Line shape diagnostics of Galactic 26Al

被引:15
作者
Kretschmer, K
Diehl, R
Hartmann, DH
机构
[1] Max Planck Inst Extraterr Phys, D-85741 Garching, Germany
[2] Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA
来源
ASTRONOMY & ASTROPHYSICS | 2003年 / 412卷 / 02期
关键词
nuclear reactions; nucleosynthesis; abundances; gamma rays : observations; supernovae : general; ISM : supernova remnants; stars : formation;
D O I
10.1051/0004-6361:20034604
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The shape of the gamma-ray line from radioactive Al-26, at 1808.7 keV energy in the frame of the decaying isotope, is determined by its kinematics when it decays, typically 10(6) y after its ejection into the interstellar medium from its nucleosynthesis source. Three measurements of the line width exist: HEAO-C's 1982 value of ( 0 + 3) keV FWHM, the GRIS 1996 value of (5.4 +/- 1.3) keV FWHM, and the recent RHESSI value of (2.0 +/- 0.8) keV FWHM, suggesting either "cold", "hot", or "warm" Al-26 in the ISM. We model the line width as expected from Galactic rotation, expanding supernova ejecta, and/or Wolf-Rayet winds, and predict a value below 1 keV ( FWHM) with plausible assumptions about Al-26 initial velocities and expansion history. Even though the recent RHESSI measurement reduces the need to explain a broad line corresponding to 540 km s(-1) mean Al-26 velocity through extreme assumptions about grain transport of Al-26 or huge interstellar cavities, our results suggest that standard Al-26 ejection models produce a line on the narrow side of what is observed by RHESSI and INTEGRAL. Improved INTEGRAL and RHESSI spatially-resolved line width measurements should help to disentangle the effects of Galactic rotation from the ISM trajectories of Al-26.
引用
收藏
页码:L47 / L51
页数:5
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