ASKAP 888 MHz radio continuum image of the galaxy cluster Abell S1136. The high-resolution image shows the sources associated with the newly discovered filaments: (A) WISEA J233615.95–313534.4 (B) WISEA J233616.55–313609.3 and (C) WISEA J233616.10–313741.1 with a radio-labeled bright head. the tail galaxy PKS 2333–318. Credit: McGregor et al., 2024.
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ASKAP 888 MHz radio continuum image of the galaxy cluster Abell S1136. The high-resolution image shows the sources associated with the newly discovered filaments: (A) WISEA J233615.95–313534.4 (B) WISEA J233616.55–313609.3 and (C) WISEA J233616.10–313741.1 with a radio-labeled bright head. the tail galaxy PKS 2333–318. Credit: McGregor et al., 2024.
An international team of astronomers has employed the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope to conduct a radio survey of the galaxy cluster known as Abell S1136. The results of the survey campaign, published on May 23 in Publications of the Astronomical Society of Australiashow that the galactic cluster receives three thin filament structures.
Galaxy clusters consist of up to thousands of galaxies bound together by gravity. They are the largest known gravitationally bound structures in the universe, and can serve as an excellent laboratory for studying galactic evolution and cosmology.
Abell S1136 is a galaxy cluster located in the Pisces-Cetus supercluster, at an orbit of 0.06. It has a radius of about 2.44 million light years, a mass of about 129 trillion solar masses and a luminosity of about 5 million QW.
Previous observations of Abell S1136 have found that it exhibits a steep, diffuse radio emission, which appears as an amorphous radio blob. The emission came from a number of cluster radio sources including radio halos, radio remnants and remnant radio galaxies.
However, now, a new ASKAP study of Abell S1136 conducted by a group of astronomers led by Peter. J. Macgregor of the University of Western Sydney in Australia, show that the radio emission that propagates in the poles has a more complex structure than previously thought.
“We find that the radio emission in the center of the cluster shows more structure than seen in previous low-resolution observations of this source, which was previously seen as an amorphous radio blob, similar to a radio halo,” the researchers wrote. on paper.
ASKAP images of Abell S1136 show a region of emission about 1,470 light-years across, three narrow filaments within the diffuse emission, each 260-460 light-years wide, and a small number of compact radio sources.
Astronomers contend that the diffuse emission shows some structure not seen in previous low-resolution observations, and its properties do not closely match those of a halo or mini-halo.
The researchers find that the three filaments are similar to those found in other cluster sources using high-sensitivity observations. However, they do not rule out the possibility that they represent an unusual long-tail (WAT) radio source—a strong, curved source typically associated with the main galaxies in a cluster or group. More studies are needed to determine which theory is true.
The study also found that Abell S1136 shows a distinct pattern of X-ray emission that closely matches the radio emission from the brightest group of galaxies. The X-ray temperature profile shows that the cluster appears to be in a quiescent state, with no evidence of a cold core.
Summarizing the results, the authors of the paper conclude that many cluster radio sources, which are considered to be well-extended sources, may show a more complex structure, as was the case with Abell S1136.
More information:
Peter. J. Macgregor et al, Mapping the Evolution of the Universe (EMU): An Investigation of Filamentary Structures in the Abell Galaxy Cluster S1136, Publications of the Astronomical Society of Australia (2024). DOI: 10.1017/pasa.2024.36. Hon arXiv: DOI: 10.48550/arxiv.2406.09709
Journal information:
arXiv
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