The distribution of radioactive ${}^{44}$Ti in Cassiopeia A

Abstract

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 \textit{NuSTAR} observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses of the ${}^{44}$Ti ejecta which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the ${}^{44}$Ti ejecta. We find an initial ${}^{44}$Ti mass of 1.54 $\pm$ 0.21 $\times 10^{-4}$ M${}_{\odot }$ which has a present day average momentum direction of 340${}^{\circ }$ $\pm$ 15${}^{\circ }$ projected on to the plane of the sky (measured clockwise from Celestial North) and tilted by 58${}^{\circ }$ $\pm$ 20${}^{\circ }$ 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 ${}^{44}$Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to the reverse shock. Where we observe ${}^{44}$Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe ${}^{44}$Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of ${}^{44}$Ti in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like $\alpha$-rich freezeout that should produce both iron and titanium.

14 pages, 13 figures (6 3D animations in the online journal). Accepted for publication in ApJ

References in corpus (10)

• Mayavi: a package for 3D visualization of scientific data
• The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant
• Asymmetries in core-collapse supernovae from maps of radioactive ${}^{44}$Ti in CassiopeiaA
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• Hard X-ray emission lines from the decay of Ti-44 in the remnant of supernova 1987A
• The signature of 44Ti in Cassiopeia A revealed by IBIS/ISGRI on INTEGRAL
• The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
• A dedicated Chandra ACIS observation of the central compact object in the Cassiopeia A supernova remnant
• The Density and Mass of Unshocked Ejecta in Cassiopeia A through Low Frequency Radio Absorption
• Locating the most energetic electrons in Cassiopeia A

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