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Title: The Three-dimensional Expansion of the Ejecta from Tycho's Supernova Remnant

Abstract

We present the first 3D measurements of the velocity of various ejecta knots in Tycho’s supernova remnant, known to result from a Type Ia explosion. Chandra X-ray observations over a 12 yr baseline from 2003 to 2015 allow us to measure the proper motion of nearly 60 “tufts” of Si-rich ejecta, giving us the velocity in the plane of the sky. For the line-of-sight velocity, we use two different methods: a nonequilibrium ionization model fit to the strong Si and S lines in the 1.2–2.8 keV regime, and a fit consisting of a series of Gaussian lines. These methods give consistent results, allowing us to determine the redshift or blueshift of each of the knots. Assuming a distance of 3.5 kpc, we find total velocities that range from 2400 to 6600 km s{sup −1}, with a mean of 4430 km s{sup −1}. We find several regions where the ejecta knots have overtaken the forward shock. These regions have proper motions in excess of 6000 km s{sup −1}. Some SN Ia explosion models predict a velocity asymmetry in the ejecta. We find no such velocity asymmetries in Tycho, and we discuss our findings in light of various explosion models, favoring thosemore » delayed-detonation models with relatively vigorous and symmetrical deflagrations. Finally, we compare measurements with models of the remnant’s evolution that include both smooth and clumpy ejecta profiles, finding that both ejecta profiles can be accommodated by the observations.« less

Authors:
;  [1]; ; ;  [2];  [3];  [4]; ; ;  [5];  [6]
  1. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  2. NASA Goddard Space Flight Center, X-ray Astrophysics Laboratory, Greenbelt, MD 20771 (United States)
  3. School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 (Australia)
  4. University of North Florida, Department of Physics, 1 UNF Drive, Jacksonville, FL 32224 (United States)
  5. Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)
  6. Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States)
Publication Date:
OSTI Identifier:
22663524
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 842; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; COMPARATIVE EVALUATIONS; EVOLUTION; EXPANSION; EXPLOSIONS; IONIZATION; KEV RANGE; PROPER MOTION; RED SHIFT; SPECTRAL SHIFT; SUPERNOVA REMNANTS; SUPERNOVAE; THREE-DIMENSIONAL CALCULATIONS; VELOCITY; VISIBLE RADIATION; X RADIATION

Citation Formats

Williams, Brian J., Depasquale, Joseph, Coyle, Nina M., Yamaguchi, Hiroya, Petre, Robert, Seitenzahl, Ivo R., Hewitt, John W., Blondin, John M., Borkowski, Kazimierz J., Reynolds, Stephen P., and Ghavamian, Parviz, E-mail: bwilliams@stsci.edu. The Three-dimensional Expansion of the Ejecta from Tycho's Supernova Remnant. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7384.
Williams, Brian J., Depasquale, Joseph, Coyle, Nina M., Yamaguchi, Hiroya, Petre, Robert, Seitenzahl, Ivo R., Hewitt, John W., Blondin, John M., Borkowski, Kazimierz J., Reynolds, Stephen P., & Ghavamian, Parviz, E-mail: bwilliams@stsci.edu. The Three-dimensional Expansion of the Ejecta from Tycho's Supernova Remnant. United States. doi:10.3847/1538-4357/AA7384.
Williams, Brian J., Depasquale, Joseph, Coyle, Nina M., Yamaguchi, Hiroya, Petre, Robert, Seitenzahl, Ivo R., Hewitt, John W., Blondin, John M., Borkowski, Kazimierz J., Reynolds, Stephen P., and Ghavamian, Parviz, E-mail: bwilliams@stsci.edu. Sat . "The Three-dimensional Expansion of the Ejecta from Tycho's Supernova Remnant". United States. doi:10.3847/1538-4357/AA7384.
@article{osti_22663524,
title = {The Three-dimensional Expansion of the Ejecta from Tycho's Supernova Remnant},
author = {Williams, Brian J. and Depasquale, Joseph and Coyle, Nina M. and Yamaguchi, Hiroya and Petre, Robert and Seitenzahl, Ivo R. and Hewitt, John W. and Blondin, John M. and Borkowski, Kazimierz J. and Reynolds, Stephen P. and Ghavamian, Parviz, E-mail: bwilliams@stsci.edu},
abstractNote = {We present the first 3D measurements of the velocity of various ejecta knots in Tycho’s supernova remnant, known to result from a Type Ia explosion. Chandra X-ray observations over a 12 yr baseline from 2003 to 2015 allow us to measure the proper motion of nearly 60 “tufts” of Si-rich ejecta, giving us the velocity in the plane of the sky. For the line-of-sight velocity, we use two different methods: a nonequilibrium ionization model fit to the strong Si and S lines in the 1.2–2.8 keV regime, and a fit consisting of a series of Gaussian lines. These methods give consistent results, allowing us to determine the redshift or blueshift of each of the knots. Assuming a distance of 3.5 kpc, we find total velocities that range from 2400 to 6600 km s{sup −1}, with a mean of 4430 km s{sup −1}. We find several regions where the ejecta knots have overtaken the forward shock. These regions have proper motions in excess of 6000 km s{sup −1}. Some SN Ia explosion models predict a velocity asymmetry in the ejecta. We find no such velocity asymmetries in Tycho, and we discuss our findings in light of various explosion models, favoring those delayed-detonation models with relatively vigorous and symmetrical deflagrations. Finally, we compare measurements with models of the remnant’s evolution that include both smooth and clumpy ejecta profiles, finding that both ejecta profiles can be accommodated by the observations.},
doi = {10.3847/1538-4357/AA7384},
journal = {Astrophysical Journal},
number = 1,
volume = 842,
place = {United States},
year = {Sat Jun 10 00:00:00 EDT 2017},
month = {Sat Jun 10 00:00:00 EDT 2017}
}
  • We show that the expansion of ejecta in Tycho's supernova remnant (SNR) is consistent with a spherically symmetric shell, based on Suzaku measurements of the Doppler broadened X-ray emission lines. All of the strong K{alpha} line emissions show broader widths at the center than at the rim, while the centroid energies are constant across the remnant (except for Ca). This is the pattern expected for Doppler broadening due to expansion of the SNR ejecta in a spherical shell. To determine the expansion velocities of the ejecta, we applied a model for each emission-line feature having two Gaussian components separately representingmore » red- and blueshifted gas, and inferred the Doppler velocity difference between these two components directly from the fitted centroid energy difference. Taking into account the effect of projecting a three-dimensional shell to the plane of the detector, we derived average spherical expansion velocities independently for the K{alpha} emission of Si, S, Ar, and Fe, and K{beta} of Si. We found that the expansion velocities of Si, S, and Ar ejecta of 4700 {+-} 100 km s{sup -1} are distinctly higher than that obtained from Fe K{alpha} emission, 4000 {+-} 300 km s{sup -1}, which is consistent with segregation of the Fe in the inner ejecta. Combining the observed ejecta velocities with the ejecta proper-motion measurements by Chandra, we derived a distance to Tycho's SNR of 4 {+-} 1 kpc.« less
  • We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's SNR. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission coming from the direction of the remnant, compatible with a point source located at 00{sup h}25{sup m}27.{sup s}0, + 64{sup 0}10'50'' (J2000). The TeV photon spectrum measured by VERITAS can be described with a power law dN/dE = C(E/3.42 TeV){sup -}{Gamma} with {Gamma} = 1.95 {+-} 0.51{sub stat} {+-} 0.30{sub sys} and C = (1.55 {+-} 0.43{sub stat} {+-} 0.47{sub sys}) x 10{sup -14} cm{supmore » -2} s{sup -1} TeV{sup -1}. The integral flux above 1 TeV corresponds to {approx}0.9% of the steady Crab Nebula emission above the same energy, making it one of the weakest sources yet detected in TeV gamma rays. We present both leptonic and hadronic models that can describe the data. The lowest magnetic field allowed in these models is {approx}80 {mu}G, which may be interpreted as evidence for magnetic field amplification.« less
  • Tycho's supernova remnant (SNR) is well-established as a source of particle acceleration to very high energies. Constraints from numerous studies indicate that the observed γ-ray emission results primarily from hadronic processes, providing direct evidence of highly relativistic ions that have been accelerated by the SNR. Here we present an investigation of the dynamical and spectral evolution of Tycho's SNR by carrying out hydrodynamical simulations that include diffusive shock acceleration of particles in the amplified magnetic field at the forward shock of the SNR. Our simulations provide a consistent view of the shock positions, the nonthermal emission, the thermal X-ray emissionmore » from the forward shock, and the brightness profiles of the radio and X-ray emission. We compare these with the observed properties of Tycho to determine the density of the ambient material, the particle acceleration efficiency and maximum energy, the accelerated electron-to-proton ratio, and the properties of the shocked gas downstream of the expanding SNR shell. We find that evolution of a typical Type Ia supernova in a low ambient density (n {sub 0} ∼ 0.3 cm{sup –3}), with an upstream magnetic field of ∼5 μG, and with ∼16% of the SNR kinetic energy being converted into relativistic electrons and ions through diffusive shock acceleration, reproduces the observed properties of Tycho. Under such a scenario, the bulk of observed γ-ray emission at high energies is produced by π{sup 0}-decay resulting from the collisions of energetic hadrons, while inverse-Compton emission is significant at lower energies, comprising roughly half of the flux between 1 and 10 GeV.« less
  • We report Swift/Burst Alert Telescope survey observations of the Tycho's supernova remnant, performed over a period of 104 months since the mission's launch. The remnant is detected with high significance (>10σ) below 50 keV. We detect significant hard X-ray emission in the 60-85 keV band, above the continuum level predicted by a simple synchrotron model. The location of the observed excess is consistent with line emission from radioactive titanium-44, so far reported only for Type II supernova explosions. We discuss the implications of these results in the context of the galactic supernova rate, and nucleosynthesis in Type Ia supernova.
  • S>Synthesis observations made with the Westerbork telescope were used to produce maps of the supernova remnants 3 C 10 and 3 C 461. The Stokes parameters I, Q, and U were determined with a resolution of about 25''. The total intensity map of 3 C 10 showed significant emission from the remnant's center, and the results can be approximately reproduced by a spherical shell of synchrotron emitting material. The best shell model, whose thickness is one-fourth of its outer radius, also requires that the magnetic fields have an ordered component predominantly in the radial direction. Such a configuration, which hasmore » been previously suggested for 3 C 461, is in accord with high frequency polarization measurements. The degree of linear polarization from 3 C 461 was generally under 1%. The polarization of Tycho's remnant is dominated by a cellular structure wherein the position angle remains constant within regions of about 1' diameter, while large changes can occur between adjacent regions. The degree of polarization within cells, running as high as 14%, was virtually the same as that obtained at higher frequencies. The interpretation most consistent with the data is that differential Faraday rotation occurs in a thin screen surrounding the remnant, and this is identified with magneto-ionic material swept up from the interstellar medium. Thus the shell of relativistic particles is surrounded by a thin, relatively dense screen of hot gas which produces the differential rotation, the weak optical emission, and, presumably, the soff x-ray emission. (auth)« less