Sentences with word «blazar»

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.

Comparing the calculations of the unattenuated gamma rays to actual measurements of the attenuation of gamma rays and X-rays from blazars at different distances allowed Dominquez et al. to quantify the evolution of the EBL — that is, to measure how the EBL changed over time as the Universe aged — out to about 5 billion years ago (corresponding to a redshift of about z = 0.5).

Black - hole - powered galaxies called blazars are the most common sources detected by NASA's Fermi Gamma - ray Space Telescope.

They say the electrons, protons and other particles accelerated in blazar jets leave a specific «fingerprint» in the infrared light they emit.

«From that, I found four new gamma ray sources and three that were earlier known as blazars but we believe are actually Seyfert galaxies.»

«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.

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.

«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.»

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 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.

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

Time - dependent search of high energy cosmic neutrinos from variable Blazars with the ANTARES telescope

This event was so exceptional that for a few days this object was the brightest blazar observed until now.

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.

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.

In 2011, Massaro, D'Abrusco and their colleagues began using WISE data to investigate Fermi blazars.

Blazars constitute more than half of the discrete gamma - ray sources seen by Fermi's Large Area Telescope (LAT).

«So, it could be that the black hole is working more efficiently in smaller, spiral systems than it is in larger objects like blazars.»

First, the coauthors compared the Fermi findings to intensity of X-rays from the same blazars measured by X-ray satellites Chandra, Swift, Rossi X-ray Timing Explorer, and XMM / Newton and lower - energy radiation measured by other spacecraft and ground - based observatories.

«WISE made it possible to explore the mid-infrared colors of known gamma - ray blazars,» said D'Abrusco.

«Sure, there are blazars farther away, but we are not able to detect them because the high - energy gamma rays they are emitting are too attenuated by EBL when they get to us — so weakened that our instruments are not sensitive enough to detect them.»

When the researchers applied this relationship to Fermi's unknown sources, they quickly found 130 potential blazars.

«NASA's WISE, Fermi missions reveal a surprising blazar connection.»

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

To find an answer, an international team has spent the past several years using a global array of radio, optical, x-ray, and gamma - ray telescopes to observe a single blazar, called BL Lac.

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

«How do blazars behave at, say, radio frequencies?

«If it is an elliptical, then it's true that we are just looking at a normal blazar.

Blazars need to have very massive black holes at their centers to be able to launch jets,» Paliya said.

It has been widely believed that only massive galaxies contain enough energy to become blazars, which are stupendous jets of radiation powerful enough to stretch thousands of light years.

Thus, the gamma ray attenuation spectrum from farther distant blazars reveals how the EBL looked at earlier eras.

«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.

Ajello and his team came to this conclusion after studying how the distribution of blazars changed over time.

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

The researchers hope to test this hypothesis with larger blazar samples.

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

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.

«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.

A new paper, called «Detection of the Cosmic γ - Ray Horizon from Multiwavelength Observations of Blazars,» by Alberto Dominguez and six coauthors, just published today by the Astrophysical Journal — based on observations spanning wavelengths from radio waves to very energetic gamma rays, obtained from several NASA spacecraft and several ground - based telescopes — describes the best measurement yet of the evolution of the EBL over the past 5 billion years.

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.

Blazars constitute more than half of the total gamma - ray sources seen by Fermi, and they make up an even greater share in a new LAT catalog of the highest - energy gamma rays.

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

The coauthors then compared those calculations of unattenuated gamma - ray flux at different energies with direct measurements from special ground - based telescopes of the actual gamma - ray flux received at Earth from those same blazars.

«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.

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.

A blazar, a galaxy that kicks out fluctuating X-rays, might also have been responsible, but blazars are easily identified by their strong radio emissions, something not apparent in this source (Nature, DOI: 10.1038 / nature08083).

A blazar is an astronomical object within an elliptical galaxy, at whose centre there is a supermassive black hole which emits jets of radiation and particles with huge energies.

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