A Caltech Library Service

Asymmetries in core-collapse supernovae from maps of radioactive ^(44)Ti in Cassiopeia A

Grefenstette, B. W. and Harrison, F. A. and Madsen, K. K. and Forster, K. and Mao, P. H. and Miyasaka, H. and Rana, V. (2014) Asymmetries in core-collapse supernovae from maps of radioactive ^(44)Ti in Cassiopeia A. Nature, 506 (7488). pp. 339-342. ISSN 0028-0836. doi:10.1038/nature12997.

PDF - Submitted Version
See Usage Policy.

[img] Image (JPEG) (Extended Data Figure 1: The background-subtracted image of Cas A in the 65–70-keV band containing the 68-keV ^(44)Ti line showing the significance of the ^(44)Ti knots.) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Figure 2: The radial profile of the ^(44)Ti emission) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Figure 3: Simulated ^(44)Ti intensity contours for a symmetric explosion and a bipolar explosion) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Figure 4: The background spectral model fit for one of the Cas A epochs) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Figure 5: The significant signals observed in the spectrum near 68 and 78 keV) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Table 1: List of observations used in this analysis) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Table 2: Best-fit continuum parameters) - Supplemental Material
See Usage Policy.

[img] Image (JPEG) (Extended Data Table 3: Results from spectral analysis) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive ^(44)Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing core and that ejected into the surrounding medium, directly probes the explosion asymmetries. Cassiopeia A is a young, nearby, core-collapse remnant from which ^(44)Ti emission has previously been detected but not imaged. Asymmetries in the explosion have been indirectly inferred from a high ratio of observed ^(44)Ti emission to estimated ^(56)Ni emission, from optical light echoes, and from jet-like features seen in the X-ray and optical ejecta. Here we report spatial maps and spectral properties of the ^(44)Ti in Cassiopeia A. This may explain the unexpected lack of correlation between the ^(44)Ti and iron X-ray emission, the latter being visible only in shock-heated material. The observed spatial distribution rules out symmetric explosions even with a high level of convective mixing, as well as highly asymmetric bipolar explosions resulting from a fast-rotating progenitor. Instead, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ReadCube access
Grefenstette, B. W.0000-0002-1984-2932
Harrison, F. A.0000-0003-2992-8024
Madsen, K. K.0000-0003-1252-4891
Forster, K.0000-0001-5800-5531
Miyasaka, H.0000-0002-8074-4186
Rana, V.0000-0003-1703-8796
Alternate Title:Asymmetries in Core-Collapse Supernovae from Maps of Radioactive 44Ti in Cassiopeia A
Additional Information:© 2014 Macmillan Publishers Limited. Received 27 August 2013. Accepted 13 December 2013. Published online 19 February 2014. This work was supported by NASA under grant no. NNG08FD60C, and made use of data from the Nuclear Spectroscopic Telescope Array (NuSTAR) mission, a project led by Caltech, managed by the Jet Propulsion Laboratory and funded by NASA. We thank the NuSTAR operations, software and calibration teams for support with execution and analysis of these observations.
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Subject Keywords:High-energy astrophysics; Particle astrophysics
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2014-02
Issue or Number:7488
Record Number:CaltechAUTHORS:20140326-135228627
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44534
Deposited By: Ruth Sustaita
Deposited On:28 Mar 2014 15:45
Last Modified:10 Nov 2021 16:53

Repository Staff Only: item control page