Volume 549, January 2013
|Number of page(s)||11|
|Section||Numerical methods and codes|
|Published online||16 January 2013|
EXSdetect: an end-to-end software for extended source detection in X-ray images: application to Swift-XRT data⋆
CAS Key Laboratory for Research in Galaxies and CosmologyDepartment of
Astronomy, University of Science and Technology of China,
2 INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
3 INFN-National Institute for Nuclear Physics, via Valerio 2, 34127 Trieste, Italy
4 INAF, Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
5 European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching bei Muenchen, Germany
6 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching bei Muenchen, Germany
Received: 22 June 2012
Accepted: 23 November 2012
Aims. We present a stand-alone software (named EXSdetect) for the detection of extended sources in X-ray images. Our goal is to provide a flexible tool capable of detecting extended sources down to the lowest flux levels attainable within instrumental limitations, while maintaining robust photometry, high completeness, and low contamination, regardless of source morphology. EXSdetect was developed mainly to exploit the ever-increasing wealth of archival X-ray data, but is also ideally suited to explore the scientific capabilities of future X-ray facilities, with a strong focus on investigations of distant groups and clusters of galaxies.
Methods. EXSdetect combines a fast Voronoi tessellation code with a friends-of-friends algorithm and an automated deblending procedure. The values of key parameters are matched to fundamental telescope properties such as angular resolution and instrumental background. In addition, the software is designed to permit extensive tests of its performance via simulations of a wide range of observational scenarios.
Results. We applied EXSdetect to simulated data fields modeled to realistically represent the Swift X-ray Cluster Survey (SXCS), which is based on archival data obtained by the X-ray telescope onboard the Swift satellite. We achieve more than 90% completeness for extended sources comprising at least 80 photons in the 0.5–2 keV band, a limit that corresponds to 10-14 erg cm-2 s-1 for the deepest SXCS fields. This detection limit is comparable to the one attained by the most sensitive cluster surveys conducted with much larger X-ray telescopes. While evaluating the performance of EXSdetect, we also explored the impact of improved angular resolution and discuss the ideal properties of the next generation of X-ray survey missions.
Key words: surveys / X-rays: galaxies: clusters / cosmology: observations / methods: statistical / techniques: image processing / galaxies: clusters: general
The Phyton code EXSdetect is available on the SXCS website http://adlibitum.oats.inaf.it/sxcs
© ESO, 2013
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.