scholarly journals Spectral modeling of type II supernovae

2020 ◽  
Vol 633 ◽  
pp. A88 ◽  
Author(s):  
C. Vogl ◽  
W. E. Kerzendorf ◽  
S. A. Sim ◽  
U. M. Noebauer ◽  
S. Lietzau ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Large Data ◽  
Training Dataset ◽  
Parameter Study ◽  
Type Ii ◽  
Data Repositories ◽  
Spectral Fitting ◽  
Explosion Mechanism ◽  
Radiative Transfer Modeling ◽  
Good Agreement

There are now hundreds of publicly available supernova spectral time series. Radiative transfer modeling of this data provides insight into the physical properties of these explosions, such as the composition, the density structure, and the intrinsic luminosity, which is invaluable for understanding the supernova progenitors, the explosion mechanism, and for constraining the supernova distance. However, a detailed parameter study of the available data has been out of reach due to the high dimensionality of the problem coupled with the still significant computational expense. We tackle this issue through the use of machine-learning emulators, which are algorithms for high-dimensional interpolation. These use a pre-calculated training dataset to mimic the output of a complex code but with run times that are orders of magnitude shorter. We present the application of such an emulator to synthetic type II supernova spectra generated with the TARDIS radiative transfer code. The results show that with a relatively small training set of 780 spectra we can generate emulated spectra with interpolation uncertainties of less than one percent. We demonstrate the utility of this method by automatic spectral fitting of two well-known type IIP supernovae; as an exemplary application, we determine the supernova distances from the spectral fits using the tailored-expanding-photosphere method. We compare our results to previous studies and find good agreement. This suggests that emulation of TARDIS spectra can likely be used to perform automatic and detailed analysis of many transient classes putting the analysis of large data repositories within reach.

scholarly journals Radiative-transfer modeling of nebular-phase type II supernovae

2020 ◽  
Vol 642 ◽  
pp. A33
Author(s):  
Luc Dessart ◽  
D. John Hillier
Keyword(s):  
Radiative Transfer ◽  
Massive Star ◽  
Line Emission ◽  
Doppler Width ◽  
Large Set ◽  
Type Ii ◽  
Non Local ◽  
Radiative Transfer Modeling ◽  
Chemical Mixing ◽  
Phase Spectra

Nebular phase spectra of core-collapse supernovae (SNe) provide critical and unique information on the progenitor massive star and its explosion. We present a set of one-dimensional steady-state non-local thermodynamic equilibrium radiative transfer calculations of type II SNe at 300 d after explosion. Guided by the results obtained from a large set of stellar evolution simulations, we craft ejecta models for type II SNe from the explosion of a 12, 15, 20, and 25 M⊙ star. The ejecta density structure and kinetic energy, the 56Ni mass, and the level of chemical mixing are parametrized. Our model spectra are sensitive to the adopted line Doppler width, a phenomenon we associate with the overlap of Fe II and O I lines with Ly α and Ly β. Our spectra show a strong sensitivity to 56Ni mixing since it determines where decay power is absorbed. Even at 300 d after explosion, the H-rich layers reprocess the radiation from the inner metal rich layers. In a given progenitor model, variations in 56Ni mass and distribution impact the ejecta ionization, which can modulate the strength of all lines. Such ionization shifts can quench Ca II line emission. In our set of models, the [O I] λλ 6300, 6364 doublet strength is the most robust signature of progenitor mass. However, we emphasize that convective shell merging in the progenitor massive star interior can pollute the O-rich shell with Ca, which would weaken the O I doublet flux in the resulting nebular SN II spectrum. This process may occur in nature, with a greater occurrence in higher mass progenitors, and this may explain in part the preponderance of progenitor masses below 17 M⊙ that are inferred from nebular spectra.

scholarly journals Radiative Transfer Modeling of Microwave Emission and Dependence on Firn Properties

1982 ◽  
Vol 3 ◽  
pp. 54-58 ◽  
Author(s):  
J. C. Comiso ◽  
H. J. Zwally ◽  
J. L. Saba
Keyword(s):  
Radiative Transfer ◽  
Rayleigh Scattering ◽  
Index Of Refraction ◽  
Microwave Emission ◽  
Scattering Coefficients ◽  
Brightness Temperatures ◽  
Significant Temperature ◽  
Radiative Transfer Modeling ◽  
Seasonal Dependence ◽  
Good Agreement

The microwave emission from a model polar firn was calculated using a numerical solution of the radiative transfer equation that included angledependent Rayleigh scattering. The depth-dependent parameters in the equation were physical temperature and the coefficients of scattering and absorption. The coefficients were based on Rayleigh scattering from the snow grains. The bulk emissivity and the seasonal dependence of brightness temperature were calculated for seven locations at which grain sizes were measured as a function of depth. When the absorption and scattering coefficients are adjusted, the modeled emissivities agree with observed emissivities at these locations. The modeled seasonal dependence of brightness temperatures also compares well with values obtained at 1.55 cm wavelength by the Nimbus-5 satellite. Good agreement with data did not occur when the imaginary part of the index of refraction (and, hence, the absorption coefficient) had a significant temperature dependence between 210 and 250 K.

scholarly journals Odin/OSIRIS observations of stratospheric NO<sub>3</sub> through sunrise and sunset

2008 ◽  
Vol 8 (18) ◽  
pp. 5529-5534 ◽  
Author(s):  
C. A. McLinden ◽  
C. S. Haley
Keyword(s):  
Radiative Transfer ◽  
Current Knowledge ◽  
Strong Dependence ◽  
Rapid Evolution ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectral Fitting ◽  
Infrared Imager ◽  
Fitting In ◽  
Radiative Transfer Modeling

Abstract. The nitrate radical (NO3) has been detected in visible limb-scattered spectra measured by the Optical Spectrograph and InfraRed Imager System (OSIRIS) on-board the Odin satellite when observing at large solar zenith angles (91–97°). Apparent slant column densities of NO3 at tangent heights between 10 and 45 km are derived via spectral fitting in the 610–680 nm window. Using observations from multiple scans spanning solar zenith angles of 91–97°, the rapid evolution of NO3 through sunrise and sunset can be traced. Slant column densities are found to be generally consistent with those simulated using a radiative transfer model with coupled photochemistry. In addition, a strong dependence of NO3 with temperature is observed. These results indicate that our current knowledge of NO3 photochemistry is generally consistent with OSIRIS observations to within the limitations of the radiative transfer modeling. Furthermore, they reveal that OSIRIS possesses signal-to-noise sufficient to make useful measurements of scattered sunlight out to solar zenith angles of 91–97° and suggest the possibility of retrieving profile information for NO3 and other species at large solar zenith angles.

scholarly journals Radiative Transfer Modeling of Microwave Emission and Dependence on Firn Properties

1982 ◽  
Vol 3 ◽  
pp. 54-58 ◽  
Author(s):  
J. C. Comiso ◽  
H. J. Zwally ◽  
J. L. Saba
Keyword(s):  
Radiative Transfer ◽  
Rayleigh Scattering ◽  
Index Of Refraction ◽  
Microwave Emission ◽  
Scattering Coefficients ◽  
Brightness Temperatures ◽  
Significant Temperature ◽  
Radiative Transfer Modeling ◽  
Seasonal Dependence ◽  
Good Agreement

The microwave emission from a model polar firn was calculated using a numerical solution of the radiative transfer equation that included angledependent Rayleigh scattering. The depth-dependent parameters in the equation were physical temperature and the coefficients of scattering and absorption. The coefficients were based on Rayleigh scattering from the snow grains. The bulk emissivity and the seasonal dependence of brightness temperature were calculated for seven locations at which grain sizes were measured as a function of depth. When the absorption and scattering coefficients are adjusted, the modeled emissivities agree with observed emissivities at these locations. The modeled seasonal dependence of brightness temperatures also compares well with values obtained at 1.55 cm wavelength by the Nimbus-5 satellite. Good agreement with data did not occur when the imaginary part of the index of refraction (and, hence, the absorption coefficient) had a significant temperature dependence between 210 and 250 K.

Immunological Determined Plasminogen Groups And Its Possible Biological Relevance

1981 ◽  
Author(s):  
V Sachs ◽  
R Dörner ◽  
E Szirmai
Keyword(s):  
Human Plasma ◽  
Type I ◽  
Type Ii ◽  
Precipitation Line ◽  
Gene Frequencies ◽  
Type Iii ◽  
Different Types ◽  
Human Plasminogen ◽  
Gel Diffusion ◽  
Good Agreement

Anti human plasminogen sera of the rabbit precipitate human plasma in the agar gel diffusion test by means of intra-basin absorption with plasminogenfree human plasma with three different types: type I is represented by one strong precipitation line, type II by two lines, a big one and a small one, and type III by three slight but distinct lines. The following frequencies of the different types have been observed in a sample of 516 human plasmas: type I 65%, type II 33% and type III 2%. Suppose the types are phenotypical groups of a diallelic system where the types I and III represent the homozygous genotypes and the type II the heterozygous the estimated gene frequencies are in good agreement with the expected values. There is also a good agreement of the distribution of plasminogen groups determined by electrofocussing from RAUM et al. and HOBART. The plasminogen groups possibly may have also a biological meaning because the plasmas of type III always have a lesser fibrinolytic activity than the plasmas of the other types.

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