Sentences with phrase «of blazars»

Astronomers currently recognize two types of blazars.

Based on other properties of blazars, the scientists believe that their interpretation of the data is accurate and that they have measured the extremely fast speeds in the three blazar jets.

Observations of blazars by NASA's Fermi Gamma Ray Telescope spacecraft for the first time detected that gamma rays from distant blazars are indeed attenuated more than gamma rays from nearby blazars, a result announced on November 30, 2012, in a paper published in Science, as theoretically predicted.

Francesco Massaro at the University of Turin in Italy and Raffaele D'Abrusco at the Harvard - Smithsonian Center for Astrophysics in Cambridge, Massachusetts, show for the first time that the mid-infrared colors of blazars in WISE data correlate to an equivalent measurement of their gamma - ray output.

At the heart of a blazar lies a supersized black hole with millions of times the sun's mass surrounded by a disk of hot gas and dust.

Looking at a distant galaxy: the radio chart (left) shows the image of the blazar PKS 1830 - 211 distorted by the gravitational lens effect.

The light of the blazar behind it passes through this space well and takes a detour — as if it were passing through a lens.

The detail on the right is a simulation of the micro-gravitational lens effect in the gamma ray region; direct observation of the orange ring — it also represents images of the blazar — is not possible due to its small size.

VLBA sequence of blazar 0827 +243 over about 8.4 months.

Not exact matches

In the second half of last year the blazar CTA 102, which is 7,600 million light years from Earth, brightened considerably, drawing the attention of all the astronomers who specialise in this kind of objects.

The infrared / gamma - ray connection led the authors to search for new blazar candidates among WISE infrared sources located within the positional uncertainties of Fermi's unidentified gamma - ray objects.

Astronomers suspect many of these are blazars, but there isn't enough information to classify them.

The relationship effectively connects the dots for blazars across an enormous swath of the electromagnetic spectrum.

«We found that when we plotted Fermi blazars by their WISE colors in a particular way, they occupied a distinctly different part of the plot than other extragalactic gamma - ray sources.»

The discovery, which was accomplished by comparing data from NASA's Wide - field Infrared Survey Explorer (WISE) and Fermi Gamma - ray Space Telescope, has enabled the researchers to uncover dozens of new blazar candidates.

They could have emerged from gamma - ray bursts, mysterious and short - lived cataclysms that briefly rank as the brightest objects in the universe; shock waves from exploding stars; or so - called blazars, jets of energy powered by supermassive black holes.

The High Altitude Water Cherenkov observatory has released its first map of the high - energy sky, catching pulsars, supernova remnants and blazars switching on and off

Related sites Abstract of paper, with link to full text Chandra X-ray Observatory FUSE satellite, used in similar studies of lower - temperature gas Observations of Markarian 421 blazar Shull's home page

Astronomer Fabrizio Nicastro of the Harvard - Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and his colleagues monitored the galaxy Markarian 421, which contains a «blazar» — an active black hole that aims powerful jets of energy toward Earth.

Partially dimmed x-rays (dips in graph) from a flaring blazar (right) reveal two filaments of hot, diffuse matter in the vast spaces between galaxies.

It so happens that there is a galaxy roughly half way between Earth and the blazar, which is billions of light years away.

Fermi has shown that much of this light arises from unresolved gamma - ray sources, particularly galaxies called blazars, which are powered by material falling toward gigantic black holes.

In a detailed analysis of high - energy EGB gamma rays, published April 14 in Physical Review Letters, Ajello and his team show that blazars and other discrete sources can account for nearly all of this emission.

This is a blazar — a rare case in which one of the two jets happens to be directed towards Earth so that the astronomers look directly into the jet along the longitudinal axis.

It turns out that blazars are powered surprisingly like the exhausts of jet engines, albeit on a cosmic scale, says astronomer and lead author Alan Marscher of Boston University.

This behaviour and further findings from observations can be best explained with an interesting assumption: Although the brightness variations in the gamma ray region also originate from the flare ups in the blazar, they are amplified to different degrees by the gravitational lens effect of individual stars in the foreground galaxy.

Now, Readhead and his colleagues argue that they're seeing the blazar's black hole emit tiny burps of plasma, magnified hundreds of times by a new kind of gravitational lens.

Instead of streaming out of a metal casing and turbine, a blazar's jets «are confined and focused by coiled magnetic fields originating near the [supermassive] black hole.»

Bright spots in the map include the Crab Nebula, which hosts a radiation - spewing stellar corpse called a pulsar, and several blazars, violent active galaxies where colossal black holes accelerate particles to more than 99 % the speed of light.

Blazars — found in the centers of some galaxies — and gamma - ray bursts are two identified wellsprings of these high - energy rays.

Blazars periodically flare when the supermassive black holes in some active galaxies» cores fill with dust and gas, releasing massive amounts of energy.

«Blazars are one type of active galaxy,» said Marco Ajello, a professor of physics and astronomy and Paliya's advisor.

However, rather than emitting violent bursts of gamma - ray radiation, like blazars, Seyfert galaxies are known for their strong ultra-violet emissions.

«It was unexpected — we have only seen that kind of gamma ray emission from blazars,» said Dieter Hartmann, a professor of physics and astronomy and co-author of the study.

The attached figure illustrates how energetic gamma rays (dashed lines) from a distant blazar strike photons of extragalactic background light (wavy lines) and produce pairs of electrons and positrons.

So, astrophysicists developed an ingenious work - around method: measuring the EBL indirectly through measuring the attenuation of — that is, the absorption of — very high energy gamma rays from distant blazars.

When a high - energy gamma ray from a blazar strikes air molecules in the upper regions of Earth's atmosphere, it produces a cascade of charged subatomic particles.

Not all the high - energy gamma rays emitted by a blazar, however, make it all the way across billions of light - years to Earth; some strike a hapless EBL photon along the way.

Thus, measuring how much gamma rays of different energies are attenuated or weakened from blazars at different distances from Earth indirectly gives a measurement of how many EBL photons of different wavelengths exist along the line of sight from blazar to Earth over those different distances.

«We can think of one blazar class as a gas - guzzling car and the other as an energy - efficient electric vehicle,» study lead researcher Marco Ajello, an astrophysicist at Clemson University in South Carolina, said in a statement.

This hybrid blazar idea implies that the luminosity of BL Lacs should decrease as their core black holes continue to lose energy and spin.

Taking advantage of the extremely sharp radio «vision» of the continent - wide VLBA, the scientists tracked individual features in the jets of three blazars at distances from Earth ranging from 7.3 to 9 billion light - years.

Blazars are active galactic nuclei — energetic regions surrounding massive black holes at the centers of galaxies.

«Now, based on independent confirmation by two groups of astronomers, we see these three blazars with apparent speeds greater than 25 times that of light,» Piner added.

The two different classes of jet - spewing active galaxies called blazars may, in fact, be a single hybrid type that evolves over time, according to new research.

«This tells us that the physical processes at the cores of these galaxies, called blazars, are extremely energetic and are capable of propelling matter very close to the absolute cosmic speed limit,» said Glenn Piner of Whittier College in Whittier, California.

«We typically see apparent speeds in blazar jets that are about five times the speed of light, and that corresponds to a true speed of more than 98 percent of light speed,» Piner said.

Blazars appear to produce more gamma radiation than other types of active galaxies, but this may be because one of their jets is pointed toward Earth.

Blazars occur when the jet of a supermassive black hole is pointing toward Earth.

Blazars are a type of active galaxy — about 1,000 have been cataloged [source: A Review of the Universe].