scholarly journals Spatial distribution of radionuclides in 3D models of SN 1987A and Cas A

2017 ◽  
Vol 12 (S331) ◽  
pp. 148-156 ◽  
Author(s):  
Hans-Thomas Janka ◽  
Michael Gabler ◽  
Annop Wongwathanarat
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
3D Models ◽  
Core Collapse ◽  
Mixing Processes ◽  
Free Expansion ◽  
3D Simulations ◽  
Sn 1987A ◽  
Explosion Mechanism ◽  
Cas A

AbstractFostered by the possibilities of multi-dimensional computational modeling, in particular the advent of three-dimensional (3D) simulations, our understanding of the neutrino-driven explosion mechanism of core-collapse supernovae (SNe) has experienced remarkable progress over the past decade. First self-consistent, first-principle models have shown successful explosions in 3D, and even failed cases may be cured by moderate changes of the microphysics inside the neutron star (NS), better grid resolution, or more detailed progenitor conditions at the onset of core collapse, in particular large-scale perturbations in the convective Si and O burning shells. 3D simulations have also achieved to follow neutrino-driven explosions continuously from the initiation of the blast wave, through the shock breakout from the progenitor surface, into the radioactively powered evolution of the SN, and towards the free expansion phase of the emerging remnant. Here we present results from such simulations, which form the basis for direct comparisons with observations of SNe and SN remnants in order to derive constraints on the still disputed explosion mechanism. It is shown that predictions based on hydrodynamic instabilities and mixing processes associated with neutrino-driven explosions yield good agreement with measured NS kicks, light-curve properties of SN 1987A and asymmetries of iron and 44Ti distributions observed in SN 1987A and Cassiopeia A.

scholarly journals Properties of gamma-ray decay lines in 3D core-collapse supernova models, with application to SN 1987A and Cas A

2020 ◽  
Vol 494 (2) ◽  
pp. 2471-2497 ◽  
Author(s):  
A Jerkstrand ◽  
A Wongwathanarat ◽  
H-T Janka ◽  
M Gabler ◽  
D Alp ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Radioactive Decay ◽  
Supernova Explosion ◽  
3D Models ◽  
Core Collapse ◽  
Line Profiles ◽  
Sn 1987A ◽  
And Shifts ◽  
Cas A ◽  
Explosive Burning

ABSTRACT Comparison of theoretical line profiles to observations provides important tests for supernova explosion models. We study the shapes of radioactive decay lines predicted by current 3D core-collapse explosion simulations, and compare these to observations of SN 1987A and Cas A. Both the widths and shifts of decay lines vary by several thousand kilometres per second depending on viewing angle. The line profiles can be complex with multiple peaks. By combining observational constraints from 56Co decay lines, 44Ti decay lines, and Fe IR lines, we delineate a picture of the morphology of the explosive burning ashes in SN 1987A. For MZAMS = 15−20 M⊙ progenitors exploding with ∼1.5 × 1051 erg, ejecta structures suitable to reproduce the observations involve a bulk asymmetry of the 56Ni of at least ∼400 km s−1 and a bulk velocity of at least 1500 km s−1. By adding constraints to reproduce the UVOIR bolometric light curve of SN 1987A up to 600 d, an ejecta mass around 14 M⊙ is favoured. We also investigate whether observed decay lines can constrain the neutron star (NS) kick velocity. The model grid provides a constraint VNS > Vredshift, and applying this to SN 1987A gives a NS kick of at least 500 km s−1. For Cas A, our single model provides a satisfactory fit to the NuSTAR observations and reinforces the result that current neutrino-driven core-collapse SN models achieve enough bulk asymmetry in the explosive burning material. Finally, we investigate the internal gamma-ray field and energy deposition, and compare the 3D models to 1D approximations.

scholarly journals Autopsy of the Supernova Remnant Cassiopeia A

2013 ◽  
Vol 9 (S296) ◽  
pp. 155-159
Author(s):  
Dan Milisavljevic ◽  
Robert A. Fesen
Keyword(s):  
Large Scale ◽  
Supernova Remnant ◽  
Three Dimensional ◽  
Radioactive Material ◽  
Core Collapse ◽  
Common Phenomenon ◽  
Cassiopeia A ◽  
Circular Rings ◽  
Cas A ◽  
Emission Line Profile

AbstractThree-dimensional kinematic reconstructions of optically emitting ejecta in the young Galactic supernova remnant Cassiopeia A (Cas A) are discussed. The reconstructions encompass the remnant's faint outlying ejecta knots, including the exceptionally high-velocity NE and SW streams of debris often referred to as ‘jets’. The bulk of Cas A's ejecta are arranged in several circular rings with diameters between approximately 30″ (0.5 pc) and 2′ (2 pc). We suggest that similar large-scale ejecta rings may be a common phenomenon of young core-collapse remnants and may explain lumpy emission line profile substructure sometimes observed in spectra of extragalactic core-collapse supernovae years after explosion. A likely origin for these large ejecta rings is post-explosion input of energy from plumes of radioactive 56Ni-rich ejecta that rise, expand, and compress non-radioactive material to form bubble-like structures.

scholarly journals 3D hydrodynamic core-collapse SN simulations for an 11.2 M⊙ star with spectral neutrino transport

2011 ◽  
Vol 7 (S279) ◽  
pp. 409-410
Author(s):  
Tomoya Takiwaki ◽  
Kei Kotake ◽  
Yudai Suwa
Keyword(s):  
Three Dimensional ◽  
3D Models ◽  
Core Collapse ◽  
Numerical Resolution ◽  
1D Model ◽  
Explosion Mechanism ◽  
Hydrodynamical Simulations ◽  
Energy Dependent ◽  
2D And 3D ◽  
Neutrino Luminosity

AbstractWe have performed three-dimensional (3D) hydrodynamical simulations of core-collapse supernovae (SNe) with multigroup neutrino transport to study non-axisymmetric effects in the context of neutrino heating explosion mechanism. By comparing one- (1D) and two dimensional (2D) results with those of 3D, we study how the increasing spatial multi-dimensionality affects the postbounce SN dynamics. The calculations were performed with an energy-dependent treatment of the neutrino transport that is solved by the isotropic diffusion source approximation scheme. In agreement with previous studies, our 1D model does not produce explosions for the 11.2 M⊙ star, while the neutrino-driven revival of the stalled bounce shock is obtained both in the 2D and 3D models. Our results show that convective matter motions below the gain radius become much more violent in 3D than 2D, making the neutrino luminosity larger for 3D. Enhanced by the large neutrino luminosity, the shock of the 3D model expands faster than that of the 2D. Our results show that the evolution of the shock is sensitive to the employed numerical resolutions. To draw a robust conclusion, 3D simulations with much higher numerical resolution and more advanced treatment of neutrino transport and gravity is needed.

scholarly journals Cutting-edge issues in core-collapse supernova theory

2011 ◽  
Vol 7 (S279) ◽  
pp. 126-133
Author(s):  
Kei Kotake
Keyword(s):  
General Relativity ◽  
First Generation ◽  
Three Dimensional ◽  
Cutting Edge ◽  
Core Collapse ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
Core Collapse Supernova ◽  
Neutrino Radiation ◽  
Explosion Mechanism

AbstractBased on our multi-dimensional neutrino-radiation hydrodynamic simulations, we report several cutting-edge issues about the long-veiled explosion mechanism of core-collapse supernovae (CCSNe). In this contribution, we pay particular attention to whether three-dimensional (3D) hydrodynamics and/or general relativity (GR) would or would not help the onset of explosions. Our results from the first generation of full GR 3D simulations including approximate neutrino transport are quite optimistic, indicating that both of the two ingredients can foster neutrino-driven explosions. We give an outlook with a summary of the most urgent tasks to draw a robust conclusion to our findings.

scholarly journals Weighing trees with lasers: advances, challenges and opportunities

2018 ◽  
Vol 8 (2) ◽  
pp. 20170048 ◽  
Author(s):  
M. I. Disney ◽  
M. Boni Vicari ◽  
A. Burt ◽  
K. Calders ◽  
S. L. Lewis ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Large Scale ◽  
Three Dimensional ◽  
Point Clouds ◽  
3D Models ◽  
Tree Form ◽  
Form And Function ◽  
Challenges And Opportunities ◽  
And Function ◽  
Non Destructive

Terrestrial laser scanning (TLS) is providing exciting new ways to quantify tree and forest structure, particularly above-ground biomass (AGB). We show how TLS can address some of the key uncertainties and limitations of current approaches to estimating AGB based on empirical allometric scaling equations (ASEs) that underpin all large-scale estimates of AGB. TLS provides extremely detailed non-destructive measurements of tree form independent of tree size and shape. We show examples of three-dimensional (3D) TLS measurements from various tropical and temperate forests and describe how the resulting TLS point clouds can be used to produce quantitative 3D models of branch and trunk size, shape and distribution. These models can drastically improve estimates of AGB, provide new, improved large-scale ASEs, and deliver insights into a range of fundamental tree properties related to structure. Large quantities of detailed measurements of individual 3D tree structure also have the potential to open new and exciting avenues of research in areas where difficulties of measurement have until now prevented statistical approaches to detecting and understanding underlying patterns of scaling, form and function. We discuss these opportunities and some of the challenges that remain to be overcome to enable wider adoption of TLS methods.

scholarly journals Studies of the ISM in the LMC using SN1987A

1991 ◽  
Vol 148 ◽  
pp. 431-431
Author(s):  
Max Pettini
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Large Magellanic Cloud ◽  
Absorption Lines ◽  
High Signal ◽  
Hii Region ◽  
Sn 1987A

The exceptional brightness of SN1987A provided a wealth of opportunities for probing not only the interstellar medium in our Galaxy and in the Large Magellanic Cloud (LMC), but also any intergalactic matter between the two. Spectroscopic work has been directed both towards searches for very weak absorption lines, which require data of exceptionally high signal-to-noise ratio, and towards recording spectra of known features at unprecedentedly high resolution. Both approaches have yielded exciting and unexpected results. The first detection of [FeX] absorption has revealed the presence of million-degree gas in the interstellar medium of the LMC, possibly resulting from the explosions of previous supernovae in the 30-Doradus HII region. The ultra-high-resolution observations have been successful in resolving the hyperfine structure of the sodium D lines in several interstellar clouds along the line of sight to the supernova. This implies that the clouds are at temperatures of, at most, 170 K and have internal turbulent velocities of not more than 0.2 km s−1; large-scale motions thus appear to be mainly subsonic in these clouds. Radio observations of HI emission at 21-cm with the Parkes telescope have been combined with measurements of a variety of ultraviolet absorption lines, obtained with the International Ultraviolet Explorer satellite, to give the most detailed picture yet of the chemical composition of the gas between the Galaxy and the LMC. Finally, photographic monitoring of the light echo of SN 1987A over the last two years has provided a three-dimensional view of the interstellar environment in which SN 1987A exploded, complementing vividly the information deduced from the spectroscopic results.

Recent Status of Multi-Dimensional Core-Collapse Supernova Models

2015 ◽  
Vol 11 (A29A) ◽  
pp. 340-344
Author(s):  
Kei Kotake ◽  
Ko Nakamura ◽  
Tomoya Takiwaki
Keyword(s):  
Energy Transport ◽  
Unique Feature ◽  
Three Dimensional ◽  
Radiation Hydrodynamics ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Self Consistent ◽  
New Type ◽  
Explosion Mechanism ◽  
Proto Neutron Star

AbstractWe report a recent status of multi-dimensional neutrino-radiation hydrodynamics simulations for clarifying the explosion mechanism of core-collapse supernovae (CCSNe). In this contribution, we present two results, one from two-dimensional (2D) simulations using multiple progenitor models and another from three-dimensional (3D) rotational core-collapse simulation using a single progenitor. From the first ever systematic 2D simulations, it is shown that the compactness parameter ξ that characterizes the structure of the progenitors is a key to diagnose the explodability of neutrino-driven explosions. In the 3D rotating model, we find a new type of rotation-assisted explosion, which makes the explosion energy bigger than that in the non-rotating model. The unique feature has not been captured in previous 2D self-consistent rotational models because the growth of non-axisymmetric instabilities is the key to foster the explosion by enhancing the energy transport from the proto-neutron star to the gain region.

scholarly journals Spectropolarimetry of stripped-envelope supernovae: observations and modelling

2017 ◽  
Vol 375 (2105) ◽  
pp. 20160273 ◽  
Author(s):  
Masaomi Tanaka
Keyword(s):  
Large Scale ◽  
Massive Stars ◽  
Three Dimensional ◽  
Core Collapse ◽  
Ion Distribution ◽  
Typical Size ◽  
Cassiopeia A ◽  
Accretion Shock

Spectropolarimetry is one of the most powerful methods to study the multi-dimensional geometry of supernovae (SNe). We present a brief summary of the spectropolarimetric observations of stripped-envelope core-collapse SNe. Observations indicate that stripped-envelope SNe generally have a non-axisymmetric ion distribution in the ejecta. Three-dimensional clumpy geometry nicely explains the observed properties. A typical size of the clumps deduced from observations is relatively large: 25% of the photosphere. Such a large-scale clumpy structure is similar to that observed in Cassiopeia A, and suggests that large-scale convection or standing accretion shock instability takes place at the onset of the explosion. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals UAV-BASED PHOTOGRAMMETRY FOR ARCHAEOLOGICAL HERITAGE SITE SURVEY AND 3D MODELING OF THE SARDUS PATER TEMPLE (ITALY)

2019 ◽  
Vol XLII-2/W17 ◽  
pp. 45-51
Author(s):  
V. Bagnolo ◽  
N. Paba
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Three Dimensional ◽  
High Standard ◽  
3D Models ◽  
Strong Increase ◽  
Active Sensors ◽  
Archaeological Heritage ◽  
Heritage Site ◽  
Effective Visualization

Abstract. Despite the high standard guaranteed by 3D scanning technology, image based modeling establishes the most widely used technique for surface reconstruction, being a cheaper and more portable approach. The strong increase in the use of Unmanned Aerial Vehicles (UAVs), is increasingly affirming and consolidating over the years. Being more cheap and portable than the active sensors approach, the combination of photogrammetry and drones is widely used for different applications both for large scale mapping and for documentation of architecture and archaeological heritage. UAV based photogrammetry allows for rapid accurate mapping and three-dimensional modelling. Over the last two decades, the study of archaeological sites have benefited from the constant evolution of sensor-based surveying techniques, finding effective application for purely visualization purposes or for the extraction of metric data. The Punic-Roman temple "Sardus Pater Babai" in southern Sardinia (Italy), has been the subject of a massive anastylosis. The close-range photogrammetry technique, exploiting the images produced by a UAV consumer and the GNSS system data, has allowed the creation of metrically correct 2D and 3D models useful also for an effective visualization of the information. A series of ortho-images has been extracted in order to represent plan, elevations and cross-sections of the monument.

scholarly journals Large-Scale Accurate Reconstruction of Buildings Employing Point Clouds Generated from UAV Imagery

2018 ◽  
Vol 10 (7) ◽  
pp. 1148 ◽  
Author(s):  
Shirin Malihi ◽  
Mohammad Valadan Zoej ◽  
Michael Hahn
Keyword(s):  
Conceptual Knowledge ◽  
Large Scale ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Evaluation Criteria ◽  
Point Clouds ◽  
3D Models ◽  
Contextual Knowledge ◽  
Segmentation Evaluation ◽  
Segmentation Approach

High-density point clouds are valuable and detailed sources of data for different processes related to photogrammetry. We explore the knowledge-based generation of accurate large-scale three-dimensional (3D) models of buildings employing point clouds derived from UAV-based photogrammetry. A new two-level segmentation approach based on efficient RANdom SAmple Consensus (RANSAC) shape detection is developed to segment potential facades and roofs of the buildings and extract their footprints. In the first level, the cylinder primitive is implemented to trim point clouds and split buildings, and the second level of the segmentation produces planar segments. The efficient RANSAC algorithm is enhanced in sizing up the segments via point-based analyses for both levels of segmentation. Then, planar modelling is carried out employing contextual knowledge through a new constrained least squares method. New evaluation criteria are proposed based on conceptual knowledge. They can examine the abilities of the approach in reconstruction of footprints, 3D models, and planar segments in addition to detection of over/under segmentation. Evaluation of the 3D models proves that the geometrical accuracy of LoD3 is achieved, since the average horizontal and vertical accuracy of the reconstructed vertices of roofs and footprints are better than (0.24, 0.23) m, (0.19, 0.17) m for the first dataset, and (0.35, 0.37) m, (0.28, 0.24) m for the second dataset.

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