Half-life of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>44</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Ti</mml:mi></mml:math>

Norman, E. B.; Browne, E.; Chan, Y. D.; Goldman, I. D.; Larimer, R. M.; Lesko, K. T.; Nelson, Morton; Wietfeldt, F. E.; Ẑlimen, I.

doi:10.1103/physrevc.57.2010

Cited by 36 publications

(23 citation statements)

References 20 publications

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“…This would imply an efficiency (number of photons per decay) error of 50% and is excluded by several measurements (Norman et al 1998;Wietfeldt et al 1999;Ahmad et al 2006). …”

Section: Flux Consistency Checkmentioning

confidence: 99%

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Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Siegert

Diehl

Krause

et al. 2015

A&A

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Context. The 340-yr old supernova remnant Cassiopeia A, located at 3.4 kpc distance, is the best-studied young core-collapse supernova remnant. Nucleosynthesis yields in radioactive isotopes have been studied with different methods, in particular for production and ejection of 44 Ti and 56 Ni, which originate in the innermost regions of the supernova. 44 Ti was first discovered in this remnant, but is not seen consistently in other core-collapse sources. Aims. We aim to measure radioactive 44 Ti ejected in Cassiopeia A and to place constraints on velocities of these ejecta by determining X-and γ-ray line-shape parameters of the emission lines. Methods. We analyzed the observations made with the SPI spectrometer on INTEGRAL together with an improved instrumental background method, to achieve a high spectroscopic resolution that enables interpretation for a velocity constraint on 44 Ti ejecta from the 1.157 MeV γ-ray line of the 44 Sc decay. Results. We observe both the hard X-ray line at 78 keV and the γ-ray line at 1157 keV from the 44 Ti decay chain at a combined significance of 3.8σ. Measured fluxes are (2.1 ± 0.4) × 10 −5 ph cm −2 s −1 and (3.5 ± 1.2) × 10 −5 ph cm −2 s −1 , which corresponds to (1.5 ± 0.4) × 10 −4 and (2.4 ± 0.9) × 10 −4 M of 44 Ti, respectively. The measured Doppler broadening of the lines implies expansion velocities of 4300 and 2200 km s −1 , respectively. By combining our results with previous studies, we determine a more precise estimate of ejected 44 Ti of (1.37 ± 0.19) × 10 −4 M . Conclusions. The measurements of the two lines are consistent with previous studies. The flux in the line originating from excited 44 Ca is significantly higher than the flux determined in the lines from 44 Sc. Cosmic-ray acceleration within the supernova remnant may be responsible for an additional contribution to this line from nuclear de-excitation following energetic particle collisions in the remnant and swept-up material.

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“…This would imply an efficiency (number of photons per decay) error of 50% and is excluded by several measurements (Norman et al 1998;Wietfeldt et al 1999;Ahmad et al 2006). …”

Section: Flux Consistency Checkmentioning

confidence: 99%

“…44 Ti has a considerably longer decay lifetime, and thus gamma-rays will escape readily. 44 Ti decays to 44 Sc within τ 86 yr (Ahmad et al 1998(Ahmad et al , 2006Görres et al 1998;Norman et al 1998;Wietfeldt et al 1999;Hashimoto et al 2001). In this first decay stage, gamma-rays of 67.87 and 78.36 keV are emitted.…”

Section: Introductionmentioning

confidence: 99%

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Siegert

Diehl

Krause

et al. 2015

A&A

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“…In L99 an e-folding time of 78 years was used for 44 Ti, as this was thought to represent a mean value from experiments. More accurate measurements of the decay time (Ahmad et al 1998;Görres et al 1998;Norman et al 1998) became available while the analysis of L99 was completed, and the results of L99 were corrected accordingly before publishing. Here, we use the more accurate e-folding time (87.0 ± 1.9 years) from the outset.…”

Section: The Model For Line Emission From the Supernovamentioning

confidence: 99%

“…44 Ti decays first to 44 Sc, on a time scale of 87.0 ± 1.9 years (Ahmad et al 1998;Görres et al 1998; see also Norman et al 1998 who obtain 86 ± 3 years), and then quickly further to 44 Ca.…”

Section: Introductionmentioning

confidence: 99%

ISO/SWS observations of SN 1987A

Lundqvist

Kozma

Sollerman

et al. 2001

A&A

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Ti. Assessing various uncertainties of the model, and checking the late optical emission it predicts, we obtain an upper limit of 1.1 × 10 −4 M . This is lower than in our previous estimate using other ISO data, and we compare our new result with other models for the late emission, as well as with expected yields from explosion models. We also show that steady-state models for the optical emission are likely to overestimate the mass of ejected 44 Ti. The low limit we find for the mass of ejected 44 Ti could be higher if dust cooling is important. A direct check on this is provided by the gamma-ray emission at 1.157 Mev as a result of the radioactive decay of 44 Ti.

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“…44 Ti is produced by explosive Si burning and the freeze out from nuclear statistical equilibrium in supernovae, and it is believed to be the primary source of 44 Ca (Timmes et al 1996). 44 Ti decays with a 59:2 AE 0:6 yr half-life (Ahmad et al 1998;Gö rres et al 1998;Norman et al 1998) to 44 Sc, producing two nuclear lines at 67.9 and 78.4 keV of essentially equal intensity. The 44 Sc decays to the first excited state of 44 Ca, which then emits a gamma ray of 1157 keV with a 3.93 hr half-life to reach the ground state.…”

Section: Introductionmentioning

confidence: 99%

Limits to the Cassiopeia A⁴⁴Ti Line Flux and Constraints on the Ejecta Energy and the Compact Source

Rothschild

Lingenfelter

2003

ApJ

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Two long observations of the Cas A supernova remnant were made by the Rossi X-Ray Timing Explorer in 1996 and 1997 to search for hard X-ray line emission at 67.9 and 78.4 keV from the decay of 44 Ti formed during the supernova event. Continuum flux was detected up to 100 keV, but the 44 Ti lines were not detected. The 90% confidence upper limit to the line flux is 3:6 Â 10 À5 photons cm À2 s À1 . This is consistent with the recent BeppoSAX detection and with the Compton Gamma Ray Observatory/Imaging Compton Telescope (CGRO/COMPTEL) detection of the companion transition line flux for 44 Sc decay. The mean BeppoSAX-COMPTEL flux indicates that 1:5 AE 0:3 Â 10 À4 M of 44 Ti was produced in the supernova explosion. On the basis of recent theoretical calculations and optical observations suggesting a WN Wolf-Rayet progenitor with an initial mass of !25 M , the observed 44 Ti yield implies that the Cas A supernova ejecta energy was $2 Â 10 51 ergs, and as a result a neutron star was formed, rather than a black hole. We suggest that Cas A is possibly in the early stages of the anomalous X-ray pulsar/soft gamma-ray repeater (AXP/SGR) scenario in which the pushback disk has yet to form, and when the disk does form, the accretion will increase the luminosity to that of present-day AXP/SGRs, and pulsed emission will commence.

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Half-life of44Ti

Cited by 36 publications

References 20 publications

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

ISO/SWS observations of SN 1987A

Limits to the Cassiopeia A⁴⁴Ti Line Flux and Constraints on the Ejecta Energy and the Compact Source

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Half-life of44Ti

Cited by 36 publications

References 20 publications

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

ISO/SWS observations of SN 1987A

Limits to the Cassiopeia A44Ti Line Flux and Constraints on the Ejecta Energy and the Compact Source

Contact Info

Product

Resources

About

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Limits to the Cassiopeia A⁴⁴Ti Line Flux and Constraints on the Ejecta Energy and the Compact Source