Systematics Uncertainties

Systematics Uncertainties#

NMMA currently uses --error-budget to specify the constant systematic uncertainties to be added to the likelihood quadrature.

However, it is now possible to use systematic error (\(\sigma_{sys}\)) prior in form of a freely sampled parameter, time dependent and/or filter dependent systematic error. This can done by specifying the file path using the --systematics-file in lightcurve-analysis command.

For more information on systematics error, please refer to the paper.

The following are the examples of the systematics file:

Example 1: Freely sampled (time independent) systematic error#

In this case the systematic error is freely sampled and is not dependent on time or filter.

config:
  withTime:
    value: false
    filters:
      - null
    time_nodes: 4
    type: Uniform
    minimum: 0
    maximum: 2
  withoutTime:
    value: true
    type: Uniform
    minimum: 0
    maximum: 2

Example 2: Time dependent systematic error#

In this configuration, a single systematic error is applied across all filters.

config:
  withTime:
    value: true
    filters:
      - null
    time_nodes: 4
    type: Uniform
    minimum: 0
    maximum: 2
  withoutTime:
    value: false
    type: Uniform
    minimum: 0
    maximum: 2

Example 3: Time and filter dependent systematic error#

In this configuration, the sdssu and ztfr filters are sampled together for systematic errors, while the 2massks filter is sampled independently. All other filters are grouped and sampled together

config:
  withTime:
    value: true
    filters:
      - [sdssu, ztfr]
      - [2massks]
      - null
    time_nodes: 4
    type: Uniform
    minimum: 0
    maximum: 2
  withoutTime:
    value: false
    type: Uniform
    minimum: 0
    maximum: 2

Distribution types#

Distribution can be of any of the analytical prior from bilby. Please refer to bilby documentation for more information on the available distribution type and their usage. Only positional arguments are required for any of the distrbutions.

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