Exploration of a 100 TeV gamma-ray northern sky using the Tibet air-shower array combined with an underground water-Cherenkov muon-detector array

Aiming to observe cosmic gamma rays in the 10 - 1000 TeV energy region, we propose a 10000 m^2 underground water-Cherenkov muon-detector (MD) array that operates in conjunction with the Tibet air-shower (AS) array. Significant improvement is expected in the sensitivity of the Tibet AS array towards celestial gamma-ray signals above 10 TeV by utilizing the fact that gamma-ray-induced air showers contain far fewer muons compared with cosmic-ray-induced ones. We carried out detailed Monte Carlo simulations to assess the attainable sensitivity of the Tibet AS+MD array towards celestial TeV gamma-ray signals. Based on the simulation results, the Tibet AS+MD array will be able to reject 99.99% of background events at 100 TeV, with 83% of gamma-ray events remaining. The sensitivity of the Tibet AS+MD array will be ~20 times better than that of the present Tibet AS array around 20 - 100 TeV. The Tibet AS+MD array will measure the directions of the celestial TeV gamma-ray sources and the cutoffs of their energy spectra. Furthermore, the Tibet AS+MD array, along with imaging atmospheric Cherenkov telescopes as well as the Fermi Gamma-ray Space Telescope and X-ray satellites such as Suzaku and MAXI, will make multiwavelength observations and conduct morphological studies on sources in the quest for evidence of the hadronic nature of the cosmic-ray acceleration mechanism.Comment: Accepted by Astroparticle Physic

Uplift, Climate and Biotic Changes at the Eocene-Oligocene Transition in Southeast Tibet

The uplift history of southeastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernisation of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly-collected plant fossil archives, we quantify the surface height of part of Tibet’s southeastern margin of Tibet in the latest Eocene (~34 Ma) to be ~3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene-Oligocene transition in southeastern Tibet witnessed leaf size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that by the latest Eocene floral modernization on Tibet had already taken place implying modernization was deeply-rooted in the Paleogene

Return of Kosi river induced by Tibet earthquake

Seismotectonics and change in river courses were correlated. Following the elastic rebound theory before the occurrence of the earthquake the subsurface rocks accumulate the energy by the tectonic movement. The Kosi river barrage was broken due to the tectonic forces accumulation in the south of Tibet Himalayas. Kosi river originates from Tibetan Himalayas and any disturbance in Tibet plateau has the potential to change the river course

The Singer of Tibet: Shabkar (1781-1851), the “Inescapable Nation,” and Buddhist Universalism

This paper examines the concept of ‘Tibet (Tib. bod)’ in the spiritual autobiography of the celebrated Tibetan Buddhist author, Shabkar Tsokdruk Rangdröl (1781–1851). I use both literal and literary modes of analysis in conjunction with Steven Grosby’s and Lama Jabb’s definitions of ‘nation’ to demonstrate how Shabkar initially builds a vivid persona— the ‘Singer of Tibet’—that is rooted in the Tibetan landscape, but then shifts to a different persona— ‘Shabkar’—that transcends Tibet altogether and embraces a sense of Buddhist universalism. Throughout the process, Shabkar evokes deities and historical figures that are fundamental to Tibetan historical, cultural, and religious memory and alludes to customs and tropes central to Tibetan culture, such as orality, song, and the bardic tradition. In addition to demonstrating the efficacy and potency of literary tropes in creating the sense of an imagined nation, this essay makes a contribution to the ‘Where is Tibet?’ debate by exploring how Tibetan identity is articulated in one of the great masterpieces of classical Tibetan Buddhist literature