More on our fake AGN

Carie’s announcement of the addition of fake AGN has stirred up a storm on the comment thread, and in the forum. I’ve replied where I can, but I think there’s a fundamental misunderstanding that it’s worth highlighting here :

We’re not trying to get you to identify AGN – we want you to classify the galaxies just as you always would. The aim is to test whether the presence of such an AGN affects the classification of the shape of the galaxy. If they do, we need to measure the size of the effect. So don’t go AGN spotting – except for fun – but keep classifying.

I hope that helps.


P.S. If you do want to know if you’ve identified a fake AGN, then the galaxy’s examine page will say so and the ID will begin AHZ7….

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6 responses to “More on our fake AGN”

  1. c_cld says :

    I’ve seen in the literature that the AGN fraction of CDF (Chandra Deep Field) is ~250 over ~25000 (~1%). If the GZ hubble images has the same fraction of AGN in the GEMS-GOODS-S field, I wonder if you want to measure a tiny effect by faking a very small sample of 116 objects.

    A recent study (arXiv:1007.1453v1 ) has shown that
    « the AGN fraction is approximately constant across colors for galaxies with similar stellar masses and that AGNs with blue and red hosts have comparable X-ray luminosities. These results imply that AGN activity is about as prevalent in massive blue galaxies as it is in red galaxies. »

    Another effect you try to measure is the influence that bulges may be smaller in blue
    (late-type) hosts (i.e., with larger Eddington ratios) than in red (early-type) hosts.

    As the AGN experiment seems to me more a color experiment, how could you infer significant results on morphology and bulge ratio by your AGN sample applicable to mass field?

    Besides these difficulties, your investigation is certainly worthwile to show positive /negative effects on human eyeball classifications.


  2. devon says :

    i think this a positivly excelent attribute to galxy zoo’ it is very informative

  3. kev says :

    sorry but…agns????what is AGNS?

  4. Speaker-to-Animals says :

    @kev The “fake AGN” link in the first sentence of the main post links to an explanation. TL;DR: AGN = Active Galactic Nuclei (see link for more info).

  5. Mark says :

    recent issues in this year of Sky & Tel and Astronomy magazines contain excellent articles about Active Galactic Nuclei (AGN) galaxies. Most AGN galaxies are variable in their light output, like variable stars. For more information, contact the American Association of Variable Star Observers. (AAVSO) go to:

  6. Tony Mach says :

    By Darwin! This is awful! Everytime I time I see one of those faint objects, I struggle to classify – with or without manipulations. The classification system can’t handle these barley above noise ink-blobs as they are. Why don’t you go and ADD meaningful classification options for these kind of objects instead? Instead of doing a study how people handle a problematic situation? Who are you, that you let us interpret ink-blobs like that? Psychologists? If I want to enroll in a psychological study, I would like to know beforehand 🙂

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