Spectral fit residuals as an indicator to increase model complexity

Abstract

Spectral fitting of X-ray data usually involves minimizing statistics like the chi-square and the Cash statistic. Here we discuss their limitations and introduce two measures based on the cumulative sum (CuSum) of model residuals to evaluate whether model complexity could be increased: the percentage of bins exceeding a nominal threshold in a CuSum array (pct${}_{CuSum}$), and the excess area under the CuSum compared to the nominal (p${}_{\text{area}}$). We demonstrate their use with an application to a $\text{Chandra}$ ACIS spectral fit.

arXiv comment3 pages, 1 figure, published in the Research Notes of the American Astronomical Society (RNAAS)

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Cited by in corpus (1)

• On Validating Angular Power Spectral Models for the Stochastic Gravitational-Wave Background Without Distributional Assumptions