Optical Spectroscopy of Supernova Remnants in M81 and M82

We present spectroscopy of 28 SNR candidates as well as one H II region in M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N II]/H{\alpha} ratios of M81 SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line ratio diagrams: an [O III]-strong group and an [O III]-weak group. The latter have larger sizes, and may have faster shock velocity. [N II]/H{\alpha} ratios of the SNRs show a strong correlation with [S II]/H{\alpha} ratios. They show a clear radial gradient in [N II]/H{\alpha} and [S II]/H{\alpha} ratios: dLog ([N II]/H{\alpha})/dLog R = -0.018 {\pm} 0.008 dex/kpc and dLog ([S II]/H{\alpha})/dLog R = -0.016 {\pm} 0.008 dex/kpc where R is a deprojected galactocentric distance. We estimate the nitrogen and oxygen abundance of the SNRs from the comparison with shock-ionization models. We obtain a value for the nitrogen radial gradient, dLog(N/H)/dLogR = -0.023 {\pm} 0.009 dex/kpc, and little evidence for the gradient in oxygen. This nitrogen abundance shows a few times flatter gradient than those of the planetary nebulae and H II regions. We find that five SNRs are matched with X-ray sources. Their X-ray hardness colors are consistent with thermal SNRs.Comment: 19 pages, 24 figures, 5 tables, ApJ accepte

Do Bars Trigger Activity in Galactic Nuclei?

We investigate the connection between the presence of bars and AGN activity, using a volume-limited sample of $\sim$9,000 late-type galaxies with axis ratio $b/a>0.6$ and $M_{r} < -19.5+5{\rm log}h$ at low redshift ($0.02\le z\lesssim 0.055$), selected from Sloan Digital Sky Survey Data Release 7. We find that the bar fraction in AGN-host galaxies (42.6%) is $\sim$2.5 times higher than in non-AGN galaxies (15.6%), and that the AGN fraction is a factor of two higher in strong-barred galaxies (34.5%) than in non-barred galaxies (15.0%). However, these trends are simply caused by the fact that AGN-host galaxies are on average more massive and redder than non-AGN galaxies because the fraction of strong-barred galaxies (\bfrsbo) increases with $u-r$ color and stellar velocity dispersion. When $u-r$ color and velocity dispersion (or stellar mass) are fixed, both the excess of \bfrsbo in AGN-host galaxies and the enhanced AGN fraction in strong-barred galaxies disappears. Among AGN-host galaxies we find no strong difference of the Eddington ratio distributions between barred and non-barred systems. These results indicate that AGN activity is not dominated by the presence of bars, and that AGN power is not enhanced by bars. In conclusion we do not find a clear evidence that bars trigger AGN activity.Comment: 13 pages, 11 figures, accepted for publication in Ap

Law-Gospel-Oriented Preaching in Martin Luther\u27s Theology of Preaching

The Goal of this thesis is to study Luther\u27s theology of preaching. As we have already seen above, the first chapter outlines the world of Luther\u27s preaching. The second chapter explores Luther\u27s preaching, focusing on his specific concern for preaching. In it, we can see that Luther regards preaching as the oral Word of God. Luther believes God is speaking when the preacher preaches. This chapter will show us that Luther\u27s understanding of preaching is concentrated upon the Lord, Christ who is the content of Gospel

Melt Elongational Flow Rheometry in Converging Channels.

The basic problem in polymer melt elongational rheometry is obtaining a stable and constant elongational flow field free from shear effects. The objective of this study is to present a technique to generate plug flow and elongational flow of polymer melts in a channel geometry. The results of the study included the development of analytical and numerical solutions for flow behavior in the coextrusion of a core polymer melt encapsulated by a sufficiently low viscous skin polymer melt for linear and converging die geometries. Studying the effects of the power-law index, viscosity ratio, and flow rate ratio on the velocity profile and shear behavior indicated that essentially all of the shear gradient could be pushed into the skin layer. In converging geometries, it was thus possible to generate nearly pure elongational flow in the core by choosing an appropriate skin material. This study also demonstrated that by designing a hyperbolic die, a constant steady elongational strain rate, which was a linear function of the core flow rate, could be induced in the core. Experimental data for polypropylene as a core and polyethylene as a skin material showed good agreement of the elongational flow behavior and the predicted constant elongational rate with the model. Finally, elongational viscosity was calculated using the experimental data