Are Ti44-Producing Supernovae Exceptional?

L. -S. The; D. D. Clayton; R. Diehl; D. H. Hartmann; A. F. Iyudin; M. D. Leising; B. S. Meyer; Y. Motizuki; V. Schonfelder

doi:10.1051/0004-6361:20054626

paper

Are Ti44-Producing Supernovae Exceptional?

arXiv:astro-ph/0601039 · doi:10.1051/0004-6361:20054626

Abstract

According to standard models supernovae produce radioactive $^{44}$ Ti, which should be visible in gamma-rays following decay to $^{44}$ Ca for a few centuries. $^{44} T i p r o d u c t i o ni s b e l i e v e d t o b e t h eso u r ceo f cos mi c$ ^{44} $C a, w h ose ab u n d an ce i s w e l l es t ab l i s h e d . Y e t, g amma - r a y t e l esco p es ha v e n o t see n t h ee x p ec t e d y o u n g r e mnan t so f cor eco l l a p see v e n t s . T h e$ ^{44} $T im e an l i f eo f$ τ\simeq $89 y an d t h e G a l a c t i cs u p er n o v a r a t eo f$ \simeq $3/100 y im pl y$ \simeq $se v er a l d e t ec t ab l e$ ^{44}Ti gamma-ray sources, but only one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which produce much $^{44} T ia r ee x p ec t e d t oocc u r p r ima r i l y in t h e inn er p a r t o f t h e G a l a x y, w h er ey o u n g ma ss i v es t a r s a r e m os t ab u n d an t . B ec a u se t h e G a l a x y i s t r an s p a r e n tt o g amma - r a y s, t hi ss h o u l d b e t h e d o minan tl oc a t i o n o f e x p ec t e d g amma - r a y so u r ces . Y e tt h e C a s A S N R a s t h eo n l y o n eso u r ce i s l oc a t e df a r f r o m t h e inn er G a l a x y (a tl o n g i t u d e 112 d e g r ee) . W ee v a l u a t e t h es u r p r i s in g ab se n ceo f d e t ec t ab l es u p er n o v a e f r o m t h e p a s tt h r eece n t u r i es . W e d i sc u ss w h e t h er o u r u n d er s t an d in g o f S N e x pl os i o n s, t h e i r$ ^{44}Ti yields, their spatial distributions, and statistical arguments can be stretched so that this apparent disagreement may be accommodated within reasonable expectations, or if we have to revise some or all of the above aspects to bring expectations in agreement with the observations. We conclude that either core collapse supernovae have been improbably rare in the Galaxy during the past few centuries, or $^{44} T i - p r o d u c in g s u p er n o v a e a r e a t y p i c a l s u p er n o v a e . W e a l so p r ese n t an e w a r g u m e n t ba se d o n$ ^{44} $C a /$ ^{40} $C a r a t i os inmain s t r e am S i C s t a r d u s t g r ain s t ha t ma y c a s t d o u b t o nma ss i v e - H e - c a pT y p e I s u p er n o v a e a s t h eso u r ceo f m os t g a l a c t i c$ ^{44}$Ca.

23 pages, 14 figures, accepted for publication in Astronomy and Astrophysics 2006. Correcting the SN type of Tycho in Table B.1. and add its associated references

Are Ti44-Producing Supernovae Exceptional?

Abstract

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