Brian W. Grefenstette
The distribution of radioactive 44Ti in Cassiopeia A
Grefenstette, Brian W.; Fryer, Chris L.; Harrison, Fiona A.; Boggs, Steven E.; DeLaney, Tracey; Laming, J. Martin; Reynolds, Stephen P.; Alexander, David M.; Barret, Didier; Christensen, Finn E.; Craig, William W.; Forster, Karl; Giommi, Paolo; Hailey, Charles J.; Hornstrup, Alan; Kitaguchi, Takao; Koglin, J.E.; Lopez, Laura; Mao, Peter H.; Madsen, Kristin K.; Miyasaka, Hiromasa; Mori, Kaya; Perri, Matteo; Pivovaroff, Michael J.; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J.; Wik, Daniel R.; Zhang, William W.; Zoglauer, Andreas
Authors
Chris L. Fryer
Fiona A. Harrison
Steven E. Boggs
Tracey DeLaney
J. Martin Laming
Stephen P. Reynolds
Professor David Alexander d.m.alexander@durham.ac.uk
Professor
Didier Barret
Finn E. Christensen
William W. Craig
Karl Forster
Paolo Giommi
Charles J. Hailey
Alan Hornstrup
Takao Kitaguchi
J.E. Koglin
Laura Lopez
Peter H. Mao
Kristin K. Madsen
Hiromasa Miyasaka
Kaya Mori
Matteo Perri
Michael J. Pivovaroff
Simonetta Puccetti
Vikram Rana
Daniel Stern
Niels J. Westergaard
Daniel R. Wik
William W. Zhang
Andreas Zoglauer
Abstract
The distribution of elements produced in the innermost layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially resolved spectroscopic analyses of the 44Ti ejecta, which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We find an initial 44Ti mass of (1.54 ± 0.21) × 10−4 M⊙, which has a present-day average momentum direction of 340° ± 15° projected onto the plane of the sky (measured clockwise from celestial north) and is tilted by 58° ± 20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to it. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti by at least a factor of two in some regions, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.
Citation
Grefenstette, B. W., Fryer, C. L., Harrison, F. A., Boggs, S. E., DeLaney, T., Laming, J. M., …Zoglauer, A. (2017). The distribution of radioactive 44Ti in Cassiopeia A. Astrophysical Journal, 834(1), Article 19. https://doi.org/10.3847/1538-4357/834/1/19
Journal Article Type | Article |
---|---|
Acceptance Date | Oct 29, 2016 |
Online Publication Date | Dec 27, 2016 |
Publication Date | Jan 1, 2017 |
Deposit Date | Jun 21, 2017 |
Publicly Available Date | Jul 3, 2017 |
Journal | Astrophysical Journal |
Print ISSN | 0004-637X |
Electronic ISSN | 1538-4357 |
Publisher | American Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 834 |
Issue | 1 |
Article Number | 19 |
DOI | https://doi.org/10.3847/1538-4357/834/1/19 |
Public URL | https://durham-repository.worktribe.com/output/1376336 |
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Copyright Statement
© 2016. The American Astronomical Society. All rights reserved.
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