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1
Graham, J. R. "Dust in supernovae and supernova remnants." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37710.
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Misanovic, Zdenka. "Search for young galactic supernova remnants." Thesis, The University of Sydney, 2001. http://hdl.handle.net/2123/795.
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A sample of 9 small-diameter radio sources has been selected from the Molonglo Galactic Plane Survey (MGPS) and observed with the Australia Telescope Compact Array (ATCA) in the radio recombination line (RRL) at 5 GHz, in a search for young Galactic SNRs. Since the RRL emission is an unambiguous indicator of a thermal source, this method has been used to eliminate HII regions from the selected sample. In addition, the IRAS and MSX infrared data and spectral index measurements have been combined with the RRL studies to distinguish thermal and non-thermal sources in the selected sample. One source (G282.8-1.2) is identified here as a possible new young Galactic supernova remnant, based on its relatively weak infrared emission, steep radio spectrum and possible x-ray emission. However, the ATCA data are inconclusive and further studies are needed to confirm this result. Radio recombination line emission (H107 alpha) has been detected in 3 of the selected sources, eliminating them from the sample of SNR candidates. In addition, the parameters of the RRL emission from the identified HII regions have been used to estimate their properties. The RRL data are inconclusive for the remaining low brightness, extended sources in the sample. However, some of these sources are likely to be thermal HII regions according to the infrared and spectral index data. The selected method for distinguishing thermal and non-thermal Galactic radio sources seems promising. The selected ATCA configuration was appropriate for imaging relatively bright, compact sources, but a slightly modified observing technique is needed to successfully image low surface brightness, extended sources.
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Misanovic, Zdenka. "A search for young galactic supernova remnants." University of Sydney. Physics, 2001. http://hdl.handle.net/2123/795.
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A sample of 9 small-diameter radio sources has been selected from the Molonglo Galactic Plane Survey (MGPS) and observed with the Australia Telescope Compact Array (ATCA) in the radio recombination line (RRL) at 5 GHz, in a search for young Galactic SNRs. Since the RRL emission is an unambiguous indicator of a thermal source, this method has been used to eliminate HII regions from the selected sample. In addition, the IRAS and MSX infrared data and spectral index measurements have been combined with the RRL studies to distinguish thermal and non-thermal sources in the selected sample. One source (G282.8-1.2) is identified here as a possible new young Galactic supernova remnant, based on its relatively weak infrared emission, steep radio spectrum and possible x-ray emission. However, the ATCA data are inconclusive and further studies are needed to confirm this result. Radio recombination line emission (H107 alpha) has been detected in 3 of the selected sources, eliminating them from the sample of SNR candidates. In addition, the parameters of the RRL emission from the identified HII regions have been used to estimate their properties. The RRL data are inconclusive for the remaining low brightness, extended sources in the sample. However, some of these sources are likely to be thermal HII regions according to the infrared and spectral index data. The selected method for distinguishing thermal and non-thermal Galactic radio sources seems promising. The selected ATCA configuration was appropriate for imaging relatively bright, compact sources, but a slightly modified observing technique is needed to successfully image low surface brightness, extended sources.
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Arthur, Sarah Jane. "Supernova remnants in inhomogeneous media." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293739.
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Kilpatrick, Charles Donald, and Charles Donald Kilpatrick. "New Observational Insight on Shock Interactions Toward Supernovae and Supernova Remnants." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621574.
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Supernovae (SNe) are energetic explosions that signal the end of a star's life. These events and the supernova remnants (SNRs) they leave behind play a central role in stellar feedback by adding energy and momentum and metals to the interstellar medium (ISM). Emission associated with these feedback processes, especially atomic and molecular line emission as well as thermal and nonthermal continuum emission is known to be enhanced in regions of high density, such as dense circumstellar matter (CSM) around SNe and molecular clouds (MCs). In this thesis, I begin with a brief overview of the physics of SN shocks in Chapter 1, focusing on a foundation for studying pan-chromatic signatures of interactions between SNe and dense environments. In Chapter 2, I examine an unusual SN with signatures of CSM interaction in the form of narrow lines of hydrogen (Type IIn) and thermal continuum emission. This SN appears to belong to a class of Type Ia SNe that shares spectroscopic features with Type IIn SNe. I discuss the difficulties of decomposing spectra in a regime where interaction occurs between SN ejecta and CSM, potentially confusing the underlying SN type. This is followed by a discussion of rebrightening that occurred at late-time in 𝐵 and 𝑉 band photometry of this SN, possibly associated with clumpy or dense CSM at large distances from the progenitor. In Chapter 3, I examine synchrotron emission from Cassiopeia A, observed in the 𝐾ₛ band over multiple epochs. The synchrotron emission is generally diffuse over the remnant, but there is one location in the southwest portion of the remnant where it appears to be enhanced and entrained as knots of emission in the SNR ejecta. I evaluate whether the 𝐾ₛ band knots are dominated by synchrotron emission by comparing them to other infrared and radio imaging that is known to be dominated by synchrotron emission. Concluding that they are likely synchrotron-emitting knots, I measure the magnetic field strength and electron density required for their evolution over the ~ 10 yr baseline they were observed and find 𝐵 ≈ 1.3-5.8 mG and 𝑛ₑ≈ 1,000-15,000 cm⁻³. The magnetic field strengths appear enhanced beyond values required by the adiabatic strong shock limit, arguing in favor of other forms of magnetic field amplification in the shock. In Chapter 4, I again discuss Cassiopeia A and interaction between the remnant and nearby MCs as seen at mid-infrared and millimeter wavelengths. I report detection of a SNR-MC interaction and analyze its signatures in broadened molecular lines. I extend this analysis in Chapter 5 to a large survey for SNR-MC interactions in the ¹²CO 𝐽=2-1 line. Although broadened ¹²CO 𝐽=2-1 line emission should be detectable toward virtually all SNR-MC interactions, I find relatively few examples; therefore, the number of interactions is low. This result favors mechanisms other than supernova feedback as the basic trigger for star formation. In addition, I find no significant association between TeV gamma-ray sources and MC interactions, contrary to predictions that SNR-MC interfaces are the primary venues for cosmic ray acceleration. I end this dissertation in Chapter 6 with a brief summary of my results and two extensions of this work: examining the late-time radio light curves of CSM-interacting SNe for signatures of radio synchrotron emission and dense or clumpy CSM at large distances from the progenitor and re-observing SNR-MC interactions in ¹²CO 𝐽=3-2 in order to verify the presence of shock-heated molecular gas and perform a census on the densities and temperatures of post-shock molecular gas.
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Hwang, Una. "X-ray studies of supernova remnants." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/26858.
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Schaudel, Daniel. "X-ray Properties of Galactic Supernova Remnants." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-11097.
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Jones, Laurence Richard. "X-ray emission from galactic supernova remnants." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35703.
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X-ray emission from galactic supernova remnants X-ray images and spectra are used to determine the structure and physical conditions of shock heated interstellar gas and stellar ejecta within three galactic supernova remnants (SNRs). Parameters describing the initial supernova explosions (total energy, ejected mass) and ambient interstellar medium (density, homogeneity) are then derived. The interior density of the "middle-aged" SNR W44 is found to be fairly uniform, and inconsistent with the standard Sedov model, but similar to that predicted by models in which thermal conduction and/or heating and evaporation of engulfed, cold, interstellar clouds are important. This expanding bubble of hot, high pressure gas is likely to be an example of the formation of the hot component of interstellar medium, as detected in the vicinity of the Sun. In addition, it is likely that the SNR has collided with a nearby dense molecular cloud. The SNR W49B is found to be probably the remnant of a Type II supernova which occurred in a relatively dense medium 2000-5000 years ago. The abundance of hot iron in the ejecta is consistent with the cosmic value. The youngest SNR studied, SN1006, is found to be the remnant of a Type I supernova which occurred in a region of low, but fairly uniform (to within a factor of 2), interstellar density. Emission from reverse shocked ejecta may be most prominent in a limited area of the SNR, explaining a discrepancy between previous X-ray spectra of the remnant. A common result in all three SNRs is the detection of hot gas at their centres; the likely effects of a reverse shock and thermal conduction within SNRs are emphasized.
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Mogawana, Orapeleng. "Meshless hydrodynamic simulations of young supernova remnants." Master's thesis, Faculty of Science, 2020. http://hdl.handle.net/11427/32810.
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The majority of massive stars end their lives by ejecting their outer envelopes in a corecollapse supernova explosion. The collision of their ejecta with the surrounding circumstellar medium results in the formation of supernova remnants that have been detected at all wavelengths, from radio to gamma-rays. For several dozen supernova remnants, very-long-baseline radio interferometers have spatially resolved the interaction region and directly measured the expansion rates of the shocked gas; many show evidence of the interaction of supernova ejecta with the dense slow winds characteristic of the red supergiant progenitors. Understanding the dynamics and morphology of the interaction region, particularly in young supernova remnants leads to estimates of the total mass of the circumstellar medium, as well as its density distribution around the star given the value of the wind velocity. Here we studied the interaction of the supernova ejecta with different circumstellar environments to investigate the hydrodynamic evolution of young supernova remnants in the SedovTaylor phase. We used the massively parallel, multi-physics magneto-hydrodynamics (MHD) and gravity code, GIZMO, for our simulations. We chose GIZMO for its flexibility in allowing the user to choose different methods to solve the fluid equations, i.e., new Lagrangian Godunovtype schemes, e.g., Meshless Finite Volume (MFV) and Meshless Finite Mass (MFM), as well as various flavors of smoothed particle hydrodynamics (SPH), or Eulerian fixed-grid schemes. Since the majority of previous studies used the latter, we focused on an extensive comparison of all the meshless methods in solving the Sedov-Taylor blastwave test, a problem for which there is an exact solution. For our given compute resources, we found the parameters (e.g., smoothing length, number of neighbours, artificial viscosity, and particle resolution) for each meshless method that gave the best agreement with the exact solution. We then carried out 2D and 3D simulations of the hydrodynamic interaction of the supernova ejecta with varying density profiles assumed for the circumstellar medium, namely: a 1/r 2 density profile, for a typical, spherically symmetric red supergiant stellar wind, and an axisymmetric torus profile, inspired by the observation of a dense, dusty torus of the circumstellar material around the red supergiant, WOH G64 (Ohnaka et al., 2008). Radially assembled Hierarchical Equal Area isoLatitude Pixelization (HEALPix) shells were used to set-up the initial density and velocity profiles for the ejecta, which is marked by a flat inner core and a steeply declining outer edge. The Weighted Voronoi Tessellation code was used to produce the 1/r 2 and axisymmetric torus density distributions. We showed that the growth of Richtmyer-Meshkov instabilities in the 2D and 3D 1/r 2 profiles are visible as early as 20 yrs into the evolution of the remnant and become increasingly unstable up to 100 yr. While 2D simulations of 1/r 2 profiles show the presence of the Richtmyer-Meshkov instabilities in the hot shell of a contact discontinuity, in 3D we see large bubbles and filamentary structure of the instabilities. Our results for the numerical approaches to simulating the systems for the 1/r 2 density cases were broadly consistent with previous studies in the literature where stationary grids were used. Two scenarios with different torus-cavity density contrasts were considered in which we found that the instability rolls along the half-opening angle takes ∼ 40 yr to develop in the axisymmetric torus with smooth density drop, whereas the axisymmetric torus with steep density drop does not develop any instability rolls up to the end of the simulation. We concluded with a discussion of the implications of our models for the morphology of supernova remnants and their expected levels of multi-wavelength emission.
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Dyer, Kristy Kathleen. "Thermal and Non-Thermal Emission in Supernova Remnants." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010806-162918.
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Supernova remnants present an excellent opportunity to study the shockacceleration of relativistic particles. X-ray synchrotron emission fromrelativistic electrons should contain important information, butextracting it requires advances in models and observations. I present thefirst test of sophisticated synchrotron models against high resolutionobservations on SN 1006, the first and best example of synchrotron X-rayemission, which has been well observed at radio, X-ray and gamma-raywavelengths. Synchrotron emission can be limited at the highest energies by finite age,radiative losses or electron escape. Earlier calculations suggested thatSN 1006 was escape limited. I adapted an escape-limited synchrotron modelfor XSPEC, and demonstrated that it can account for the dominantlynonthermal integrated spectrum of SN 1006 observed by ASCA-GIS and RXTEwhile constraining the values of the maximum electron energy and otherparameters. Combined with TeV observations, the fits give a mean postshockmagnetic field strength of 9 microgauss and 0.7% of the supernova energyin relativistic electrons. Simultaneous thermal fits gave abundances farabove solar, as might be expected for ejecta but had not previously beenobserved. I created subsets of the escape-limited model to fit spatially resolvedASCA SIS observations. I found only small differences between thenortheast and southwest limbs. A limit of less than 9% was placed on theamount of nonthermal flux elsewhere in the remnant. Important findingsinclude the possibility that rolloff frequency may change across theremnant face, and ruling out cylindrical symmetry for SN 1006 along aNW/SE axis. These models have implications far beyond SN 1006. The only previousmodel available to describe X-ray synchrotron emission was a powerlaw.These new models are superior to powerlaws both for their robustconstraints and because they shed physical insight on the accelerationmechanism. As new instruments increase our spatial and spectral resolutionI predict many more remnants will be found with varying amounts of X-raysynchrotron emission, hidden along with thermal lines and continuum. Theability to separate thermal and nonthermal emission is essential tounderstanding both nonthermal emission as well as the thermal component.
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Parkinson, Michael Lawrence. "Supernova remnants' interactions with the inter-stellar medium." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6813/.
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All-sky data at a number of different wavelengths are used to examine the Giant Radio Loops. The x-ray emission of Loop I is modelled as being due to a Supernova Remnant (SNR) that has evolved in a hot, homogeneous, quasi-isotropic medium. The shock is found to weaken towards higher latitudes, and this is attributed to an increase in the ambient gas temperature away from the galactic plane. Other evolutionary possibilities are examined. Radio spectral index maps from 38 to 1420MHz of the northern celestial hemisphere are produced, and the spectra of loops I and III are modelled on the assumption that the energy distribution of electrons accelerated in the shocks will have an upper energy cut-off due to the finite age of the remnants. It is found that the steepening spectra can be fitted by such a model. The electron distribution below the cut-off of order l0GeV is found to fit best if a flatter spectrum than predicted by simple shock theory is assumed. The idea that shocks. Interacting with clouds can explain this flatter spectrum and enhance the soft x-ray emission is put forward as an alternative evolutionary possibility, bringing together the two separate x-ray and radio emission mechanisms. Other galactic SNR are examined to support this idea, including a newly discovered SNR that exists inside the error circle of the COS-B source 2CG342-02. Although this remnant’s association with the γ-ray source cannot be excluded, no firm evidence is found to identify it as the source.
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Caprioli, Damiano. "Non-linear Cosmic Ray acceleration in Supernova Remnants." Doctoral thesis, Scuola Normale Superiore, 2009. http://hdl.handle.net/11384/85827.
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[Excerpt from a 9 pages abstract]: Long time has passed since 1912, when some balloon experiments of the
Austrian physicist Victor Hess found that natural radioactivity increases
again above 600 m from the ground, despite the larger distance from the
radioactive elements in the Earth crust. For the first time an unknown,
extraterrestrial, source of radiation usually shielded by the atmosphere had
been observed. ...
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Gaensler, Bryan Malcolm. "Barrels, jets and smoke-rings: Understanding the bizarre shapes of radio supernova remnants." Thesis, The University of Sydney, 1999. http://hdl.handle.net/2123/399.
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This thesis considers the various morphologies of radio supernova remnants (SNRs), and attempts to determine whether their appearance results from the properties of the progenitor star and its supernova explosion, or from the structure of the interstellar medium (ISM) and ambient magnetic field into which a SNR consequently expands. High-resolution observations of Supernova 1987A show a young remnant whose appearance and evolution are completely dominated by the structure of its progenitor wind. A statistical study of the Galactic population of bilateral SNRs demonstrates that the symmetry axes of these remnants run parallel to the Galactic Plane. This result can be explained by the interaction of main sequence stellar wind-bubbles with the ambient magnetic field; expansion of SNRs into the resulting elongated cavities results in a bilateral appearance with the observed alignment. Radio observations of SNR G296.8-00.3 show a double-ringed morphology which is best explained by expansion either into an anisotropic main-sequence progenitor wind or into multiple cavities in the ISM. Data on SNRs G309.2-00.6 and G320.4-01.2 (MSH 15-52) make a strong case that the appearance of both remnants is significantly affected by collimated outflows from a central source; for G309.2-00.6 the source itself is not detected, but for G320.4-01.2 there is now compelling evidence that the remnant is associated with and is interacting with the young pulsar PSR B1509-58. I conclude that, while the youngest SNRs are shaped by their progenitor's circumstellar material, the appearance of most SNRs reflects the properties of the local ISM and magnetic field. Remnants which interact with an associated pulsar or binary system appear to be rare, and are easily distinguished by their unusual and distorted morphologies.
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Gaensler, Bryan Malcolm. "Barrels, jets and smoke-rings: Understanding the bizarre shapes of radio supernova remnants." University of Sydney, Physics, 1999. http://hdl.handle.net/2123/399.
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This thesis considers the various morphologies of radio supernova remnants (SNRs), and attempts to determine whether their appearance results from the properties of the progenitor star and its supernova explosion, or from the structure of the interstellar medium (ISM) and ambient magnetic field into which a SNR consequently expands. High-resolution observations of Supernova 1987A show a young remnant whose appearance and evolution are completely dominated by the structure of its progenitor wind. A statistical study of the Galactic population of bilateral SNRs demonstrates that the symmetry axes of these remnants run parallel to the Galactic Plane. This result can be explained by the interaction of main sequence stellar wind-bubbles with the ambient magnetic field; expansion of SNRs into the resulting elongated cavities results in a bilateral appearance with the observed alignment. Radio observations of SNR G296.8-00.3 show a double-ringed morphology which is best explained by expansion either into an anisotropic main-sequence progenitor wind or into multiple cavities in the ISM. Data on SNRs G309.2-00.6 and G320.4-01.2 (MSH 15-52) make a strong case that the appearance of both remnants is significantly affected by collimated outflows from a central source; for G309.2-00.6 the source itself is not detected, but for G320.4-01.2 there is now compelling evidence that the remnant is associated with and is interacting with the young pulsar PSR B1509-58. I conclude that, while the youngest SNRs are shaped by their progenitor's circumstellar material, the appearance of most SNRs reflects the properties of the local ISM and magnetic field. Remnants which interact with an associated pulsar or binary system appear to be rare, and are easily distinguished by their unusual and distorted morphologies.
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Stroman, Wendy Jane. "Radio polarimetry studies of magnetic turbulence in supernova remnants." [Ames, Iowa : Iowa State University], 2008.
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Robbins, William. "An investigation of radio supernova remnants and their environments." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12378.
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In this thesis, I investigate the properties of emission from several supernova remnants (SNRs) and the connections of these observations to the properties of their progenitors, environments, and stages of evolution. I find that the highly-energetic pulsar B1338-62 near the centre of SNR G308.8-0.1 powers a pulsar wind nebula. I conclude that the unusual radio morphology of SNR G308.8-0.1 is best explained by the expansion of a young remnant into an environment with a strongly asymmetric density profile. The coincidence of an extraordinarily well-ordered magnetic field along one high surface-brightness section of SNR B0454-683 with a hydrogen cloud suggests that this segment of the remnant is well-evolved. In this interpretation, the strong compression of ambient magnetic fields by a non-adiabatic shock is responsible for the well-ordered magnetic field and high surface brightness. Using high sensitivity, high angular resolution follow-up observations, I detect the radio counterpart to the X-ray synchrotron shell of the young composite SNR G310.6-1.6. Additionally, I follow up three radio-selected SNR candidates and conclude that they are most likely extragalactic radio sources. I demonstrate that the radio source G296.593-0.975, previously considered an HII region, overlaps along the line-of-sight with middle-aged SNR G296.7-0.9.
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Brantseg, Thomas Felton. "Core-Collapse Supernova Remnants and Interactions with Their Surroundings." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4823.
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This thesis examines three core-collapse supernova remnants (SNR) - the Cygnus Loop in the Milky Way and 0453-68.5 and 0540-69.3 in the Large Magellanic Cloud - of varying ages and in varying states of interaction with the surrounding interstellar medium (ISM), using X-ray imaging spectroscopy with Chandra and supplemental data from other wavelengths. We use results from our analysis to address three main questions. First, we examine the applicability of the common Sedov-Taylor adiabatic blast wave model to core-collapse supernovae. Second, we determine the elemental abundances around the shell of these supernova remnants to determine if the use of SNRs as a gauge of abundances in the ISM is justified. Finally, we examine the pulsar wind nebulae (PWNe) in 0453-68.5 and 0540-69.3 and search for evidence of interaction between these PWNe and their immediate surroundings.
We see highly inhomogeneous ISM surrounding all three surveyed SNRs, contrary to the key assumption in the Sedov-Taylor model of a uniform surrounding medium. In all three studied SNRs, we find that shock speeds are dependent on the density of the surrounding material. As subsidiary results, we also find depleted elemental abundances of oxygen, magnesium, and silicon, relative to typical ISM, around all three studied supernova remnants. Although this subsidiary result is not conclusive, we believe that it merits a followup study.
In 0540-69.3 and 0453-68.5, which contain central pulsars, we find that the explosion directionality, which can be inferred from the pulsar's proper motion relative to the SNR, is not related to the morphology of the SNR itself. We conclude from this that the asymmetric shapes common in core-collapse supernova remnants can be more a function of the complex environments surrounding the progenitors of core- collapse supernovae than of the supernova explosions themselves.
Finally, we see that the PWN in 0453-68.5 shows signs of having mixed with the surrounding thermal- emitting material, while the PWN in 0540-69.3 appears to have not mixed with or interacted with the surrounding SNR material to any substantial degree. We believe that this result may indicate that the degree of interaction between a PWN and its surroundings is dependent on age and possibly shell morphology, although further study is needed.
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Cristofari, Pierre. "Are supernova remnants the sources of galactic cosmic rays?" Paris 7, 2013. http://www.theses.fr/2013PA077294.
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Les rayons cosmiques ont été découverts il y a plus d'un siècle, mais leur origine reste inconnue. L'hypothèse la plus populaire est que les vestiges de supernova sont la source des rayons cosmiques. L'observation de plusieurs vestiges en rayons gamma, attendus comme produits de l'interaction entre les rayons cosmiques accélérés au niveau du vestige de supernova et le milieu interstellaire, est sans doute l'argument le plus fort pour soutenir cette hypothèse, mais ne constitue pas une preuve incontestable. En effet, un autre mécanisme, leptonique, peut aussi rendre compte des émissions gamma observées, et dans bien des cas, la situation reste ambiguë. Au lieu de se baser sur une étude au cas par cas des vestiges de supernova, nous proposons une étude de population reposant sur des simulations Monte Carlo, et nous estimons le nombre de vestiges de supernova qu'un télescope donné peut espérer détecter en partant de l'hypothèse que les vestiges sont effectivement les sources des rayons cosmiques Galactiques. Nos prédictions sont en accords avec les observations actuels du télescope H. E. S. S. , et notre travail constitue un nouveau test statistique pour l'hypothèse de départ. Le modèle développé peut alors être utilisé pour estimer la population de vestiges de supernova que les télescopes de la prochaine génération, comme par exemple le Cherenkov Telescope Array (CTA), peuvent espérer détecter. Enfin, cette procédure est utilisée pour commenter sur les chances de détection de neutrinos, qui témoigneraient directement de la présence de mécanismes hadroniques, et pourraient confirmer incontestablement que les vestiges de supernova sont les sources des rayons cosmiques GalactiquesCosmic rays have been discovered more than one century ago, but their orirign remains unknown. The most popular hypothesis is that supernova remnants are the source of Galactic cosmic rays. The observation of several remnants in gamma rays, which are indeed expected as the result of hadronic interactions between the cosmic rays accelerated at the remnant and the interstellar medium, is probably the strongest support to this idea. However, another mechanism, leptonic, can also account for the the observed gamma—ray émission, and in many cases the situtation remains ambiguous. Instead of relying on a case—by—case study, we adopt here a different approach and consider a population study using Monte Carlo simulations. We investigate the the number of supernova remnants that a given telescope can expect to detect, starting from the hypothesis that supernova remnant are the sources of Galactic cosmic rays. We find that our predictions are in aggrement with current observation results, such as the one of H. E. S. S, thus providing a novel consistency check for the supernova remnant paradigm for the origin of Galactic cosmic rays. The developed model can then be used to investigate the population of remnants that the next generation of telescope can expect to detect, such as the Cherenkov Telescope Array (CTA). Finally, we discuss on the hope of detection of neutrinos fron supernova remnants, which would testify that hadronic mechanisms are at stake, and could show unequivocally that supernova remnants are the sources of Galactic cosmic rays
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Eriksen, Kristoffer Albert. "New Observational and Theoretical Insights on Cassiopeia A." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195729.
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Using two techniques not previously applied to Cassiopeia A (Cas A), we measure the reddening toward its expansion center. An estimate of AV from the near-IR [Fe II] lines is hampered by uncertain atomic data, though the spatial variation in their flux ratio allows relative measurement of the extinction in regions without previous optical estimates. We use a second technique based on the broad-band IR shape of the synchrotron emission, and find Aᵥ = 6.2 ± 0.6 for a knot 13" from the expansion center. Assuming a plausible lower limit on the apparent magnitude of the SN in outburst, the ⁵⁶Ni yield was 0.058 < M(Ni) < 0.16M⊙. With the ⁴⁴Ti mass from published gamma-ray observations, this implies a ⁴⁴Ca/ ⁵⁶Fe ratio consistent with the solar abundance. Recently published Spitzer Space Telescope IRS observations detect dust and line emission from cold gas interior to Cas A’s reverse shock. Using simple physical arguments and new hydrodynamic, non-equilibrium photoionization calculations, we infer the physical conditions in this material. We find that the mid-IR bright clumps are photoionized by the SNR shocks, over-dense relative to the expected average in the interior of the remnant, and have abundances consistent with incomplete oxygen burning. The lack of detectable iron lines indicates that any Si-burning material still interior to the reverse shock must be far more tenuous than the clumps of O-burning ashes. Finally, we present calculations from a new multi-dimensional hydrodynamics and non-equilibrium ionization and cooling code designed to model the emission from SNR shocks. Two-dimensional simulations of a shock-cloud interaction in a pure-oxygen plasma, with flow parameters relevant to Cas A, show a wider range of temperatures and ionization states than is typical in single-zone or 1D calculations, indicating that fluid and cooling instabilities play a role in producing the observed spectra of radiative shocks in metal-rich gas.
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Font, Andreea. "Shocked molecular gas in three supernova remnants, W28, W44, 3C391." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ56709.pdf.
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West, Jennifer Lorraine. "The connection between supernova remnants and the Galactic magnetic field." Astronomy & Astrophysics, EDP Sciences, 2016. http://hdl.handle.net/1993/31675.
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The study of Supernova Remnants (SNRs) is fundamental to understanding the chemical enrichment and magnetism in galaxies, including our own Milky Way. In an effort to understand the connection between the morphology of SNRs and the Galactic Magnetic Field (GMF), we have examined the radio images of all known SNRs in our Galaxy and compiled a large sample that have an axisymmetric morphology, which we define to mean SNRs with a bilateral or barrel-shaped morphology, in addition to one-sided shells. We selected the cleanest examples and model each of these at their appropriate Galactic position using two GMF models, one of which includes a vertical halo component, and another that is oriented entirely parallel to the plane. Since the magnitude and relative orientation of the magnetic field changes with distance from the Sun, we analyze a range of distances, from 0.5 to 10 kpc in each case. Using a physically motivated model of an SNR expanding into an ambient GMF that includes a vertical halo component, we find it is possible to reproduce observed morphologies of many SNRs in our sample. These results strongly support the presence of an off-plane, vertical component to the GMF, and the importance of the Galactic field on SNR morphology. Our approach also provides a potentially new method for determining distances to SNRs, or conversely, distances to features in the large-scale GMF if SNR distances are known.
The mechanism for acceleration of cosmic rays in SNRs is another outstanding question in the field. To investigate this, the same sample of axisymmetric SNRs was again modelled, but this time using two competing, and physically motivated, Cosmic Ray Electron (CRE) acceleration cases: quasi-perpendicular and quasi-parallel. We find that the quasi-perpendicular CRE acceleration case is much more consistent with the data than the quasi-parallel CRE acceleration case, with G327.6+14.6 (SN1006) being a notable exception. We propose that SN1006 may be an example of a case where both quasi-parallel and quasi-perpendicular acceleration is simultaneously at play in a single SNR.October 2016
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Okon, Hiromichi. "X-ray Study on Supernova Remnants Interacting with Dense Clouds." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263456.
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Ozawa, Midori. "Study of Recombination X-rays from Supernova Remnants with Suzaku." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120649.
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Yamaguchi, Hiroya. "X-ray study of ejecta-dominated supernova remnants with Suzaku." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136881.
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Wilcox, Patrick Dean. "Observations of supernova remnants at very high energies with VERITAS." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/7045.
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The constant flux of cosmic rays that bombard Earth from within our own galaxy are understood to come from both shell-type supernova remnants and pulsar wind nebulae (PWNe). Multiwavelength study of these objects can help us to understand what types of particles are accelerated, and gamma-ray emission is key to understanding the highest energy cosmic rays. In this thesis, I analyze and interpret observations made with the Very Energetic Radiation Imaging Telescope Array System (VERITAS), a gamma-ray telescope located in Southern Arizona.
LS 5039 and HESS J1825-137 occupy the same field of view on the sky and were observed for about 8 hours with VERITAS. LS 5039 is a gamma-ray binary, and the observations supports theories that the compact object hosts a PWN which is continuously interacting with the nearby star. HESS J1825-137 is a very extended PWN with an extent of diameter greater than 1 degree on the sky. Using the VERITAS observations, I am able to measure the radial profile and compare the gamma-ray luminosity to other PWN.
DA 495, a "Crab-like" PWN with unusually strong magnetic fields, was observed for about 70 hours with VERITAS. In this study, results are combined with radio and X-ray spectral information to allow for detailed astrophysical modeling of the region. This broadband spectral modeling places constraints on the properties of the particle population in this PWN and allows for both leptonic and hadronic emission scenarios to be evaluated. Hadronic scenarios instil doubt on the pure PWN interpretation and favor a previously undetected shell-type remnant being present.
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TUTONE, Antonio. "Study on Supernova Remnants evolution and their gamma-ray emission." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/533639.
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Gaensler, Bryan M. "Barrels, jets and smoke-rings understanding the bizarre shapes of radio supernova remnants /." Connect to full text, 1999. http://hdl.handle.net/2123/399.
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Thesis (Ph. D.)--University of Sydney, 1999.Title from title screen (viewed Apr. 16, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.
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Galindo, Fernández Daniel. "Study of the extreme gamma-ray emission from Supernova Remnants and the Crab Pulsar." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663414.
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In our Galaxy, supernova remnants and pulsars are the two most numerous populations of non-thermal objects. The goal of this thesis is to study the extreme gamma-ray emission from these two astrophysical objects with Fermi -LAT and MAGIC. In particular, supernova remnants Cassiopeia A and SNR G24.7+0.6 and the Crab pulsar.
Cassiopeia A, one of the historical supernova remnants and the prime candidate of its class to be a PeVatron accelerator, has been discarded as so since we provided the first measurement of a turn-off in the gamma-ray spectrum at 3 TeV, implying the emission observed is produced by the decay of neutral pions, produced in proton- proton interactions of a parent population of accelerated protons with an energy cut-off at about 10TeV. Such a maximum energy of accelerated cosmic rays in Cassiopeia A falls short to explain the high energy end ( PeV) of the Galactic cosmic ray spectrum. Considering that Cassiopeia A was the main PeVatron candidate, the results obtained in this work challenge the existence of supernova remnants as galactic Pevatrons and therefore the popular conviction that supernova remnants are the main source of Galactic cosmic ray up to the knee.
In the case of SNR G24.7+0.6, the remnant is evolving in a dense medium and might be interacting with the CO-rich surrounding. The observations performed allowed us to detect for the first time the counterpart of the radio emission, MAGIC J1835–069, from 60MeV up to 5TeV. This very high energy emission results from proton-proton interactions between the runaway protons from the supernova remnant and a nearby molecular cloud. These observations of the field of view of SNR G24.7+0.6, also resulted in the detection of another new source, MAGIC J1837–073, that is likely to be associated with a stellar cluster as suggested by its localization in a region rich in molecular content and crowded of sources. The total energy obtained in accelerated protons can be explained assuming a quasi-continuous injection of cosmic rays during the cluster lifetime.
The second part of this thesis is focused on the study and understanding of the Crab pulsar, the young and most energetic pulsar in our galaxy. Observations carried out with MAGIC resulted in the first ever detection of very energetic pulsed emission from a pulsar, reaching up to about 1.5 TeV. Moreover, the light curve of the Crab above 400 GeV shows two peaks synchronized with those measured at lower energies. Such extremely energetic pulsed emission has to be produced by electrons with very high Lorentz factor scattering low energy photons in the vicinity of the light cylinder, either inside or outside of it. Currently, none of the postulated models is yet capable of reproducing at the same time the light curve and the spectral shape for both peaks above 400 GeV.Esta tesis tiene como objetivo el estudio de la emisión extrema de rayos gamma proveniente de remanentes de supernova y el pulsar del Cangrejo. Dos remanentes de supernova han sido observados tanto con Fermi, como con MAGIC; Cassiopeia A y SNR G24.7+0.6. Cassiopeia A, el principal candidato de su clase a revelarse como PeVatrón, ha sido descartado como tal, al haberse detectado un corte en el espectro de rayos gamma en torno a 3 TeV, lo cual implica que, la emisión observada es producida por el de- caimiento de piones neutros, originados en colisiones protón-protón por una población de protones que presenta un corte exponencial en su espectro en torno a una energía de 10 TeV. Esta energía máxima a la que son acelerados estos rayos cósmicos pone en serias dudas la existencia de remanentes de supernova que se comporten como PeVa- trones, y por tanto, la teoría de que éstos son la fuente principal de rayos cósmicos galácticos. En el caso de SNR G24.7+0.6, con las observaciones llevadas a cabo, hemos conseguido detectar por primera vez la contrapartida de la emisión radio a energías desde 60 MeV hasta 5 TeV, MAGIC J1835–069, producida por protones que escapan del remanente de supernova y que interaccionan con una nube molecular cercana. En estas mismas observaciones, hemos podido detectar otra fuente nueva, MAGIC J1837–073, la cual está asociada, muy probablemente, con un cumulo estelar tal y como sugiere su lo- calización. Su emisión puede ser explicada asumiendo una inyección casi continua de rayos cósmicos durante la totalidad de la vida estimada del cumulo estelar. Por otra parte, el estudio del púlsar del Cangrejo, llevado a cabo con MAGIC ha re- sultado en el descubrimiento de emisión pulsada hasta 1.5 TeV, refutando cualquiera de los modelos presentados hasta el momento. Además, la curva de luz que carac- teriza la emisión proveniente del púlsar por encima de 400 GeV, presenta dos picos sincronizados en fase con los picos hallados a energías más bajas. Esta emisión, ex- tremadamente energética, únicamente puede ser producida por electrones acelerados hasta factores de Lorentz muy altos en regiones cercanas al cilindro de luz, ya sea en su interior o en su exterior, y que posteriormente colisionan y transfieren su energía a fotones térmicos.
29
Hayashi, Ichizou. "Systematic X-ray Spectroscopy of Supernova Remnants in the Magellanic Clouds." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/202434.
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Dufour, François. "Modeling of the galactic distribution of 44Ti emitting young supernova remnants." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107867.
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Following the lone detection of the Galactic supernova remnant Cas A by gamma-ray detectors aboard CGRO and hard X-ray detectors aboard INTEGRAL in the nuclear lines of the 44Ti decay chain, The et al, 2006, argued that these surveys should have detected several sources, given models for the yield of 44Ti and an estimate of the Galactic supernova rate. In this thesis, this result is revisited by exploring the effect of various newer yield models of Type II supernovae, which include yields that differ by approximately an order of magnitude. We also consider several estimates of the Galactic supernova rate, which also differ by an order of magnitude, and various models for the Galactic distribution of massive stars. We find that the lone detection of Cas A is in fact consistent with a large number of reasonable models. We find that in order to detect a significant number of previously unknown remnants in a survey for 44Ti and thus constrain supernova models, a sensitivity to fluxes of less than 1E-7 photon per square cm per second within an absolute Galactic latitude of less than 5 degrees is required.Suivant la seule détection dans les lignes de désintégration nucléaires du 44Ti de Cassiopeia A avec les détecteurs à bord de CGRO et d'INTEGRAL, The et al, 2006 ont présenté une analyse de la distribution de jeunes restants de supernova dans la Galaxie dont la conclusion est que ces missions auraient dû detecter plusieurs sources. Ce mémoire vise a reproduire et raffiner ce résultat en prenant compte de différents modèles pour la production du 44Ti (qui sont incertains par approximativement un ordre de grandeur), de différents modèles de la répartition des étoiles massives dans la Galaxie et de différents taux de supernovae dans la Galaxie (également incertain par un ordre de grandeur). Nous concluons que la detection de Cassiopeia A est consistante avec une large gamme de modèles raisonnables. Finalement, nous extrapolons qu'il serait nécessaire qu'un futur relevé ait une limite de détection de moins de 1E-7 photon par cm carré par seconde dans le plan Galactique (ie. a une latitude Galactique absolue de moins de 5 degrés) afin de déctecter une quantité non-nulle de jeunes restants de supernova jusqu'ici inconnus dans le but de contraindre les modèles de supernova.
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GRECO, Emanuele. "X-Ray Spectroscopy of Ejecta and Compact Objects in Supernova Remnants." Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/520391.
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Castelletti, Gabriela. "Procesos físicos en restos de supernovas y en su interacción con el medico interstelar = Physical processes in supernova remnants and in their interaction with the interstellar medium / [by] Gabriela Castelletti." S. l. : Universidad de Buenos Aires, 2005. http://69.63.217.22/elibsql44N_10017D_ocuments/Castellettit_hesis5_95.pdf.
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Wheaton, Vivienne. "Investigation of radio emission from Supernova Remnant 1987A." Thesis, The University of Sydney, 2002. https://hdl.handle.net/2123/27884.
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This thesis investigates the recent radio emission from the remnant of Supernova
1987A in the Large Magellanic Cloud. Radio emission from this developing supernova
remnant was detected in June 1990, just over three years after the initial
outburst from the supernova explosion. Monitored with the Molonglo Observatory
Synthesis Telescope and the Australia Telescope Compact Array, the SNR has been
increasing in radio brightness to the present day. Observations from the Hubble
Space Telescope, ROSAT and Chandra confirm that the remnant is also brightening
in optical and X-ray wavelengths. The continued brightening has been understood
as the interaction of the expanding supernova shock front with density structures
from the progenitor’s stellar wind. The hydrodynamical processes involved in the
expansion of shock fronts in supernova remnants are modelled using self similar solutions.
Such solutions are used in constructing scaling models to describe radio
emission from supernova remnants. Assumptions need to be made about the way
physical parameters are scaled to fit observed emission. Variations of the “minishell”
scaling models (Chevalier 1996) are applied to the observed radio emission
from SNR 1987A in order to generate plausible scalings of the magnetic field and
electron energy distribution which combine to create the observed synchrotron emission.
34
Williams, Brian Jeffrey. "Supernova Remnants as a Probe of Dust Grains in the Interstellar Medium." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-03092010-171032/.
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Interstellar dust grains play a crucial role in the evolution of the galactic interstellar medium (ISM). Despite its importance, however, dust remains poorly understood in terms of its origin, composition, and abundance throughout the universe. Supernova remnants (SNRs) provide a laboratory for studying the evolution of dust grains, as they are one of the only environments in the universe where it is possible to observe grains being both created and destroyed. SNRs exhibit collisionally heated dust, allowing dust to serve as a diagnostic both for grain physics and for the plasma conditions in the SNR. I present theoretical models of collisionally heated dust which calculate grain emission as well as destruction rates. In these models, I incorporate physics such as nonthermal sputtering caused by grain motions through the gas, a more realistic approach to sputtering for small grains, and arbitrary grain compositions porous and composite grains. I apply these models to infrared and X-ray observations of Kepler's supernova and the Cygnus Loop in the galaxy, and SNRs 0509-67.5, 0519-69.0, and 0540-69.3 in the LMC. X-ray observations characterize the hot plasma while IR observations constrain grain properties and destruction rates. Such a multi-wavelength approach is crucial for a complete understanding of gas and dust interaction and evolution. Modeling of both X-ray and IR spectra allows disentangling of parameters such as pre and postshock gas density, as well as swept-up masses of gas and dust, and can provide constraints on the shock compression ratio. Observations also show that the dust-to-gas mass ratio in the ISM is lower by a factor of several than what is inferred by extinction studies of starlight. Future observatories, such as the James Webb Space Telescope and the International X-ray Observatory, will allow testing of models far beyond what is possible now.
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Zeng, Houdun, Yuliang Xin, Siming Liu, J. R. Jokipii, Li Zhang, and Shuinai Zhang. "EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623101.
Full textAbstract:
Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in gamma-ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2 degrees on the sky: RX J1713.7-3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and gamma-ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factor of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.
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LORU, SARA. "Modelling the radio spectra of spatially-resolved Supernova Remnants at high frequencies." Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/259898.
Full textAbstract:
The main
characteristics of the radio continuum spectra of Supernova Remnants (SNRs) result from simple synchrotron emission.
In addition, electron acceleration mechanisms can shape the spectra in specific ways, especially
at high radio frequencies. These features are connected to the age and the peculiar conditions of
the local ISM interacting with the SNR.
Whereas the bulk radio emission is expected at up to 20 − 50 GHz, sensitive high-
resolution images of SNRs above ∼ 10 GHz are lacking and are not easily achievable.
Indeed, interferometric observations are certainly
unbeatable in terms of image resolution, but synthesis imaging becomes difficult in the context of
extended sources (10 − 30 arcmin) at high radio frequencies (above a few GHz). On the other hand,
sensitive radio continuum observations can be performed with single-dish telescopes, offering in
this way a good trade-off between sensitivity and resolution in the frequency range 5 − 50 GHz.
The Sardinia Radio Telescope (SRT) represents a great instrument in this context, thanks to its
active surface that characterises the primary 64-m-diameter mirror, and which improves spatial
resolution at high frequencies.
We observed the middle-aged SNRs W44 and IC443 with SRT at 1.55 GHz (L-band), 7.0 GHz
(C-band) and 21.4 GHz (K-band). We also observed the young Tycho SNR at 21.4 GHz. These
observations provided, for the first time, single-dish high-resolution images of W44 and IC443 at
7 GHz and 21.4 GHz, which demonstrated that a good mapping quality of large structures can be
maintained with SRT in the single-dish configuration at up to high-radio frequencies. Our images
provided integrated sensitive flux density measurements that we coupled with the radio data
available in the literature in order to characterise the integrated and spatially-resolved spectra
of these SNRs. We performed spatially-resolved spectral measurements of W44 and IC443 by
coupling 1.5 GHz and 7.0 GHz maps. For both W44 and IC443, the obtained spectral index maps
reveal a spread in the spectral slope distribution.
We coupled the SRT measurements with
radio data available in the literature in order to characterise the integrated spectra of these SNRs
at up to high-radio frequencies.
We provided, for the first time, direct evidence for spectral break in the radio spectral energy
distribution of W44 at an exponential cut-off frequency of 15 ± 2 GHz. This result constrains the
maximum energy of the accelerated cosmic-ray electrons in the range 6 − 13 GeV, in agreement
with predictions indirectly derived from AGILE and Fermi-LAT gamma-ray observations. With
regard to IC443, our results confirm the noticeable presence of a bump in the integrated spectrum
around 20 − 70 GHz that could result from a spinning dust emission mechanism.
In view of the results obtained with SRT in the context of single-dish imaging of extended
sources, we decided to observe the very extended and interesting SNR Cygnus Loop at 8.3
GHz with the Medicina radio telescope. From these observations, we obtained the integrated
flux density measurement of Cygnus Loop at the highest frequency carried out so far with
a single-dish telescope.
Although comparable in age, our
observations show that W44, IC443 and Cygnus Loop present different spectral features at high
radio frequencies. We ascribed this evidence to the environmental differences between these
SNRs, which could lead to an enhancement of the secondary electron populations produced by
hadronic interactions in regions where the SNR shock collides with dense molecular clouds.
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Egger, Roland. "Der Supernova-Überrest North Polar Spur in der ROSAT- Himmelsdurchmusterung." Garching bei München : Max-Planck-Institut für extraterrestrische Physik, 1993. http://catalog.hathitrust.org/api/volumes/oclc/29509967.html.
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Tomita, Hiroshi. "Synchrotron emission from the Shell-like Supernova Remnants and the Cosmic Ray Origin." 京都大学 (Kyoto University), 1999. http://hdl.handle.net/2433/181947.
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要旨pdfファイル:タイトル「Synchrotron emission from the Shell-like Supernova Remnants and the Comsic-Ray Origin」Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第7643号
理博第2028号
新制||理||1084(附属図書館)
UT51-99-G237
京都大学大学院理学研究科物理学・宇宙物理学専攻
(主査)教授 小山 勝二, 教授 笹尾 登, 教授 舞原 俊憲
学位規則第4条第1項該当
39
Lakicevic, Masa. "The impact of supernova remnants on interstellar dust within the Large Magellanic Cloud." Thesis, Keele University, 2015. http://eprints.keele.ac.uk/2492/.
Full textAbstract:
This thesis presents the first population study of supernova remnants (SNRs) in one whole galaxy – the Large Magellanic Cloud (LMC) on submm and FIR wavelengths. The first part is about the dust production in supernovae (SNe) and SNRs, based on several observations of SN1987A on mm and submm wavelengths that I made using the ATCA and APEX telescopes. SN1987A is found to produce ∼0.7 M⊙ of dust, which is 2 orders of magnitude higher than the masses found in most of other SN/SNR observations. I constrained the spectral energy distribution (SED) of SN1987A, confirming Herschel data using better resolution, but did not manage to resolve the object. These data were used in the preparation of the ALMA observations (Kamenetzky et al. 2013; Indebetouw et al. 2014). The second part of the thesis is the population study of all LMC SNRs using Herschel and Spitzer data, which resulted in the conclusion that SNRs are significant dust destroyers. This conclusion is based on dust mass maps of SNRs and their surroundings which have shown that there is less dust within SNRs than outside. My study shows that a SNR in the LMC removes on average 4–6 M⊙. I conclude that SNRs might not be the main suppliers of dust in galaxies, and that it is possible that other sources of dust production are needed to explain the origin of the dust at high red-shifts. I estimate the mass of sputtered dust from all SNRs in LMC to be ∼373+746 249 M⊙, a dust destruction rate in the LMC of ∼0.037+0.074 −0.025 M⊙ yr−1 due to SNRs and an average lifetime for interstellar dust in the regions close to SNRs of ∼2+4 −1.3 × 107 yr.
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Theiling, Mark. "Observations of very high energy gamma ray emission from supernova remnants with VERITAS." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263397351/.
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Ueno, Masaru. "Supernova remnants selected with X-rays : contribution to the galactic cosmic-ray acceleration." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145075.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11307号
理博第2865号
新制||理||1428(附属図書館)
22950
UT51-2005-D58
京都大学大学院理学研究科物理学･宇宙物理学専攻
(主査)教授 小山 勝二, 教授 今井 憲一, 教授 中村 卓史
学位規則第4条第1項該当
42
Hahn, Joachim [Verfasser], and Werner [Akademischer Betreuer] Hofmann. "Supernova Remnants with H.E.S.S.: Systematic Analysis and Population Synthesis / Joachim Hahn ; Betreuer: Werner Hofmann." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1177810867/34.
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Ozaki, Masanobu. "Observational Study on Thermal and Non-thermal X-rays from Shell-like Supernova Remnants." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/160917.
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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第6658
理博第1793号
新制||理||984(附属図書館)
UT51-97-H42
京都大学大学院理学研究科物理学第二専攻
(主査)教授 小山 勝二, 教授 佐藤 文隆, 教授 堀内 昶
学位規則第4条第1項該当
44
Pivato, Giovanna. "Supernova remnants observed by the Fermi Large Area Telescope: the case of HB 21." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424603.
Full textAbstract:
Since their discovery, Cosmic Rays (CRs) are one of the most studied phenomena in the Universe.
The origin of the spectrum, which extends for more than 12 orders of magnitude, is still debated.
Up to ~10^15 eV, cosmic rays are accelerated in the Galaxy, and Supernova remnants (SNRs) are the most likely candidates to accelerate them.
If an expanding SNR interacts with molecular clouds, particles accelerated in the expanding shock can produce high-energy photons, the observation of which can provide valuable information about the accelerated particles population.
Of particular interest are combined gamma-ray and radio observations: accelerated particles emit radio waves via synchrotron emission and gamma rays via bremsstrahlung, inverse Compton and nucleon-nucleon interaction.
Thanks to its unprecedent angular resolution and sensitivity, the Fermi Gamma-ray Space Telescope is the gamma-ray detector ideal for the study of extended structures in the Galaxy.
We present the analysis of Fermi Large Area Telescope gamma-ray observations of HB 21 (G89.0+4.7).
We detected significant gamma-ray emission associated with the remnant: the flux above 100 MeV is 9.4± 0.8(stat)±1.6(syst)x10¹¹ erg cm² s-¹.
HB 21 is well modeled by a uniform disk centered at l=88°.75±0°.04, b=+4°.65±0°.06 with a radius of 1°.19±0°.06.
The gamma-ray spectrum shows clear evidence of curvature, suggesting a cutoff or break in the underlying particle population at an energy of a few GeV.
We complement gamma-ray observations with the analysis of the WMAP 7 yr data from 23 to 93 GHz, achieving the first detection of HB 21 at these frequencies.
In combination with archival radio data, the radio spectrum shows a spectral break, which helps to constrain the relativistic electron spectrum, hence parameters of simple non-thermal radiation models.
In one-zone models multi-wavelength data favor the origin of gamma rays from nucleon-nucleon collisions.
A single population of electrons cannot produce both gamma rays through bremsstrahlung and radio emission through synchrotron radiation.
A predominantly inverse-Compton origin of the gamma-ray emission is disfavored because it requires lower interstellar densities than the ones inferred for HB 21.
In the hadronic-dominated scenarios, accelerated nuclei contribute a total energy of ~3x10⁴⁹ erg, while, in a two-zone bremsstrahlung-dominated scenario, the total energy in accelerated particles is ~1x10⁴⁹ erg.Fin dalla loro scoperta, i raggi cosmici sono uno dei fenomeni più studiati nell'Universo. L'origine del loro spettro, che si estende per più di 12 ordini di grandezza, è ancora incerta e dibattuta. Fino ad energie dell'ordine di ~10^15 eV, si ipotizza che i raggi cosmici siano accelerati all'interno della Galassia, e che i resti di supernova siano i principali acceleratori. Espandendosi, un resto di supernova può interagire con le nubi molecolari presenti nel mezzo circostante, in questo caso le particelle accelerate possono produrre fotoni di alta energia la cui osservazione può fornire informazioni sulla popolazione dei raggi cosmici. Di particolare interesse sono le osservazioni combinate nella bade gamma e radio: le particelle accelerate emettono nel radio tramite radiazione di sincrotrone, e nel gamma tramite Bremsstrahlung, effetto Compton inverso e interazione inelastica nucleone-nucleone. Grazie alla sua ottima risoluzione angolare e precisione spaziale, il Telescopio Spaziale Fermi è il rivelatore di raggi gamma ideale per lo studio di sorgenti estese. La tesi presenta l'analisi effettuata con dati Fermi della sorgente estesa HB 21 (G89.0+4.7). Riveliamo significativa emissione gamma associata al resto di supernova: il flusso sopra 100 MeV è di 9.4± 0.8(stat)±1.6(syst)x10¹¹ erg cm² s-¹. Dal punto di vista morfologico, l'emissione è ben modellata da un disco uniforme, centrato alle coordinate Galattiche l=88°.75±0°.04, b=+4°.65±0°.06 di raggio 1°.19±0°.06. Lo spettro gamma mostra un'evidente curvatura che suggerisce un taglio o un'interruzione dello spettro nella popolazione di particelle che generano lo spettro gamma, ad energie di qualche GeV. Insieme ai dati gamma , sono stati inclusi anche dati provenienti dal radio usando 7 anni di dati raccolti dall'esperimento WMAP da 23 a 93 GHz, che hanno portato alla prima osservazione di HB 21 a queste frequenze. Unendo tali dati ai quelli di archivio, si è potuto osservare come lo spettro radio presenti un'interruzione. Tale caratteristica aiuta a determinare lo spettro degli elettroni relativistici e, quindi, anche i parametri dei modelli di radiazione non termica. Nei modelli di singola zona, i dati su più lunghezze d'onda favoriscono un'origine dei raggi gamma da collisioni nucleone-nucleone. Una singola popolazione di elettroni non può spiegare contemporaneamente sia l'emissione di Bremsstrahlung nel gamma che quella di sincrotrone nel radio. L'effetto Compton inverso, invece, non può riprodurre bene lo spettro gamma perché richiederebbe basse densità del mezzo interstellare, molto più basse di quelle calcolate intorno a HB 21. Quindi, nello scenario adronico, i nuclei accelerati forniscono un'energia di ~3x10⁴⁹ erg, mentre in uno scenario in cui le zone di emissione di radio e gamma siano diverse e l'emissione gamma è dominata dal Bremsstrahlung, l'energia totale in particelle accelerate è di ~1x10⁴⁹ erg.
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Dinçel, Baha [Verfasser], Ralph [Gutachter] Neuhäuser, Ulrich [Gutachter] Heber, and den Heuvel Ed [Gutachter] Van. "Massive runaway stars inside supernova remnants = Massereiche Schnellläufersterne in Supernova-Überresten / Baha Dinçel ; Gutachter: Ralph Neuhäuser, Ulrich Heber, Ed Van den Heuvel." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177598345/34.
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Kumar, Harsha Sanjeev. "X-ray studies of highly magnetized neutron stars and their environs." Astrophysical Journal Letters, 2008. http://hdl.handle.net/1993/22091.
Full textAbstract:
Supernova explosions are among the most energetic events known in the universe, leaving supernova remnants (SNRs) as their relics. The cores of massive stars collapse to form neutron stars, among the most compact and strongest magnets in the cosmos. The thesis studies a sample of such magnetic "beauties" in X-rays, the magnetars and high-magnetic field pulsars (HBPs), with the motivation to understand their evolutionary links. We also address the connection between these sources by investigating their environs through their securely associated SNRs. Magnetars have ultra-high magnetic fields B ~ 10^{14} - 10^{15} Gauss (G) and include the soft-gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). The HBPs have magnetic fields B ~ 10^{13} - 10^{14} G, intermediate between the classical rotation-powered pulsars (B ~ 10^{12} G) and magnetars.
We focussed on two HBPs: J1119-6127 and J1846-0258, with similar spin-properties and associated with the SNRs G292.2-0.5 and Kes 75, respectively. In our studies, magnetar-like behavior was discovered from the Crab-like pulsar J1846-0258, clearly establishing a connection between the HBPs and magnetars for the first time, while no such behavior has been observed from PSR J1119-6127 so far. J1119-6127's overall X-ray properties together with its compact pulsar wind nebula resemble more the classical rotation-powered pulsars. We studied two magnetars, one from each sub-class: SGR 0501+4516 and AXP 1E 1841-045. The spectral and statistical analysis of the bursts and the persistent X-ray emission properties observed from them were found consistent with the magnetar model predictions as well as those seen in other SGRs. Finally, we probed the environment of these stellar magnets by performing a detailed X-ray imaging and spatially resolved spectroscopic study of two SNRs: G292.2-0.5 and Kes 73 associated with J1119-6127 and 1E 1841-045, respectively. We found that both SNRs point to very massive progenitors (>~25 solar masses), further supporting the growing evidence for magnetars originating from massive progenitors using other multiwavelength studies.
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Reichardt, Candel Ignasi. "Search for gamma-ray emission from supernova remnants with the Fermi/LAT and MAGIC telescopes." Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/98414.
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Bamba, Aya. "A Detailed Spatial and Spectral Study of Synchrotron X-rays from Supernova Remnants with Chandra." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147810.
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Pais, Matteo [Verfasser], and Christoph [Akademischer Betreuer] Pfrommer. "Magneto-hydrodynamical simulation with cosmic ray acceleration at supernova remnants. / Matteo Pais ; Betreuer: Christoph Pfrommer." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/122083632X/34.
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Sato, Toshiki, Satoru Katsuda, Mikio Morii, Aya Bamba, John P. Hughes, Yoshitomo Maeda, Manabu Ishida, and Federico Fraschetti. "X-Ray Measurements of the Particle Acceleration Properties at Inward Shocks in Cassiopeia A." IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/626534.
Full textAbstract:
We present new evidence that the bright nonthermal X-ray emission features in the interior of the Cassiopeia A supernova remnant are caused by inward-moving shocks, based on Chandra and NuSTAR observations. Several bright inward-moving filaments were identified using monitoring data taken by Chandra in 2000-2014. These inward-moving shock locations are nearly coincident with hard X-ray (15-40 keV) hot spots seen by NuSTAR. From proper-motion measurements, the transverse velocities were estimated to be in the range of similar to 2100-3800 km s(-1) for a distance of 3.4 kpc. The shock velocities in the frame of the expanding ejecta reach values of similar to 5100-8700 km s(-1), which is slightly higher than the typical speed of the forward shock. Additionally, we find flux variations (both increasing and decreasing) on timescales of a few years in some of the inward-moving shock filaments. The rapid variability timescales are consistent with an amplified magnetic field of B similar to 0.5-1 mG. The high speed and low photon cut-off energy of the inward-moving shocks are shown to imply a particle diffusion coefficient that departs from the Bohm regime (k(0) = D-0/D-0,D-Bohm similar to 3-8) for the few simple physical configurations we consider in this study. The maximum electron energy at these shocks is estimated to be similar to 8-11 TeV, which is smaller than the values of similar to 15-34 TeV that were inferred for the forward shock. Cassiopeia A is dynamically too young for its reverse shock to appear to be moving inward in the observer frame. We propose instead that the inward-moving shocks are a consequence of the forward shock encountering a density jump of 5-8 in the surrounding material.