11.1.3 Summary of Apsis data products in Gaia DR3

Author(s): Orlagh L. Creevey, Ulrike Heiter, Frédéric Thévenin

The data products produced by CU8 in Gaia DR3 are either 1D data, e.g. $T_{\mathrm{eff}}$, or multi-dimensional (MD) data e.g. a self-organising map of outliers. Each of these products is described in this section.

1D data: There are several APs that are estimated by multiple modules, and several fields that are related. In order to facilitate the use of the archive, the following convention was adopted for each 1D data field name:

parameter_module_variant_detail

Here, parameter is one of the 43 main APs listed in Section 11.1.1 along with the auxiliary APs and these are given in the first column of Table 11.2 – Table 11.6. Next, module is the name of the Apsis module that derived the AP, see Section 11.1.2. Then, variant describes a variant of the method, models, or input data used to derive the AP. This part may be blank if only one method was used, or if the parameter value comes from the ”best” of several methods. Finally, detail may be blank if it is the value of the AP, or it takes on values such as upper, lower or uncertainty, where upper and lower imply upper and lower confidence levels (generally implying a 68% confidence interval but see data model descriptions). As an example, teff_gspphot_marcs_upper is the upper confidence level of the $T_{\mathrm{eff}}$ value estimated by the module GSP-Phot using the MARCS library of synthetic stellar spectra; classprob_espels_pne is the class probability value of being a PNe (planetary nebula) from the module ESP-ELS; mass_flame is the mass value derived from the module FLAME.

The full list of data products for each table, along with their variants, details, and cross-references to the data model description, are given in Table 11.2 to Table 11.6. In Table 11.2 which describes the largest archive table from CU8, astrophysical_parameters, due to its length, we only list those parameters that have variants or details, and we do not list all of the abundances nor the auxiliary parameters. The following are parameters not listed in that table: the non-variant parameters are spectraltype_esphs, classlabel_espels, evolstage_flame, and dibp0_gspspec. We use xfe to denote abundances, where x is an element symbol, and this implies the following 11 abundances relative to iron: nfe_gspspec, mgfe_gspspec, sife_gspspec, sfe_gspspec, cafe_gspspec, tife_gspspec, crfe_gspspec, nife_gspspec, zrfe_gspspec, cefe_gspspec, and ndfe_gspspec, for nitrogen, magnesium, silicon, sulphur, calcium, titanium, chromium, nickel, zirconium, cerium and neodymium, respectively, and the iron abundances relative to the total metallicity: fem_gspspec and feiim_gspspec. The following are the auxiliary parameters not listed in the table: flags_esphs, flags_espucd, flags_flame, flags_gspspec, flags_msc, flags_oa, classlabel_espels_flag, activityindex_espcs_input,dibqf_gspspec, mcmcdrift_msc, logchisq_gspspec, libname_gspphot, mcmcaccept_gspphot, mcmcaccept_msc, logposterior_gspphot, logposterior_msc, and bc_flame.

Table 11.3 describes the content of the astrophysical_parameters_supp table, and contains the variants of a number of parameters, which are not included in Table 11.2. In Table 11.3 we list all parameters, including the auxiliary parameters. Table 11.4 and Table 11.5 contain parameters relevant to quasar and galaxy candidates, respectively.

MD data: The tables and fields for the MD data are specific to a module and do not entirely follow the same naming convention. Table 11.7 – Table 11.11 describe the contents of the MD data tables. In gaia_source there are two boolean fields indicating whether a source appears in either of the MCMC tables called has_mcmc_gspphot and has_mcmc_msc.

Flags: Some of the Apsis modules (in particular, GSP-Spec, ESP-ELS, ESP-HS, ESP-UCD, FLAME, MSC, OA and QSOC) provide flags which indicate quality or processing information which might be useful for the user. We have adopted a common format for the reported flags appearing in the astrophysical parameter tables. Each flag is a string containing $N$ characters where $N$ is the number of items to report to the user and is typically 1 or 2 characters, with the exception of GSP-Spec which provides 41 characters in flags_gspspec. Each character can take on a specific numeric value, where ’0’ always indicates nothing to report. As a concrete example, flags_msc has $N=1$ characters and it can take on a value of 0 or 1. The information contained in the flags is provided in the description of the corresponding field for which the name starts with flags followed by the module name. An exception is the ESP-ELS module which provides the two parameter-specific flag fields ew_espels_halpha_flag and classlabel_espels_flag.

Filters: Filtering on astrophysical parameters was done during the postprocessing of the operational data of the individual modules. Details of filtering is therefore described in Section 11.3.