Galaxy Zoo Starburst Talk

Investigating the color outliers

  • JeanTate by JeanTate

    enter image description here

    That's a plot of the objects in the QS catalog (excluding the duplicates).

    The orange diamonds are the 'photometric/image' outliers, which are in the Outliers - summary thread, under 'Star', 'Overlap', and 'not main/central part of galaxy' sections1. Clearly, quite a few of those are also color outliers.

    But what about the others? There are ~ten blue points which seem to be well away from the main 'QS cloud'; what are they? That's what this thread is about!

    Here is the corresponding QC plot:

    enter image description here

    While there are also clearly some 'blue point' color outliers, the edge of the 'QC cloud' seems fuzzier than that of the QS cloud. And there seems to be a clump beyond the red (g-r) end. In this thread I'll look at them too.

    1 I need to check that this is up to date!

    Posted

  • JeanTate by JeanTate

    QS color outliers

    AGS ID (SDSS DR7 ObjId), g-r, r-i: comments

    AGS0000272 (587742060001820696), -0.27, -1.16: star-burst merger (not post-quench)? off-center, spectrum unlikely to representative of whole galaxy:

    enter image description here

    AGS00001bl (588017726012129327), -0.10, 0.59: DR9 image (first) is not centered on DR7 object (second); off-center; not post-quench?

    enter image description here enter image description here

    AGS00000fq (588007004179660890), 0.11, 0.20: starburst; not at all quenched!

    enter image description here

    AGS00001n5 (587738067277119551), 1.63, 0.63: very interesting! Low redshift (0.037) but very red ... due to huge amounts of dust?

    enter image description here

    AGS00000dt (587728668806348953), 0.35, -1.05: Hmm, H-alpha, -beta, -gamma, -delta, and even -epsilon are in emission; not at all like an A type spectrum.

    enter image description here

    AGS0000242 (587742627995058239), 0.56, -0.14: off-center

    enter image description here

    AGS000027c (587742062689583159), 0.81, 0.05: post-starburst? not yet quenched?

    enter image description here

    AGS00000ds (587728669343613075), 1.49, 0.69: overlap

    enter image description here

    AGS000029c (587742012757180541), 1.29, 0.16: off-center

    enter image description here

    AGS000017f (588298664112881826), 1.29, 0.16: off-center

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    AGS00001eg (588017702403965079), 1.25, 0.16: overlap? Spectrum is very A-like

    enter image description here

    AGS00001se (587739294015553579), 0.92, 0.15: strange; double nucleus? overlap? Spectrum is very A-like

    enter image description here

    AGS0000153 (587736619322114241), 0.41, 0.6: overlap (main Eos seems undisturbed) or merger

    enter image description here

    Not really outliers, more like fringe-dwellers

    AGS00001ww (587739651037790549), 0.27, 0.0: intense starburst

    enter image description here

    AGS00000j3 (587731512071028908), 1.24, 0.67: strong [SII], [NII], H-alpha (emissions); weak [OIII]; dust-choked post-starburst?

    enter image description here

    Posted

  • JeanTate by JeanTate

    QC outliers

    AGS ID (SDSS DR7 ObjId), g-r, r-i: comments

    AGS00002wk (588848901515182119), -0.20, -0.20: intense starburst, possible overlap

    enter image description here

    AGS00003yw (587736940906872995), 1.0, 0.0: DR9 image (first) is not centered on DR7 object (second); off-center

    enter image description here enter image description here

    AGS000037i (587738411946737807), 2.0, 0.55: complex overlap/merger

    enter image description here

    AGS00002iu (587725039563505701), 0.09, 0.63: overlapping bright star messed up the photometry?

    enter image description here

    AGS0000462 (587739407324283127), 1.49, 1.08: no idea why it's so far from the QC cloud!

    enter image description here

    Posted

  • mlpeck by mlpeck

    Even though the DR8+ photometric pipeline was supposed to improve on previous efforts there are much larger outliers than in your first post above. On the other hand fiber magnitudes show a much tighter relationship:

    enter image description here

    The vertical and horizontal lines are estimated errors taken from the photObj table. The cloud of red points are my estimates of the k-corrected, galactic extinction corrected, and emission corrected colors.

    Posted