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Opis: The Telescope Array has accumulated the largest UHECR data set in the Northern hemisphere. We make use of these data to search for large- and small-scale anisotropy of UHECR arrival directions. At small angular scales, we report an update on searches for clustering of events and on correlations with various classes of putative sources. At large angular scales, we revisit, with the new data and with new tests, the localized excess of events known as the TA “hot spot”. We review some other studies of the arrival directions and corresponding implications for the nature of UHECR sources.
Najdeno v: ključnih besedah
Povzetek najdenega: ...The Telescope Array has accumulated the largest UHECR data set in the Northern hemisphere. We...
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno: 29.04.2020; Ogledov: 1717; Prenosov: 74
Polno besedilo (581,87 KB)

Opis: Telescope Array (TA) was designed to answer important questions about the UHECR flux with energies above 10^17 eV such as spectrum, arrival direction, and mass composition. Because the UHECR flux is rapidly falling in this energy region, TA’s large exposure makes it one of the few experiments in the world that can adequately explore these issues. Composition is particularly difficult to measure because mass can not be measured directly due to the low flux. TA’s multiple methods of observing UHECR induced air showers will be explained, as well as how composition can be measured by these methods. Good agreement among the different measurement techniques is found leading to greater confidence in measuring UHECR mass composition and a way to test and understand TA systematic uncertainties.
Najdeno v: ključnih besedah
Povzetek najdenega: ...designed to answer important questions about the UHECR flux with energies above 10^17 eV such as...
Ključne besede: UHECR, cosmic rays, composition
Objavljeno: 29.04.2020; Ogledov: 1849; Prenosov: 92
Polno besedilo (758,27 KB)

Opis: We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in starburst galaxies, one matching the arrival direction data in the South (the radio galaxy Cen A) and one in the North (the starburst galaxy M82). The most likely identification of the origin of observed Gravitational Wave (GW) events is stellar binary black hole (BH) mergers in starburst galaxies such as M82 with the highest rate of star formation, so the highest far-infrared (FIR) luminosity, at the edge of the universe visible in 10 - 300 Hz GWs; at low heavy element abundance Zch the formation of stellar BHs extends to a larger mass range. A radio galaxy such as Cen A sequence of events involves first the merger of two Super-Massive Black Holes (SMBHs), with the associated ejection of low frequency GWs, then the formation of a new relativistic jet aiming into a new direction: ubiquitous neutrino emission follows accompanied by compact TeV photon emission, detectable more easily if the direction is towards Earth. The ejection of UHECRs is last. Both these sites are the perfect high energy physics laboratory: We have observed particles up to ZeV, neutrinos up to PeV, photons up to TeV, 30 - 300 Hz GW events, and hope to detect soon of order µHz to mHz GW events. Energy turnover in single low frequency GW events may be of order ∼1063 erg. How can we further test these concepts? First of all by associating individual UHECR events, or directional groups of events, with chemical composition in both the Telescope Array (TA) Coll. and the Auger Coll. data. Second by identifying more TeV to PeV neutrinos with recent SMBH mergers. Third by detecting the order < mHz GW events of SMBH binaries, and identifying the galaxies host to the stellar BH mergers and their GW events in the range up to 300 Hz. Fourth by finally detecting the formation of the first generation of SMBHs and their mergers, surely a spectacular discovery.
Najdeno v: ključnih besedah
Povzetek najdenega: ...to explain Ultra High Energy Cosmic Rays ( UHECRs), one based on radio galaxies and their...
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno: 29.04.2020; Ogledov: 1709; Prenosov: 114
Polno besedilo (372,72 KB)

Opis: The seven year Telescope Array (TA) Middle Drum hybrid composition measurement shows agreement between Ultra-High Energy Cosmic Ray (UHECR) data and a light composition obtained with QGSJetII-03 or QGSJet-01c models. The data are incompatible with a pure iron composition, for all models examined, for energies log10(E/eV)>18.4. This is consistent with previous TA results. This analysis is presented using an updated version of the pattern recognition analysis (PRA) technique developed by TA.
Najdeno v: ključnih besedah
Ključne besede: UHECR, cosmic rays, hybrid detection, composition
Objavljeno: 29.04.2020; Ogledov: 1777; Prenosov: 72
Polno besedilo (150,19 KB)

Opis: Increased event statistics will be required to definitively answer the question of the origin(s) of Ultra-High Energy Cosmic Rays (UHECR). Using current technologies however, achieving the necessary statistics may be financially and practically impossible. We describe the status and plans of the TARA project, an effort to detect Ultra-High-Energy Cosmic Rays by their forward scattered or “bistatic” radar signature. Bistatic radar holds promise as a new remote sensing technique for UHECR, without the duty cycle limitations of nitrogen fluorescence detectors. Such a technique could prove key in advancing the study of UHECR beyond the constraints of the current generation of cosmic ray observatories. TARA consists of a low-VHF television transmitter illuminating the air above the Telescope Array (TA), and a set of radio receivers on the far side of TA approximately 50 km distant from the transmitter. We have collected radar data since April 2011 using a 2 kW transmitter at 54.1 MHz. Recently, we received permission to increase our broadcast power to 40 kW and our effective radiated power (ERP) to 6 MW. On the receiver end, we are employing software-defined radio receivers and developing real-time trigger algorithms based on the expected air shower radar echo. In addition to presenting an overview of the project status and future plans, we will present the most recent results of searches for coincidences between radar echoes and Telescope Array air shower events.
Najdeno v: ključnih besedah
Ključne besede: UHECR, cosmic rays, radar detection
Objavljeno: 29.04.2020; Ogledov: 1912; Prenosov: 81
Polno besedilo (623,59 KB)