Looking at Quasar,

Are quasars that show up in VLASS directed at us? Why are there these big dark gaps and bright regions?


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Does anyone know what these green clouds or jets are?



The VLASS six-sided pattern comes from its point-spread function (or the radio version of that). I’m not sure why it goes dark in between.

Somehow I doubt radio would allow a point-spread of a Very Large one of those Dustin :wink: Even in 2022 …

Thank you so much. I will get back to point-spread, but the reason I highlight those green clouds is they are super radio hot, compared to what I’ve seen, like that whole area, I’m guessing they are some (very large?) astrophysical jets. idk hoping someone who knows more than me can chime in. I don’t exactly understand this point spread function thing. Like do you have a galaxy zoo of serseic profiles of galaxies that you model…and have a different point spread for each. Ugh really confused by this, kind of hoping for a tutorial or something. Does point spread matter for spectroscopy? Isn’t that like 10000 different point sources. Really could use some help here. Are you saying the light enters the lens, spreads, and that you unspread it? I think this has somethign to do with the models and residuals. Idk I still am way confused.

If you space bar the VLASS and switch between HSC and it, you can see what I mean by the area being radio hot, but it is pretty hard for me to interpret the VLASS and I can’t find any videos on the subject.

These galaxies are known radio-loud AGN, so no surprise they’re bright in VLASS. I’m not sure the “green clouds” are actually as green as they look. take a look at HSC DR3:


On the PSF thing, there isn’t really a ‘lens’ for the light to enter, as VLASS uses the VLA, which is an array of radio dishes. The PSF is just how a telescope reacts to point sources. I wouldn’t feel confident in speculating why it looks like a radiation warning sign; I don’t have any experience carrying out analysis of radio data, let alone knowledge of a how a PSF would change with an array rather than a single telescope.

For the VLA, the PSF has that six-sided shape because the physical layout of the dishes is three spokes

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Okay thank you Tom, I am wondering about a few of your points, and this is totally not a hill for me to die on, but I would like my reasoning improved. If these galaxies are known to be radio loud, as you say, and I did a little digging, and yes, one of these galaxies is known to be radio loud, but don’t we want a smoking gun around a voorwerp?
This is the galaxy that is “radio loud” 4C 00.46 – Active Galaxy Nucleus
There are a lot of galaxies right there, but the radio signature is quite large, like pretty much larger than other radio galaxies, so to me it is surprising and bizzare - not like the radio bubbles similar to fermi bubbles exactly. But I’m no radiologist… :slight_smile:

This is a Radio Galaxy, NGC 4055, are those jets that you see on the right side the visual outcome of the jet interacting with two different types of gas or is that an artifact? It is in the same plane as the radio jet. I used the VLASS to find this, but then looked it up and found that others had already found the radio jets that drift off.

But around these “nebula echo” objects or whatever that is… there are huge radio signatures like that beautiful voorwerp that Ine found too.

Your point about it not being as green as I suspect, where are you finding HSC DR3 images? It is hard for me to find them on the web, but I can’t really tell from your image because it is dominated by redness if that is truly green, which I suppose is the point you were making. Still this is a large radio signature, and in a different conformation than just “bubbles” around a radio galaxy or a point source, like a quasar. Idk, I guess what would you say that green stuff is, and its okay to be nothing… I just sort of want to know why or where all I’m going wrong

Thank you!!

There’s an HSC map web site, hscMap where you can explore their imaging, including looking at the other bands they have (g,r,i,z,y).

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Okay great. Thanks guys, learning so much. Sorry for the bad joke, but I’m feel like I’m happier than pharell right now.

Okay so
So I know no one asked, but here is the object in the different bands. It is dim in the green band, shoes up in the red and blue and then dims again. Again thank you for the HSC-DR3 direction. I suppose originally Hanny’s Voorwerp was found to be interesting because it narrowly showed up in the green band, being a signature of one emission line., where as this is dominantly in R and I. But you guys are sure this isn’t anything?

Here it is with the radio overlayed at 30 percent opacity. Does anyone know how to create a frame of a specific pixel position and width with SDSS? I was using the lateral nail folds on my hand as pointers with my fingers pressed against the screen to get that… and the snipping tool (which doesn’t have a frame function)

Does any of this tell us anything?

there’s an SDSS layer in the legacy surveys viewer, if that helps?

I don’t know how that would help. Don’t we have a problem with resolution? Of course I would like to see if the object is in different telescopes vision (thus not an artifact), which is why I am pointing out the huge radio signature around that space and the strange shape… idk man, it seems like everyone assumes artifact, but I don’t really see a good way to find the difference between smoething new, and an abberation.