Table 2.

SFH parameters and priors.

NoteParameterDescriptionPrior
1zredRedshiftUniform: zspec ± 0.01
2log (M/M)Total mass formedMZR: clipped normal, min = 8, max = 15
3|$\hat{\tau }_{\lambda ,2}$|Diffuse dust optical depthUniform: min = 0, max = 4
4log (Z/Z)Stellar metallicityMZR: clipped normal, min = −2, max = 0.19
5|$\log \left(\frac{\mathrm{SFR}(t)}{\mathrm{SFR}(t+\Delta t)}\right)$|Ratio of the SFR ratios in adjacent age binsStudent t: μ = 0, σ = 0.3, 2 dof
6spec_normNormalization of the spectraUniform: min = 0, max = 100
7p1, p2, p3Continuum shape correction polynomial coefficientsUniform: min = −0.1/(n + 1), max = 0.1/(n + 1)
8spec_jitterSpectra white noise modelUniform: min = 1, max = 3
9|$f_\mathrm{outlier,\, spec}$|Spectra outlier fractionUniform: min = 10−5, max = 0.5
NoteParameterDescriptionPrior
1zredRedshiftUniform: zspec ± 0.01
2log (M/M)Total mass formedMZR: clipped normal, min = 8, max = 15
3|$\hat{\tau }_{\lambda ,2}$|Diffuse dust optical depthUniform: min = 0, max = 4
4log (Z/Z)Stellar metallicityMZR: clipped normal, min = −2, max = 0.19
5|$\log \left(\frac{\mathrm{SFR}(t)}{\mathrm{SFR}(t+\Delta t)}\right)$|Ratio of the SFR ratios in adjacent age binsStudent t: μ = 0, σ = 0.3, 2 dof
6spec_normNormalization of the spectraUniform: min = 0, max = 100
7p1, p2, p3Continuum shape correction polynomial coefficientsUniform: min = −0.1/(n + 1), max = 0.1/(n + 1)
8spec_jitterSpectra white noise modelUniform: min = 1, max = 3
9|$f_\mathrm{outlier,\, spec}$|Spectra outlier fractionUniform: min = 10−5, max = 0.5

Note. 1 – Spectroscopic redshift. 2 – Total mass is the sum of total stellar mass and mass lost to outflows; see note 3 for a comment on the prior. 3 – We assume a Milky Way extinction curve (Cardelli et al. 1989). 4 – We assume a prior on the stellar mass–metallicity relation (MZR) according to the local trend reported by Gallazzi et al. (2005), where we add the systematic offset between parametric and non-parametric stellar mass estimates (see Appendix  C). 5 – Ratio of the SFRs in adjacent bins of the 10-bin non-parametric SFH. The age bins are spaced in lookback time: 0, 30, 100, 500 Myr, and 1 Gyr, five equally spaced bins, and lastly 0.95× the age of our Universe at the observed redshift. For N age bins, there are N − 1 free parameters. 6 – The normalization of the spectra is a free parameter to account for systematics in the relative flux calibration. 7 – The shape of the spectral continuum can be adjusted by a third degree Chebyshev polynomial to account for systematics in the relative flux calibration. 8 – The uncertainty on the spectra can be increased by a given factor, with a likelihood penalty for factors giving reduced χ2 < 1. 9 – An outlier pixel model can increase the errors for individual pixels by a factor of 50, to accommodate for poor matches between the data and spectral templates.

Table 2.

SFH parameters and priors.

NoteParameterDescriptionPrior
1zredRedshiftUniform: zspec ± 0.01
2log (M/M)Total mass formedMZR: clipped normal, min = 8, max = 15
3|$\hat{\tau }_{\lambda ,2}$|Diffuse dust optical depthUniform: min = 0, max = 4
4log (Z/Z)Stellar metallicityMZR: clipped normal, min = −2, max = 0.19
5|$\log \left(\frac{\mathrm{SFR}(t)}{\mathrm{SFR}(t+\Delta t)}\right)$|Ratio of the SFR ratios in adjacent age binsStudent t: μ = 0, σ = 0.3, 2 dof
6spec_normNormalization of the spectraUniform: min = 0, max = 100
7p1, p2, p3Continuum shape correction polynomial coefficientsUniform: min = −0.1/(n + 1), max = 0.1/(n + 1)
8spec_jitterSpectra white noise modelUniform: min = 1, max = 3
9|$f_\mathrm{outlier,\, spec}$|Spectra outlier fractionUniform: min = 10−5, max = 0.5
NoteParameterDescriptionPrior
1zredRedshiftUniform: zspec ± 0.01
2log (M/M)Total mass formedMZR: clipped normal, min = 8, max = 15
3|$\hat{\tau }_{\lambda ,2}$|Diffuse dust optical depthUniform: min = 0, max = 4
4log (Z/Z)Stellar metallicityMZR: clipped normal, min = −2, max = 0.19
5|$\log \left(\frac{\mathrm{SFR}(t)}{\mathrm{SFR}(t+\Delta t)}\right)$|Ratio of the SFR ratios in adjacent age binsStudent t: μ = 0, σ = 0.3, 2 dof
6spec_normNormalization of the spectraUniform: min = 0, max = 100
7p1, p2, p3Continuum shape correction polynomial coefficientsUniform: min = −0.1/(n + 1), max = 0.1/(n + 1)
8spec_jitterSpectra white noise modelUniform: min = 1, max = 3
9|$f_\mathrm{outlier,\, spec}$|Spectra outlier fractionUniform: min = 10−5, max = 0.5

Note. 1 – Spectroscopic redshift. 2 – Total mass is the sum of total stellar mass and mass lost to outflows; see note 3 for a comment on the prior. 3 – We assume a Milky Way extinction curve (Cardelli et al. 1989). 4 – We assume a prior on the stellar mass–metallicity relation (MZR) according to the local trend reported by Gallazzi et al. (2005), where we add the systematic offset between parametric and non-parametric stellar mass estimates (see Appendix  C). 5 – Ratio of the SFRs in adjacent bins of the 10-bin non-parametric SFH. The age bins are spaced in lookback time: 0, 30, 100, 500 Myr, and 1 Gyr, five equally spaced bins, and lastly 0.95× the age of our Universe at the observed redshift. For N age bins, there are N − 1 free parameters. 6 – The normalization of the spectra is a free parameter to account for systematics in the relative flux calibration. 7 – The shape of the spectral continuum can be adjusted by a third degree Chebyshev polynomial to account for systematics in the relative flux calibration. 8 – The uncertainty on the spectra can be increased by a given factor, with a likelihood penalty for factors giving reduced χ2 < 1. 9 – An outlier pixel model can increase the errors for individual pixels by a factor of 50, to accommodate for poor matches between the data and spectral templates.

Close
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Close