DETERMINING X-RAY SOURCE INTENSITY AND CONFIDENCE BOUNDS IN CROWDED FIELDS

We present a rigorous description of the general problem of aperture photometry in high-energy astrophysics photon-count images, in which the statistical noise model is Poisson, not Gaussian. We compute the full posterior probability density function for the expected source intensity for various cas...

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Bibliographic Details
Published in:The Astrophysical journal 2014-11, Vol.796 (1), p.1-14, Article 24
Main Authors: Primini, F A, Kashyap, V L
Format: Article
Language:English
Subjects:
APERTURES
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Cases (containers)
Confidence
Confidence intervals
DATA ANALYSIS
DISTRIBUTION
Gaussian
Mathematical models
NOISE
PHOTOMETRY
PHOTONS
PROBABILITY DENSITY FUNCTIONS
STATISTICAL MODELS
X RADIATION
X-RAY SOURCES
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Summary:We present a rigorous description of the general problem of aperture photometry in high-energy astrophysics photon-count images, in which the statistical noise model is Poisson, not Gaussian. We compute the full posterior probability density function for the expected source intensity for various cases of interest, including the important cases in which both source and background apertures contain contributions from the source, and when multiple source apertures partially overlap. A Bayesian approach offers the advantages of allowing one to (1) include explicit prior information on source intensities, (2) propagate posterior distributions as priors for future observations, and (3) use Poisson likelihoods, making the treatment valid in the low-counts regime. Elements of this approach have been implemented in the Chandra Source Catalog.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/796/1/24