Three-dimensional morphological asymmetries in the ejecta of Cassiopeia A using a component separation method in X-rays

Picquenot, Adrien; Acero, Fabio; Holland-Ashford, Tyler; Lopez, Laura A.; Bobin, J.

doi:10.1051/0004-6361/202039170

Cited by 16 publications

(9 citation statements)

References 48 publications

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“…An updated version of this algorithm, the pGMCA (see Bobin et al 2020), has been developed to take into account the Poissonian nature of X-ray data. It was first used on Cas A data to probe the three-dimensional morphological asymmetries in the ejecta distribution (Picquenot et al 2021), and proved perfectly suited to producing clear, detailed, and unpolluted images of both the ejecta and the synchrotron at different energies. Thanks to these new images, we are able to study the profiles of some filamentary structures associated with the forward shock, and also find some associated with the reverse shock.…”

Section: Introductionmentioning

confidence: 99%

The X-ray synchrotron rims in Cassiopeia A narrow with energy

Picquenot

Williams

Acero

et al. 2023

A&A

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Context. Some young supernova remnants exhibit thin filaments of X-ray synchrotron radiation coinciding with the forward shock due to accelerated electrons interacting with the local magnetic field. The two main models accounting for the radial brightness evolution of these filaments differ in their prediction of the narrowing (or not) of the filaments with increasing photon energy. Aims. In this paper, we report our observation of such a narrowing of the synchrotron filaments in Cassiopeia A at X-ray energies, and how this finding could inform our understanding of the mechanisms at stake in their formation. Methods. We used a new blind-source-separation method on the 1 Ms Chandra observation of Cassiopeia A in order to obtain detailed and unpolluted images of the synchrotron emission in three energy bands. We then extracted the profiles of several filaments at the forward shock and the reverse shock to estimate and compare their widths. Results. We find that there is indeed a narrowing with energy of the synchrotron filaments both at the forward and at the reverse shocks in Cassiopeia A. The energy dependency of this narrowing seems stronger at high energy, which is indicative of a damping effect that is also suggested by radio observations.

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Section: Introductionmentioning

confidence: 99%

The X-ray synchrotron rims in Cassiopeia A narrow with energy

Picquenot

Williams

Acero

et al. 2023

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…An updated version of this algorithm, the pGMCA (see Bobin et al 2020), has been developed to take into account the Poissonian nature of X-ray data. It was first used on Cas A data to probe the threedimensional morphological asymmetries in the ejecta distribution (Picquenot et al 2021), and proved perfectly suited for producing clear, detailed and unpolluted images of both the ejecta and the synchrotron at different energies. Thanks to these new images, we are able to study the profiles of some filamentary structures associated with the forward shock, as well as find some associated with the reverse shock.…”

Section: Thin X-ray Rims In Cassiopeia Amentioning

confidence: 99%

The X-ray synchrotron rims in Cassiopeia A narrow with energy

Picquenot¹,

Williams²,

Acero³

et al. 2023

Preprint

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Context. Some young supernova remnants exhibit thin filaments of X-ray synchrotron radiation coinciding with the forward shock due to accelerated electrons interacting with the local magnetic field. The two main models accounting for the radial brightness evolution of these filaments differ in their prediction of the narrowing (or not) of the filaments with increasing photon energy. Aims. In this paper, we report our observation of such a narrowing of the synchrotron filaments in Cassiopeia A at X-ray energies, and how this finding could help in understanding the mechanisms at stake in their formation. Methods. We used a new blind source separation method on the 1 Ms Chandra observation of Cassiopeia A, in order to obtain detailed and unpolluted images of the synchrotron emission in three energy bands. We then extracted the profiles of several filaments at the forward shock and the reverse shock to estimate and compare their widths. Results. We find that there is indeed a narrowing with energy of the synchrotron filaments both at the forward and at the reverse shocks in Cassiopeia A. The energy dependency of this narrowing seems stronger at high energy, which is indicative of a damping effect, confirmed by radio observations.

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“…Multiscale methods like wavelets (Starck et al 2002) for point-source detection have been efficiently implemented for X-ray images (Freeman et al 2002), and matched-filter techniques have been successfully used to detect galaxy clusters in ROSAT data (Vikhlinin et al 1998), but extended structures remain difficult to find and characterize in these lowcount Poisson data. Other techniques are generally optimized for high signal-to-noise ratio (S/N) images: they apply adaptive binning, or set S/N thresholds to smoothed images with point sources removed (e.g., Sanders & Fabian 2001;Sanders 2006); adapt methods developed for the analysis of cosmic microwave background images (e.g., Bobin et al 2016); limit themselves to restrictive assumptions like modeling a combination of point sources ((E)BASCS; Jones et al 2015;Meyer et al 2021), or require spectral model similarity across the field of view (Picquenot et al 2019(Picquenot et al , 2021. Currently, most astronomical images with complex structures that are processed for public display use some form of fluxnonconserving adaptive smoothing (Ebeling et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Identifying Diffuse Spatial Structures in High-energy Photon Lists

Fan

Wang

Kashyap

et al. 2023

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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.

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Three-dimensional morphological asymmetries in the ejecta of Cassiopeia A using a component separation method in X-rays

Cited by 16 publications

References 48 publications

The X-ray synchrotron rims in Cassiopeia A narrow with energy

The X-ray synchrotron rims in Cassiopeia A narrow with energy

The X-ray synchrotron rims in Cassiopeia A narrow with energy

Identifying Diffuse Spatial Structures in High-energy Photon Lists

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