SDSS J165620.60+640752.9 SDRAGN candidate?
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by sisifolibre
SDSS J165620.60+640752.9 seems disk, perhaps with spiral features. I would say new good #SDRAGN candidate. Of course as alwais can be an overlap but...
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by Dolorous_Edd
CFHT image of the possible host, IMO you can clearly see arms
Mapping: G-band to Blue; R-band to Green; I-band to Red
BUT SDSS J165620.67+640801.4 also could be the host
and better centered
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by JeanTate
Got it. It's in RGZG, Subject 18823886. Selected for observation by the Hubble. ๐
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by sisifolibre
Yeah! Thanks. According with your thread "who discovered..." from "I. Vasquez Baez&HAndernach personal collection 2012"
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by JeanTate in response to sisifolibre's comment.
You might remember that I asked for recommendations, I think around the time the possibility of a Hubble gap-filler program was first raised. I got a lot of inputs! ๐ Some - such as this one - came to me via PM or email.
Anyway, this is a good opportunity for me to repeat something important: what's in that RGZG Talk thread is only what I found, with some help from others; it is possible - even likely - that there are others whose names/handles should be added. So if you find any errors or omissions, please let me know!
Oh, and for the SDRAGN candidates, I also checked the professional literature ("papers") to see if there was even a hint that any professional astronomer had found that any of the RGZG targets is a spiral (or even a lenticular). While there are definitely papers which include every target, even if only as part of a huge table (for some targets NED lists a great many papers), none mention an SDRAGN nature. Not even for 3C223.1, the top-ranked RGZG target, which is in many papers and has been observed by the Hubble before; it is definitely an SDRAGN, one "hiding in plain sight"! ๐
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by sisifolibre
Perhaps they knew that is SDRAGN but is more important to do other investigations?
how "important" is to caracterice SDRAGN? How known are this rare beasts for professional astronomers? I haven't read almost nothing about them out of this forum.
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by JeanTate in response to sisifolibre's comment.
This paper, on arXiv, briefly mentions a summer program run by HAndernach (to use his RGZ handle): "A Search for double-lobed radio emission from Galactic Stars and Spiral Galaxies" (Ortiz Martรญnez+ 2016). It doesn't mention SDSS J165620.60+640752.9 as an SDRAGN candidate ... but then perhaps only a minority of the Subjects in RGZG were flagged by the volunteer "discoverers" as such either (or even as being odd in some way).
There are perhaps a couple of dozen or so papers, by professional astronomers, on SDRAGNs, and only a dozen or so "confirmed" SDRAGNs in the literature (there are several false positives).
Perhaps even more curious: it seems to be widely accepted that lenticulars (S0 galaxies) are also hosts of double-lobe radio sources, as are ellipticals. However, in my research into this so far, galaxies which are clearly lenticular and clearly hosts of DLs are just as rare as are spirals ๐ฎ In fact, many "lenticulars" which are reported in early papers (from the 1950s!) as being such hosts have turned out to be ellipticals, when observed more carefully. Of course, the boundary between "elliptical" and "lenticular" is a bit fuzzy ... but then, so is the boundary between "lenticular" and "spiral". So it may turn out that the key distinction is not how "early" a galaxy is (spirals can't host DLs because their interstellar media are too dense for the jets to "punch through"), but whether the galaxy has a substantial stellar disk.
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