Cosmic events
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Cosmic Events: Insights from Recent Research
AD775 Cosmic Event: Solar Flare or Cosmic Ray?
The AD775 cosmic event, initially reported by Miyake et al. (2012), was thought to be an extreme cosmic event too strong to be caused by a solar flare under standard theories. This led to speculations about exotic sources such as a giant cometary impact or a gamma-ray burst. However, recent analyses using independent datasets, including 10 Be series and newly measured 14 C annual data, have revised the event's magnitude. The revised data suggest that the event was indeed a strong solar energetic particle event, consistent with increased auroral activity recorded in historical chronicles1.
Energetic Cosmic-Ray Events: Historical and Recent Observations
An energetic cosmic ray event recorded between September 1959 and May 1960 at the M.I.T. station near Albuquerque provided detailed data on the shower center, radius, axis direction, and composition. This event has been modeled to understand its characteristics better2. Additionally, the Antarctic Impulsive Transient Antenna (ANITA) has detected unusual upward-going cosmic-ray-like events, which may be produced by the atmospheric decay of upward-propagating τ leptons. These events challenge the standard model neutrino cross section and suggest the possibility of transient neutrino sources3 8.
Solar Cosmic Ray Phenomena: Classification and Models
Solar cosmic ray events are classified into two main categories: prompt and delayed events. Prompt events are associated with immediate solar flare activities, while delayed events involve more complex processes such as near-Sun particle storage and secondary injection triggered by distant solar flares. These events are linked to various electromagnetic phenomena, including optical, X-ray, and microwave emissions. Models have been developed to predict the magnitude of solar cosmic ray events based on early spectrometer data, aiding in the projection of total expected event doses4 9.
Exotic Cosmic Ray Events: Search for New Particles
Several unusual cosmic ray events, such as the Yunnan event and the Kolar events, have been recorded, suggesting the presence of heavy and slow-moving particles produced from cosmic ray interactions. These particles might be related to weakly interacting massive particles (WIMPs), potential candidates for dark matter. The detection of heavy and charged particles with relatively long lifetimes further supports this hypothesis. Dedicated magnetic spectrometers have been proposed to identify these exotic particles in cosmic rays5.
Causal Relationships in Cosmological Events
Research has derived criteria for determining whether two cosmological events can share a causal past or future, assuming a Friedmann-Lemaitre-Robertson-Walker universe. For instance, pairs of quasars with redshifts z >= 3.65 have no shared causal past with each other or with our past worldline. These criteria help understand the constraints on signaling between cosmic events before the end of time, given the finite conformal lifetime of our observable universe6.
Probabilistic Cross-Identification of Cosmic Events
A novel approach using Bayesian hypothesis testing has been developed to identify cosmic events in separate and independent observations. This method assigns probabilities to matches by studying their rates of occurrence, making the classification and analysis of true events, such as supernova explosions, more efficient. This approach has been illustrated with a case study of Type Ia supernovae, demonstrating the effectiveness of using light curves in the cross-identification process7.
Conclusion
Recent research has provided significant insights into various cosmic events, from historical solar flares to exotic cosmic ray interactions and the causal relationships between cosmological events. These studies enhance our understanding of the universe's dynamic processes and the potential existence of new particles, contributing to the broader field of astrophysics and cosmology.
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Most relevant research papers on this topic
The AD775 cosmic event revisited: the Sun is to blame
The AD775 cosmic event was likely caused by a strong solar flare, not an impossibly strong solar flare, and is consistent with historical records of increased auroral activity.
Highly CitedExtremely Energetic Cosmic-Ray Event
The extremely energetic cosmic ray event recorded at M.I.T. between Sept. 1959 and May 1960 was analyzed using a model, providing information on the shower center, radius, axis direction, composition, and arrival times at various counters.
Highly CitedObservation of an Unusual Upward-Going Cosmic-Ray-like Event in the Third Flight of ANITA.
This upward-going cosmic-ray-like event, observed in the third flight of ANITA, could be caused by the atmospheric decay of an upward-propagating lepton produced by a _ interaction.
Highly CitedSolar cosmic ray phenomena
Solar cosmic ray phenomena are mainly of common origin, with halo and core events, energetic storm particle events, EDP events, and proton recurrent regions being mainly of common origin.
Highly CitedSearch for new massive particles in cosmic rays
This paper suggests that there is a heavy and neutral component in cosmic rays, potentially related to the weakly interacting massive particle (WIMP), and suggests a dedicated magnetic spectrometer for identifying these particles.
The Shared Causal Pasts and Futures of Cosmological Events
Two cosmological events cannot have a shared causal past or future, and pairs of objects with redshifts z >= 3.65 have no shared past with each other or our worldline.
PROBABILISTIC CROSS-IDENTIFICATION OF COSMIC EVENTS
Bayesian hypothesis testing can efficiently identify cosmic events like supernova explosions by associating streams of events in space and time, using light curves for efficient matching.
Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA.
Four radio-detected cosmic-ray-like events observed with ANITA show characteristics consistent with a primary emerging from the surface of the ice, suggesting a possible -lepton decay origin.
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