Prospects on high-energy source searches based on pattern recognition: Object detection in the H.E.S.S. Galactic Plane Survey and catalogue cross-matches

Abstract

The H.E.S.S. Galactic Plane Survey (HGPS) represents one of the most sensitive surveys of the Galactic Plane at very high energies (VHE, 0.1-100 TeV). However the source detection algorithm of the HGPS pipeline is not well-suited for complex regions, including sources with shell-like morphologies. As an alternative and complementary approach, we have investigated blind search methods for VHE gamma-ray source detection based on well-known and widely used image processing and pattern recognition techniques. Our goal is to build in a short amount of computational time a list of potentially valuable objects without prior case-specific morphological assumptions. We aim to classify and rank the detected objects in order to identify only the most promising source candidates for further multi-wavelength-association searches, dedicated analyses, or deeper observations. In the approach proposed, we extract sparse and pertinent structural information from the significance maps using a edge detection operator. We then apply a Hough circle transform and detect a collection of objects as local maxima in the Hough space. On the basis of morphological parameters we can characterize different object classes. Classification can be used to identify valuable source candidates sharing the characteristics of well-known sources. We show that using these pattern recognition techniques we can detect objects with partial circular symmetry irrespective of a morphological template (e.g. point-like, Gaussian-like, or shell-like). All the shell-type supernova remnants (SNRs) catalogued in the HGPS are associated with at least one detected object. Catalogue cross-matches indicate that several detected objects not catalogued in the HGPS are spatially coincident with multi-wavelength counterparts. Further investigation on the most promising candidates will be conducted in dedicated follow-up analyses.

References in corpus (25)

• Fermi Large Area Telescope First Source Catalog
• Design Concepts for the Cherenkov Telescope Array
• The McGill Magnetar Catalog
• Fermi-LAT Observations of the Diffuse Gamma-Ray Emission: Implications for Cosmic Rays and the Interstellar Medium
• Acceleration of petaelectronvolt protons in the Galactic Centre
• The H.E.S.S. Galactic plane survey
• Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• Discovery of very high energy gamma-ray emission coincident with molecular clouds in the W28 (G6.4-0.1) field
• The 1st Fermi Lat Supernova Remnant Catalog
• A Census of High-Energy Observations of Galactic Supernova Remnants
• A Measurement of the Spatial Distribution of Diffuse TeV Gamma Ray Emission from the Galactic Plane with Milagro
• The population of TeV pulsar wind nebulae in the H.E.S.S. Galactic Plane Survey
• Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations
• Very high energy gamma rays from the composite SNR G0.9+0.1
• H.E.S.S. observations of RX J1713.7-3946 with improved angular and spectral resolution; evidence for gamma-ray emission extending beyond the X-ray emitting shell
• Diffuse Galactic gamma-ray emission with H.E.S.S
• A new SNR with TeV shell-type morphology: HESS J1731-347
• Structure Detection in Low Intensity X-Ray Images
• Characterising the VHE diffuse emission in the central 200 parsecs of our Galaxy with H.E.S.S
• Deeper H.E.S.S. observations of Vela Junior (RX J0852.0$-$4622): Morphology studies and resolved spectroscopy
• A catalogue of 294 Galactic supernova remnants
• A search for new supernova remnant shells in the Galactic plane with H.E.S.S
• Detailed spectral and morphological analysis of the shell type SNR RCW 86
• Poisson Denoising on the Sphere: Application to the Fermi Gamma Ray Space Telescope

Cited by in corpus (3)

• Prospects for a survey of the Galactic plane with the Cherenkov Telescope Array
• Multiwavelength constraints on the unidentified Galactic TeV sources HESS J1427$-$608, HESS J1458$-$608, and new VHE $\gamma$-ray source candidates
• Unveiling the nature of the unidentified gamma-ray sources 4FGL J1908.6+0915e, HESS J1907+089/HOTS J1907+091, and 3HWC J1907+085 in the sky region of the magnetar SGR 1900+14