Long-term measurement of the 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>

Wietfeldt, F. E.; Schima, F.J.; Coursey, Bert M.; Hoppes, D.D.

doi:10.1103/physrevc.59.528

Cited by 23 publications

(14 citation statements)

References 16 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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“…Because of the short lifetime of ∼80 years (e.g. Wietfeldt et al 1999), the mere detection of hard Xray and γ-ray de-excitation lines at 69.7, 78.4, and 1157 keV from the 44 Ti radioactive decay products can be used to constrain significantly the SNR age. So far, however, these lines have only been detected unambiguously from Cassiopeia A (age presumably ∼330 years), with COMPTEL onboard CGRO (Iyudin et al 1994), PDS onboard BeppoSAX (Vink et al 2001), and the ISGRI imager onboard INTEGRAL (Renaud et al 2006c).…”

Section: Radio Spectrummentioning

confidence: 99%

Theory of cosmic ray and γ-ray production in the supernova remnant RX J0852.0-4622

Berezhko¹,

Puhlhoefer²,

Völk³

2009

A&A

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Aims. The properties of the Galactic supernova remnant (SNR) RX J0852.0-4622 are theoretically analysed.Methods. An explicitly time-dependent, nonlinear kinetic model of cosmic ray (CR) acceleration in SNRs is used to describe the properties of SNR RX J0852.0-4622, the accelerated CRs, and the nonthermal emission. The source is assumed to be at a distance of ≈1 kpc in the wind bubble of a massive progenitor star. An estimate of the thermal X-ray flux in this configuration is given. Results. We find that the overall synchrotron spectrum of RX J0852.0-4622 as well as the filamentary structures in hard X-rays lead to an amplified magnetic field B > 100 μG in the SNR interior. This implies that the leptonic very high energy (VHE) γ-ray emission is suppressed, and that the VHE γ-rays are hadronically dominated. The energy spectrum of protons produced over the lifetime of the remnant until now may well reach "knee" energies. The derived γ-ray morphology is consistent with the HESS measurements. The amount of energy in energetic particles corresponds to about 35% of the hydrodynamic explosion energy. A remaining uncertainty concerns the thermal X-ray flux at 1 keV. A rough estimate, which is possibly not quite appropriate for the assumed wind bubble configuration, is found to be higher than the nonthermal flux at this energy. Conclusions. It is concluded that this SNR expanding into the wind bubble of a massive star in a dense gas environment can be a hadronic γ-ray source that is consistent with all existing multiwavelength constraints, except possibly the thermal X-ray emission.

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“…It is expected that in the near future much scientific activity will be centered around 44 Ti. With the recent precise measurements of the 44 Ti half-life (59.0 6 0.6 yr [5], 60.3 6 1.3 yr [6], 62 6 2 yr [7], and 60.7 6 1.2 yr [8]) and with the launch of the next-generation space-based gamma-ray observatory INTEGRAL [9] (scheduled for 2001), new supernova remnants are likely to be discovered and the total mass of 44 Ti ejected in the supernova events will be determined.…”

mentioning

confidence: 99%

The44Ti(α,p)Reaction and its Implication on the
Sonzogni
¹
,
Rehm²,
Ahmad³
et al. 2000
Phys. Rev. Lett.
47
2
45
1
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Long-term measurement of the half-life of44Ti

Cited by 23 publications

References 16 publications

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Theory of cosmic ray and γ-ray production in the supernova remnant RX J0852.0-4622

The44Ti(α,p)Reaction and its Implication on the
Sonzogni
¹
,
Rehm²,
Ahmad³
et al. 2000
Phys. Rev. Lett.
47
2
45
1
View full text Add to dashboard Cite

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Long-term measurement of the half-life of44Ti

Cited by 23 publications

References 16 publications

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

Theory of cosmic ray and γ-ray production in the supernova remnant RX J0852.0-4622

The44Ti(α,p)Reaction and its Implication on theSonzogni1, Rehm2, Ahmad3 et al. 2000Phys. Rev. Lett.472451View full textAdd to dashboardCite

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Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

The44Ti(α,p)Reaction and its Implication on the
Sonzogni
¹
,
Rehm²,
Ahmad³
et al. 2000
Phys. Rev. Lett.
47
2
45
1
View full text Add to dashboard Cite