MessageToEagle.com -
They are among the most fascinating cosmic phenomena. Astronomers know them as blazars and each of them harbors a supermassive black hole and jets
emanating in opposite directions from near its poles. These sources are unique evidence of the most extreme speeds and energies known in the extreme Universe.
The blazar's jet is pointing in the general direction of the Earth. Only one blazar would be enough to endanger our existence so it is
good that none of them is located too close to our planet Earth.
Their strong, oppositely directed jets can travel outward into large regions of intergalactic space. Blazars emit over the widest range of
frequencies, demonstrate very strong variations in brightness and spew huge amounts of energy from their centers, far more than ordinary galaxies.
Markarian 421 - one of the most extreme and powerful variable sources of photons with energies ranging from the radio to the gamma-ray regimes.
This blazar was observed in 1992 using imaging atmospheric Cherenkov telescopes.
Powerful blazars have weak emission lines or even none at all, which may be caused by very little or no gas at all in their cores.
The shortage of gas means that there are few if any atoms to produce these emission lines.
Another possibility is that the blazars have emission lines of normal strength, but very strong and continuous radiation, makes
it very difficult to detect them.
This artist's concept reveals the anatomy of a blazar. Image Credit: NASA
A few years ago, a team of scientists from Boston University, led by Alan Marscher watched the phenomenon, using the National Radio Astronomy
Observatory's VLBA composed of ten powerful radio telescopes spread across the US.
"We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything
we see supports the idea that twisted, coiled magnetic fields are propelling the material outward," said Alan Marscher.
"This is a major advance in our understanding of a remarkable process that occurs throughout the Universe."
Marscher's team studied a blazar at the centre of BL Lacertae, a galaxy some 950 million light years from Earth.
The blazar jet points almost directly at Earth and it fires powerful bursts of radiation that last for several days and occur about once or twice a year.
PKS 2155-304 is a blazar galaxy and it is also the archetypical X-ray BL Lac object. It is one of the brightest BL Lac objects in the sky at optical
through X-ray energies. It is located in the southern constellation Piscis Austrinus.
In 2006 the jets underwent a burst that caused the galaxy to become the brightest source of gamma-ray energies in the sky. Image Credits:gems.gsfc.nasa.gov
In 2009, Fermi, which detected a large number of blazars during it first year of operation, observed a blazar, PKS 2155-304.
It is located 1.5 billion light-years away in the southern constellation of Piscis Austrinus and is usually a detectable but faint gamma-ray source.
The blazar's jet contributed to the brightest source in the sky at the highest gamma-ray energies scientists can detect -- up to 50 trillion times
the energy of visible light.
Even from strong sources, only about one gamma ray this energetic strikes a square yard at the top of Earth's atmosphere each month, reported scientists.
Blazars at Galactic North Pole, Seen in Fermi's First Year of Observations Credit: NASA/DOE/Fermi LAT Collaboration
Also in 2009, NASA's Fermi Gamma-ray Space Telescope paid attention to the object as 3C 454.3, an active galaxy (the brightest source in the gamma-ray sky,
at that time) located 7.2 billion light-years away in the constellation Pegasus.
What makes a blazar so bright in gamma rays is its orientation: One of the jets happens to be aimed straight at us.
Many blazars have apparent superluminal features within the first few parsecs of their jets, and outshines the entire galaxy!
We all know that the brightest persistent source in the gamma-ray sky is the Vela pulsar, at a distance of only 1,000 light-years from Earth.
This time, Vela has got a competitor - the object 3C 454.3. When the object is undergoing a flaring episode, 3C 454.3 is spectacularly bright.
"3C 454.3 is millions of times farther away, yet the current flare makes it twice as bright as Vela," said Lise Escande at the
Center for Nuclear Studies in Gradignan, near Bordeaux, France.
"That represents an incredible energy release, and one the source can't sustain for very long."
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Doesn't Secret Dark Matter Exist?
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The more scientists study dark matter they know lesser and are not particularly optimistic about their results.
After completing this study, we know less about dark matter than we did before," said Matt Walker, of the Harvard-Smithsonian Center for Astrophysics.
A mysterious and still unknown substance is totally invisible in the Universe and reveals its presence only through its gravitational pull...
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The Milky Way will have merged with the Andromeda galaxy to form the Milkomeda galaxy. Many of its stars, including our Sun, will have burned out.
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about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.
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MessageToEagle.com -
They are among the most fascinating cosmic phenomena. Astronomers know them as blazars and each of them harbors a supermassive black hole and jets
emanating in opposite directions from near its poles. These sources are unique evidence of the most extreme speeds and energies known in the extreme Universe.
The more scientists study dark matter they know lesser and are not particularly optimistic about their results.
WASP-12b is the first carbon-rich world ever observed. It is an extremely hot and large gas giant orbiting another star and it has unusual amount of carbon.
Carbon is a common component of planetary systems and a key ingredient of life on Earth.
Does it mean some kind of life might exist on WASP-12b?
The sun gives off more than just heat and light. One astronomer thinks it makes music, too.
From here on Earth, that great ball of fire in the sky appears to be perfectly round. But closer study reveals storms and
giant gaseous eruptions covering the surface of the sun. Now one scientist has found a way to translate those eruptions into strangely beautiful music.
The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously
seen from the object. On April 12, NASA's Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days...
A team of astrophysicists from Germany, France and Italy have discovered in the constellation Leo is an old star.
The star's existence raised at once many questions for scientists.
The object is definitely not as its "contemporaries" that appeared immediately after the Big Bang event.
It's a very important discovery!
For the first time, an international team of scientists have detected all phases of thermonuclear burning in a
neutron star, located close to the center of the galaxy in the globular cluster Terzan 5.
Four CfA astronomers, Zachory Berta, David Charbonneau, Jean-Michel Desert, and Jonathan Irwin, together with six colleagues,
used the Hubble Space Telescope to probe the atmosphere around the transiting super-Earth known as GJ1214b.
This exoplanet has a mass of 6.5 Earth-masses and a radius of 2.7 Earth-radii, and it orbits a small M-dwarf star (its diameter
is only 21% of the Sun's).
Twenty five years ago, on 1987 February 23, the brightest supernova of modern times was observed in the Large Magellanic Cloud.
Astronomers from Center for Astrophysics of the University of Porto, Portugal and Oskar Klein Centre, Stockholm University, Sweden come up
with new findings regarding one of the most studied objects - the dwarf galaxy I Zw 18.
Have you ever wondered what the Universe will look like for a future alien astronomer?
NGC 5907 is sometimes called the "Splinter" or Knife Edge Galaxy because of its unusual appearance.
It is a spiral galaxy lying in the Dragon constellation,
about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.
The Milky Way is hard to map because we are sitting on the edge of the galaxy looking through it.
However, we know that spiral galaxies like the Milky Way have magnetic fields that follow a particular pattern so we were able
use polarised light to map the magnetic fields...