351 research outputs found
Supernova Remnants in High Definition
No full textAs the observable products of explosive stellar death, supernova remnants reveal some of the most direct information on the physics of the explosions, the properties of the progenitor systems, and the demographics of compact objects formed in the supernova events. High sensitivity X-ray observations have allowed us to probe the properties of the shocked plasma, providing constraints on abundances and ionization states that connect directly progenitor masses and metallicities, the nature of the explosions (core-collapse vs. thermonuclear), and the physics of shock heating and particle acceleration in fast shocks. Studies of SNRs in the Magellanic Clouds have provided information on source demographics in a low metallicity environment, and deep searches for point sources in Galactic SNRs imply that many remnants contain rapidly cooling neutron stars or black holes. Based on Chandra observations, we know that crucial measurements required to advance our knowledge in these areas are possible only with much more sensitive observations at high angular resolution. From identifying the effects of particle acceleration on the post-shock gas in young SNRs like Tycho to obtaining spatially resolved spectra - and identifying compact objects - for young SNRs in the Magellanic Clouds, the capabilities of a facility like the X-ray Surveyor are required. Here I present a summary of recent advances brought about by spectral investigations of SNRs, and discuss particular examples of new advances that will be enabled by X-ray Surveyor capabilities.Session 2 continued: Plasma Physics
Chair: Rob Petr
Data products and software for `X-ray diagnostics of Cassiopeia A's "Green Monster": evidence for dense shocked circumstellar plasma`
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<h2>Data Reproduction Package for the publication ‘X-ray diagnostics of Cassiopeia A’s “Green Monster”: evidence for dense shocked circumstellar plasma’</h2>
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<h3>Authors: Jacco Vink, Manan Agarwal, Patrick Slane, Ilse De Looze, Dan Milisavljevic, Daniel Patnaude, and Tea Temim.</h3>
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<h3>Link to paper: <a href="https://doi.org/10.3847/2041-8213/ad2fc5">https://doi.org/10.3847/2041-8213/ad2fc5</a> </h3>
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<h4>This package was prepared by Jacco Vink and Manan Agarwal (University of Amsterdam)</h4>
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<h3>Summary</h3>
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<p>This data reproduction package contains the data files in FITS format used to<br>generate the figures in the paper. The data files concern the revised manuscript, which incorporates changes made in response to the journal’s referee report.</p>
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<p>The paper is based on Chandra X-ray Observatory (CXO) data of Cassiopeia A taken in 2004. The raw archival data used, maintained by the Chandra Data Archive, can be retrieved using the following DOI link: <a href="https://doi.org/10.25574/cdc.209">https://doi.org/10.25574/cdc.209</a>.</p>
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<p>Additional James Webb Space Telescope (JWST) data are stored at the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The data used in the paper can be downloaded through DOI link <a href="https://doi.org/10.17909/szf2-bg42">https://doi.org/10.17909/szf2-bg42</a>.</p>
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<p>The data produced from the above raw data are stored in the files:</p>
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<li>green_monster_image_data.tar.gz</li>
<li>spectral_files_and_models.tar.gz</li>
<li>imaging_and_pca_code.tar.gz</li>
<li>green_monster_pca_input_output.tar.gz</li>
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<p>The repository contains JWST/MIRI mosaics of Cassiopeia A which are described in detail in the paper "A JWST Survey of the Supernova Remnant Cassiopeia A", by D. Milisavljevic, T. Temim, I. De Looze, et al.; see https://arxiv.org/abs/2401.02477, to be published in ApJ letters.<br> </p>
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SERENDIPITOUS DISCOVERY OF AN INFRARED BOW SHOCK NEAR PSR J1549-4848 WITH SPITZER
No full textWe report on the discovery of an infrared cometary nebula around PSR J1549-4848 in our Spitzer survey of a few middle-aged radio pulsars. Following the discovery, multi-wavelength imaging and spectroscopic observations of the nebula were carried out. We detected the nebula in Spitzer Infrared Array Camera 8.0, Multiband Imaging Photometer for Spitzer 24 and 70 mu m imaging, and in Spitzer IRS 7.5-14.4 mu m spectroscopic observations, and also in the Wide-field Infrared Survey Explorer all-sky survey at 12 and 22 mu m. These data were analyzed in detail, and we find that the nebula can be described with a standard bow shock shape, and that its spectrum contains polycyclic aromatic hydrocarbon and H-2 emission features. However, it is not certain which object drives the nebula. We analyze the field stars and conclude that none of them can be the associated object because stars with a strong wind or mass ejection that usually produce bow shocks are much brighter than the field stars. The pulsar is approximately 15 '' away from the region in which the associated object is expected to be located. In order to resolve the discrepancy, we suggest that a highly collimated wind could be emitted from the pulsar and produce the bow shock. X-ray imaging to detect the interaction of the wind with the ambient medium-and high-spatial resolution radio imaging to determine the proper motion of the pulsar should be carried out, which will help verify the association of the pulsar with the bow shock nebula
Supernova Remnants interactiong with molecular clouds: X-ray and Gamma-ray signatures
No full textThe giant molecular clouds (MCs) found in the Milky Way and similar galaxies play a crucial role in the evolution of these systems. The supernova explosions that mark the death of massive stars in these regions often lead to interactions between the supernova remnants (SNRs) and the clouds. These interactions have a profound effect on our understanding of SNRs. Shocks in SNRs should be capable of accelerating particles to cosmic ray (CR) energies with efficiencies high enough to power Galactic CRs. X-ray and gamma-ray studies have established the presence of relativistic electrons and protons is some SNRs and provided strong evidence for diffusive shock acceleration as the primary acceleration mechanism, including strongly amplified magnetic fields, temperature and ionization effects on the shock-heated plasmas, and modifications to the dynamical evolution of some systems. Because protons dominate the overall energetics of the CRs, it is crucial to understand this hadronic component even though electrons are much more efficient radiators and it can be difficult to identify the hadronic component. However, near MCs the densities are sufficiently high to allow the gamma-ray emission to be dominated by protons. Thus, these interaction sites provide some of our best opportunities to constrain the overall energetics of these particle accelerators. Here we summarize some key properties of interactions between SNRs and MCs, with an emphasis on recent X-ray and gamma-ray studies that are providing important constraints on our understanding of cosmic rays in our Galaxy.Fil: Slane, Patrick. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Bykov, Andrei. A.F. Ioffe Institute for Physics and Technology; Rusia. St. Petersburg State Polytechnical University; RusiaFil: Ellison, Donald C.. University Of North Carolina; Estados UnidosFil: Dubner, Gloria Mabel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Castro, Daniel. MIT-Kavli Center for Astrophysics and Space Research; Estados Unido
Information brokers, fairness, and privacy in publicly accessible information
No full textThe European Union, Canada, and the United States have each grappled with what counts as fair business practices in relation to information services that collect and package personal information that has ended up in one way or another online. On the open internet, this personal information often originates from two types of online sources: public records like arrests, mugshots, court decisions, and bankruptcy records; and user-generated content hosted on social media platforms and sites. This article argues that personal information that has been exposed to public view — be it by a government institution, another individual or organization, or by the data subject him or herself — should not be considered fair game to any and all subsequent commercial exploitation. The blunt concept of “public” information should be refined to a more nuanced understanding of “publicly accessible” information, where public access can be limited to particular purposes. By focusing on fairness in business dealings in publicly accessible personal information, it should be possible to move beyond a fixation on locating the elusive divide between private and public online information, and instead frame privacy as situated in a three-way balance of interests between the business, the public, and the data subject
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