Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies
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JeanTate
From today's astro-ph, arXiv:1711.09611, by A. D. Kapinska, I. Terentev, O. I. Wong, S. S. Shabala, H. Andernach, L. Rudnick, L. Storer, J. K. Banfield, K. W. Willett, F. de Gasperin, C. J. Lintott, A. R. Lopez-Sanchez, E. Middelberg, R. P. Norris, K. Schawinski, N. Seymour, B. Simmons:
Hybrid morphology radio sources are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of hybrid morphology radio sources, we embarked on a large-scale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies (L_median = 4.7x10^{24} W/(Hz sr) at redshifts 0.14<z<1.0. Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high- and two as low-excitation galaxies. Two candidate HyMoRS are giant (>1Mpc) radio galaxies, one resides at a centre of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the Radio Galaxy Zoo in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.
And a blog post today, Radio Galaxy Zoo finds rare HyMoRS!
Congratulations Anna, Ivan, and the rest of the team! 😃
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sisifolibre
Great!
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akapinska
scientist
Definitely paper with a great involvement of both professional and citizen science team!
The official publication of the paper can be also freely accessed through the journal (Open Access for all 😃 )
Astronomical Journal (2017) 154, 253
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sisifolibre
I want talk a little about this: "there is an unknown bias associated with which sources were tagged as hybrid or asymmetric"
Can anyone give more clues about how identify an #hybrid candidate to reduce these "unknow bias"? I want to make better classifications... and I hope this post helps to identify these "unknow bias". Perhaps I miss some posts explaining it? I only can find this text in "Suggested Hashtags" post: "Hybrid radio sources are a rare class of objects where one side is a #hourglass-shaped, and the other looks like a #plume. These are very interesting because they give us vital clues about how the radio sources interact with inter-galactic gas through which they are moving."
I think that is important to use the images, definitions and argot that we can find in RGZ. My general criteria using the usual tags in RGZ is that a subject that seems halfhourglass-halfplume ( in article "FRI radio structures on one side of the nucleus and FR II on other").
But ... perhaps I missunderstand when one side is a plume (has FR II structure)? See some examples:
https://radiotalk.galaxyzoo.org/#/subjects/ARG00000ul
Here @ivywong sais: "the hotspot needs to be further offset to one side". Some times @Dolorous_Edd has referred this "hotspot", what does it mean exactly?
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https://radiotalk.galaxyzoo.org/#/subjects/ARG00006p8
what I am thinking wrong?======================================================================================================
https://radiotalk.galaxyzoo.org/#/subjects/ARG000231o How it would be if it would be an #hybrid candidate?
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JeanTate
in response to sisifolibre's comment.
Can anyone give more clues about how identify an #hybrid candidate [...]
What a great question! 😄
I think it's worth a Discussion thread of its own, a sort of mini-tutorial. And I'd write (or at least start) one ... except that I have more questions than answers about how to confidently make such a classification! 😦
I want talk a little about this: "there is an unknown bias associated with which sources were tagged as hybrid or asymmetric"
I'm hoping Anna or Ivan can address this.
As I understand it, the "unknown bias" is certainly associated with the tags (hashtags) applied. Myself, I use #asym (and similar) far more often than #hydrid (or #HyMoR), but it's certainly possible that some which I've tagged asymmetric are, in fact, also hybrids. And it's possible that there are sources which are hybrids, but I've not tagged them as anything unusual. How would one go about determining the "bias" in my own classifications? I really don't know! And how would one do that for all of us who've used either tag?
Perhaps this "bias" thing is deeper? For one, "bias" has a somewhat different meaning here than it does in everyday English (at least, I think it does). For another, there's certainly a "classifier" bias: only some of us write Comments (or add to a Collection, or Favorites; or start or add to a Discussion thread); only some of us write about unusual objects (whether asymmetric or hybrid or SDRAGN or ...); we may not be consistent in what we write/add hashtags to/etc (I know my classifying has changed greatly since RGZ started); and so on.
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ivywong
scientist, admin
I guess we are being very picky here because until we have higher resolution follow-up observations, pinpointing the core or hotspot is not so easily when the emission is mostly unresolved. This is why what we are more likely to find larger systems here from the FIRST data where the hot spot and the core is well-separated and the host galaxy's position is more certain.
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JeanTate
There are 25 HyMoRS (hybrids) in "the Anna+Ivan paper" (Kapinska+ 2017). They all have positions for the host the authors feel is the most likely. And there are really detailed contour overlay images of each in the paper, most with just FIRST, but some with both NVSS and FIRST.
I have tracked down one ARG field for each of the 25 (there are two for RGZ J083352.2+045822) and created a Collection with them; I've called it AIHyMoR. There are, very likely, more ARG fields containing at least some (or some part) of these. By looking at these 25 (26) ARG fields, we volunteers may get a good idea of what a hybrid is.
Some important notes:
- 3o5g: overedge, SW lobe not visible in FIRST
- 19iz: overedge
- 21rf: overedge
- 24bn: overedge
- 3e9u: the host is a Green Bean (per the paper; myself I don't think it is)
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