Hubble captures green ‘quasar ghosts’ from past radiation blast


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The NASA/ESA Hubble Space Telescope has imaged a set of enigmatic quasar ghosts — ethereal green objects which mark the graves of these objects that flickered to life and then faded. The eight unusual looped structures orbit their host galaxies and glow in a bright and eerie goblin-green hue. They offer new insights into the turbulent pasts of these galaxies.

Hubble Space Telescope has discovered manifestations from the remote past, bright streams of gas, which look like immense looped objects glowing green, once ionized by quasars that no longer exist.

The telescope, which will turn 25 in 20 days, has taken photos of eight unusual space objects glowing emerald in the depths of space. Light emitting space areas dubbed ‘Hanny’s Voorwerp’ are tens of thousands of light years across.

The first object of this kind was spotted by Dutch schoolteacher Hanny van Arkel in 2007.

Hubble spies eight green filaments lit up by past quasar blasts

The ethereal wisps in these images were illuminated, perhaps briefly, by a blast of radiation from a quasar — a very luminous and compact region that surrounds a supermassive black hole at the center of a galaxy. Galactic material falls inwards towards the central black hole, growing hotter and hotter, forming a bright and brilliant quasar with powerful jets of particles and energy beaming above and below the disc of infalling matter.

In each of these eight images a quasar beam has caused once-invisible filaments in deep space to glow through a process called photoionisation. Oxygen, helium, nitrogen, sulphur and neon in the filaments absorb light from the quasar and slowly re-emit it over many thousands of years. Their unmistakable emerald hue is caused by ionised oxygen, which glows green.

hese objects were found in a spin-off of the Galaxy Zoo project, in which about 200 volunteers examined over 16 000 galaxy images in the SDSS to identify the best candidates for clouds similar to Hanny’s Voorwerp. A team of researchers analysed these and found a total of twenty galaxies that had gas ionised by quasars. Their results appear in a paper in the Astronomical Journal.

Source : RT , Spacetelescope.org

Black Hole 12 Billion Times Bigger Than the Sun Discovered


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Scientists say they have discovered a black hole so big that it challenges the theory about how they grow.

The scientists were initially reluctant to classify it as a black hole because it was too bright, its luminosity equal to the brightness of 420 trillion suns. Most of the people do not believe black holes to be bright, though they can be. This is particularly so because black holes suck everything inside them but just before that there is tremendous friction which produces a lot of light.

Scientists said this black hole was formed about 900 million years after the Big Bang.

But with measurements indicating it is 12 billion times the size of the Sun, the black hole challenges a widely accepted hypothesis of growth rates.

“Based on previous research, this is the largest black hole found for that period of time,” Dr Fuyan Bian, Research School of Astronomy and Astrophysics, Australian National University (ANU).

“Current theory is for a limit to how fast a black hole can grow, but this black hole is too large for that theory.”

The creation of supermassive black holes remains an open topic of research. However, many scientists have long believed the growth rate of black holes was limited.

Black holes grow, scientific theory suggests, as they absorb mass. However, as mass is absorbed, it will be heated creating radiation pressure, which pushes the mass away from the black hole.

“Basically, you have two forces balanced together which sets up a limit for growth, which is much smaller than what we found,” said Bian.

The black hole was discovered a team of global scientists led by Xue-Bing Wu at Peking University, China, as part of the Sloan Digital Sky Survey, which provided imagery data of 35 percent of the northern hemisphere sky.

The ANU is leading a comparable project, known as SkyMapper, to carry out observations of the Southern Hemisphere sky.

Bian expects more black holes to be observed as the project advances.

Source : Reuters , ScienceTimes

Mystery of the ‘spooky’ pattern in the universe: Scientists find that supermassive black holes are ALIGNED


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A European research team has found that the rotation axes of the central supermassive black holes in a sample of quasars are parallel to each other over distances of billions of light-years. An artist’s impression of the alignment is pictured

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Black holes are one of the strangest objects in the universe, preventing anything from escaping their grip – even light.

Now astronomers have discovered something even more peculiar about these enigmatic objects; they are aligned with each other over distances stretching billions of light-years

The remarkable observations were made by the Very Large Telescope (VLT) in Chile, which found an eerie alignment between enormous interstellar objects called quasars.

Quasars are galaxies with very active supermassive black holes at their centres. They shine more brightly than all the stars in the rest of their host galaxies put together.

A European research team has found that the rotation axes of the central supermassive black holes in a sample of quasars are parallel to each other over vast distances.

Source : Dailymail

Success in the search for quiet, distant quasars


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If quasars weren’t so luminous, we couldn’t see them so far away in space and time. But how about modest quasars, also far away? Astronomers say they’ve found some.

Astronomers at the Institute of Astrophysics of Andalusia (IAA-CSIC) in Spain say they have at last discovered a population of quiet, distant quasars. Nearly all the quasars we see at great distances are ultraluminous, and no wonder. They must be extremely luminous in order for us to glimpse them over the vastness of space. And yet astronomers have thought there must be, at those same vast distances, some quasars that were relatively quiet. Now, they say, they’ve found some and have been able to compare them both with the ultraluminous quasars in the early universe and also with closer quasars of moderate luminosity.

The farther away we look in space, the deeper we are looking into the past. Thus the ultraluminous quasars at great distances are showing us events taking place in the early universe: mergers of great galaxies containing gigantic black holes, with masses equivalent to billions of our suns, at their cores. These objects and events in the young universe are what we see as the distant quasars. The question has been, do the distant, tremendously high energy quasars have local relatives, in their same region of space and time, with much lower energy? And are those quiet quasars at great distances the dying versions of formerly ultraluminous quasars? Or are they something else entirely?

Jack W. Sulentic, astronomer at the Institute of Astrophysics of Andalusia (IAA-CSIC), who is leading the research, said:

Astronomers have always wanted to compare past and present, but it has been almost impossible because at great distances we can only see the brightest objects and nearby such objects no longer exist.

Until now we have compared very luminous distant quasars with weaker ones close by, which is tantamount to comparing household light bulbs with the lights in a football stadium.

Now, these astronomers say, they have detected the first distant, quiet quasars.

They say they employed the light-gathering power of the Gran Telescopio Canarias – known as GranTeCan or GTC telescope – located on the island of La Palma, in the Canary Islands in Spain. This telescope let Sulentic and his team obtain the first spectroscopic data from distant, low luminosity quasars similar to typical nearby ones.

They say their data are reliable enough to let them establish essential parameters of the quiet, distance quasars such as their chemical composition, and the mass of the central black hole or rate at which it absorbs surrounding gas and dust.

Quasars appear to evolve with distance. That is, the farther away they are in space, the brighter they are. This could indicate that quasars extinguish over time. Or it could be the result of anobservational bias masking a different reality: that gigantic quasars evolving very quickly, most of them already extinct, coexist with a quiet population that evolves more slowly, but which our technological limitations have not allowed astronomers to study. Ascensión del Olmo, another IAA-CSIC researcher who took part in this study, said:

We have been able to confirm that, indeed, apart from the highly energetic and rapidly evolving quasars, there is another population that evolves slowly. This population of quasars appears to follow the quasar main sequence … There does not even seem to be a strong relation between this type of quasars, which we see in our environment and those ‘monsters’ that started to glow more than 10 billion years ago.

Are there also differences between distant, quiet quasars and the moderate quasars closer to us in space? These astronomers say there are, and these differences are not surprising. Jack W. Sulentic said:

The local quasars present a higher proportion of heavy elements such as aluminum, iron or magnesium, than the distant relatives, which most likely reflects enrichment by the birth and death of successive generations of stars.

Bottom line: Astronomers in Spain have been able to identify a population of quiet quasars located in the distant universe, that is, in the early universe. They have compared them both to ultraluminous quasars in the early universe and also to quasars closer to us in space and time … and found differences in both cases.

Source : earth sky