Cosmic Gamma-Ray Spectroscopy

Diehl, R.

doi:10.1080/21672857.2013.11519720

Cited by 7 publications

(9 citation statements)

References 73 publications

(125 reference statements)

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“…The sensitivity currently reached for a typical observing time of 10 6 s is about 10 −5 ph cm −1 s −1 , so that we were only able to measure the brightest of the expected variety of gamma-ray line sources. The achieved spatial resolution is of order 2-3 degrees only, while spectral resolution, however, is sufficient for astrophysical detail studies from line shapes and centroid shifts for several lines and sources of interest [22]. Examples for proposed next-generation instruments [23,24] have demonstrated that about one order of magnitude improvements or more would be feasible, affordability assessment by the scientific funding communities set aside.…”

Section: Measuring Cosmic Gamma-ray Linesmentioning

confidence: 99%

“…Diffuse nuclear-line and annihilation-line emission will be discussed thereafter, with respect to the underlying source populations. 44 Ti ccSN interior nucleosynthesis 0.078 radioactive decay: 44 Ti ccSN interior nucleosynthesis 0.122 radioactive decay: 57 Ni supernova nucleosynthesis 0.158 radioactive decay: 56 Ni supernova nucleosynthesis 0.478 radioactive decay: 7 Be nova nucleosynthesis 0.511 positron annihilation nucleosynthesis, compact stars, binaries 0.812 radioactive decay: 56 Ni supernova nucleosynthesis 0.847 radioactive decay: 56 Co supernova nucleosynthesis 1.157 radioactive decay: 44 Ti ccSN interior nucleosynthesis 1.173 radioactive decay: 60 Fe,Co ccSN ejected nucleosynthesis 1.238 radioactive decay: 56 Co supernova nucleosynthesis 1.275 radioactive decay: 22 Na nova nucleosynthesis 1.332 radioactive decay: 60 Fe,Co ccSN ejected nucleosynthesis 1.634 nuclear excitation: 20 Ne cosmic ray / ISM interactions 1.809 radioactive decay: 26 Al massive-star and ccSN nucleosynthesis 2.230 neutron capture by H energetic nucleon interactions 2.313 nuclear excitation: 14 N cosmic ray / ISM interactions 2.754 nuclear excitation: 24 Mg cosmic ray / ISM interactions 4.438 nuclear excitation: 12 C cosmic ray / ISM interactions 6.129 nuclear excitation: 16 O cosmic ray / ISM interactions…”

Section: -4mentioning

confidence: 99%

“…Here, the annihilation occurs in hot plasma clouds near the black hole, kinematic shift and broadening from the Doppler effect results in the bumb feature between 0.5 and 1 MeV, consistent with theoretical expectations(rightmost). 60 Fe was predicted to also be a product of massive star nucleosynthesis, from neutron capture on iron nuclei, in particular in the He and C shells of massive stars, where neutron release from the 13 C(α,n) and 22 Ne(α,n) reactions were expected [72]. This nuclear processing in the shells of massive stars occurs at an evolutionary phase, however, where no link to the mass loss at the surface exists.…”

Section: Al and 60 Fe From Cumulative Nucleosynthesismentioning

confidence: 99%

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About cosmic gamma ray lines

Diehl

2017

AIP Conference Proceedings

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Abstract. Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or highenergy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26 Al and 60 Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56 Ni and 44 Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

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Section: Measuring Cosmic Gamma-ray Linesmentioning

confidence: 99%

Section: -4mentioning

confidence: 99%

Section: Al and 60 Fe From Cumulative Nucleosynthesismentioning

confidence: 99%

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About cosmic gamma ray lines

Diehl

2017

AIP Conference Proceedings

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“…Therefore, even after two major observatory missions for imaging and spectroscopy [Diehl, 2013a;Gehrels et al, 1993;Schoenfelder et al, 1996;, currently achieved sensitivities allow to only see Galactic sources and exceptionally-bright supernovae from up to few Mpc distance, and spatial resolution is of order 2-3 degrees only. The spectral resolution, however, has been advanced to and beyond astrophysical needs and expectations, allowing line shape constraints in detail for the lines and sources of interest [Diehl, 2013b].…”

Section: Nuclear Astronomy In the Context Of Astrophysics Messengersmentioning

confidence: 99%

New insights from cosmic gamma rays

Diehl

2016

J. Phys.: Conf. Ser.

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Abstract. The measurement of gamma rays from cosmic sources at ∼MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from β-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and corecollapse supernova radioactivities have been measured though 56 Ni, 56 Co, and 44 Ti lines, and a beginning has thus been made to complement conventional supernova observations with such measurements of the prime energy sources of supernova light created in their deep interiors. The diffuse radioactive afterglow of massive-star nucleosynthesis in gamma rays is now being exploited towards astrophysical studies on how massive stars feed back their energy and ejecta into interstellar gas, as part of the cosmic cycle of matter through generations of stars enriching the interstellar gas and stars with metals. Large interstellar cavities and superbubbles have been recognised to be the dominating structures where new massive-star ejecta are injected, from 26 Al gamma-ray spectroscopy. Also, constraints on the complex interiors of stars derive from the ratio of 60 Fe/ 26 Al gamma rays. Finally, the puzzling bulge-dominated intensity distribution of positron annihilation gamma rays is measured in greater detail, but still not understood; a recent microquasar flare provided evidence that such objects may be prime sources for positrons in interstellar space, rather than distributed nucleosynthesis. We also briefly discuss the status and prospects for astronomy with telescopes for the nuclear-radiation energy window.

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“…Positron annihilation and nuclear de-excitation * sergi@lns.infn.it † Deceased following the decays of these radioactive isotopes lead to gamma-ray line fluxes. Their measurement would shed light into the physical processes occurring in the early phases of the explosion, although their detection is currently difficult to be performed due to the still present observational difficulties, as discussed in [4]. The short-lived 13 N and the synthesized 18 F isotopes are the main contributors of positrons in nova envelopes.…”

Section: Introduction a Astrophysical Backgroundmentioning

confidence: 99%