Lintott - suggested checks of the zeta method

willettk / gzhubble

Reduction and analysis materials for the Galaxy Zoo: Hubble project.

http://hubble.galaxyzoo.org

MIT License

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Lintott - suggested checks of the zeta method #46

Closed willettk closed 8 years ago

willettk commented 8 years ago

Old suggestions from @chrislintott (Jul 2015 telecon), noted here for completeness:

Plot zeta as a function of color to examine what effect that has on the boosting
Look at the galaxies getting significantly boosted. What did the CANDELS team (GOODS) in Jeyhan's catalog say about those? Are they really marginal disks?
What is the evolution of the cutoff p_features-mu point as a function of redshift? Is it a linear fit? If so, could we extrapolate it to CANDELS?

willettk commented 8 years ago

Regarding point 2: we matched GZH against Kartaltepe+15, Table 3. We looked at galaxies in the correctable sample with p_features,raw < 0.2 and p_features,best > 0.5 (so galaxies getting significantly boosted from smooth to disks). K15 only have eight such galaxies in their sample. Of those, they classify:

5 as spheroids
2 disks
1 irregular/disk

Visual inspection of the ACS images shows almost all at very low surface brightness, so it's difficult to tell if features are present. At least one of the K15 spheroids looks to have an extended component that the CANDELS classifiers missed.

Caveats: sample size is only 8 galaxies; entirely different wavelengths and image conditions; difficulty in matching their vote fractions to GZH (see Brooke's GZC paper).

vrooje commented 8 years ago

Did any of the K15 galaxies get marked in that catalog as having a morphological K-correction (one of the bands having a significantly different morphology than H... usually the ACS band)?

willettk commented 8 years ago

Do you know what that column would be named in K15, by any chance?

On Thu, May 5, 2016 at 4:20 PM Brooke Simmons notifications@github.com wrote:

Did any of the K15 galaxies get marked in that catalog as having a morphological K-correction (one of the bands having a significantly different morphology than H... usually the ACS band)?

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub https://github.com/willettk/gzhubble/issues/46#issuecomment-217283569

Dr. Kyle Willett Research Associate School of Physics and Astronomy University of Minnesota

vrooje commented 8 years ago

It's 3 columns: f_?diff where ? is V, z, or J. From looking at the catalogs most of the things with really high values of one or more of those appear to be dropouts.

willettk commented 8 years ago

Don't see that in this catalog - there's fFlag? with V, z, and J ...

On Thu, May 5, 2016 at 9:09 PM Brooke Simmons notifications@github.com wrote:

It's 3 columns: f_?diff where ? is V, z, or J. From looking at the catalogs most of the things with really high values of one or more of those appear to be dropouts.

— You are receiving this because you modified the open/close state.

Reply to this email directly or view it on GitHub https://github.com/willettk/gzhubble/issues/46#issuecomment-217331347

Dr. Kyle Willett Research Associate School of Physics and Astronomy University of Minnesota

vrooje commented 8 years ago

Hmm, maybe it changed names between the team version and the public version? It's columns 23-25 in the catalog I have...