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Afterglow Observations of Fermi Large Area Telescope Gamma-ray Bursts and the Emerging Class of Hyper-energetic Events

Afterglow Observations of Fermi Large Area Telescope Gamma-ray Bursts and the Emerging Class of Hyper-energetic Events

Past modeling of broadband GRB afterglows, however, has not always revealed this to be the case. Of the past GRBs with sufficient radio observations to estimate the circumburst density, the derived values span a large range from 1.9 × 10 − 3 cm − 3 (GRB 990123; Panaitescu & Kumar 2002) to 680 cm −3 (GRB 050904; Frail et al. 2006). We plot in Figure 11 the derived circumburst densities for these previous events (either n or A ∗ , depending on the circumburst density profile) as a function of isotropic afterglow kinetic energy, along with three events from our LAT sample (we have not included GRB 090926A as lack of radio coverage makes density estimates highly degenerate). It is clear that the events detected by the LAT have on average larger isotropic energies and smaller densities than the previous sample.
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Astrophysical Constraints on Dark Matter

Astrophysical Constraints on Dark Matter

Constraints on annihilating DM have been made using dwarf galaxies Acker- mann et al. [2011a]; Geringer-Sameth & Koushiappas [2011] and galaxy clusters (e.g., . Ando & Nagai [2012]; Han et al. [2012d]; Chapter 2). Several independent groups have reported evidence of extended excess gamma-ray emission above the diffuse galactic background (DGB) from the central 1 ◦ − 2 ◦ around the Galactic center Abazajian & Kaplinghat [2012a, 2013]; Boyarsky et al. [2011]; Goodenough & Hooper [2009a]; Hooper & Goodenough [2011]; Hooper et al. [2012]; Hooper & Linden [2011a]. These investigations were based on Fermi Large Area Telescope (LAT) data. Although the Fermi-LAT Collaboration have not yet published a full Galactic Center analysis, in a preliminary study with one year of data, the Fermi team has reported an excess in observed counts peaking at energies of ∼ 2 − 5 GeV Vitale & Morselli [2009]; Vitale et al. [2011]. Two main alternative explanations for its origin have been posited:
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A panchromatic view of relativistic jets in narrow-line Seyfert 1 galaxies

A panchromatic view of relativistic jets in narrow-line Seyfert 1 galaxies

Abstract: The discovery by the Large Area Telescope on board Fermi of variable γ-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible third class of AGN with relativistic jets in addition to blazars and radio galaxies. Considering that NLSy1 are usually hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects and the formation of relativistic jets. We report on a systematic investigation of the γ-ray properties of a sample of radio-loud NLSy1, including the detection of new objects, using 7 years of Fermi-LAT data with the new Pass 8 event-level analysis. In addition we discuss the radio-to-very-high-energy properties of the γ-ray emitting NLSy1, their host galaxy, and black hole mass in the context of the blazar scenario and the unification of relativistic jets at different scales.
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Relativistic jets in narrow-line Seyfert 1 galaxies. New discoveries and open questions

Relativistic jets in narrow-line Seyfert 1 galaxies. New discoveries and open questions

Abstract. Before the launch of the Fermi satellite only two classes of AGNs were known to produce relativistic jets and thus emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope on board Fermi confirmed that these two are the most numerous classes of identified sources in the extragalactic γ-ray sky, but the discovery of γ-ray emission from 5 radio-loud narrow-line Seyfert 1 galaxies revealed the presence of a possible emerging third class of AGNs with relativistic jets. Considering that narrow-line Seyfert 1 galaxies seem to be typically hosted in spiral galaxy, this finding poses intriguing questions about the nature of these objects, the onset of production of relativistic jets, and the cosmological evolution of radio-loud AGN. Here, we discuss the radio-to-γ-rays properties of the γ-ray emitting narrow-line Seyfert 1 galaxies, also in comparison with the blazar scenario.
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Remotely Controlled Low Cost Digital Telescope

Remotely Controlled Low Cost Digital Telescope

Abstract. This paper presents a low-cost web controlled digital telescope which can benefit educational institutions. The system is composed of two webcams to acquire data. One is used as a wide field of view for localization purpose and the second one is used as a narrow field of view using a 40 cm focal length lens and an achromatic doublet to visualize celestial objects. The telescope orientation is performed remotely using two motors through Internet with an in-house developed software running on a Raspberry Pi 3 device. Message Queue Telemetry Transport (MQTT) based server is used to provide a full wireless communication between the user and the telescope for orientation control, data visualization and acquisition. The telescope structure is built using a 3D-printer. An image processing algorithm is presented to calibrate mounting camera misalignment. The overlapping calibration is performed to localize the telescope image onto the large field-of-view image. It is based on Fourier domain cross-correlation technique.
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The possibility of the telescope

The possibility of the telescope

The lens P of plate glass see Figure 4 is backed by a concave of flint glass G of less refraction power, thus leaving a surplus of refraction to the convex, the effect being that we get [r]

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Gravitational Telescope

Gravitational Telescope

It’s proposed to use a global seismic antenna (GSA) as a gravitational telescope, arbitrary “quiet” seismic stations are its elements, and aperture of GSA must be of the order 10,000 km. The relative displacements of various points of the Earth are detected by GSA, these displacements are de- scribed as quasi-harmonic elliptical signals generated by gravitational waves, their amplitude ≈ 2.5 × 10 −15 m. It is found that these waves cause deformation (strain) of the order h ≈ 10 −21 . Pulsars

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The peculiar radio galaxy 4C 35.06: a case for recurrent AGN activity?

The peculiar radio galaxy 4C 35.06: a case for recurrent AGN activity?

Acknowledgements. LOFAR, the Low Frequency Array designed and con- structed by ASTRON, has facilities in several countries that are owned by vari- ous parties (each with their own funding sources), and that are collectively op- erated by the International LOFAR Telescope (ILT) foundation under a joint scientific policy. Data taken with the Westerbork Synthesis Radio Telescope were part of this work. It is operated by ASTRON (Netherlands Institute for Radio Astronomy) with support from the Netherlands Foundation for Scientific Research (NWO). This research has made use of the NASA / IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The VLA images used in this work were produced as part of the NRAO VLA Archive Survey, (c) AUI / NRAO. This research has made use of APLpy, an open-source plotting package for Python hosted at http:// aplpy.github.com. R.M. gratefully acknowledges support from the European Research Council under the European Union’s Seventh Framework Programme (FP / 2007 − 2013) / ERC Advanced Grant RADIOLIFE-320745. R.Jv.W. acknowl- edges the support by NASA through the Einstein Postdoctoral grant number PF2-130104 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.
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Pulsating variable stars and large spectroscopic surveys

Pulsating variable stars and large spectroscopic surveys

Abstract. In the past decade, the research of pulsating variable stars has taken a giant leap forward thanks to the photometric measurements provided by space missions like M ost , C o R o T, Kepler/K2, and B rite . These missions have provided quasi uninterrupted photometric time-series with an ultra-high quality and a total length that is not achiev- able from Earth. However, many of the success stories could not have been told without ground-based spectroscopic follow-up observations. Indeed, spectroscopy has some im- portant assets as it can provide (more) accurate information about stellar parameters (like the effective temperature, surface gravity, metallicity, and abundances that are mandatory parameters for an in-depth asteroseismic study), the radial velocity (that is important for the detection of binaries and for the confirmation of cluster membership, if applicable), and the projected rotational velocity (that allows the study of the effects of rotation on pul- sations). Fortunately, several large spectroscopic surveys are (becoming) available that can be used for these purposes. For some of these surveys, sub-projects have been initi- ated with the specific goal to complement space-based photometry. In this review, several spectroscopic surveys are introduced and compared with each other. We show that a large amount of spectroscopic data is (becoming) available for a large variety of objects.
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Atmospheric monitoring at the site of the Telescopio Nazionale Galileo

Atmospheric monitoring at the site of the Telescopio Nazionale Galileo

While the GAWS is placed in a strategical position for the site characterization [7], because it is windward as far as the main trade winds are concerned and not affected by the presence of buildings and structures of the Observatory, it is on the contrary misplaced as far as the safety of the telescope is concerned. Clouds, which typically come from the East and from the edge of the Caldera, arrive at the telescope way before than being detected by the GAWS. Furthermore every winter the tower becomes a column of ice; the combined effect of ice, wind and sun brakes the weather sensors one by one and it is really difficult to maintain the tower continuously operative (access to replace the broken sensors is by climbing on the tower). We often had to observe without our weather sensors in the bad weather season and rely only on the information given from the meteo web pages of the other telescopes on the mountain. To mitigate the above problems in the year 2000 we set up a Davis weather station on the roof of the rotating dome which is much easier to maintain and has much cheaper spare parts. Begin so close to the building it is not reliable for site characterization and it still is too close to the building to give enough response time in case of bad weather.
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Acoustic Particle Detection with the ANTARES Detector

Acoustic Particle Detection with the ANTARES Detector

Copyright © 2010 C. Richardt et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The (Antares Modules for Acoustic Detection Under the Sea) AMADEUS system within the (Astronomy with a Neutrino Telescope and Abyss environmental RESsearch) ANTARES neutrino telescope is designed to investigate detection techniques for acoustic signals produced by particle cascades. While passing through a liquid a cascade deposits energy and produces a measurable pressure pulse. This can be used for the detection of neutrinos with energies exceeding 10 18 eV. The AMADEUS setup consists
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Urban Construction and Transformation for Large Area Management

Urban Construction and Transformation for Large Area Management

The specific connotation of urban places is their spatial quality with features as articulated as different are the languages used to define the special character of the (urban) space: distance, context, location, place, street, suburb, urban area, development route in a play on words which is usually and ritually declined through opposites: inside/out, indoor/outdoor, centre/outskirts, continuous/discontinuous, far/close, higher/lower. This spatial quality is not only physical and material, measured in terms of distance in meters from a still element given as the starting point; the spatial quality we refer to corresponds to interchangeable systems of reference, sets of two-way relationships, multi- directional paths whose distances tend to be overcome when it is decided to make the points closer and through them to approach our languages, that is, when we start to talk of a common project using a common language.
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Synthesis and application of large area graphene stacks

Synthesis and application of large area graphene stacks

The application that has some of the most extreme requirements for barriers are OLEDs. They are required to work for years but only need a tiny amount of oxygen or water in order to be completely destroyed. Additionally, the barrier has to be transparent so the light can get out of the device and if the barrier is also conductive it can serve as an electrode, saving one component. Graphene theoretically fulfils all of these requirements. However, it is unlikely that it will indeed make a good enough barrier for OLEDs. However, even as a transparent, flexible electrode it would be of significant value already. To check the viability of graphene stacks for electronic applications they were incorporated into OLEDs by Philips corporation and their performance compared to ITO electrodes, the current industrial standard. This is not the first study of graphene for OLED electrodes. As a matter of fact, almost immediately after the discovery of graphene and its extraordinary properties, the concept of a graphene-based OLED electrode was patented many times. [171–174] Making an OLED is not particularly difficult any more. The difficulty lies with making it efficient, large-area and, most impor- tantly, lasting. The standard comparison is comparing the graphene electrode to an ITO electrode which is the current industrial standard. Even solution ex- foliated graphene flakes have been shown to be comparable ITO in some cases but showed significant hysteresis in a relatively simple device structure. [135] The
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Large area micropatterning of cells on polydimethylsiloxane surfaces

Large area micropatterning of cells on polydimethylsiloxane surfaces

The patterned surfaces were studied for cell adhesion and growth with a focus on cell avoidance to the PEG regions and confinement to PDMS. Since native PDMS does not promote cell attachment due to its high hydrophobicity [12], coating the PDMS with fibronectin allowed cell adhesion and proliferation. In our experi- ments, two cell lines - 3T3 mice fibroblasts and human dermal fibroblasts (HDFs) were tested at a density of 5×10 4 cells/well on fibronectin coated PDMS samples. After 6 days, the PEG-DA hydrogel regions showed no cell attachment as expected. The cells were shown to be fully proliferated and interconnected at high density throughout the microchannel patterns to form a net- work over a large area (Figure 4). Here we show repre- sentative images of each culture. The 50 μm channels showed the aggregation of several cells compared to the smaller 25 μm ones which had only a few cells aligned. This indicated that not only was the adhesion confined
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Nano/biosensors Based On Large-Area Graphene

Nano/biosensors Based On Large-Area Graphene

Two dimensional materials have properties that make them ideal for applications in chemical and biomolecular sensing. Their high surface/volume ratio implies that all atoms are exposed to the environment, in contrast to three dimensional materials with most atoms shielded from interactions inside the bulk. Graphene additionally has an extremely high carrier mobility, even at ambient temperature and pressure, which makes it ideal as a transduction device. The work presented in this thesis describes large-scale fabrication of Graphene Field Effect Transistors (GFETs), their physical and chemical characterization, and their application as biomolecular sensors. Initially, work was focused on developing an easily scalable fabrication process. A large-area graphene growth, transfer and photolithography process was developed that allowed the scaling of production of devices from a few devices per single transfer in a chip, to over a thousand devices per transfer in a full wafer of fabrication. Two approaches to biomolecules sensing were then investigated, through nanoparticles and through chemical linkers.
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The dual-mirror Small Size Telescope for the Cherenkov Telescope Array

The dual-mirror Small Size Telescope for the Cherenkov Telescope Array

The SST array will be implemented just on the southern site for reason of costs and taking into account that the very high energy emission can be observed just for galactic sources, unless non standard processes are invoked. In order to allow the implementation of the large number (∼ 70) of telescopes foreseen for the SST sub-array, containing the costs to be ≤ 500 kEuro per unit is essential. It should be noted that classical parabolic or Davies-Cotton (DC) single–mirror configurations have been used so far for Cherenkov telescopes, and they are adopted also for the CTA LST and MST telescopes respectively. However they are dominated by the cost of the camera, which is based on classical large-size photo-multipliers and they do not seem ideal for making the wide-field SST units. A possible solution is to implement the classical DC solution with Winston cone light guides, to squeeze the light with an aggressive concentration ratio, but with the crucial drawbacks of a difficult implementation and limited number of pixels [4]. But a particularly attractive solution to realize the SST telescopes is the use of a dual-mirror (2M) solution, adopting the so called Schwarzschild–Couder (SC) configuration. This enables good angular resolution across the entire field of view, almost 10 ◦ in diameter, and also reduces the effective focal length and camera size [5]. As has previously been demonstrated, 2M SC telescopes allow better correction of aberrations at large field angles and hence the construction of telescopes with a smaller focal ratio. This implies that, for a given primary mirror and angular pixel size, the physical pixels are smaller. This approach allows the use of low-cost, compact, and low power consumption cameras, based on silicon photomultipliers (SiPM) or multi-anode photomultipliers (MAPM), commercially available sensors with typical pixel size of ∼ 6 × 6 mm 2 . The trigger threshold of 1 TeV implies primary mirror diameter D ' 4 m. The SST group within CTA has designed 2M telescopes which have the potential to provide the required optical performance and allow exploitation of these technologies.
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Discovery of a new Galactic bona fide luminous blue variable with Spitzer

Discovery of a new Galactic bona fide luminous blue variable with Spitzer

We are grateful to I.D. Howarth (the referee) for useful sugges- tions on the manuscript. Some observations reported in this paper were obtained with the Southern African Large Telescope (SALT), programmes 2010-1-RSA_OTH-001, 2013-1-RSA_OTH-014 and 2013-2-RSA_OTH-003. VVG and LNB acknowledge the Russian Science Foundation grants 14-12-01096 and 14-22-00041, respec- tively. AYK acknowledges support from the National Research Foundation (NRF) of South Africa. This work is based in part on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA, and has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration, the SIMBAD data base and the VizieR catalogue access tool, both operated at CDS, Strasbourg, France.
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Bending losses in large mode area holey fibres

Bending losses in large mode area holey fibres

As mentioned in Section 1.2.4, fabricating long lengths of uniform holey fibre can be chal- lenging due to the interaction between air pressure and surface tension within the fibre. Indeed, in air/glass holey fibres drawn down to small dimensions, the cladding air holes can be significantly distorted from their original circular geometry, as shown in Fig. 1.6 (a). This is not a problem in conventional solid optical fibres, and km-long lengths of fibre with the parameters of the preform can be simply fabricated. However, the novel optical properties of a holey fibre, which arise from the wavelength scale air holes in the cladding, are not restricted to air/glass structures. In theory, two uniform solid materials could be used to create a solid microstructured fibre with similarly unusual optical properties if the refractive index contrast between the two materials is sufficiently high. The most chal- lenging aspect of realising this type of microstructured fibre is finding two solid materials that are both thermally and chemically compatible, and that also possess a sufficiently large refractive index difference. A solid microstructured fibre made from two lead-silicate glasses with refractive indices of 1.53 and 1.76 has recently been fabricated [69]. In this solid holey (SOHO) fibre, the cladding is defined by a hexagonal arrangement of circular low-index glass regions and the fibre geometry is shown to be essentially unchanged during fibre drawing. Indeed, the relative size, shape and position of the low index regions are shown to remain virtually identical even when the fibre dimensions are reduced such that micron scale features are achieved in the cladding. In addition, solid microstructured fibres possess several practical advantages in terms of polishing, angle cleaving and splicing.
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Calibration and testing of a prototype of the JEM-EUSO telescope on Telescope Array site

Calibration and testing of a prototype of the JEM-EUSO telescope on Telescope Array site

Aim of the project is to calibrate the detector with UV light coming from known sources such as the ELS - Electron Light Source, and laser from the CLF (Central Laser facility). Furthermore the response to artificial light will be correlated with that of the TA Fluorescence light telescope in order to calibrate the EUSO-Ground response with that of TA and reduce the systematic of the measurement.

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LAPM: a tool for underwater large-area photo-mosaicking

LAPM: a tool for underwater large-area photo-mosaicking

ilar technique is widely used in photography for the pro- duction of panoramas. However, an interest in using photo- mosaics to map deep-sea environments is growing among the scientific community, and several works have focused on developing algorithms to reliably build underwater mo- saics (Gracias and Santos-Victor, 2001; Eustice et al., 2002; Pizarro and Singh, 2003; Vincent et al., 2003; Allais et al., 2004; Ferrer et al., 2007; Escart´ın et al., 2008). Indeed, tra- ditional panorama-dedicated programs usually fail to cope with underwater imagery correctly. The deep sea is a very challenging environment, and the reasons for failure are man- ifold; moving camera, strong lighting heterogeneities, low contrasts, perspective distortions, poor accuracy of camera positioning data, or adverse camera motions due to bottom currents are the various hindrances to the construction of large photo-mosaics with low distortion.
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