes form, but it's an exciting possibility that this black hole's corona was beginning to form the base of a jet before it collapsed."


How could the researchers tell the corona moved? The corona gives off X-ray light that has a slightly different spectrum -- X-ray "colors" -- than the light coming from the disk around the black hole. By analyzing a spectrum of X-ray light from Mrk 335 across a range of wavelengths observed by both Swift and NuSTAR, the researchers could tell that the corona X-ray light had brightened -- and that this brightening was due to the motion of the corona.


Coronas can move very fast. The corona associated with Mrk 335, according to the scientists, was traveling at about 20 percent the speed of light. When this happens, and the corona launches in our direction, its light is brightened in an effect called relativistic Doppler boosting.


Putting this all together, the results show that the X-ray flare from this black hole was caused by the ejected corona.


"The nature of the energetic source of X-rays we call the corona is mysterious, but now with the ability to see dramatic changes like this we are getting clues about its size and structure," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology in Pasadena, who was not affiliated with the study.


Many other black hole brainteasers remain. For example, astronomers want to understand what causes the ejection of the corona in the first place.


NuSTAR is a Small Explorer mission led by Caltech and managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. JPL is managed by Caltech for NASA.

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Story Source:
The above post is reprinted from materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.

Mitochondrial DNA Recovered From Alaska’s Ancient Infants

(Courtesy Ben Potter, UAF)

FAIRBANKS, ALASKA—Archaeologist Ben Potter of the University of Alaska Fairbanks, and geneticists Dennis O’Rourke and Justin Tackney of the University of Utah have analyzed mitochondrial DNA recovered from the remains of two infants found at the Upward Sun River site in Interior Alaska.

The cremated remains of a three-year-old child were also recovered at the site, but they did not yield any genetic material. “These infants are the earliest human remains in northern North America and they carry distinctly Native American lineages.


These genetic variations had not previously been known to have existed this far north and speak to the early genetic diversity of the time,” O’Rourke said in a press release. O’Rourke adds that “there had to be a period of isolation for these distinctive Native American lineages to have evolved away from their Asian ancestors. We believe that was in Beringia.”

Human remains older than 8,000 years have been found at only eight sites in North America, and all five major Native American lineages have been found in them. “That indicates they were present in the early population in Beringia that gave rise to all modern Native Americans,” Tackney explained.


To read more, go to "America, in the Beginning."

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Very interesting posting over at Archaerology http://archaeology.org/news/3832-151027-alaska-infant-dna
so next time some loud-mouth shouts out that Native Americans are a "minority" it might be worth pointing out that their native lineages can be traced back 11,500 years. Loud-mouths can probably only be traced back a few hundred!

That aside, these are very interesting results.

Rosetta Detects Molecular Oxygen

 

 

The amount of information coming back from Rosetta and other probes has been almost mind-blowing at times.  I suspect we may be in for a few more surprises yet.

 

I encourage anyone interested to bookmark ESAs website:http://www.esa.int/Our_Activities/Space_Science/Rosetta/First_detection_of_molecular_oxygen_at_a_comet

 

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Rosetta’s detection of molecular oxygen

28 October 2015

  ESA’s Rosetta spacecraft has made the first in situ detection of oxygen molecules outgassing from a comet, a surprising observation that suggests they were incorporated into the comet during its formation.
Rosetta has been studying Comet 67P/Churyumov–Gerasimenko for over a year and has detected an abundance of different gases pouring from its nucleus. Water vapour, carbon monoxide and carbon dioxide are the most prolific, with a rich array of other nitrogen-, sulphur- and carbon-bearing species, and even ‘noble gases’ also recorded.

Oxygen is the third most abundant element in the Universe, but the simplest molecular version of the gas, O₂, has proven surprisingly hard to track down, even in star-forming clouds, because it is highly reactive and readily breaks apart to bind with other atoms and molecules.

For example, oxygen atoms can combine with hydrogen atoms on cold dust grains to form water, or a free oxygen split from O₂ by ultraviolet radiation can recombine with an O₂ molecule to form ozone (O₃).

Despite its detection on the icy moons of Jupiter and Saturn, O₂ had been missing in the inventory of https://www.blogger.com/blogger.g?blogID=1852083566641563826#editor/target=post;postID=6708866505507146432volatile species associated with comets until now.

“We weren’t really expecting to detect O₂ at the comet – and in such high abundance – because it is so chemically reactive, so it was quite a surprise,” says Kathrin Altwegg of the University of Bern, and principal investigator of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument, ROSINA.

“It’s also unanticipated because there aren’t very many examples of the detection of interstellar O₂. And thus, even though it must have been incorporated into the comet during its formation, this is not so easily explained by current Solar System formation models.”

The team analysed more than 3000 samples collected around the comet between September 2014 and March 2015 to identify the O₂. They determined an abundance of 1–10% relative to H₂O, with an average value of 3.80 ± 0.85%, an order of magnitude higher than predicted by models describing the chemistry in molecular clouds.

The amount of molecular oxygen detected showed a strong relationship to the amount of water measured at any given time, suggesting that their origin on the nucleus and release mechanism are linked. By contrast, the amount of O₂ seen was poorly correlated with carbon monoxide and molecular nitrogen, even though they have a similar volatility to O₂. In addition, no ozone was detected.

 

Comet on 18 October 2015 – NavCam 

 

 

Over the six-month study period, Rosetta was inbound towards the Sun along its orbit, and orbiting as close as 10–30 km from the nucleus. Despite the decreasing distance to the Sun, the O₂/H₂O ratio remained constant over time, and it also did not change with Rosetta’s longitude or latitude over the comet.

In more detail, the O₂/H₂O ratio was seen to decrease for high H₂O abundances, an observation that might be influenced by surface water ice produced in the observed daily sublimation–condensation process.

The team explored the possibilities to explain the presence and consistently high abundance of O₂ and its relationship to water, as well as the lack of ozone, by first considering photolysis and radiolysis of water ice over a range of timescales.  

In photolysis, photons break bonds between molecules, whereas radiolysis involves more energetic photons or fast electrons and ions depositing energy into ice and ionising molecules – a process observed on icy moons in the outer Solar System, and in Saturn’s rings. Either process can, in principle, lead to the formation and liberation of molecular oxygen.

Radiolysis will have operated over the billions of years that the comet spent in the Kuiper Belt and led to the build-up of O₂ to a few metres depth. But these top layers must all have been removed in the time since the comet moved into its inner Solar System orbit, ruling this out as the source of the O₂ seen today.

More recent generation of O₂ via radiolysis and photolysis by solar wind particles and UV photons should only have occurred in the top few micrometres of the comet.

“But if this was the primary source of the O₂ then we would have expected to see a decrease in the O₂/H₂O ratio as this layer was removed during the six-month timespan of our observations,” says Andre Bieler of the University of Michigan and lead author of the paper describing the new results in the journal Nature this week.

“The instantaneous generation of O₂ also seems unlikely, as that should lead to variable O₂ ratios under different illumination conditions. Instead, it seems more likely that primordial O₂ was somehow incorporated into the comet’s ices during its formation, and is being released with the water vapour today.”

In one scenario, gaseous O₂ would first be incorporated into water ice in the early protosolar nebula stage of our Solar System. Chemical models of protoplanetary discs predict that high abundances of gaseous O₂ could be available in the comet forming zone, but rapid cooling from temperatures above –173ºC to less than –243ºC would be required to form water ice with O₂ trapped on dust grains. The grains would then have to be incorporated into the comet without being chemically altered.

“Other possibilities include the Solar System being formed in an unusually warm part of a dense molecular cloud, at temperatures of 10–20ºC above the –263ºC or so typically expected for such clouds,” says Ewine van Dishoeck of Leiden Observatory in the Netherlands, co-author of the paper.
“This is still consistent with estimates for the comet formation conditions in the outer solar nebula, and also with previous findings at Rosetta’s comet regarding the low abundance of N₂.”
 
Alternatively, radiolysis of icy dust grains could have taken place prior to the comet’s accretion into a larger body. In this case, the O₂ would remain trapped in the voids of the water ice on the grains while the hydrogen diffused out, preventing the reformation of O₂ to water, and resulting in an increased and stable level of O₂ in the solid ice.

Incorporation of such icy grains into the nucleus could explain the observed strong correlation with H₂O observed at the comet today.

“Regardless of how it was made, the O₂ was also somehow protected during the accretion stage of the comet: this must have happened gently to avoid the O₂ being destroyed by further chemical reactions,” adds Kathrin.

“This is an intriguing result for studies both within and beyond the comet community, with possible implications for our models of Solar System evolution,” says Matt Taylor, ESA’s Rosetta project scientist.

Notes for Editors
“Abundant molecular oxygen in the coma of 67P/Churyumov–Gerasimenko,” by A. Bieler et al is published in the 29 October 2015 issue of the journal Nature.