Radio Galaxy Zoo Talk

ARG0001hup: is the tiny, 1-contour source to the W real?

  • JeanTate by JeanTate

    Or is it an #artifact? (Note: the brighter, 2-contour source seems quite real; it's a #compact)

    If the tiny source is real, is it likely to be a #lobe?

    For sources like this, is it possible to distinguish between something real and an artifact? If so, how to do so, objectively?

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  • JeanTate by JeanTate

    ARG00014f2 is another example; in this case, however, I think the 1-pixel radio source is real, and corresponds to the core

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  • JeanTate by JeanTate

    Another: ARG0001yj1. The 1-pixel radio source seems real, also corresponds to the core, host zph 0.38 SDSS J142136.51+260808.8, maybe

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  • sisifolibre by sisifolibre

    May be these are similar? : http://radiotalk.galaxyzoo.org/#/collections/CRGS00013d

    Some of these galaxies are near, and look like are real sources, may be are some kind of onesided?

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  • JeanTate by JeanTate in response to sisifolibre's comment.

    Yes, I think ~half those in your Collection are similar to ones I've posted in this thread.

    I'm hoping a radio astronomer will drop by and comment, especially re whether there is an objective way to assess whether a tiny, faint radio source (in an ARG field) is real or not. Of course, with deeper observations, it would likely be straight-forward; absent those however ...?

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  • JeanTate by JeanTate

    It seems these are surprisingly common; here's another one, that seems real: ARG00015zv

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  • sisifolibre by sisifolibre

    Yes, they are very common, I was making these collection for a few days, when I saw that they are very ussual I stopped collecting them.

    I don't remember where but I'm almost sure that I have read a comment about this saying that are real faint lobes...

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  • 42jkb by 42jkb scientist, admin

    The contours begin at a signal-to-noise ratio of 5 so this 1-contour source is at the 5sigma level. So I would agree that this is possible a very faint lobe. Sometimes you will see this in a spiral galaxy and would indicate a region of star formation.

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  • JeanTate by JeanTate

    Thanks sisifolibre, 42jkb.

    If there's a contour, and contours are for 5-sigma only, then by chance we would expect no more than perhaps one or two in the whole ARG database, right?

    However, how likely is it that 'faint, small, 1-contour' sources are artifacts, side-lobes for example? There are surely some such, but how many? And how to tell which are side-lobe (or other) artifacts?

    When such a tiny, faint source seems to coincide with a faint IR/optical source, the temptation is to assume they are related, especially if such an IR/optical source is a galaxy.

    But chance coincidences of artifacts and IR/optical source certainly occur!

    How to tell them apart?

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  • ivywong by ivywong scientist, admin

    The short answer is that we can't. Until someone digs deeper and obtain more observations, we have to be open to the possibility that what we are up against the observation limitations.

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  • JeanTate by JeanTate in response to ivywong's comment.

    Thanks Ivy.

    To what extent does the FIRST catalog parameter SIDEPROB help?

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