Galaxy Zoo Starburst Talk

"Post-Quenched" = "E+A" = "K+A"?

  • JeanTate by JeanTate

    And maybe "post-starburst" too?

    If so, then these are, perhaps, not so new to at least some zooites! For example, I wrote about them in an OotD (Object of the Day), in the GZ forum "Saturday, 19th February 2011: new galaxy type - "E+A progenitor"", and zooite c_cld posted a collection of them in the forum, in a thread called Post Starburst galaxy.

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  • trouille by trouille scientist, moderator, admin

    Very cool. Yes, all those names refer to this type of galaxy. We'll be using the term 'post-quenched galaxies' for our sample, because that's the most appropriate naming for them. The spectra for the galaxies in our sample give the indication that they had star formation within the past few hundred million years, but they're not currently forming new stars. Something caused the star formation to quench relatively abruptly and recently.

    The name post-starburst has always been problematic because it is used to refer to galaxies that may not have had an actual starburst, but just simply had their star formation quenched. It seemed a misleading name.

    E+A and K+A are names that do a good job representing the spectral features of these galaxies, but they're not as enticing sounding as post-quenched galaxies!

    BTW, E+A refers to 'Elliptical + A-star spectral mix' and K+A refers to 'K-star + A-star spectral mix'.

    Anyone have a good link or reference to information on spectral types? I like these:
    http://apod.nasa.gov/apod/ap040418.html
    http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php

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  • trouille by trouille scientist, moderator, admin

    There's also a GZ article that came out about very low redshift post-starburst galaxies, by Ivy Wong and collaborators. Great article. Definite inspiration for this project.

    Check out http://postquench.blogspot.com/ for a summary and access to that article.

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  • JeanTate by JeanTate

    Thanks! 😃

    Will we - GZQ project members - have access to the earlier GZ classifications of these ~6k galaxies? Could prove interesting, in terms of independent classifications (and helping bring to light subtle biases).

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  • KWillett by KWillett scientist

    Hi Jean,

    That shouldn't be a problem. Most of them don't have previous GZ classifications - only about a quarter of them were in GZ2, mostly because these galaxies tend to be a little fainter than those we included in GZ2. However, it's a good idea to look at earlier data as calibration for some of the GZ Quench tasks. The data will be available by the time classifications for GZQ are finished.

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

    In both GZ forum threads I mentioned, zooite zutopian provided links to Ivy's two GZ blog posts on this paper: Post-starburst galaxies paper submitted! and Post-starburst galaxies paper accepted!.

    That's a very nice write-up, on the Post Quench Blogspot! Did you write that, Laura?

    A down note: unless things have changed in the last year or so, no zooite in China can ever read what you wrote 😦 Blogger, like Twitter and Facebook (and many more), is behind blocked by The Great Firewall. WordPress, which the Zooniverse uses for its blogs, is not (as far as I know).

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

    Cool! 😄

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  • trouille by trouille scientist, moderator, admin

    I didn't know about blogger being blocked. We'll be porting those summaries over into Talk in the next couple of days, so that won't be an issue soon.

    Mike Zevin, Adler Mission Specialist and awesome future astronomer, wrote those summaries.

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

    The SDSS DR5 cross-correlation templates would be perfect ... if they were re-done to match what DR8 spectra look like!

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  • zutopian by zutopian

    Jean had asked.:

    "Will we - GZQ project members - have access to the earlier GZ classifications of these ~6k galaxies? Could prove interesting, in terms of independent classifications (and helping bring to light subtle biases)."

    KWillett replied.:

    "Hi Jean, That shouldn't be a problem. Most of them don't have previous GZ classifications - only about a quarter of them were in GZ2, mostly because these galaxies tend to be a little fainter than those we included in GZ2. However, it's a good idea to look at earlier data as calibration for some of the GZ Quench tasks. The data will be available by the time classifications for GZQ are finished."

    Referring to above posts, I would like to mention following remark by Kevin Schawinski in an old GZ blog post.:

    "The conclusion – post starburst galaxies are dominated by objects who have intermediate morphology (often half of you thought they were disks and half thought they were ellipticals – telling us that they are just hard to classify!)."

    http://blog.galaxyzoo.org/2011/06/07/post-starburst-galaxies-at-the-aas/

    PS: I mentioned that remark also in the bias discussion.: http://quenchtalk.galaxyzoo.org/#/boards/BGS0000001/discussions/DGS0000058

    EDIT:
    PPS: I found some GZQ images, which are actually easy to classify, but however the classification results are wrong!
    http://quenchtalk.galaxyzoo.org/#/collections/CGSS0000ct

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