Nuclear de-excitation line spectrum of Cassiopeia A

Elsässer, Dominik; Mannheim, K.

doi:10.1051/0004-6361/201117267

Cited by 18 publications

(13 citation statements)

References 41 publications

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“…More analysis, in particular of other candidate nuclear de-excitation lines, is required to support this hypothesis. The most promising approach would be the detection of the de-excitation lines at 4.4 MeV and 6.1 MeV, which are the most prominent de-excitation lines caused by cosmic ray interaction in the shock front (Summa et al 2011). A first search for these lines shows that flux values as high as those suggested by Summa et al (2011) can be excluded.…”

Section: A83 Page 8 Of 15mentioning

confidence: 97%

⁴⁴Ti ejecta in young supernova remnants

Weinberger

Diehl

Pleintinger

et al. 2020

A&A

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Context. Tracing unstable isotopes produced in supernova nucleosynthesis provides a direct diagnostic of supernova explosion physics. Theoretical models predict an extensive variety of scenarios, which can be constrained through observations of the abundant isotopes 56Ni and 44Ti. Direct evidence of the latter was previously found only in two core-collapse supernova events, and appears to be absent in thermonuclear supernovae. Aims. We aim to to constrain the supernova progenitor types of Cassiopeia A, SN 1987A, Vela Jr., G1.9+0.3, SN1572, and SN1604 through their 44Ti ejecta masses and explosion kinematics. Methods. We analyzed INTEGRAL/SPI observations of the candidate sources utilizing an empirically motivated high-precision background model. We analyzed the three dominant spectroscopically resolved de-excitation lines at 68, 78, and 1157 keV emitted in the decay chain of 44Ti→44Sc→44Ca. The fluxes allow the determination of the production yields of 44Ti. Remnant kinematics were obtained from the Doppler characteristics of the lines. Results. We find a significant signal for Cassiopeia A in all three lines with a combined significance of 5.4σ. The fluxes are (3.3 ± 0.9) × 10−5 ph cm−2 s−1, and (4.2 ± 1.0) × 10−5 ph cm−2 s−1 for the 44Ti and 44Sc decay, respectively. This corresponds to a mass of (2.4 ± 0.7) × 10−4 M⊙ and (3.1 ± 0.8) × 10−4 M⊙, respectively. We obtain higher fluxes for 44Ti with our analysis of Cassiopeia A than were obtained in previous analyses. We discuss potential differences. We interpret the line width from Doppler broadening as expansion velocity of (6400 ± 1900) km s−1. We do not find any significant signal for any other candidate sources. Conclusions. We obtain a high 44Ti ejecta mass for Cassiopeia A that is in disagreement with ejecta yields from symmetric 2D models. Upper limits for the other core-collapse supernovae are in agreement with model predictions and previous studies. The upper limits we find for the three thermonuclear supernovae (G1.9+0.3, SN1572 and SN1604) consistently exclude the double detonation and pure helium deflagration models as progenitors.

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Section: A83 Page 8 Of 15mentioning

confidence: 97%

⁴⁴Ti ejecta in young supernova remnants

Weinberger

Diehl

Pleintinger

et al. 2020

A&A

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“…A nuclear line de-excitation spectrum including those C and O lines may be expected also from particle acceleration sites and sources, as energetic particles interact with ambient gas within or near the accelerating region. For a supernova remnant, a detailed prediction is found in [124], showing rather broad lines from C and O at 4.4 and 6.1 MeV. Estimated fluxes fall close to the sensitivity of COMPTEL; due to the large line width, these are well below INTEGRAL's capabilities.…”

Section: Low-energy Cosmic Ray Interactionsmentioning

confidence: 62%

Cosmic Gamma-Ray Spectroscopy

Diehl

2013

Astronomical Review

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Penetrating gamma-rays require complex instrumentation for astronomical spectroscopy measurements of gamma-rays from cosmic sources. Multiple-interaction detectors in space combined with sophisticated postprocessing of detector events on ground have lead to a spectroscopy performance which is now capable to provide new astrophysical insights. Spectral signatures in the MeV regime originate from transitions in the nuclei of atoms (rather than in their electron shell). Nuclear transitions are stimulated by either radioactive decays or high-energy nuclear collisions such as with cosmic rays. Gamma-ray lines have been detected from radioactive isotopes produced in nuclear burning inside stars and supernovae, and from energetic-particle interactions in solar flares. Radioactive-decay gamma-rays from 56 Ni directly reflect the source of supernova light. 44 Ti is produced in core-collapse supernova interiors, and the paucity of corresponding 44 Ti gamma-ray line sources reflects the variety of dynamical conditions herein. 26 Al and 60 Fe are dispersed in interstellar space from massive-star nucleosynthesis over millions of years. Gamma-rays from their decay are measured in detail by gamma-ray telescopes, astrophysical interpretations reach from massive-star interiors to dynamical processes in the interstellar medium. Nuclear de-excitation gamma-ray lines have been found in solar-flare events, and convey information about energetic-particle production in these events, and their interaction in the solar atmosphere. The annihilation of positrons leads to another type of cosmic gamma-ray source. The characteristic annihilation gamma-rays at 511 keV have been measured long ago in solar flares, and now throughout the interstellar medium of our Milky Way galaxy. But now a puzzle has appeared, as a surprising predominance of the central bulge region was determined. This requires either new positron sources or transport processes not yet known to us. In this paper we discuss instrumentation and data processing for cosmic gamma-ray spectroscopy, and the astrophysical issues and insights from these measurements.

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“…In all figures above, the composition of the ambient medium is fixed to the solar abundance. However, in certain astronomical locations, the composition might be different, in particular, it might be enhanced by heavy elements in metal-rich environments, such as the Galactic center (Benhabiles-Mezhoud et al 2013), or in the young SNR Cas A (Summa et al 2011). The higher abundance can dramatically en- hance the γ-ray line fluxes and makes these sources prime targets for observations with next-generation MeV γ-ray detectors.…”

Section: Resultsmentioning

confidence: 99%

Nuclear de-excitation lines as a probe of low-energy cosmic rays

Liu,

Yang,

Aharonian

2021

Preprint

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Low-energy cosmic rays (LECRs) contribute substantially to the energy balance of the interstellar medium. They play also significant role in the heating and chemistry of gas, and, consequently, on the star formation process. Because of the slow propagation coupled with enhanced energy losses of subrelativistic particles, LECRs are concentrated around their acceleration sites. LECRs effectively interact with the ambient gas through nuclear reactions. Although these processes are energetically less effective compared to heating and ionization, they are extremely important from the point of view of nuclear de-excitation lines, which carry unique information about LECRs. We present results on production of de-excitation lines combining the numerical treatment of nuclear reactions using the code TALYS, with the propagation and energy losses of LECRs.

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Nuclear de-excitation line spectrum of Cassiopeia A

Cited by 18 publications

References 41 publications

⁴⁴Ti ejecta in young supernova remnants

⁴⁴Ti ejecta in young supernova remnants

Cosmic Gamma-Ray Spectroscopy

Nuclear de-excitation lines as a probe of low-energy cosmic rays

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Nuclear de-excitation line spectrum of Cassiopeia A

Cited by 18 publications

References 41 publications

44Ti ejecta in young supernova remnants

44Ti ejecta in young supernova remnants

Cosmic Gamma-Ray Spectroscopy

Nuclear de-excitation lines as a probe of low-energy cosmic rays

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⁴⁴Ti ejecta in young supernova remnants

⁴⁴Ti ejecta in young supernova remnants