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Title: The Distribution of Radioactive 44Ti in Cassiopeia A

The distribution of elements produced in the inner-most 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 nd an initial 44Ti mass of 1.54±0.21x10 -4 M which has a present day average momentum direction of 340°±15° projected on to the plane of the sky (measured clockwise from Celestial North) and 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 the reverse shock. 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 tomore » suppress the production of 44Ti in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.« less
Authors:
 [1] ; ORCiD logo [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [1] ;  [11] ;  [12] ;  [9] ;  [13] ;  [14] ;  [15] ;  [1] ;  [1] more »;  [1] ;  [16] ;  [17] ;  [18] ;  [17] ;  [1] ;  [1] ;  [9] ;  [19] ;  [20] ;  [3] « less
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of California, Berkeley, CA (United States)
  4. West Virginia Wesleyan College, Buckhannon, WV (United States)
  5. Naval Research Lab. (NRL), Washington, DC (United States)
  6. North Carolina State Univ., Raleigh, NC (United States)
  7. Durham Univ. (United Kingdom)
  8. Univ. of Toulouse (France)
  9. Technical Univ. of Denmark, Lyngby (Denmark)
  10. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Berkeley, CA (United States)
  11. ASI Science Data Center (ASDC), Rome (Italy)
  12. Columbia Univ., New York, NY (United States). Columbia Astrophysics Lab.
  13. Hiroshima Univ. (Japan)
  14. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  15. The Ohio State Univ., Columbus, OH (United States)
  16. Columbia Univ., New York, NY (United States)
  17. ASI Science Data Center (ASDC), Rome (Italy); Istituto Nazionale di Astrofisica (INAF), Monteporizio (Italy)
  18. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  19. Johns Hopkins Univ., Baltimore, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  20. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
Publication Date:
Report Number(s):
LA-UR-16-26243
Journal ID: ISSN 1538-4357; TRN: US1701086
Grant/Contract Number:
AC52-06NA25396; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 834; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy and Astrophysics
OSTI Identifier:
1345938
Alternate Identifier(s):
OSTI ID: 1361151

Grefenstette, Brian W., Fryer, Christopher Lee, 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 H., Miyasaka, Hiromasa, Mori, Kaya, Perri, Matteo, Pivovaroff, Michael J., Puccetti, Simonetta, Rana, Vikram, Stern, Daniel, Westergaard, Niels J., Wik, Daniel R., Zhang, William W., and Zoglauer, Andreas. The Distribution of Radioactive 44Ti in Cassiopeia A. United States: N. p., Web. doi:10.3847/1538-4357/834/1/19.
Grefenstette, Brian W., Fryer, Christopher Lee, 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 H., 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. The Distribution of Radioactive 44Ti in Cassiopeia A. United States. doi:10.3847/1538-4357/834/1/19.
Grefenstette, Brian W., Fryer, Christopher Lee, 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 H., Miyasaka, Hiromasa, Mori, Kaya, Perri, Matteo, Pivovaroff, Michael J., Puccetti, Simonetta, Rana, Vikram, Stern, Daniel, Westergaard, Niels J., Wik, Daniel R., Zhang, William W., and Zoglauer, Andreas. 2016. "The Distribution of Radioactive 44Ti in Cassiopeia A". United States. doi:10.3847/1538-4357/834/1/19. https://www.osti.gov/servlets/purl/1345938.
@article{osti_1345938,
title = {The Distribution of Radioactive 44Ti in Cassiopeia A},
author = {Grefenstette, Brian W. and Fryer, Christopher Lee and Harrison, Fiona A. and Boggs, Steven E. and DeLaney, Tracey and Laming, J. Martin and Reynolds, Stephen P. and Alexander, David M. and Barret, Didier and Christensen, Finn E. and Craig, William W. and Forster, Karl and Giommi, Paolo and Hailey, Charles J. and Hornstrup, Alan and Kitaguchi, Takao and Koglin, J. E. and Lopez, Laura and Mao, Peter H. and Madsen, Kristin H. and Miyasaka, Hiromasa and Mori, Kaya and Perri, Matteo and Pivovaroff, Michael J. and Puccetti, Simonetta and Rana, Vikram and Stern, Daniel and Westergaard, Niels J. and Wik, Daniel R. and Zhang, William W. and Zoglauer, Andreas},
abstractNote = {The distribution of elements produced in the inner-most 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 nd an initial 44Ti mass of 1.54±0.21x10-4 M which has a present day average momentum direction of 340°±15° projected on to the plane of the sky (measured clockwise from Celestial North) and 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 the reverse shock. 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 in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.},
doi = {10.3847/1538-4357/834/1/19},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 834,
place = {United States},
year = {2016},
month = {12}
}