$\mathsf{^{26}}$Al in the inner Galaxy

Diehl, R.; Halloin, Hubert; Kretschmer, Karsten; Strong, A. W.; Wang, W.; Jean, P.; Lichti, G.; Knoedlseder, J.; Roques, J. P.; Schanne, S.; Schöenfelder, V.; Kienlin, A. von; Weidenspointner, G.; Winkler, Christoph; Wunderer, C.

doi:10.1051/0004-6361:20054301

Cited by 55 publications

(79 citation statements)

References 26 publications

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“…The 26 Al gamma-ray flux from the inner Galaxy turns out as (2.93 ± 0.15) × 10 −4 ph cm −2 s −1 rad −1 . This is consistent with our earlier values (3.3 ± 0.4) × 10 −4 ph cm −2 s −1 rad −1 (Diehl et al 2006a(Diehl et al , 2006b, and also with the COMPTEL imaging-analysis value of (2.8 ± 0.4) × 10 −4 ph cm −2 s −1 rad −1 (Plüschke et al 2001). The above value is derived using an asymmetric line shape as best matching our expectations from SPI's spectral response and eventual additional celestial line broadening.…”

Section: Diffuse 26 Al Emission Of the Inner Galaxysupporting

confidence: 93%

“…Earlier INTEGRAL analysis had used 1.5 years of SPI data to first explore the large-scale spectral characteristics of 26 Al emission in the inner Galaxy (Diehl et al 2006a(Diehl et al , 2006b. A detection of the 26 Al line from the inner Galaxy with a significance of ∼ 16σ hadconfirmedthe narrowness of the 26 Al line (FWHM < 2.8 keV, 2σ), which had already been seen by RHESSI (Smith et al 2003) and HEAO-C (Mahoney et al 1984) earlier.…”

Section: Diffuse 26 Al Emission Of the Inner Galaxymentioning

confidence: 93%

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Diffuse emission of 26Al and 60Fe in the Galaxy

Wang¹

2012

Astrophysics

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Cosmic gamma-ray line signals are very weak, and the gamma-ray photons are absorbed by the atmosphere. The detection of Galactic radioactivity must be based on the gamma-ray detectors aboard balloons and spacecrafts. The first gamma-ray line observations were from OSO-3, OSO-7 in 1960's, which revealed the strong 2.223 MeV line from solar flares (Brandt, 1969). This line results from the formation of deuterium via the union of a neutron and proton; in a solar flare the neutrons appear as secondaries from interactions of high-energy

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Section: Diffuse 26 Al Emission Of the Inner Galaxysupporting

confidence: 93%

Section: Diffuse 26 Al Emission Of the Inner Galaxymentioning

confidence: 93%

Diffuse emission of 26Al and 60Fe in the Galaxy

Wang¹

2012

Astrophysics

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“…We cut out from it a region which lies above the plane of the Galaxy and towards the ScoCen sources here, defined as a circle centered at (l, b) = (350 • , 20 • ) with a radius of 8 • . 26 Al is ejected at velocities of ∼1000-1500 km s −1 and slows down in interstellar medium from interactions with the gas; in our large-scale Galactic average, but also in the Cygnus region, we find velocities are certainly below 200 km s −1 from Doppler broadening limits on the observed line width (Diehl et al 2006b;Martin et al 2009). The size of our region of choice corresponds to 26 Al coasting with interstellar velocities of 10 km s −1 , hence will not include faster 26 Al and miss part of the production in this region.…”

Section: Spi Observations and Data Analysismentioning

confidence: 50%

“…We plausibly employ several alternatives: the 26 Al sky A&A 522, A51 (2010) as observed with COMPTEL and determined with MaximumEntropy or Multi-Resolution Expectation Maximization algorithms for imaging deconvolution (Knödlseder et al 1999b), but also geometrical models which had been found to adequately represent 26 Al emission, from COMPTEL and SPI analysis (e.g. Knödlseder et al 1999a;Diehl et al 2006b). Examples of the latter are double-exponential disks with Galactocentric scale radius 3.5 to 4 kpc and scale heights 130 to 300 pc, the free-electron model derived from pulsar dispersion measurements by Taylor & Cordes (1993) (we use the NE2001 model, Cordes & Lazio (2002), with an imprinted vertical scale height of the exponential distribution above the plane of 180 or 140 pc), or the FIR emission from warm dust as measured with COBE/DIRBE across the sky (Bennett et al 1992).…”

Section: Spi Observations and Data Analysismentioning

confidence: 99%

Radioactive²⁶Al from the Scorpius-Centaurus association

Diehl

Lang

Martin

et al. 2010

A&A

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129

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Context. The Scorpius-Centaurus association is the most-nearby group of massive and young stars. As nuclear-fusion products are ejected by massive stars and supernovae into the surrounding interstellar medium, the search for characteristic γ-rays from radioactivity is one way to probe the history of activity of such nearby massive stars on a My time scale through their nucleosynthesis. 26 Al decays with a radioactivity lifetime τ ∼1 My, 1809 keV γ-rays from its decay can be measured with current γ-ray telescopes. Aims. We aim to identify nucleosynthesis ejecta from the youngest subgroup of Sco-Cen stars, and interpret their location and bulk motion from 26 Al observations with INTEGRAL's γ-ray spectrometer SPI. Methods. Following earlier 26 Al γ-ray mapping with NASA's Compton observatory, we test spatial emission skymaps of 26 Al for a component which could be attributed to ejecta from massive stars in the Scorpius-Centaurus group of stars. Such a model fit of spatial distributions for large-scale and local components is able to discriminate 26 Al emission associated with Scorpius-Centaurus, in spite of the strong underlying nucleosynthesis signal from the Galaxy at large. Results. We find an 26 Al γ-ray signal above 5σ significance, which we associate with the locations of stars of the Sco-Cen group. The observed flux of 6 × 10 −5 ph cm −2 s −1 corresponds to ∼1.1 × 10 −4 M of 26 Al. This traces the nucleosynthesis ejecta of several massive stars within the past several million years. Conclusions. We confirm through direct detection of radioactive 26 Al the recent ejection of massive-star nucleosynthesis products from the Sco-Cen association. Its youngest subgroup in Upper Scorpius appears to dominate 26 Al contributions from this association. Our 26 Al signal can be interpreted as a measure of the age and richness of this youngest subgroup. We also estimate a kinematic imprint of these nearby massive-star ejecta from the bulk motion of 26 Al and compare this to other indications of Scorpius-Centaurus massive-star activity.

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“…The 26 Al image derived with COMPTEL [50], and a spectrum from the inner Galaxy as measured with INTE-GRAL/SPI [51]. This line reflects current nucleosynthesis in the Galaxy over the past Myrs.…”

Section: Roland Diehlmentioning

confidence: 99%

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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$\mathsf{^{26}}$Al in the inner Galaxy

Cited by 55 publications

References 26 publications

Diffuse emission of 26Al and 60Fe in the Galaxy

Diffuse emission of 26Al and 60Fe in the Galaxy

Radioactive²⁶Al from the Scorpius-Centaurus association

About cosmic gamma ray lines

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$\mathsf{^{26}}$Al in the inner Galaxy

Cited by 55 publications

References 26 publications

Diffuse emission of 26Al and 60Fe in the Galaxy

Diffuse emission of 26Al and 60Fe in the Galaxy

Radioactive26Al from the Scorpius-Centaurus association

About cosmic gamma ray lines

Contact Info

Product

Resources

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Radioactive²⁶Al from the Scorpius-Centaurus association