Detecting abrupt changes in the spectra of high-energy astrophysical sources

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Title: Detecting abrupt changes in the spectra of high-energy astrophysical sources
Authors: Wong, RKW
Kashyap, VL
Lee, TCM
Van Dyk, DA
Item Type: Journal Article
Abstract: Variable-intensity astronomical sources are the result of complex and often extreme physical processes. Abrupt changes in source intensity are typically accompanied by equally sudden spectral shifts, that is, sudden changes in the wavelength distribution of the emission. This article develops a method for modeling photon counts collected from observation of such sources. We embed change points into a marked Poisson process, where photon wavelengths are regarded as marks and both the Poisson intensity parameter and the distribution of the marks are allowed to change. To the best of our knowledge, this is the first effort to embed change points into a marked Poisson process. Between the change points, the spectrum is modeled nonparametrically using a mixture of a smooth radial basis expansion and a number of local deviations from the smooth term representing spectral emission lines. Because the model is over-parameterized, we employ an ℓ1ℓ1 penalty. The tuning parameter in the penalty and the number of change points are determined via the minimum description length principle. Our method is validated via a series of simulation studies and its practical utility is illustrated in the analysis of the ultra-fast rotating yellow giant star known as FK Com.
Issue Date: 22-Jul-2016
Date of Acceptance: 12-Apr-2016
ISSN: 1941-7330
Publisher: Institute of Mathematical Statistics
Start Page: 1107
End Page: 1134
Journal / Book Title: Annals of Applied Statistics
Volume: 10
Issue: 2
Copyright Statement: © Institute of Mathematical Statistics 2016. The version of record is also available from the journal website:
Sponsor/Funder: The Royal Society
Commission of the European Communities
Funder's Grant Number: WM110023
Keywords: Statistics & Probability
Publication Status: Published
Appears in Collections:Mathematics
Faculty of Natural Sciences

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