Instrumentation and Methods for Astrophysics Publications (50)

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Instrumentation and Methods for Astrophysics Publications

Many focal-reducer spectrographs, currently available at state-of-the art telescopes facilities, would benefit from a simple refurbishing that could increase both the resolution and spectral range in order to cope with the progressively challenging scientific requirements but, in order to make this update appealing, it should minimize the changes in the existing structure of the instrument. In the past, many authors proposed solutions based on stacking subsequently layers of dispersive elements and record multiple spectra in one shot (multiplexing). Although this idea is promising, it brings several drawbacks and complexities that prevent the straightforward integration of a such device in a spectrograph. Read More


We compare the existent methods including the minimum spanning tree based method and the local stellar density based method in measuring mass segregation of star clusters. We find that the minimum spanning tree method reflects more the compactness, which represents the global spatial distribution of massive stars, while the local stellar density method reflects more the crowdedness, which provides the local gravitational potential information. It is suggested to measure the local and the global mass segregation simultaneously. Read More


Supernova cosmology without spectra will be the bread and butter mode for future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism -- zBEAMS -- that fully addresses this problem by marginalising over the unknown or contaminated supernova redshifts to produce unbiased cosmological estimates that are competitive with entirely spectroscopic data. Read More


Hamiltonian systems such as the gravitational N-body problem have time-reversal symmetry. However, all numerical N-body integration schemes, including symplectic ones, respect this property only approximately. In this paper, we present the new N-body integrator JANUS, for which we achieve exact time-reversal symmetry by combining integer and floating point arithmetic. Read More


TUS (Tracking Ultraviolet Set-up), the first orbital detector of extreme energy cosmic rays (EECRs), those with energies above 50 EeV, was launched into orbit on April 28, 2016, as a part of the Lomonosov satellite scientific payload. The main aim of the mission is to test a technique of registering fluorescent and Cherenkov radiation of extensive air showers generated by EECRs in the atmosphere with a space telescope. We present preliminary results of its operation in a mode dedicated to registering extensive air showers in the period from August 16, 2016, to November 4, 2016. Read More


We simulate the expected variations of background flux at two particular sites of the Latin American Giant Observatory (LAGO) and found that these fluxes are sensible to the latitude and that neutrons and muons components, of cosmic rays, are affected due to the variation of the geomagnetic field (GF). Read More


The propagation of charged cosmic rays through the Galactic environment influences all aspects of the observation at Earth. Energy spectrum, composition and arrival directions are changed due to deflections in magnetic fields and interactions with the interstellar medium. Today the transport is simulated with different simulation methods either based on the solution of a transport equation (multi-particle picture) or a solution of an equation of motion (single-particle picture). Read More


Observations of the Earth's exosphere have unveiled an extended envelope of hydrogen reaching further than 10 Earth radii (R$_E$) composed of atoms orbiting around the Earth. This large envelope increases significantly the opacity of the Earth to Lyman-alpha (Lya) photons coming from the Sun, to the point of making feasible to detect the Earth's transit signature from 1.35 pc with an 8~meter primary mirror space telescope, as we show. Read More


We have constructed the most-comprehensive catalog of photometry and proper motions ever assembled for a globular cluster (GC). The core of $\omega$Cen has been imaged over 650 times through WFC3's UVIS and IR channels for the purpose of detector calibration. There exist from 4 to over 60 exposures through each of 26 filters, stretching continuously from F225W in the UV to F160W in the infrared. Read More


The Auger Engineering Radio Array (AERA) aims at the detection of air showers induced by high-energy cosmic rays. As an extension of the Pierre Auger Observatory, it measures complementary information to the particle detectors, fluorescence telescopes and to the muon scintillators of the Auger Muons and Infill for the Ground Array (AMIGA). AERA is sensitive to all fundamental parameters of an extensive air shower such as the arrival direction, energy and depth of shower maximum. Read More


After the first direct detection of gravitational waves (GW), detection of stochastic background of GWs is an important next step, and the first GW event suggests that it is within the reach of the second-generation ground-based GW detectors. Such a GW signal is typically tiny, and can be detected by cross-correlating the data from two spatially-separated detectors if the detector noise is uncorrelated. It has been advocated, however, that the global magnetic fields in the Earth-ionosphere cavity produce the environmental disturbances at low-frequency bands, known as Schumann resonances, which potentially couple with GW detectors. Read More


The annual modulation measured by the DAMA/LIBRA experiment can be explained by the interaction of dark matter WIMPs in NaI(Tl) scintillator detectors. Other experiments, with different targets or techniques, exclude the region of parameters singled out by DAMA/LIBRA, but the comparison of their results relies on several hypotheses regarding the dark matter model. ANAIS-112 is a dark matter search with 112. Read More


Pulsar Wind Nebulae (PWNe) constitute an ideal astrophysical environment to test our current understanding of relativistic plasma processes. It is well known that magnetic fields play a crucial role in their dynamics and emission properties. At present, one of the main issues concerns the level of magnetic turbulence present in these systems, which in the absence of space resolved X-ray polarization measures cannot be directly constrained. Read More


Imaging Atmospheric Cherenkov Telescopes (IACTs) need imaging optics with large apertures to map the faint Cherenkov light emitted in extensive air showers onto their image sensors. Segmented reflectors fulfill these needs using mass produced and light weight mirror facets. However, as the overall image is the sum of the individual mirror facet images, alignment is important. Read More


For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. Read More


The machine learning techniques are widely applied in many modern optical sky surveys, i.e. Pan-STARRS1, PTF/iPTF and Subaru/Hyper Suprime-Cam survey, to reduce the human intervention for data verification. Read More


Different combinations of input parameters to filament identification algorithms, such as Disperse and FilFinder, produce numerous different output skeletons. The skeletons are a one pixel wide representation of the filamentary structure in the original input image. However, these output skeletons may not necessarily be a good representation of that structure. Read More


Determining the velocity distribution of halo stars is essential for estimating the mass of the Milky Way and for inferring its formation history. Since the stellar halo is a dynamically hot system, the velocity distribution of halo stars is well described by the 3-dimensional velocity dispersions $(\sigma_r, \sigma_\theta, \sigma_\phi)$, or by the velocity anisotropy parameter $\beta=1-(\sigma_\theta^2+\sigma_\phi^2)/(2\sigma_r^2)$. Direct measurements of $(\sigma_r, \sigma_\theta, \sigma_\phi)$ consistently suggest $\beta =0. Read More


POLAR is space-borne detector designed for a precise measurement of gamma-ray polarization of the prompt emissions of Gamma-Ray Bursts in the energy range 50 keV - 500 keV. POLAR is a compact Compton polarimeter consisting of 40$\times$ 40 plastic scintillator bars read out by 25 multi-anode PMTs. In May 2015, we performed a series of tests of the POLAR flight model with 100\% polarized x-rays beams at the European Synchrotron Radiation Facility beam-line ID11 aming to study thresholds, crosstalk between channels and responses of POLAR flight model to polarized X-ray beams. Read More


A future compact and modular X and gamma-ray spectrometer (XGS) has been designed and a series of prototypes have been developed and tested. The experiment envisages the use of CsI scintillator bars read out at both ends by single-cell 25 mm2 Silicon Drift Detectors. Digital algorithms are used to discriminate between events absorbed in the Silicon layer (lower energy X rays) and events absorbed in the scintillator crystal (higher energy X rays and gamma-rays). Read More


Extensive air showers still are our only access to the highest-energy particles in the universe, namely cosmic-ray nuclei with energies up to several 100 EeV. Studying open questions in cosmic-ray physics, like their yet unknown origin requires the reconstruction of the energy and mass of the primary particles from the air-shower measurements. Great progress has been achieved lately in the development of the radio detection technique for this purpose. Read More


2017Apr
Authors: H. Aihara1, N. Arimoto2, R. Armstrong3, S. Arnouts4, N. A. Bahcall5, S. Bickerton6, J. Bosch7, K. Bundy8, P. L. Capak9, J. H. H. Chan10, M. Chiba11, J. Coupon12, E. Egami13, M. Enoki14, F. Finet15, H. Fujimori16, S. Fujimoto17, H. Furusawa18, J. Furusawa19, T. Goto20, A. Goulding21, J. P. Greco22, J. E. Greene23, J. E. Gunn24, T. Hamana25, Y. Harikane26, Y. Hashimoto27, T. Hattori28, M. Hayashi29, Y. Hayashi30, K. G. Hełminiak31, R. Higuchi32, C. Hikage33, P. T. P. Ho34, B. -C. Hsieh35, K. Huang36, S. Huang37, H. Ikeda38, M. Imanishi39, A. K. Inoue40, K. Iwasawa41, I. Iwata42, A. T. Jaelani43, H. -Y. Jian44, Y. Kamata45, H. Karoji46, N. Kashikawa47, N. Katayama48, S. Kawanomoto49, I. Kayo50, J. Koda51, M. Koike52, T. Kojima53, Y. Komiyama54, A. Konno55, S. Koshida56, Y. Koyama57, H. Kusakabe58, A. Leauthaud59, C. -H. Lee60, L. Lin61, Y. -T. Lin62, R. H. Lupton63, R. Mandelbaum64, Y. Matsuoka65, E. Medezinski66, S. Mineo67, S. Miyama68, H. Miyatake69, S. Miyazaki70, R. Momose71, A. More72, S. More73, Y. Moritani74, T. J. Moriya75, T. Morokuma76, S. Mukae77, R. Murata78, H. Murayama79, T. Nagao80, F. Nakata81, M. Niida82, H. Niikura83, A. J. Nishizawa84, Y. Obuchi85, M. Oguri86, Y. Oishi87, N. Okabe88, Y. Okura89, Y. Ono90, M. Onodera91, M. Onoue92, K. Osato93, M. Ouchi94, P. A. Price95, T. -S. Pyo96, M. Sako97, S. Okamoto98, M. Sawicki99, T. Shibuya100, K. Shimasaku101, A. Shimono102, M. Shirasaki103, J. D. Silverman104, M. Simet105, J. Speagle106, D. N. Spergel107, M. A. Strauss108, Y. Sugahara109, N. Sugiyama110, Y. Suto111, S. H. Suyu112, N. Suzuki113, P. J. Tait114, T. Takata115, M. Takada116, N. Tamura117, M. M. Tanaka118, M. Tanaka119, M. Tanaka120, Y. Tanaka121, T. Terai122, Y. Terashima123, Y. Toba124, J. Toshikawa125, E. L. Turner126, T. Uchida127, H. Uchiyama128, K. Umetsu129, F. Uraguchi130, Y. Urata131, T. Usuda132, Y. Utsumi133, S. -Y. Wang134, W. -H. Wang135, K. C. Wong136, K. Yabe137, Y. Yamada138, H. Yamanoi139, N. Yasuda140, S. Yeh141, A. Yonehara142, S. Yuma143
Affiliations: 1HSC Collaboration, 2HSC Collaboration, 3HSC Collaboration, 4HSC Collaboration, 5HSC Collaboration, 6HSC Collaboration, 7HSC Collaboration, 8HSC Collaboration, 9HSC Collaboration, 10HSC Collaboration, 11HSC Collaboration, 12HSC Collaboration, 13HSC Collaboration, 14HSC Collaboration, 15HSC Collaboration, 16HSC Collaboration, 17HSC Collaboration, 18HSC Collaboration, 19HSC Collaboration, 20HSC Collaboration, 21HSC Collaboration, 22HSC Collaboration, 23HSC Collaboration, 24HSC Collaboration, 25HSC Collaboration, 26HSC Collaboration, 27HSC Collaboration, 28HSC Collaboration, 29HSC Collaboration, 30HSC Collaboration, 31HSC Collaboration, 32HSC Collaboration, 33HSC Collaboration, 34HSC Collaboration, 35HSC Collaboration, 36HSC Collaboration, 37HSC Collaboration, 38HSC Collaboration, 39HSC Collaboration, 40HSC Collaboration, 41HSC Collaboration, 42HSC Collaboration, 43HSC Collaboration, 44HSC Collaboration, 45HSC Collaboration, 46HSC Collaboration, 47HSC Collaboration, 48HSC Collaboration, 49HSC Collaboration, 50HSC Collaboration, 51HSC Collaboration, 52HSC Collaboration, 53HSC Collaboration, 54HSC Collaboration, 55HSC Collaboration, 56HSC Collaboration, 57HSC Collaboration, 58HSC Collaboration, 59HSC Collaboration, 60HSC Collaboration, 61HSC Collaboration, 62HSC Collaboration, 63HSC Collaboration, 64HSC Collaboration, 65HSC Collaboration, 66HSC Collaboration, 67HSC Collaboration, 68HSC Collaboration, 69HSC Collaboration, 70HSC Collaboration, 71HSC Collaboration, 72HSC Collaboration, 73HSC Collaboration, 74HSC Collaboration, 75HSC Collaboration, 76HSC Collaboration, 77HSC Collaboration, 78HSC Collaboration, 79HSC Collaboration, 80HSC Collaboration, 81HSC Collaboration, 82HSC Collaboration, 83HSC Collaboration, 84HSC Collaboration, 85HSC Collaboration, 86HSC Collaboration, 87HSC Collaboration, 88HSC Collaboration, 89HSC Collaboration, 90HSC Collaboration, 91HSC Collaboration, 92HSC Collaboration, 93HSC Collaboration, 94HSC Collaboration, 95HSC Collaboration, 96HSC Collaboration, 97HSC Collaboration, 98HSC Collaboration, 99HSC Collaboration, 100HSC Collaboration, 101HSC Collaboration, 102HSC Collaboration, 103HSC Collaboration, 104HSC Collaboration, 105HSC Collaboration, 106HSC Collaboration, 107HSC Collaboration, 108HSC Collaboration, 109HSC Collaboration, 110HSC Collaboration, 111HSC Collaboration, 112HSC Collaboration, 113HSC Collaboration, 114HSC Collaboration, 115HSC Collaboration, 116HSC Collaboration, 117HSC Collaboration, 118HSC Collaboration, 119HSC Collaboration, 120HSC Collaboration, 121HSC Collaboration, 122HSC Collaboration, 123HSC Collaboration, 124HSC Collaboration, 125HSC Collaboration, 126HSC Collaboration, 127HSC Collaboration, 128HSC Collaboration, 129HSC Collaboration, 130HSC Collaboration, 131HSC Collaboration, 132HSC Collaboration, 133HSC Collaboration, 134HSC Collaboration, 135HSC Collaboration, 136HSC Collaboration, 137HSC Collaboration, 138HSC Collaboration, 139HSC Collaboration, 140HSC Collaboration, 141HSC Collaboration, 142HSC Collaboration, 143HSC Collaboration

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2m Subaru telescope on the summit of Maunakea. A team of scientists from Japan, Taiwan and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. Read More


In the last few years, integrated optics (IO) beam combiners have facilitated the emergence of 4-telescope interferometers such as PIONIER or GRAVITY, boosting the imaging capabilities of the VLTI. However, the spectral range beyond 2.2microns is not ideally covered by the conventional silica based IO. Read More


A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the measurement of stellar positions by means of a meridian circle, then the fundamental instrument of astrometry. Read More


Resolvable Supermassive Black Hole Binaries are promising sources for Pulsar Timing Array based gravitational wave searches. Search algorithms for such targets must contend with the large number of so-called pulsar phase parameters in the joint log-likelihood function of the data. We compare the localization accuracy for two approaches: Maximization over the pulsar phase parameters (MaxPhase) against marginalization over them (AvPhase). Read More


In the late 1620s the Neapolitan telescope maker Francesco Fontana was the first to observe the sky using a telescope with two convex lenses, which he had manufactured himself. Fontana succeeded in drawing the most accurate maps of the Moon's surface of his time, which were to become popular through a number of publications spread all over Europe but without acknowledging the author. At the end of 1645, in a state of declining health and pressed by the need to defend his authorship, Fontana carried out an intense observational campaign, whose results he hurriedly collected in his Novae Coelestium Terrestriumque rerum Observationis (1646), the only book he left to posterity. Read More


Current constraints on models of galaxy evolution rely on morphometric catalogs extracted from multi-band photometric surveys. However, these catalogs are altered by selection effects that are diffcult to model, correlate in non trivial ways and can lead to contradictory predictions if not taken into account carefully. To address this issue, we have developed a new approach combining Approximate Bayesian Computation techniques and empirical modeling with realistic image simulations that reproduce a large fraction of these selection effects. Read More


Segmented aperture telescopes require an alignment procedure with successive steps from coarse alignment to monitoring process in order to provide very high optical quality images for stringent science operations such as exoplanet imaging. The final step, referred to as fine phasing, calls for a high sensitivity wavefront sensing and control system in a diffraction-limited regime to achieve segment alignment with nanometric accuracy. In this context, Zernike wavefront sensors represent promising options for such a calibration. Read More


We propose a new mathematical model for $n-k$-dimensional non-linear correlations with intrinsic scatter in $n$-dimensional data. The model is based on Riemannian geometry, and is naturally invariant under coordinate transformations. We combine the model with a Bayesian approach for estimating the parameters of the correlation relation and the intrinsic scatter. Read More


We present a toolbox of new techniques and concepts for the efficient forecasting of experimental sensitivities. These are applicable to a large range of scenarios in (astro-)particle physics, and based on the Fisher information formalism. Fisher information provides an answer to the question what is the maximum extractable information from a given observation?. Read More


Direct imaging of exoplanets represents a challenge for astronomical instrumentation due to the high-contrast ratio and small angular separation between the host star and the faint planet. Multi-star systems pose additional challenges for coronagraphic instruments due to the diffraction and aberration leakage caused by companion stars. Consequently, many scientifically valuable multi-star systems are excluded from direct imaging target lists for exoplanet surveys and characterization missions. Read More


When modern efforts for radio detection of cosmic rays started about a decade ago, hopes were high but the true potential was unknown. Since then, we have achieved a detailed understanding of the radio emission physics and have consequently succeeded in developing sophisticated detection schemes and analysis approaches. In particular, we have demonstrated that the important air-shower parameters arrival direction, particle energy and depth of shower maximum can be reconstructed reliably from radio measurements, with a precision that is comparable with that of other detection techniques. Read More


The lunar technique is a method for maximising the collection area for ultra-high-energy (UHE) cosmic ray and neutrino searches. The method uses either ground-based radio telescopes or lunar orbiters to search for Askaryan emission from particles cascading near the lunar surface. While experiments using the technique have made important advances in the detection of nanosecond-scale pulses, only at the very highest energies has the lunar technique achieved competitive limits. Read More


We examine the gender balance of the 18th and 19th meetings of the Cambridge Workshop on Cool Stellar Systems and the Sun (CS18 and CS19). The percent of female attendees at both meetings (31% at CS18 and 37% at CS19) was higher than the percent of women in the American Astronomical Society (25%) and the International Astronomical Union (18%). The representation of women in Cool Stars as SOC members, invited speakers, and contributed speakers was similar to or exceeded the percent of women attending the meetings. Read More


This paper addresses maximum likelihood (ML) estimation based model fitting in the context of extrasolar planet detection. This problem is featured by the following properties: 1) the candidate models under consideration are highly nonlinear; 2) the likelihood surface has a huge number of peaks; 3) the parameter space ranges in size from a few to dozens of dimensions. These properties make the ML search a very challenging problem, as it lacks any analytical or gradient based searching solution to explore the parameter space. Read More


New scientific instruments are starting to generate an unprecedented amount of data. LOFAR, one of the Square Kilometre Array pathfinders, is already producing data on a petabyte scale. The calibration of these data presents a huge challenge for final users: a) extensive storage and computing resources are required; b) the installation and maintenance of the processing software is not trivial; and c) the requirements of (experimental) calibration pipelines are quickly evolving. Read More


Determination of absolute parallaxes by means of a scanning astrometric satellite such as Hipparcos or Gaia relies on the short-term stability of the so-called basic angle between the two viewing directions. Uncalibrated variations of the basic angle may produce systematic errors in the computed parallaxes. We examine the coupling between a global parallax shift and specific variations of the basic angle, namely those related to the satellite attitude with respect to the Sun. Read More


While in the case of zero offset data with horizontal beds, it is clear that the recorded trace is a convolution of the wavelet and reflectivity series, the situation in the case of finite offset is a bit more complex as the direction of the incident ray is not vertical, the natural direction in which the reflectivity series is measured.We examine the consequences of this hitherto neglected fact. Read More


We evaluate the performance of four different machine learning algorithms (ANN, Adaboost, GBC, XGBoost), in the separation of pulsars from radio frequency interference (RFI) and other sources of noise, using a dataset consisting of pulsar candidates obtained from the post-processing of a pulsar search pipeline. This dataset was previously used for cross-validation of the {\tt SPINN}-based machine learning engine, which was used for the re-processing of the HTRU-S survey. We report a variety of quality metrics from all four of these algorithms. Read More


Astrophysics and cosmology are rich with data. The advent of wide-area digital cameras on large aperture telescopes has led to ever more ambitious surveys of the sky. Data volumes of entire surveys a decade ago can now be acquired in a single night and real-time analysis is often desired. Read More


The current generation of radio and millimeter telescopes, particularly the Atacama Large Millimeter Array (ALMA), offers enormous advances in observing capabilities. While these advances represent an unprecedented opportunity to advance scientific understanding, the increased complexity in the spatial and spectral structure of even a single spectral line is hard to interpret. The complexity present in current ALMA data cubes therefore challenges not only the existing tools for fundamental analysis of these datasets, but also users' ability to explore and visualize their data. Read More


The requirements-driven OSIRIS-REx Camera Suite (OCAMS) acquires images essential to collecting a sample from the surface of Bennu. During proximity operations, these images document the presence of satellites and plumes, record spin state, enable an accurate digital terrain model of the shape of the asteroid and identify any surface hazards. They confirm the presence of sampleable regolith on the surface, observe the sampling event itself, and image the sample head in order to verify its readiness to be stowed. Read More


2017Apr
Authors: M. Remazeilles, A. J. Banday, C. Baccigalupi, S. Basak, A. Bonaldi, G. De Zotti, J. Delabrouille, C. Dickinson, H. K. Eriksen, J. Errard, R. Fernandez-Cobos, U. Fuskeland, C. Hervías-Caimapo, M. López-Caniego, E. Martinez-González, M. Roman, P. Vielva, I. Wehus, A. Achucarro, P. Ade, R. Allison, M. Ashdown, M. Ballardini, R. Banerji, N. Bartolo, J. Bartlett, D. Baumann, M. Bersanelli, M. Bonato, J. Borrill, F. Bouchet, F. Boulanger, T. Brinckmann, M. Bucher, C. Burigana, A. Buzzelli, Z. -Y. Cai, M. Calvo, C. -S. Carvalho, G. Castellano, A. Challinor, J. Chluba, S. Clesse, I. Colantoni, A. Coppolecchia, M. Crook, G. D'Alessandro, P. de Bernardis, G. de Gasperis, J. -M. Diego, E. Di Valentino, S. Feeney, S. Ferraro, F. Finelli, F. Forastieri, S. Galli, R. Genova-Santos, M. Gerbino, J. González-Nuevo, S. Grandis, J. Greenslade, S. Hagstotz, S. Hanany, W. Handley, C. Hernandez-Monteagudo, M. Hills, E. Hivon, K. Kiiveri, T. Kisner, T. Kitching, M. Kunz, H. Kurki-Suonio, L. Lamagna, A. Lasenby, M. Lattanzi, J. Lesgourgues, A. Lewis, M. Liguori, V. Lindholm, G. Luzzi, B. Maffei, C. J. A. P. Martins, S. Masi, D. McCarthy, J. -B. Melin, A. Melchiorri, D. Molinari, A. Monfardini, P. Natoli, M. Negrello, A. Notari, A. Paiella, D. Paoletti, G. Patanchon, M. Piat, G. Pisano, L. Polastri, G. Polenta, A. Pollo, V. Poulin, M. Quartin, J. -A. Rubino-Martin, L. Salvati, A. Tartari, M. Tomasi, D. Tramonte, N. Trappe, T. Trombetti, C. Tucker, J. Valiviita, R. Van de Weijgaert, B. van Tent, V. Vennin, N. Vittorio, K. Young, for the CORE collaboration

We demonstrate that, for the baseline design of the CORE satellite mission, the polarized foregrounds can be controlled at the level required to allow the detection of the primordial cosmic microwave background (CMB) $B$-mode polarization with the desired accuracy at both reionization and recombination scales, for tensor-to-scalar ratio values of $r\gtrsim 5\times 10^{-3}$. Under the assumption of perfect control of lensing effects, CORE would measure an unbiased estimate of $r=5\times 10^{-3}$ with an uncertainty of ${\sigma(r=5\times 10^{-3})=0.4\times 10^{-3}}$ after foreground cleaning. Read More


We describe an experiment, located in south-east Colorado, USA, that measured aerosol optical depth profiles using two Lidar techniques. Two independent detectors measured scattered light from a vertical UV laser beam. One detector, located at the laser site, measured light via the inelastic Raman backscattering process. Read More


One proposed method for spacecraft to reach nearby stars is by accelerating sails using either solar radiation pressure or beamed lasers. This idea constitutes the thesis behind the Breakthrough Starshot Initiative, which aims to accelerate a gram-mass spacecraft up to one-fifth the speed of light towards Proxima Centauri. For such a case, the spacecraft's low mass and relativistic terminal velocity render classical treatments invalid. Read More


Soft gamma repeaters and anomalous X-ray pulsars are thought to be magnetars, neutron stars with strong magnetic fields of order $\mathord{\sim} 10^{13}$--$10^{15} \, \mathrm{gauss}$. These objects emit intermittent bursts of hard X-rays and soft gamma rays. Quasiperiodic oscillations in the X-ray tails of giant flares imply the existence of neutron star oscillation modes which could emit gravitational waves powered by the magnetar's magnetic energy reservoir. Read More


MOEMS Deformable Mirrors (DM) are key components for next generation instruments with innovative adaptive optics systems, in existing telescopes and in the future ELTs. These DMs must perform at room temperature as well as in cryogenic and vacuum environment. Ideally, the MOEMS-DMs must be designed to operate in such environment. Read More


The IceCube neutrino telescope monitors one cubic kilometer of deep Antarctic ice by detecting Cherenkov photons emitted from charged secondaries produced when neutrinos interact in the ice. The geometry of the detector, which comprises a lattice of 5160 photomultipliers, is optimized for the detection of neutrinos above 100 GeV. However, at subfreezing ice temperatures, dark noise rates are low enough that a high flux of MeV neutrinos streaming through the detector may be recognized by a collective rate enhancement in all photomultipliers. Read More