Selecting variable sources with median colours using a self-organising map

December 2024 • 2024PASA...41..110V

Authors • Venville, Thomas • Capak, Peter L. • Faisst, Andreas L. • Lee, Bomee • Thanjavur, Karun G. • Flynn, Chris

Abstract • A key objective for upcoming surveys, and when re-analysing archival data, is the identification of variable stellar sources. However, the selection of these sources is often complicated by the unavailability of light curve data. Utilising a self-organising map (SOM), we demonstrate the selection of diverse variable source types from a catalogue of variable and non-variable SDSS Stripe 82 sources whilst employing only the median u-g , g-r , r-i , and i-z photometric colours for each source as input, without using source magnitudes. This includes the separation of main sequence variable stars that are otherwise degenerate with non-variable sources ( u-g , g-r ) and ( r-i , i-z ) colour-spaces. We separate variable sources on the main sequence from all other variable and non-variable sources with a purity of 80.0% and completeness of 25.1% , figures which can be modified depending on the application. We also explore the varying ability of the same method to simultaneously select other types of variable sources from the heterogeneous sample, including variable quasars and RR-Lyrae stars. The demonstrated ability of this method to select variable main sequence stars in colour-space holds promise for application in future survey reduction pipelines and for the analysis of archival data, where light curves may not be available or may be prohibitively expensive to obtain.

Links

• ELECTR https://doi.org/10.1017%2Fpasa.2024.118