ZTF Ia Phone-con: 2021-Dec-15

Meeting Agenda:

1. SNe of the week [Joel J]

2. Sub-WG updates [Ana S, Jeremy L, Suhail D, Mat S, Georgios D]

7. AOB / Close

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Participants (21):

• Adam M, Ana S, Alice T, Bastien C, Benjamin R, Dominique F, Estelle R, Georgios D, Jacco T, Jakob N, Jeremy L, Joel J, Kate M, Leander L, Mat S, Mickael R, Nora N, Philippe R, Suhail D, Valery B, Young-Lo K
• Apologies: Remi J

Transients of the Week:

• ZTF is off the telescope, so no fun discoveries ;(.

wg-spectra update (Jeremy):

• HyperGal has been run on all of the DR2 sample. The results are stable: <5% of cases fail.
  • The predominant failure is that Jeremy doesn't have access to the data or the calibration file is unavailable.
• Preliminary classifications imply that hypergal is better than pySEDm: especially in bright backgrounds.
• The key is to find:
  • a metric for determining a classification. Input from the community would be appreciated.
  • to identify pathologic failures when the galaxy spectrum is wrong or the SN spectrum is mistaken for the host.
    • Joel and others to provide examples and to compare to SDSS
  • "the truth": we're getting SEDm spectra of the hosts to compare the non-SN spectra to native hyperGal

wg-simulations update (Ana S):

• We met yesterday. It was a nice opening discussion: lots of people are using simsurvey:
  • Jacco on late time interaction; Ana on lensing; Melissa on selection; Bastien of fsigma8
• We need to ensure that everyone is using a consistent set of logs and that noise is treated correctly.
  • The plan is to investigate the effect of GAIN. This, by default is wrong, but might be accident by optimal!
• The plan is also to start editing the code to incorporate changes that people have made locally into the GitHub
  • With that, we can start to develop the code to include more features and to make the code more robust.
• If you want particular features then sign up and help!
• Mickael: did we discuss timelines? In short: things to be moving over Christmas and stable early in the spring.

wg-populations update (Mat S):

• Mat: the populations analysis is moving, but we're being slowed down trying to finalise the data.
• The plan is to 'finalise' the data (photometry, spectra, hosts) in the next month and then push on to 'model' (N21, BS21, SK16?) testing component.
• The current focus is to ensure the photometry is consistent across methods. The #force-photometry group is hopefully going to meet next week. We need to optimise / agree on a criteria for identifying bad images and a baseline correction.
• Georgios has been looking at an individual object and sees a large scatter: why?! He's also looking at flags and trying to find a consistent cut. The next step is to calculate the cloudy parameter to see if that does what's needed.

wg-externaldata update (Suhail D):

• A first, first draft of the ZTF-TRGB PoC paper is in progress. This contains the 1 SN with a measured TRGB distance.
  • We're hoping to have this submitted by the HST deadline: it highlights what ZTF will be able to do once the full dataset is finalised. Uncertainties to be addressed include the measured distance and the SN photometry.
• New H0-Cepheids results were released last week: Pantheon+. They find a consistent 73.
  • Plenty of improvements on the SN side: we're now up to 42 events.
  • From the Cepheid side, the distance to the Maser galaxy is now consistent with the LMC: what happened?
  • They are also cutting to only include star-forming (/spiral) galaxies. Interesting ;).

estimating galaxy properties (Young-Lo K):

• The recent P+ analysis uses LePhare to estimate galaxy properties, but force unphysical extinction values.
• Young-Lo is looking at the effect of this. Using a more physical value results in a local mass step, contrary to what was seen in the Jones 2018 analysis.
• => assumptions about the physics underlying a galaxy impact the recovered mass step.
• Suhail: are we going to get localSFR for the calibrator sample? Mickael it's super difficult!

Closing remarks:

• Christmas next week. Back on the 5th :).