The isotopic composition of cosmic-ray beryllium and its implication for the cosmic ray's age

Lukasiak, A.; Ferrando, P.; McDonald, F. B.; Webber, W. R.

doi:10.1086/173818

Cited by 79 publications

(60 citation statements)

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“…If measurements derived from this value of α are omitted, and the average SNR lifetime of τ snr ≈ 10 4 years is taken, this results in a residency time of 4.4 − 16.0 million years. Although there is a large spread of possible values, this is in line with the residency time of CRs within the Galaxy of 15 ± 1.6 Myr (Lukasiak et al 1994), and with the value found by the same method for M 33 of 7.5−10.1 Myr (Gordon et al 1998). Consequently, these results are in agreement with the hypothesis that SNRs are a predominate source for CR acceleration in the LMC.…”

Section: Radio Surface Brightness Evolutionsupporting

confidence: 89%

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Bozzetto

Filipović

Vukotić

et al. 2017

ApJS

116

158

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We construct the most complete sample of supernova remnants (SNRs) in any galaxy -the Large Magellanic Cloud (LMC) SNR sample. We study their various properties such as spectral index (α), size and surface-brightness. We suggest an association between the spatial distribution, environment density of LMC SNRs and their tendency to be located around supergiant shells. We find evidence that the 16 known type Ia LMC SNRs are expanding in a lower density environment compared to the Core-Collapse (CC) type. The mean diameter of our entire population (74) is 41 pc, which is comparable to nearby galaxies. We didn't find any correlation between the type of SN explosion, ovality or age. The N (< D) relationship of a = 0.96 implies that the randomised diameters are readily mimicking such an exponent. The rate of SNe occurring in the LMC is estimated to be ∼1 per 200 yr. The mean α of the entire LMC SNR population is α=-0.52, which is typical of most SNRs. However, our estimates show a clear flattening of the synchrotron α as the remnants age. As predicted, our CC SNRs sample are significantly brighter radio emitters than the type Ia remnants. We also estimate the Σ − D relation for the LMC to have a slope ∼3.8 which is comparable with other nearby galaxies. We also find the residency time of electrons in the galaxy

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Section: Radio Surface Brightness Evolutionsupporting

confidence: 89%

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Bozzetto

Filipović

Vukotić

et al. 2017

ApJS

116

158

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“…As deduced from earlier measurements [15,16], the Ne results indicate that GCRs are not just an accelerated sample of FIGURE 6. The measured 22 Ne/ 20 Ne ratio in various samples of matter, including lunar and meteoritic Ne-A [26] and Ne-B [30], solar wind [27] and SEPs [31], the GCR source [24,25], and ACRs from Voyager [16], SAMPEX [34], and ACE/SIS (this work). Unlike the lunar and meteoritic values, which are averaged over many samples, the 22 Ne/ 20 Ne ratio in 11 individual SEP events is displayed.…”

Section: Resultsmentioning

confidence: 99%

“…Curves (a) through (c) in Figure 4 show the expected 22 Ne spectrum, if the ACR 22 Ne/ 20 Ne ratio is the same as that in (a) the GCR source, (b) the meteoritic component Neon-A, or (c) the solar wind. The observed ACR 22 Ne intensity is clearly well below that of the GCR source, where the 22 Ne/ 20 Ne ratio is calculated to be between 0.322 [24] and 0.448 [25], depending on the GCR transport model and fragmentation cross sections used in interpreting the measurements. The 22 Ne intensity also appears low compared to what it would be if the 22 Ne/ 20 Ne ACR ratio were similar to that of the meteoritic component Neon-A, with 22 Ne/ 20 Ne = 0.122 [26].…”

Section: Isotopic Analysismentioning

confidence: 99%

Anomalous cosmic ray composition from ACE

Leske¹

2000

AIP Conference Proceedings

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Abstract. During solar quiet periods, the Solar Isotope Spectrometer (SIS) on the Advanced Composition Explorer (ACE) measures the composition and energy spectra of anomalous cosmic rays (ACRs) with energies > 8 MeV/nucleon in interplanetary space at 1 AU. In particular, the spectra of individual isotopes for the ACR elements N, 0, and Ne are studied with SIS. Intensity enhancements are found in low energy 18 O and 22 Ne, with relative abundances of 18 O/ 16 O ~ 0.002 and 22 Ne/ 20 Ne ~ 0.1. The neon abundance ratio appears more similar to that found in the solar wind than in meteorites and is far below that determined for the galactic cosmic ray (GCR) source, indicating that GCRs contain material from sources other than just the local interstellar medium.

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“…The result (e.g., Simpson & Garcia-Munoz 1988;Lukasiak et al 1994;Connell 1998) is thatρ 0.3ρg, i.e., cosmic rays encounter a mean density about 1/3 of that of the interstellar medium in the disk (ng 1 cm −3 ). This is usually interpreted to mean that the cosmic rays spend a significant part of their lives outside of the disk and in the halo, where the gas density is much lower.…”

Section: Cosmic Ray Data and Energy Requirementsmentioning

confidence: 99%

Standard cosmic ray energetics and light element production

Fields

Olive

Cassé

et al. 2001

A&A

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Abstract. The recent observations of an approximately linear relationship between both Be and B and iron in metal-poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. In addition to standard secondary production of BeB, it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary), and in which freshly synthesized C, O and He are accelerated by supernova shock waves. Primary mechanisms are expected to be dominant at low metallicity. At metallicities higher than [O/H] > ∼ −1.75, some existing data indicate that secondary production is dominant. In this paper, we focus on the secondary process, related to the standard Galactic cosmic rays, and we examine the cosmic ray energy requirements for both present and past epochs. We find the power input to maintain the present-day Galactic cosmic ray flux is about 1.5 10 41 erg/s = 5 10 50 erg/century; this estimate includes energy losses from both the escape of high-energy particle and ionization losses from low-energy particles. This implies that, if supernovae are the sites of cosmic ray acceleration, the fraction of explosion energy going to accelerated particles is about ∼30%, a value which we obtain consistently both from considering the present cosmic ray flux and confinement and from the present 9 Be and 6 Li abundances. Using the abundances of 9 Be (and 6 Li) in metal-poor halo stars, we extend the analysis to show the effect of the interstellar gas mass on the standard Galactic cosmic ray energetic constraints on models of Li, Be, and B evolution. The efficiency of the beryllium production per erg may be enhanced in the past by a factor of about 10; thus the energetic requirement by itself cannot be used to rule out a secondary origin of light elements. Only a clear and indisputable observational determination of the O-Fe relation in the halo will discriminate between the two processes.

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The isotopic composition of cosmic-ray beryllium and its implication for the cosmic ray's age

Cited by 79 publications

References 0 publications

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Anomalous cosmic ray composition from ACE

Standard cosmic ray energetics and light element production

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