Radio halo in galaxy cluster Abell 2256 investigated in detail

Utilizing varied radio telescopes, a world crew of astronomers has carried out deep low-frequency radio observations of a merging galaxy cluster Abell 2256. The observational marketing campaign delivered extra insights into the properties of the cluster’s radio halo. The findings have been detailed in a paper revealed September 7 on arXiv.org.

Radio halos are huge areas of diffuse radio emission, often discovered on the facilities of galaxy clusters. Nonetheless, diffuse emissions usually have very low floor brightness, notably at GHz frequencies, which makes them exhausting to detect. Their brightness will increase at lower frequencies, unveiling the presence of those areas.

With the potential of acquiring deep, high-resolution, high-fidelity and low-frequency radio photographs, the LOw Frequency ARray (LOFAR) is a superb instrument for finding out radio halos at low frequencies with unprecedented element and sensitivity. Subsequently, a bunch of researchers led by Kamlesh Rajpurohit of the College of Bologna in Italy, has employed LOFAR as a way to examine radio halo in Abell 2256—a close-by (at a redshift of 0.058) huge galaxy cluster exhibiting sturdy emission in any respect wavelengths. The crew additionally used the upgraded Big Metrewave Radio Telescope (uGMRT) and the Karl G. Jansky Very Giant Array (VLA) to look at this halo.

“We current the primary detailed evaluation of the radio halo within the merging galaxy cluster Abell 2256 utilizing the LOw Frequency ARray (LOFAR), the upgraded Big Metrewave Radio Telescope (uGMRT) and the VLA. Radio observations (120 MHz-2 GHz) mixed with archival Chandra and XMM-Newton X-ray knowledge allowed us to check the halo emission with unprecedented element,” the researchers wrote within the paper.

The astronomers managed first deep, excessive spatial decision radio photographs of Abell 2256’s radio halo. The halo emission was detected by them in any respect frequencies, specifically 144 MHz, 350 MHz, 675 MHz and 1.5 GHz. The most important linear measurement of this halo was measured to be about 2.93 million mild years at 144 MHz and 1.63 million light years at 1.5 GHz, which means that its outermost area has a steep spectrum.

On the whole, the research discovered that emission from the halo follows a power-law spectrum between 144 MHz and 1.5 GHz, and has an extremely steep spectrum with an built-in spectral index of −1.63. Furthermore, the spatially resolved spectral index maps revealed a spectral steepening with growing radius.

The analysis discovered that the morphology of the radio halo is remarkably just like that in X-rays. Specifically, the X-ray peak in the primary mass element coincides with the radio peak. Moreover, the point-to-point comparability between the radio and X-ray floor brightness throughout the halo signifies a powerful sublinear correlation.

The observations additionally revealed a powerful anti-correlation between the spectral index and the X-ray floor brightness throughout the halo. In keeping with the researchers, that is in keeping with radial steepening.

Summing up the outcomes, the authors of the paper underlined that the properties of radio halo in Abell 2256 make it a really peculiar object, whose additional investigation might advance our data about particle acceleration mechanisms on very giant scales.

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