What is this app about? This app produces a visualization of the minimum spanning tree (MST) of the pulsar (millisecond pulsar) population, considering a properly normalized Euclidean distance based on 8 pulsar magnitudes: the spin period (P0), the spin period derivative (P1), the spin-down energy loss (EDOT), the characteristic age (AGE), the magnetic field at the surface (BSURF), the magnetic field at the light cylinder (BLC), the surface electric voltage (SEV), and the Goldreich-Julian charge number density (GJC). The latter six magnitudes cannot be measured directly, and their values for each pulsar are computed here within the rotating dipole model context. The MST shown is also obtained using the principal components, with PC1 and PC2 accounting for the full variance of the population.

For the MST of the millisecond pulsar population, the feature space above is extended with the orbital period (PB), the projected semi-major axis (A1), and the median mass companion (MC), while AGE is ruled out (see García et al., 2024 for more details).

Details Our original reference (García et al., 2022) provides details on graph theory concepts necessary for constructing the MST and its properties. It also includes explicit formulas for all the magnitudes used here, as well as the distance. Information about branch and trunk definitions can be found in (García & Torres, 2023) and (García et al., 2024).

What the app does? The app usage is largely straightforward. You can zoom in, select a group of pulsars, mark one or a region of pulsars, and see the location of a specific pulsar, a group of pulsars, or a subpopulation of pulsars. You can choose any axis in the right-panel plot using the provided buttons, and all such plots share the same features. The selected pulsars can be downloaded in table format (.csv), which displays all the magnitudes used and the ranking of the 10 closest pulsars based on Euclidean distance for each pulsar listed in the table. The app is using the dataset contained in the ATNF Catalog v2.6.3. The noted classes of pulsars are taken from the following compilations when their members are also quoted in ATNF, which is our base sample:

How does the finder work? You can use the pulsar finder to search for a specific or several pulsars of interest, e.g., J1824-2452A, or several together, e.g., J2053+1718,J1759+5036 (note that the separation between the pulsar labels can be with a blank space, a comma, or a semicolon).

How does the filter work? Using the given names for each of the variables, and the units in which they can be read and appear in the diagram and table, one can select whatever range of pulsars to be noted in the plots. For instance, 0.002< P0<0.003; or EDOT>1e35&BSURF>1e14; (the symbol & separates two different ranges). You can apply a filter to all available variables at once. The color priority when selecting different pulsars based on functionalities is finder, class select, and filter.

What is behind the app? The app is done using Bokeh. The math behind the app is coded in Python, as described in the papers quoted above.

Citations: If you find this app useful please quote our original papers