Identifying diffuse spatial structures in high-energy photon lists
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
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.
Date Issued
2023-02-01
Date Acceptance
2022-11-17
Citation
The Astrophysical Journal: an international review of astronomy and astronomical physics, 2023, 165 (2)
ISSN
0004-637X
Publisher
American Astronomical Society
Journal / Book Title
The Astrophysical Journal: an international review of astronomy and astronomical physics
Volume
165
Issue
2
Copyright Statement
© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms
of the Creative Commons Attribution 4.0 licence. Any further
distribution of this work must maintain attribution to the author(s) and the title
of the work, journal citation and DOI.
of the Creative Commons Attribution 4.0 licence. Any further
distribution of this work must maintain attribution to the author(s) and the title
of the work, journal citation and DOI.
License URL
Identifier
http://arxiv.org/abs/2208.07427v2
Subjects
astro-ph.IM
astro-ph.IM
astro-ph.HE
Publication Status
Published
Article Number
ARTN 66
Date Publish Online
2023-01-23