Imperial College London
Portrait Picture

Professor David van Dyk

Faculty of Natural Sciences, Department of Mathematics

Chair in Statistics
 
 
 
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Contact

 

+44 (0)20 7594 8574d.van-dyk Website

 
 
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Assistant

 

Mr David Whittaker +44 (0)20 7594 8481

 
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Location

 

539Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Fan:2023:1538-3881/aca478,
author = {Fan, M and Wang, J and Kashyap, VL and Lee, TCM and Dyk, DAV and Zezas, A},
doi = {1538-3881/aca478},
journal = {The Astrophysical Journal: an international review of astronomy and astronomical physics},
title = {Identifying diffuse spatial structures in high-energy photon lists},
url = {http://dx.doi.org/10.3847/1538-3881/aca478},
volume = {165},
year = {2023}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Data from high-energy observations are usually obtained as lists of photon events. A common analysis task for such data is to identify whether diffuse emission exists, and to estimate its surface brightness, even in the presence of point sources that may be superposed. We have developed a novel nonparametric event list segmentation algorithm to divide up the field of view into distinct emission components. We use photon location data directly, without binning them into an image. We first construct a graph from the Voronoi tessellation of the observed photon locations and then grow segments using a new adaptation of seeded region growing that we call Seeded Region Growing on Graph, after which the overall method is named SRGonG. Starting with a set of seed locations, this results in an oversegmented data set, which SRGonG then coalesces using a greedy algorithm where adjacent segments are merged to minimize a model comparison statistic; we use the Bayesian Information Criterion. Using SRGonG we are able to identify point-like and diffuse extended sources in the data with equal facility. We validate SRGonG using simulations, demonstrating that it is capable of discerning irregularly shaped low-surface-brightness emission structures as well as point-like sources with strengths comparable to that seen in typical X-ray data. We demonstrate SRGonG's use on the Chandra data of the Antennae galaxies and show that it segments the complex structures appropriately.
AU  - Fan,M
AU  - Wang,J
AU  - Kashyap,VL
AU  - Lee,TCM
AU  - Dyk,DAV
AU  - Zezas,A
DO  - 1538-3881/aca478
PY  - 2023///
SN  - 0004-637X
TI  - Identifying diffuse spatial structures in high-energy photon lists
T2  - The Astrophysical Journal: an international review of astronomy and astronomical physics
UR  - http://dx.doi.org/10.3847/1538-3881/aca478
UR  - http://arxiv.org/abs/2208.07427v2
UR  - http://hdl.handle.net/10044/1/101322
VL  - 165
ER  -
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