Introducing PxP: A Population Synthesis Framework for Predicting Young Stellar Object Properties

Abstract The most direct method of measuring the star formation rate is with young stellar objects (YSOs), but this requires high-resolution observations and high-quality models. Using the latest YSO radiation transfer and stellar evolution models, we have developed a population synthesis code that generates model YSO populations that can be observed by JWST. We combine these model populations with principal component analysis (PCA) and maximum likelihood fitting to create a complete framework for predicting the ages and masses of YSO populations. We dub this combination of population synthesis and PCA as PxP, and show that it is effective at predicting masses and ages with self-fitting tests. We apply PxP to Spitzer Space Telescope–identified YSOs in N44 and find a mass of (1.1 ± 0.1) × 10 4 M ⊙ and an age of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.7</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> Myr, consistent with previous work. Next, we identify 112 YSO candidates in the archival JWST observations of NGC 604. Applying PxP to this newly identified population we find a mass of (2.2 ± 0.2) × 10 4 M ⊙ and an age of 0.62 ± 0.01 Myr. This first look at this framework demonstrates its effectiveness with a specific set of models and leaves clear opportunities for future exploration. PxP allows us to directly determine the recent (&lt;3 Myr) star formation history, giving an unprecedented look at the effect of the large-scale environment on individual star formation.