The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to accurately observe ultra-high-energy cosmic rays (UHECRs) and cosmic neutrinos from space with sensitivity over the full ...celestial sky. POEMMA will observe the air fluorescence produced by extensive air showers (EASs) from UHECRs and potentially UHE neutrinos above 20 EeV. Additionally, POEMMA has the ability to observe the Cherenkov signal from upward-moving EASs induced by Earth-interacting tau neutrinos above 20 PeV. The POEMMA spacecraft are designed to quickly re-orientate to follow up transient neutrino sources and obtain currently unparalleled neutrino flux sensitivity. Developed as a NASA Astrophysics Probe-class mission, POEMMA consists of two identical satellites flying in loose formation in 525 km altitude orbits. Each POEMMA instrument incorporates a wide field-of-view (45°) Schmidt telescope with an optical collecting area of over 6 sq. m. The hybrid focal surface of each telescope includes a fast (1 μs) near-ultraviolet camera for EAS fluorescence observations and an ultrafast (10 ns) optical camera for Cherenkov EAS observations. In a 5-year mission, POEMMA will provide measurements that open new multi-messenger windows onto the most energetic events in the universe, enabling the study of new astrophysics and particle physics at these extreme energies.
We explore the effect of pulsars, in particular those born with millisecond periods, on their surrounding supernova ejectas. While they spin down, fast-spinning pulsars release their tremendous ...rotational energy in the form of a relativistic magnetized wind that can affect the dynamics and luminosity of the supernova. We estimate the thermal and non-thermal radiations expected from these specific objects, concentrating at times a few years after the onset of the explosion. We find that the bolometric light curves present a high luminosity plateau (that can reach 1043-1044 erg s−1) over a few years. An equally bright TeV gamma-ray emission, and a milder X-ray peak (of the order of 1040-1042 erg s−1) could also appear a few months to a few years after the explosion, as the pulsar wind nebula emerges, depending on the injection parameters. The observations of these signatures by following the emission of a large number of supernovae could have important implications for the understanding of core-collapse supernovae and reveal the nature of the remnant compact object.
We study the phenomenology of cosmic-rays (CRs) at the galactic/extragalactic transition, focusing on two opposite models for the composition of the extragalactic (EG) component. Model A assumes a ...mixed source composition, with nuclear abundances similar to that of the low-energy CRs, while model B assumes that EG sources accelerate only protons. We study the limits within which both scenarios can reproduce the observed high-energy CR spectrum and composition. The ankle in model A is interpreted as the GCR/EGCR transition, while in model B it is the pair-production dip. Model A has a source spectrum ∝
E
−
x
with
x
∼
2.2–2.3, while model B requires
x
∼
2.6–2.7. We compare the predictions of both models with the available data on the energy evolution of the high-energy CR composition using the two main composition-related observables:
X
max and 〈ln
A〉. We conclude that model A is currently favoured. Uncertainties are discussed and distinctive features of the two models are identified, which should allow one to distinguish between the models in the near future when more precise measurements are available with higher statistics experiments.
Abstract
Mini-EUSO is a telescope observing the Earth in the ultraviolet band from the International Space Station. It is a part of the JEM-EUSO program, paving the way to future larger missions, ...such as K-EUSO and POEMMA, devoted primarily to the observation of ultrahigh-energy cosmic rays from space. Mini-EUSO is capable of observing extensive air showers generated by ultrahigh-energy cosmic rays with an energy above 10
21
eV and to detect artificial showers generated with lasers from the ground. Other main scientific objectives of the mission are the search for nuclearites and strange quark matter, the study of atmospheric phenomena such as transient luminous events, meteors, and meteoroids, the observation of sea bioluminescence and of artificial satellites and man-made space debris. Mini-EUSO will map the nighttime Earth in the UV range (290–430 nm), with a spatial resolution of about 6.3 km and a temporal resolution of 2.5
μ
s, through a nadir-facing UV-transparent window in the Russian Zvezda module. The instrument, launched on 2019 August 22, from the Baikonur Cosmodrome, is based on an optical system employing two Fresnel lenses and a focal surface composed of 36 multianode photomultiplier tubes, 64 channels each, for a total of 2304 channels with single-photon counting sensitivity and an overall field of view of 44°. Mini-EUSO also contains two ancillary cameras to complement measurements in the near-infrared and visible ranges. In this paper, we describe the detector and present the various phenomena observed in the first months of operations.
EUSO-Balloon
is a pathfinder for
JEM-EUSO
, the mission concept of a spaceborne observatory which is designed to observe Ultra-High Energy Cosmic Ray (UHECR)-induced Extensive Air Showers (EAS) by ...detecting their UltraViolet (UV) light tracks “from above.” On August 25, 2014,
EUSO-Balloon
was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. After reaching a floating altitude of 38 km,
EUSO-Balloon
imaged the UV light in the wavelength range ∼290–500 nm for more than 5 hours using the key technologies of
JEM-EUSO
. The flight allowed a good understanding of the performance of the detector to be developed, giving insights into possible improvements to be applied to future missions. A detailed measurement of the photoelectron counts in different atmospheric and ground conditions was achieved. By means of the simulation of the instrument response and by assuming atmospheric models, the absolute intensity of diffuse light was estimated. The instrument detected hundreds of laser tracks with similar characteristics to EASs shot by a helicopter flying underneath. These are the first recorded laser tracks measured from a fluorescence detector looking down on the atmosphere. The reconstruction of the direction of the laser tracks was performed. In this work, a review of the main results obtained by
EUSO-Balloon
is presented as well as implications for future space-based observations of UHECRs.
We consider the stochastic propagation of high-energy protons and nuclei in the cosmological microwave and infrared backgrounds, using revised photonuclear cross-sections and following primary and ...secondary nuclei in the full 2D nuclear chart. We confirm earlier results showing that the high-energy data can be fit with a pure proton extragalactic cosmic ray (EGCR) component if the source spectrum is $\propto$ E-2.6. In this case the ankle in the CR spectrum may be interpreted as a pair-production dip associated with the propagation. We show that when heavier nuclei are included in the source with a composition similar to that of Galactic cosmic-rays (GCRs), the pair-production dip is not present unless the proton fraction is higher than 85%. In the mixed composition case, the ankle recovers the past interpretation as the transition from GCRs to EGCRs and the highest energy data can be explained by a harder source spectrum $\propto$ E-2.2–E-2.3, reminiscent of relativistic shock acceleration predictions, and in good agreement with the GCR data at low-energy and holistic scenarios.
The significant attenuation of the cosmic ray flux above ~5 × 10^19 eV suggests that the observed high energy spectrum is shaped by the so-called GZK effect (GZK: Greisen-Zatsepin-Kuzmin). This ...interaction of ultra-high energy cosmic rays (UHECRs) with the ambient radiation fields also affects their composition. We review the effect of photodissociation interactions on different nuclear species and analyze the phenomenology of secondary-proton production as a function of energy. We show that, by itself, the UHECR spectrum does not constrain the composition of cosmic rays at their extragalactic sources. While the propagated composition (i.e., as observed at Earth) cannot contain significant amounts of intermediate mass nuclei (say between He and Si), whatever the source composition, and while it is vastly proton dominated when protons are able to reach energies above 10^20 eV at the source, we show that the propagated composition can be dominated by Fe and sub-Fe nuclei at the highest energies, either if the sources are very strongly enriched in Fe nuclei (a rather improbable situation), or if the accelerated protons have a maximum energy of a few 10^19 eV at the sources. We also show that in the latter cases, the expected flux above 3 × 10^20 eV is very much reduced as compared to the case when protons dominate in this energy range, both at the sources and at Earth.
To identify dietary patterns among young adults and the relationships with socio-economic, demographic and lifestyle characteristics.
Population-based, cross-sectional analysis of a cohort study. ...Food intake was assessed by a frequency questionnaire, and dietary patterns were identified using principal components analysis.
Southern Brazil.
A total of 4202 men and women aged 23 years, who participated in the 1982 Pelotas Birth Cohort Study.
Five dietary patterns were identified: common Brazilian, processed food, vegetable/fruit, dairy/dessert and tubers/pasta. Subjects who had low own or maternal educational levels, low social position or who were always poor throughout life had high adherence to the common Brazilian dietary pattern. In contrast, the processed food pattern was more likely to be followed by those belonging to middle and high social position and who were never poor. Men and smokers showed high adherence to the processed food and common Brazilian dietary patterns. Vegetable/fruit pattern was more likely to be followed by women and subjects engaged in physical activity. Women also showed high adherence to the dairy/dessert pattern.
Our study among young Brazilian adults has identified distinct dietary patterns that are clearly influenced by socio-economic and lifestyle characteristics, which have important policy implications in a country with marked social and economic inequalities.
Context . Observations of meteors in the Earth’s atmosphere offer a unique tool for determining the flux of meteoroids that are too small to be detected by direct telescopic observations. Although ...these objects are routinely observed from ground-based facilities, such as meteor and fireball networks, space-based instruments come with notable advantages and have the potential to achieve a broad and uniform exposure. Aims . In this paper, we describe the first observations of meteor events with Mini-EUSO, a very wide field-of-view telescope launched in August 2019 from the Baikonur cosmodrome and installed on board the Russian Zvezda module of the International Space Station. Mini-EUSO can map the night-time Earth in the near-UV range (290-130 nm) with a field of view equal to 44° × 44° and a spatial resolution of about 4.7 km at an altitude of 100 km from the ground. The detector saves triggered transient phenomena with a sampling frequency of 2.5 µs and 320 µs, as well as a continuous acquisition at 40.96 ms scale that is suitable for meteor observations. Methods . We designed two dedicated and complementary trigger methods, together with an analysis pipeline able to estimate the main physical parameters of the observed population of meteors, such as the duration, horizontal speed, azimuth, and absolute magnitude. To compute the absolute flux of meteors from Mini-EUSO observations, we implemented a simulation framework able to estimate the detection efficiency as a function of the meteor magnitude and the background illumination conditions. Results . The instrument detected 24 thousand meteors within the first 40 data-taking sessions from November 2019 to August 2021, for a total observation time of approximately 6 days with a limiting absolute magnitude of +6. Our estimation of the absolute flux density of meteoroids in the range of mass between 10 −5 kg to 10 −1 kg was found to be comparable to other results available in the literature. Conclusions . The results of this work prove the potential for space-based observations to increase the statistics of meteor observations achievable with instruments operating on the ground. The slope of the mass distribution of meteoroids sampled with Mini-EUSO suggests a mass index of either s = 2.09 ± 0.02 or s = 2.31 ± 0.03, according to two different methodologies for the computation of the pre-atmospheric mass starting from the luminosity of each event.
We discuss the differences induced by the assumed composition of extragalactic sources on the predicted UHECR spectrum and the energy evolution of $\langle X_{\max} \rangle$, i.e. the mean value of ...the atmospheric depth at the cosmic-ray air shower maximum. We show that different assumptions for the source power evolution do not modify our earlier finding that in the case of a mixed composition the ankle can be interpreted as the end of the transition from galactic to extragalactic cosmic rays. We show the characteristic features in the shape of $\langle X_{\max} \rangle$(E) that are associated with this transition for each cosmic-ray composition model. These characteristic features are present whatever the hadronic model used for the calculation. In the mixed composition cases, a signature of the interactions of nuclei with the photon backgrounds is also expected above 1019 eV. The comparisons with Stereo HiRes and Fly's Eye data favour an extragalactic mixed composition and the corresponding interpretation of the ankle. Confrontation of model predictions with future data at the highest energies will allow a better determination of the transition features and of the cosmic-ray source composition, independently of hadronic models. We also emphasize that in the pure proton case, a combined analysis of the spectrum and composition below the ankle could lead to constraints on the source power evolution with redshift.
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