Radio Galaxy Zoo Talk

Shedding light on the mutual alignment of radio sources

  • JeanTate by JeanTate

    That's the title of a blog post, dated 18 November, 2017. It's about a paper that will be published in MNRAS this month, and which appeared in astro-ph in August, "Radio Galaxy Zoo: Cosmological Alignment of Radio Sources", by O. Contigiani, F. de Gasperin, G. K. Miley, L. Rudnick, H. Andernach, J. K. Banfield, A. D. Kapińska, S. S. Shabala, and O. I. Wong. Here's the abstract:

    We study the mutual alignment of radio sources within two surveys, FIRST and TGSS. This is done by producing two position angle catalogues containing the preferential directions of respectively 30059 and 11674 extended sources distributed over more than 7000 and 17000 square degrees. The identification of the sources in the FIRST sample was performed in advance by volunteers of the Radio Galaxy Zoo project, while for the TGSS sample it is the result of an automated process presented here. After taking into account systematic effects, marginal evidence of a local alignment on scales smaller than 2.5deg is found in the FIRST sample. The probability of this happening by chance is found to be less than 2 per cent. Further study suggests that on scales up to 1.5deg the alignment is maximal. For one third of the sources, the Radio Galaxy Zoo volunteers identified an optical counterpart. Assuming a flat ΛCDM cosmology with Ωm=0.31,ΩΛ=0.69, we convert the maximum angular scale on which alignment is seen into a physical scale in the range [19,38] Mpc h−170. This result supports recent evidence reported by Taylor and Jagannathan of radio jet alignment in the 1.4 deg2 ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The TGSS sample is found to be too sparsely populated to manifest a similar signal.

    And one from the day before, "RGZ team spotlight: Francesco de Gasperin" (link)

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