Constraints on the kinematics of the 44Ti ejecta of Cassiopeia A from INTEGRAL-SPI - Astrophysics > High Energy Astrophysical PhenomenaReport as inadecuate




Constraints on the kinematics of the 44Ti ejecta of Cassiopeia A from INTEGRAL-SPI - Astrophysics > High Energy Astrophysical Phenomena - Download this document for free, or read online. Document in PDF available to download.

Abstract: The medium-lived 44Ti isotope is synthesised by explosive Si-burning incore-collapse supernovae. It is extremely sensitive to the dynamics of theexplosion and therefore can be used to indirectly probe the explosion scenario.The young supernova remnant Cassiopeia A is to date the only source ofgamma-ray lines from 44Ti decay. The emission flux has been measured byCGRO-COMPTEL, BeppoSAX-PDS and INTEGRAL-IBIS. The high-resolution spectrometerSPI on-board the INTEGRAL satellite can provide spectrometric information aboutthe emission. The line profiles reflect the kinematics of the 44Ti inCassiopeia A and can thus place constraints on its nucleosynthesis andpotentially on the associated explosion process. Using 4 years of data fromINTEGRAL-SPI, we have searched for the gamma-ray signatures from the decay ofthe 44Ti isotope. The overwhelming instrumental background noise required anaccurate modelling and a solid assessment of the systematic errors in theanalysis. Due to the strong variability of the instrumental background noise,it has not been possible to extract the two lines at 67.9 and 78.4keV.Regarding the high-energy line at 1157.0keV, no significant signal is seen inthe 1140-1170keV band, thereby suggesting that the line signal from CassiopeiaA is broadened by the Doppler effect. From our spectrum, we derive a ~ 500km-slower limit at 2sigma on the expansion velocity of the 44Ti ejecta. Our resultdoes not allow us to constrain the location of 44Ti since the velocitiesinvolved throughout the remnant, derived from optical and X-ray studies, areall far above our lower limit.



Author: Pierrick Martin, Jürgen Knödlseder, Jacco Vink, Anne Decourchelle, Matthieu Renaud

Source: https://arxiv.org/







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