Radio Galaxy Zoo Talk

Need help? Come here first! (FAQ)

  • vrooje by vrooje admin, scientist

    Fellow science team member Stas (@stasmanian) has compiled this list of Frequently Asked Questions:

    Q: Why does Radio Galaxy Zoo use a combination of optical / infrared and radio data?

    Radio Galaxy Zoo is designed to search for exploding supermassive black holes. These show up best in the radio part of the electromagnetic spectrum. But black holes live in galaxies, and in order to understand what causes the black hole eruptions, and how much they can affect their surroundings, we need to know what sort of galaxies these black holes live in. This information comes from optical and infrared data.

    There is also another reason for looking at radio and infrared images together. In many galaxies (like those we call “starburst galaxies”), the radio emission comes from normal stars rather than black holes. Comparing the shapes of the infrared emission (the galaxy) and the radio emission (which could be due to the star formation in the galaxy or due to the black hole) gives important clues as to where the radio emission is actually coming from.

    Q: Why have a slider? I find it confusing.

    The slider is there to help you decide how well the radio and infrared emission match up. Initially you see an image with just the radio data. You can gradually introduce more and more infrared data (coloured red) as you move the slider left to right. When the slider is far across to the right, you can still see the radio emission as contours. Moving the slider back and forth helps you decide whether the radio emission is associated with a single infrared galaxy or not, and whether the sizes of the radio source and galaxy are similar (i.e. the radio source is compact).

    If the radio source is extended, the slider has another function: it helps you look for symmetry. Many types of emission from active black holes are symmetric. In other words, the shape of the radio emission can be the same either side of the central infrared galaxy. Having said that, some of the most interesting radio sources are ones where this symmetry is broken! You can tag these using various #hashtags below.

    Q: How do I know if different radio blobs are connected?

    If the radio contours join various blobs together, either directly or by a chain of partly disconnected low-level contours, they probably belong to the same source. This is often true even if the contours don't quite connect the blobs but are extended towards each other.

    Also, if the blobs are symmetric, especially when placed around a central optical/infrared source, then they are probably connected and belong to the same source. On the other hand, if each blob is separate and associated with a different infrared galaxy, they are probably two different sources. If you find connected blobs, feel free to tag them using the #hashtags below, depending on the shapes of the various blobs.

    Q: Why can’t a computer classify these galaxies?

    The human brain is still most advanced computer on Earth, and humans are very good at recognizing complicated patterns. For example, humans are much better than automated computer algorithms at ignoring spurious noise, and recognizing symmetric patterns.

    Q: The image looks like a train wreck, with contours/radio emission all over the place.

    Sometimes the radio emission will have no clear shape, and be scattered over large parts of the image. This could be either a faded black hole eruption, or radio emission of background radio sources not well resolved (nothing to do with the black hole indicated by the optical/IR source). Feel free to tag this as #diffuse or #messy.

    Q: There are lots of infrared sources. Which ones are relevant?

    What we see on the sky is a two-dimensional projection of a three-dimensional Universe. So many galaxies will appear close to each other in projection, but actually be physically separated by very large distances. Please pick out the infrared galaxy or galaxies that you think are associated with what appears to be the centre (or core) of the radio source.

    If there are other questions you keep seeing here on Talk, please post them here (and also do post if you know the answer)!

    Cheers,
    -Brooke

    Posted

  • planetaryscience by planetaryscience

    Quite an informing Q&A, but I wasn't aware that Black Holes exploded....

    Posted

  • DocR by DocR scientist

    The language is a little poetic. The black holes themselves don't explode, but there is a high-energy expulsion of material from them, often in the form of jets that may be moving at close to the speed of light. The material doesn't come from inside the black holes, but from material that has fallen (almost) in from the surroundings.

    Posted

  • planetaryscience by planetaryscience

    Okay, thanks for clarifying. Could you edit it to be a bit more specific please? Also, it seems a bit crazy that it takes so much energy to propel something to the speed of light, yet a black hole a few million kilometers across can do it pretty easily for thousands of light years.

    Posted

  • ivywong by ivywong scientist, admin

    More specific changes are on the way. Thanks for your patience

    Posted

  • planetaryscience by planetaryscience

    I'm going to make a "how to classify galaxies" help discussion once I get the hang of this and I learn how to put the pictures including both radio AND infrared images.

    Posted

  • ivywong by ivywong scientist, admin

    These black holes are approximately 100 million times the mass of our Sun. The energetics involve are indeed "out-of-this-world" (pardon the pun) and some of the jets are very straight because they are collimated by some very strong magnetic fields.

    Posted

  • N5bz by N5bz

    I am seeing the marking for the IR source showing up to the right about 10% of the overall image width and about 5% lower than the point I clicked on. Browser is Chrome running on Win7. Suggestions?

    Posted

  • N5bz by N5bz in response to N5bz's comment.

    See http://tinyurl.com/mnt8cg6 to see a screen snapshot of this problem.

    Posted

  • 42jkb by 42jkb scientist, admin

    @N5bz, interesting. I will forward this on to the developers to see what is going on. You should be able to remove the IR circle by clicking on the 'x'.

    Posted

  • N5bz by N5bz

    yes, but the circle is needed. It just doesn't show up in the location where I click!
    I am not sure if it gets reported correctly and just looks wrong on my screen or it would be reported wrong (in which case I can always click 'high and to the left'

    Posted

  • N5bz by N5bz

    I just posted the image to help after I 'aimed high and to the left' to get the circle in the correct location.

    Posted

  • 42jkb by 42jkb scientist, admin

    Thank you for letting us know about this. I have sent this on to see what needs to be fixed.

    Posted

  • N5bz by N5bz in response to 42jkb's comment.

    Let me know if I can be of any help by gathering any data.

    Posted

  • Veegee by Veegee

    I must be particularly stupid, but I don't get it and the tutorial is sadly lacking. I go to the supposed 'expert' finds on the left side of the screen, and they look totally different than the example of the tutorial. Guess I will wait for the next project to come along

    Posted

  • ivywong by ivywong scientist, admin

    @Veegee, I very much doubt that you are stupid. Can you please explain where you're getting confused? Perhaps I can guide you through it?

    Posted

  • duaned by duaned

    I'm getting similar results to that of N5bz except mirrored as compared to N5bz.

    Posted

  • 42jkb by 42jkb scientist, admin

    @duaned are you using the same browser as @N5bz?

    Posted

  • N5bz by N5bz in response to duaned's comment.

    @duaned, try resetting your zoom level (ctrl-zero). That fixed my offset problem.

    Posted

  • smo by smo

    There's nothing like a dumb question, so here I go:
    I dont get the geometry of the scene. How come, we have the galaxy somewhere in the IR image and then two (2) radio lobes, (hopefully connected with the super black hole in it)!?

    Arent the radio emissions emanating in the opposite directions (2PI space angle) from the source in the galaxy?. Like one of them pointing towards Europe and the other one towards NZ, if the suspect galaxy is in the center of the earth?

    And (supplementary Q), given equatorial planes of candidate galaxies all over the 4PI range... Are we seeling/looking just for a specific, narrow population of cases?

    TiA

    smo

    edit: ... or are we seeing radio emissions in some - e.g. equatorial - plane?

    Posted

  • ivywong by ivywong scientist, admin

    @smo: No such thing as a dumb question, only dumb answers 😉 So hopefully this is a less dumb answer. The resolution of the IR images are not as good as those in SDSS so many of the distant galaxies are unresolved. Check out this link to see how the resolution of the telescope affects how you see the Universe: http://coolwiki.ipac.caltech.edu/index.php/Resolution

    The radio emission can be emanating in opposite directions or then can be bent sometime. The images that we host on this website have not been corrected for viewing angle so our viewing angle are for those from Earth out. In cases where we are viewing straight into the jets, we will get a #compact source. These radio sources are easy for computers to match to their IR galaxies so we have left out some of these source from the Radio Zoo project.

    I hope this is helpful.

    Posted

  • m_bright by m_bright

    How faint is the IR source allowed to be for us to still click it? Or does it only count if it's "white" ?

    Posted

  • DocR by DocR scientist

    Here's the short answer: click on anything that looks "real" to you. We know there's a problem with the WISE survey (see discussion on "WISE Sources Everywhere" http://radiotalk.galaxyzoo.org/#/boards/BRG0000003/discussions/DRG00001m9 )
    but we're going to need to sort that out later, figuring out statistically how far down we can trust. But we need people to be doing the clicks so we can figure that out. Thanks!

    Posted

  • m_bright by m_bright in response to DocR's comment.

    Great! That's what I've been doing so I'll carry on.Thanks for your help.

    Posted

  • hardan by hardan in response to 42jkb's comment.

    I'm getting the same problem except the circle is about an inch to the LEFT and a quarter inch up; clicking on radio contours is fine. Running Win8 with IE10. Takes several tries to get the circle mostly over the IR source.

    Posted

  • ivywong by ivywong scientist, admin

    @hardan: Can you please see if you can update to IE11 and see if it helps?

    Posted

  • Ptd by Ptd

    I think I need help navigating the site, I've been trying to find an image of ARG0002xeg with the coordinates listed and with the active slider, because I'd like to see if it is available in any other surveys, but all I can seem to find is a dumb image, can anyone help?

    Many thanks

    Posted

  • planetari7 by planetari7

    Ответьте пожалуйста. Почему на некоторых слайдах, появляются светящиеся полосы по контору слайда, сверху и снизу? Это что-то значит или не обращать на это внимание?

    Posted

  • Daniel222 by Daniel222

    Why am I seeing the radio sourse, but in IR are dark red field??

    Posted

  • JeanTate by JeanTate in response to Daniel222's comment.

    Which object were you looking at (the identifier which begins with the letters ARG)?

    Posted

  • JeanTate by JeanTate in response to planetari7's comment.

    Welcome to Radio Galaxy Zoo, planetari7!

    I do not understand Russian, but with the help of Google Translate I think you are asking why there are glowing stripes on some images (at the top and bottom)?

    As I do not remember seeing anything like this, I can't really answer you. Do you have the identifier - a string of characters which begins with the letters ARG - of any of these? That would help.

    Happy hunting! 😃

    Posted

  • Daniel222 by Daniel222 in response to JeanTate's comment.

    Unfortunately I wasn ' t add this object to favourite, but I searched in recents and find this: ARG0001u4o, ARG00026br. I ' m not sure in 100% if these are the objects which interested me. Sorry for my english

    Posted

  • Doctor50 by Doctor50

    So how aligned are the pictures? If they're taken at slightly different times, wouldn't they be different, or do reaction wheels work effectively enough?

    Posted

  • ivywong by ivywong scientist, admin

    Hi Doctor50,

    The images have all been aligned based on their World Coordinate System (WCS) so they should be aligned but there can be fields where the uncertainty in the alignment can be off by a pixel or so. Does this help?

    Posted

  • KWillett by KWillett scientist, admin, translator

    The component to the radio source may be either bright or dim, depending on how far away the galaxy is and how luminous it is. Generally you should use the position as your main guide - either look for radio jets pointing toward specific points, or infrared galaxies that are very nearby the radio jets.

    Posted

  • DocR by DocR scientist

    Sorry for a long delay for reply. Radio sources are shown as contours. You click on as many contours as you think belong to one source. Then you click done and then click which one infrared object/galaxy goes with that radio source (contours). Then, if there are still more radio contours, you can start on the next source, or you can be finished. Might be useful to check out the tutorial once more. Again, sorry for delay in replying.

    Posted

  • 42jkb by 42jkb scientist, admin

    When you click on "Discuss" in the main RGZ interface, it brings you to Radio Talk. At the bottom of the image there are links (in blue) to FIRST, NVSS, SDSS, WISE. Click on the SDSS link and you will get the SDSS image.

    Hope this helps.

    Posted

  • KWillett by KWillett scientist, admin, translator

    If you hover your mouse over a post, you'll see a button that says "Remove" appear in the upper right corner. Click that to remove any post that you've made.

    Posted

  • angelaschneider78 by angelaschneider78

    Why are there radio images without obvious IR sources?

    Posted

  • JeanTate by JeanTate in response to angelaschneider78's comment.

    Welcome to Radio Galaxy Zoo, angelaschneifer78! 😃

    There are several answers, depending on what you're actually referring to. For example:

    • many extended radio sources (the bits in the images we get to classify which are within the white contours, and which are white when you move the slider to the far-left) are, physically, giant clouds of gas (actually plasma, to use the correct technical term) which do not emit enough IR to be detected by WISE (the satellite used to map the IR sky, and whose data we use in this project). The association of these radio sources with IR sources is one of the key objectives of this project

    • some of the IR sources at the same position (on the sky) as radio sources are quite faint, so you may not notice them easily

    • in some of the classification images, the IR background is bright, even completely white (due to it being in a large, nearby galaxy, or near a very bright star, or because of some failure in the WISE instrumentation); in these (few) cases, there will be no obvious IR source

    • perhaps the most exciting cases are called IFRS (infrared faint radio sources); these are bright radio sources (usually more or less circular in shape) with no obvious IR counterpart. They are thought to be some of the first galaxies (or super-massive black holes) in the universe (Ray Norris wrote a Galaxy Zoo blog post on these, IFRS: The first supermassive black holes?)

    I hope this reply is helpful to you; if you've got more questions, please don't hesitate to ask! 😄

    Posted

  • juno5724 by juno5724

    Hi. Can you tell me how to view images which have been referred to in other posts i.e. if someone mentions ARG0001u4o where can I input that to bring it up? (I've tried the search box but that must be wrong as it brings up narry a thing.) Also, can a compact radio source be smaller than the IR source? I thought I'd read a comment which said it was very unlikely but so far I've seen quite a few where there is a small, compact radio source directly over a larger IR source. And if the IR galaxy is not the host galaxy how do you mark the image? As no IR source? Thanks.

    Posted

  • 42jkb by 42jkb scientist, admin in response to juno5724's comment.

    Hi juno5724,

    You can access the id by http://radiotalk.galaxyzoo.org/#/subjects/ARG0001u4o and you can replace the ARG code with the source you are interested in.

    Yes, a radio compact source can be smaller than the host galaxy. Objects like this can be the inner core of the AGN or maybe have to do with star formation if not at the centre of the host galaxy.

    The IR host galaxy may not be at the centre of the image, it can be off to the side or there may be no IR host galaxy at all. If there is no IR host galaxy there is a button that says "no infrared", just click on this to classify the object.

    Thanks for classifying!

    Posted

  • AliceV by AliceV

    Can someone answer me the 1st stage of classification is easy the next we must mark only the sourses which are inside it ???

    Posted

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

    Hi AliceV. and welcome to RGZ! 😃

    When you took the tutorial (the second 'button' to the right, in the blue circle, the one which looks a bit like a computer monitor with an arrow in it), were you able to follow along OK? And is the Spotter's Guide (pop-out cyan bar on the left) clear on what infrared (IR) sources should be clicked for each of the examples?

    For single radio sources, you would generally look for an IR source within the contour outlines (and if none, click the "No Infrared" button). For extended radio sources, the IR source to click may be within one or other set of contours, or it may not ... depends on which IR source you think is the galaxy whose nucleus is creating the radio emission (and it may be that you think there is no IR source).

    Hope this helps.

    Posted

  • ivywong by ivywong scientist, admin

    Thanks @JeanTate!

    Posted

  • sdixit2000 by sdixit2000

    I really wish that the tutorials did a better job of explaining exactly what is happening. Especially the planetary/space ones, seem to be very poorly explained in the tutorials. Can we improve them?

    Posted

  • DZM by DZM Zooniverse Team

    Something that seems to help a lot is when we add a link to this Talk-based FAQs from the classification interface. That way it can be continually updated.

    We've done that on a couple of other projects, now... Would people find it useful on RGZ as well?

    Thanks!!

    Posted

  • shocko61 by shocko61

    Hi everyone I have been away for about 7 months , and for the life of me I cannot find how to get an image into talk , it is like there is something missing on the classify page also when I click talk all I get is a blank page like it cannot open in talk . any help please, Ian ,shocko61

    Posted

  • DZM by DZM Zooniverse Team in response to shocko61's comment.

    Hey Ian, are you saying that when you click the "discuss" button after classifying an image, it doesn't take you to Talk?

    Thanks!!

    Posted

  • magdalen_n by magdalen_n

    Some glitches. I've had to reload the page a few times:

    1. for something to appear in the central box (navigating back from the Science page)
    2. to see the contours (they wouldn't appear even if I clicked on hide/show contours)
    3. for my recent contributions to show up on my Profile screen (I have seen this glitch in other zooniverse projects)
      [Firefox 35.0.1 running on Mac OSX 10.9.4]

    Requests:

    1. I wish that I could see the radio contours with the IR images when I look at my galaxies again on my Profile page. If I had to pick between radio and IR, I'd pick radio as it's the jets that are most interesting, but having the IR image with teh radio contours overlaid would be best.
    2. On the Profile page, I wish there was a counter, not just the squares showing the IR images.

    Posted

  • magdalen_n by magdalen_n

    Follow-up: looking at the tutorial makes the contours go away. Reloading the page makes them come back.

    Posted

  • ivywong by ivywong scientist, admin

    @magdalen_n: thanks for the heads-up. I will check with the developers. Can you please let me know which Internet browser you are using and what version ? For example, I am using Firefox 35.0.1 and it works fine.

    Posted

  • Rimbaud by Rimbaud

    Just how spot on do the Radio and IR images have to be for us to tag them as associated?

    How faint can a IR image be that seems associated Radio image and still "count?"

    Posted

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

    Good questions!

    Just how spot on do the Radio and IR images have to be for us to tag them as associated?

    I don't know what others do, but for compact sources (and slightly extended ones too), I tag the IR and radio sources as "associated" if the apparent center of the radio is within the boundary of the IR source. I also mark these as associated if they're ~a few arcsecs off, and note this as #offset.

    For (radio) double lobes it's more difficult: sometimes they are nicely symmetric, with an obvious IR source right in the middle; however, mostly it's my own judgement ...

    How faint can a IR image be that seems associated Radio image and still "count?"

    Technically, I guess the IR smudge would need to be identified as a source in a WISE catalog. Of course, while you're classifying, you do not have access to that! My rule of thumb is to pick as associated even a very faint IR source ... and to then note it in a Comment, as #faintIR. This will lead to some "false positives" (i.e. IR sources that are not real, just noise), but that'll get sorted out when all our clicks are analyzed.

    Hope this helps, and happy hunting! 😃

    Posted

  • A13_23_ by A13_23_

    Does anyone know the radio contour interval of every image?

    Posted

  • JeanTate by JeanTate in response to A13_23_'s comment.

    I think the ratio of the intensity (flux density) of two adjacent contours is sqrt(2).

    Perhaps someone could confirm this?

    Posted

  • ivywong by ivywong scientist, admin in response to JeanTate's comment.

    Hi Jean,
    The lowest contour typically begins at 4 times the rms noise of the image and then increases in steps of sqrt(3).
    Ivy

    Posted

  • aka_xena by aka_xena

    I'm sorry if this was already posted, but I find that there are some Radio sources that "should" be marked, that aren't and I can't mark them. I've put them in the discussion section, but is it just me?
    for example: ARG00008lw at the 11 o'clock position (ish) is not marked, along with some others.

    It would be great if there was a "this was missed" or "I think I found something interesting" identifier would be a nice addition

    Posted

  • ivywong by ivywong scientist, admin

    Hi @aka_xena,
    Please click the "Discuss" button anytime you notice anything strange with any of the images, you can then leave a comment for the subject so that future scientists (both citizens and professionals) will know of your issue.

    With regards specifically to ARG00008lw , the only radio source is a compact at the centre of the subject. The minor spots that you see around 11-oclock that resemble a lattice-like structure are processing artefacts and not real.
    cheers,
    Ivy

    Posted

  • mbstone12 by mbstone12

    What should be done when the image of the contours is only partial in the corner?

    Posted

  • JeanTate by JeanTate in response to mbstone12's comment.

    Welcome to Radio Galaxy Zoo, mbstone12! 😃

    I'm not 100% sure what you're referring to (perhaps something like this, or this?), but my advice would be to click within the contours (they should turn cyan), and click on any WISE (IR) source which seems to be associated with the radio emission. Often there will be none, so respond accordingly.

    Sometimes such #overedge sources are part of a larger radio structure - one might be part of a lobe for example, or perhaps the core - be sure to mark all radio sources you think are associated with the larger structure.

    Hope this helps, and happy hunting! 😃

    Posted

  • Service55 by Service55

    I am a little confused. When I mark a contour(s) and shift to the infrared and a bright blob shows up under the contours is that a positive or negative? I just do not want to mark the wrong things.

    Posted

  • ivywong by ivywong scientist, admin

    Hi @Service55,
    The bright (or white) blob is the infrared emission of the galaxy's stellar population. Typically a compact radio source (a radio point source) will be spatially coincident with the position of the host galaxy. However, if we view it from the side, we often see 2 radio components sandwiching the location of the host galaxy without necessarily overlapping spatially.

    I urge you to redo the Tutorial so that you get more familiar with the classification process. If the Tutorial does not automatically start up, please click the middle of 3 circular buttons that you can see to the top right of the classification subject. This should start a tutorial.

    I hope that this is helpful.

    Posted

  • nickoftona by nickoftona

    no images appear - i just finished work on another project ok

    Posted

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

    Welcome to Radio Galaxy Zoo, nickoftona!

    Sorry to hear that you do not see any images. May I ask, are you trying to classify what's on this page? What is it that you actually see when you bring that page up in your browser?

    Hope that you resolve this soon, and start hunting for supermassive black holes! 😃

    Posted

  • repairmanscully by repairmanscully

    Hi, I just stumbled on this very interesting project. I have some immediate questions, after going through the IR/radio image pairs.

    Firstly, what immediately comes to my mind is that these images are not correlated. How certain are we that there are not substantial gravitational lensing issues that separate the wavelengths from each source like a prism, making essentially different skies appear when looking at such varied wavelengths? So many of the pictures, when going from radio to IR, appear to fade away and be replaced by a completely different construction of objects unrelated to the other. Has this possibility been ruled out, that though the images are in the same position in the sky they are still not related? It makes me wonder if the matches that are found are either illusory or from sources proximal enough to keep the separation limited, with everything more distant basically being lensed so much that a completely different image in a different range of wavelengths overlaps the first.

    Also, it would be useful to be able to look around the images at surroundings--is there any way to see what is directly outside the image for a larger picture? What is shown is hard to decipher what is actually correlated with what, if anything is at all, without larger regions to consider.

    This is very fascinating, but it would seem that if the source of the IR were near the source of the radio waves, even if we didn't see the sources themselves we would still see some semblance of their presence in the shape of the other regions, but the only time there appears to be any match at all is when the IR and radio images happen to contain overlaps, which I would propose (without the capacity to see larger regions) that this may be an optical illusion where IR and radio waves from different sources which are lensed differently, like a prism, just so happen to arrive at Earth in precisely the same angle in space and make it appear like the IR and radio matches we do see are correlated when they are not, with most cases showing no overlapping.

    Is this possible? Has this been ruled out by larger scale pictures that have more statistically proven correlations?

    Posted

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

    Welcome to RGZ, repairmanscully! 😃

    How certain are we that there are not substantial gravitational lensing issues that separate the wavelengths from each source like a prism, making essentially different skies appear when looking at such varied wavelengths?

    Good question. Strong gravitational lenses (gravlenses) very rarely produce images or arcs that are bigger than ~10" (arcseconds), yet the fields (images) we get to classify are far bigger (2.4x2.4', that's arcminutes; 1' = 60"). Second, gravlenses are quite rare; even with the Hubble, you can find only ~10-20 per square degree, and almost all of those are far too small to distinguish from a point in RGZ images. Finally, gravitational lensing is achromatic: all wavelengths are bent by exactly the same amount.

    Has this possibility been ruled out, that though the images are in the same position in the sky they are still not related?

    This is also a good question, one that is independent of gravlenses. That there are chance alignments is certain, given how big the sky is and how many different IR and radio sources there are. But how many of the matches we find are chance alignments, and how many are physically related? Limits on this can be established by analysis of the data we provide (by our clicks); this is on-going. From my own experience, I'd say chance alignments are pretty unusual, say 2% or less.

    is there any way to see what is directly outside the image for a larger picture?

    While classifying, no. Once your classification is done, you can see the larger environment by clicking on the NVSS, WISE, FIRST, and SDSS links. All but the SDSS one gives you, by default, a bigger field (for SDSS you have to click on the marks between the + and - signs). From my experience, about one in ~20 fields have radio sources, or host galaxies, that are outside the classification field (the ARGs).

    Hope this helps, and happy hunting! 😃

    Posted