Skies and Universes Johan Comparat (UAM CSIC IFT) SelGIFS workshop, - - PowerPoint PPT Presentation

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Skies and Universes Johan Comparat (UAM CSIC IFT) SelGIFS workshop, - - PowerPoint PPT Presentation

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Skies and Universes Johan Comparat (UAM CSIC IFT) SelGIFS workshop, Universidad autonoma de madrid november 2016 Skies and universes, rationale To overcome the cultural barrier and communicate or co-work efficiently, one needs a solid structure

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Skies and Universes

Johan Comparat (UAM CSIC IFT) SelGIFS workshop, Universidad autonoma de madrid november 2016

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Skies and universes, rationale

To overcome the cultural barrier and communicate or co-work efficiently, one needs a solid structure that in the case of astrophysics or cosmology can be reduced to a cluster of computers where data, code and resources are in open access and documented. It aims to be a very special place to connect ideas to data and theory in the most versatile, fluid manner. Currently exist many high-quality databases related to telescopes and virtual observatories: www.sdss.org, http://vizier.u-strasbg.fr/, etc. But these are not directly connected with scientific code repositories, theoretical predictions nor computing facilities. This multiplication of interfaces between the scientist and these three entities, leads to important time losses. Such a co-working space also enables better reproducibility and easier teamwork.

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code data simulations http://projects.ift.uam-csic.es/skies-universes/

Collaborators:

  • J. Comparat
  • F. Prada
  • G. Favole
  • S. Rodriguez-Torres
  • P. Zarrouk
  • E. Burtin
  • C. Maraston
  • V. Gonzalez-Perez
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Software & Database

Classes Libraries

DATA RELATED Class GalaxySurvey{SurveyName}

  • Overall calibration methods
  • Converts flux => luminosities

Class GalaxySpectrum{SurveyName}

  • Opens spectra
  • Spectra calibration
  • plotting

SCIENCE RELATED Class LineLuminosityFunction

  • derives LF from a catalog: completeness, weighting, uncertainty

Class ModelLuminosityFunction

  • fitModel: Schechter or Saunders

Libraries

  • filterList
  • Decam, megacam (cfht), sdss broad band filter curves
  • LineFittingLibrary
  • Integrates spectrum, fits emission line (single or doublet) models (Gaussian, Lorentzian, pseudoVoigt)
  • lib_plot
  • Produce standard plots from the catalogs
  • lineListAir / Vac
  • Line list to consider. Depends on pyneb

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Emission-line-luminosity-selected galaxy samples

Based on Comparat et al. 2016. MNRAS. Arxiv 1605.02875

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DATA

  • Use major spectroscopic magnitude limited surveys that cover more

than a square degree

  • Fold data into a common data base (skies and universes) to enhance

control over flux limits determination, weighting and completeness

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DATA

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Workflow DATA SCIENCE

  • flux calibration for DEEP2 spectra
  • fit emission line to spectra (VVDS, DEEP2, VIPERS)
  • create emission line catalogs
  • convert observed flux into luminosity
  • Compute TSR and SSR
  • Determine magnitude limit and flux limit

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  • Estimate line luminosity function
  • Convert references to Planck cosmology
  • Fit Saunders and Schechter models
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Fitting Example

Signal to noise is low therefore convergence is tricky. It depends on * resolution * redshift * line flux * estimation of the continuum * estimation of the uncertainty

  • n the flux

* …

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Results, [OII] LF

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[OIII] 5007 LF

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H beta LF: new !

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Fit results

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Results

  • Skies and universes started a year

ago

  • It hosts a few projects:
  • 2 published (1507.04356,

1605.02875), the latter is 100% end- to-end reproducible.

  • 2 in the referee process (1611.05457)
  • 4 in preparation
  • And many more to come :-)
  • New collaborators are welcome !
  • Emission line LFs
  • The models plugged-in to an analysis

allow comparison to any observed field: “where do I stand with respect to the mean density of line emitters.”

  • Great tool to plan observations,

understand and forward model completeness

  • In preparation
  • relation between line LF and stellar

populations models

  • Conditional emission line LFs

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Exercise

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Arxiv: 1507.07979

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Fitting emission line models

  • In the folder “ELG-

composite” taken from Zhu, Comparat et al. arxiv:1507.07979. It contains :

  • High SNR ELG stack:

average properties of

  • bserved ELGs
  • Two scripts
  • Three data files
  • Open and read

“pysu_tutorial.py”

  • 1. With the composite spectrum:
  • 1.a. Fit emission line models to the the [OIII] 5007 line existing

in the composite spectrum provided here :

  • 1.b. plot the best emission line models found along with the

data, discuss the chi2 / degrees of freedom found.

  • 1.c. Artificially increase / decrease the uncertainty on the flux

(errors) and look at how the line model parameters vary. Discuss the importance of the error.

  • 1.d. Fit models to other lines: [OII] doublet, H beta. Discuss

the challenges corresponding to each lines.

  • 2. With the stellar population model (SPM):
  • 2.a. compare the SPM spectrum provided and the composite
  • spectra. Is it a reasonable model ?
  • 2.b subtract the SPM from the composite and fit emission line

models to the residual spectrum. Be careful with the estimation of the errors on the residual spectrum

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