Context
. We are operating an elastic light detecting and ranging system (LIDAR) for the monitoring of atmospheric conditions during regular observations of the MAGIC telescopes.
Aims
. We present ...and evaluate methods for converting aerosol extinction profiles, obtained with the LIDAR, into corrections of the reconstructed gamma-ray event energy and instrument response functions of Imaging Atmospheric Cherenkov Telescopes.
Methods
. We assess the performance of these correction schemes with almost seven years of Crab Nebula data obtained with the MAGIC telescopes under various zenith angles and different aerosol extinction scenarios of Cherenkov light.
Results
. The methods enable the reconstruction of data taken under nonoptimal atmospheric conditions with aerosol transmissions down to ~0.65 with systematic uncertainties comparable to those for data taken under optimal conditions. For the first time, the correction of data affected by clouds has been included in the assessment. The data can also be corrected when the transmission is lower than 0.65, but the results are less accurate and suffer from larger systematics.
The purpose of this article is to broaden the information available on the chronology of the Inca expansion in Collasuyu by analyzing all radiocarbon dates obtained in Argentina’s Inca sites. We ...evaluated and classified all the dates (n=178) into three different groups (G1, G2, and G3), according to the quantity and quality of contextual information, and the possibility of effectively verifying this information through published articles. The interpretation was mainly based on the dates showing the best information regarding the origin and context of the samples (28 of the G1, and 36 of the G2). Our results indicate that the Inca advance started towards the beginnings of 15th Century AD in the northernmost part of Argentina and rapidly continued southwards, probably reaching the province of Mendoza some 50 years later. This study confirms the differences between the ethnohistoric chronology and the radiocarbon data, previously pointed out by other authors. Moreover, it suggests a sequence of at least three stages in which the Incas would have incorporated the existing territories until ca. 24°, 28°, and 34° 30' S, respectively. This is the first global study of Inca chronology in Argentina, and the first time that dates are classified to determine their level of context information and reliability.
The Cherenkov Telescope Array (CTA) represents the next generation of ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed at improving on the sensitivity of ...current-generation experiments by an order of magnitude and providing coverage over four decades of energy. The current CTA design consists of two arrays of tens of imaging atmospheric Cherenkov Telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array located in each of the Northern and Southern Hemispheres. To study the effect of the site choice on the overall CTA performance and support the site evaluation process, detailed Monte Carlo simulations have been performed. These results show the impact of different site-related attributes such as altitude, night-sky background and local geomagnetic field on CTA performance for the observation of VHE gamma rays.
Abstract
The Cherenkov Telescope Array (CTA) is the next-generation ground-based very-high-energy gamma-ray observatory. By using three types of telescopes CTA can cover a wide energy range (20 ...GeV–300 TeV) with an order of magnitude higher sensitivity than the current telescopes. The Large-Sized Telescope (LST) is designed to detect 20 GeV–1 TeV gamma rays thanks to the large light collection area, sensitive photosensors, a fast trigger system, and readout electronics. The camera readout system must have a high signal-to-noise ratio and a linear signal sampling with a large dynamic range in order to efficiently detect dim and low-energy atmospheric showers. To meet this requirement we use the Domino Ring Sampler version 4 (DRS4), which also enables ultra-fast sampling with low power consumption. Some of the intrinsic characteristics of DRS4 chips require software corrections. These procedures lower the effect of non-Gaussian noise contribution and improve the timing resolution of the system. In this contribution we discuss the calibration algorithms and the resulting performance.
The Crab supernova remnant has been observed regularly with the stereoscopic system of five imaging air Cerenkov telescopes that was part of the High Energy Gamma Ray Astronomy (HEGRA) experiment. In ...total, close to 400 hr of useful data have been collected from 1997 to 2002. The differential energy spectrum of the combined data set can be approximated by a power law-type energy spectrum: d Phi /dE = Phi sub(0) (E/TeV) Gamma , Phi sub(0) = (2.83 plus or minus 0.04 sub(stat) plus or minus 0.6 sub(sys)) 10 super(-11) photons cm super(-2) s super(-1) TeV super(-1), and Gamma = -2.62 plus or minus 0.02 sub(stat) plus or minus 0.05 sub(sys). The spectrum extends up to energies of 80 TeV and is well matched by model calculations in the framework of inverse Compton scattering of various seed photons in the nebula, including for the first time a recently detected compact emission region at millimeter wavelengths. The observed indications for a gradual steepening of the energy spectrum in data is expected in the inverse Compton emission model. The average magnetic field in the emitting volume is determined to be 161.6 plus or minus 0.8 sub(stat) plus or minus 18 sub(sys) mu G. The presence of protons in the nebula is not required to explain the observed flux, and upper limits on the injected power of protons are calculated to be as low as 20% of the total spin-down luminosity for bulk Lorentz factors of the wind in the range of 10 super(4)-10 super(6). The position and size of the emission region have been studied over a wide range of energies. The position is shifted by 13" to the west of the pulsar, with a systematic uncertainty of 25". No significant shift in the position with energy is observed. The size of the emission region is constrained to be less than 2' at energies between 1 and 10 TeV. Above 30 TeV the size is constrained to be less than 3'. No indication of pulsed emission has been found, and upper limits in differential bins of energy have been calculated reaching typically 1%-3% of the unpulsed component.
Five barley chloroplast DNA microsatellites (cpSSRs) were used to study genetic relationships among a set of 186 barley accessions-34 Hordeum vulgare ssp. spontaneum (HS accessions) from Morocco, ...Ethiopia, Cyprus, Crete, Libya, Iraq, Iran, Turkey, Afghanistan and Israel, 122 H. vulgare ssp. vulgare landraces (HV landraces) from Spain, Bolivia (old Spanish introductions), Morocco, Libya and Ethiopia and 20 modern European spring barleys (HV cultivars). All loci were polymorphic in the material studied, with the number of alleles per locus ranging from two to three. Fifteen multi-locus haplotypes were observed, 11 in HS accessions and seven in HV landraces and cultivars. Of the seven haplotypes found in the HV lines, three were shared with the HS accessions, and four were unique. Cluster analysis revealed two main groups, one consisting of HS accessions from Ethiopia and the HV landraces from Spain, Bolivia (old Spanish), Morocco and Ethiopia, whereas the other larger group contained all of the other accessions studied. Based on these grouping and the existence of haplotypes found in the HV landraces and cultivars but not in the HS wild barley, a polyphyletic origin is proposed for barley, with further centres of origin in Ethiopia and the Western Mediterranean.
The Cherenkov Telescope Array (CTA), an array of many tens of Imaging Atmospheric Cherenkov Telescopes deployed on an unprecedented scale, is the next-generation instrument in the field of very high ...energy gamma-ray astronomy. An average data stream of about 0.9 GB/s for about 1300 hours of observation per year is expected, therefore resulting in 4 PB of raw data per year and a total of 27 PB/year, including archive and data processing. The start of CTA operation is foreseen in 2018 and it will last about 30 years. The installation of the first telescopes in the two selected locations (Paranal, Chile and La Palma, Spain) will start in 2017. In order to select the best site candidate to host CTA telescopes (in the Northern and in the Southern hemispheres), massive Monte Carlo simulations have been performed since 2012. Once the two sites have been selected, we have started new Monte Carlo simulations to determine the optimal array layout with respect to the obtained sensitivity. Taking into account that CTA may be finally composed of 7 different telescope types coming in 3 different sizes, many different combinations of telescope position and multiplicity as a function of the telescope type have been proposed. This last Monte Carlo campaign represented a huge computational effort, since several hundreds of telescope positions have been simulated, while for future instrument response function simulations, only the operating telescopes will be considered. In particular, during the last 18 months, about 2 PB of Monte Carlo data have been produced and processed with different analysis chains, with a corresponding overall CPU consumption of about 125 M HS06 hours. In these proceedings, we describe the employed computing model, based on the use of grid resources, as well as the production system setup, which relies on the DIRAC interware. Finally, we present the envisaged evolutions of the CTA production system for the off-line data processing during CTA operations and the instrument response function simulations.
Numerous studies have explored mobility along the Qhapaq Ñan. Most of them examine how the road influenced local, regional, and imperial dynamics by fostering exchange relationships and connecting ...societies, people, and territories. These investigations explicitly or implicitly assume that it was male individuals who mobilized to build the Tahuantinsuyo, while women remained within the domestic unit or were confined to imperial buildings. In this study, we seek to acknowledge potential patterns of women’s mobility as part of female collectives, including those identified as acllas (chosen ones) or mamaconas (matrons) within the Tahuantinsuyo territory, through a gender perspective. We do so by drawing on five cases supported by biogenetic data and published textile analysis, as well as ethnohistorical data from Inca llacta cemeteries and capacocha ritual events (a ritual of obligation to the Inca state where infants were offered). We identified modes of movement that consider the distance traveled, the age of female individuals, and the political motives framing each activity, and which, in turn, construct identity, Finally, our analysis indicates that the visualization and analysis of individuals’ mobility experiences are associated with types of movement related to local, regional, or imperial political interests that reveal certain logics of movement that have been hidden, in this case, those of female experiences within the Tahuantinsuyo.
Las investigaciones acerca de la movilidad sobre el Qhapaq Ñan han sido múltiples. La mayoría identifican las distintas maneras en que el camino ha determinado las dinámicas locales, regionales e imperiales, construyendo relaciones de intercambio, articulando sociedades, personas y territorios. Estas investigaciones asumen de manera explícita o implícita que fueron individuos masculinos quienes se movilizaron para construir el Tahuantinsuyo, mientras que las mujeres estarían dentro de la unidad doméstica o recluidas en edificios imperiales. En este trabajo nos proponemos, mediante una perspectiva de género, identificar posibles patrones de movilidad de las mujeres parte de colectivos femeninos, algunas de las cuales han sido identificadas como acllas (escogidas) o mamaconas (matronas) dentro del territorio del Tahuantinsuyo. Para ello hemos utilizado cinco casos que cuentan con información biogenética y análisis de textiles publicados, así como datos etnohistóricos que provienen de cementerios en llactas incas y de eventos rituales de capacocha —ritual de obligación al estado incaico donde se ofrendaban infantes—. Se identificaron maneras de desplazarse que tienen en cuenta la distancia a caminar, la edad de los individuos femeninos y los motivos políticos que enmarcan cada actividad y que, a su vez, construyen identidad. Finalmente, se indica que la visualización y el análisis de la experiencia de la movilidad de los individuos se asocian a tipos de movimiento relacionados con intereses políticos locales, regionales o imperiales que revelan ciertas lógicas de movimiento que han estado ocultas, en este caso, de las experiencias femeninas dentro del Tahuantinsuyo.
The unidentified TeV source in Cygnus is now confirmed by follow-up observations from 2002 with the HEGRA stereoscopic system of Cherenkov Telescopes. Using all data (1999 to 2002) we confirm this ...new source as steady in flux over the four years of data taking, extended with radius 6.2′ (±$1.2^\prime_{\rm stat}$ ± $0.9^\prime_{\rm sys}$) and exhibiting a hard spectrum with photon index -1.9. It is located in the direction of the dense OB stellar association, Cygnus OB2. Its integral flux above energies $E>1$ TeV amounts to ~5% of the Crab assuming a Gaussian profile for the intrinsic source morphology. There is no obvious counterpart at radio, optical nor X-ray energies, leaving TeV J2032+4130 presently unidentified. Observational parameters of this source are updated here and some astrophysical discussion is provided. Also included are upper limits for a number of other interesting sources in the FoV, including the famous microquasar Cygnus X-3.
For the first time an excess of photons above an energy threshold of 730 GeV from the giant radio galaxy M 87 has been measured at a significance level above 4 σ. The data have been taken during the ...years 1998 and 1999 with the HEGRA stereoscopic system of 5 imaging atmospheric Cherenkov telescopes. The excess of $107.4\,\pm\,26.8$ events above 730 GeV corresponds to an integral flux of 3.3% of the Crab flux or $N_\gamma(E > 730\,\mbox{GeV}) = (0.96 \pm 0.23) \times 10^{-12}$ phot cm-2 s-1. M 87 is located at the center of the Virgo cluster of galaxies at a relatively small redshift of $z = 0.00436$ and is a promising candidate among the class of giant radio galaxies for the emission of TeV γ-radiation. The detection of TeV γ-rays from M 87 – if confirmed – would establish a new class of extragalactic source in this energy regime since all other AGN detected to date at TeV energies are BL Lac type objects.
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