RAS_WEB (Page 4,535)

An Algorithm for the Visualization of Relevant Patterns in Astronomical Light Curves. (arXiv:1903.03254v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Pieringer_C/0/1/0/all/0/1">Christian Pieringer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pichara_K/0/1/0/all/0/1">Karim Pichara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Catelan_M/0/1/0/all/0/1">M&#xe1;rcio Catel&#xe1;n</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Protopapas_P/0/1/0/all/0/1">Pavlos Protopapas</a> Within the last years, the classification of variable stars with Machine Learning has become a mainstream area of research. Recently, visualization of time series is attracting more attention in data science as a tool to visually help scientists to recognize significant patterns in complex dynamics. Within the Machine Learning literature, dictionary-based methods have been widely used to encode relevant parts of image data. These methods intrinsically assign a degree of importance to patches in pictures, according to their contributionRead More →

Coherent radio emission from a twisted magnetosphere after magnetar-quake. (arXiv:1903.03257v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_W/0/1/0/all/0/1">Weiyang Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_B/0/1/0/all/0/1">Bing Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_X/0/1/0/all/0/1">Xuelei Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_R/0/1/0/all/0/1">Renxin Xu</a> Magnetars are a class of highly magnetized, slowly rotating neutron stars, only a small fraction of which exhibit radio emission. We propose that the coherent radio curvature emission is generated by net charge fluctuations from a twist-current-carrying bundle (the j-bundle) in the scenario of magnetar-quake. Two-photon pair production is triggered, which requires a threshold voltage not too much higher than $10^9$ V in the current-carrying bundle, and which can be regarded as the `open field lines’ of a magnetar. Continued untwisting ofRead More →

Science from an Ultra-Deep, High-Resolution Millimeter-Wave Survey. (arXiv:1903.03263v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sehgal_N/0/1/0/all/0/1">Neelima Sehgal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nguyen_H/0/1/0/all/0/1">Ho Nam Nguyen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meyers_J/0/1/0/all/0/1">Joel Meyers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Munchmeyer_M/0/1/0/all/0/1">Moritz Munchmeyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mroczkowski_T/0/1/0/all/0/1">Tony Mroczkowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mascolo_L/0/1/0/all/0/1">Luca Di Mascolo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baxter_E/0/1/0/all/0/1">Eric Baxter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cyr_Racine_F/0/1/0/all/0/1">Francis-Yan Cyr-Racine</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Madhavacheril_M/0/1/0/all/0/1">Mathew Madhavacheril</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beringue_B/0/1/0/all/0/1">Benjamin Beringue</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holder_G/0/1/0/all/0/1">Gil Holder</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nagai_D/0/1/0/all/0/1">Daisuke Nagai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dicker_S/0/1/0/all/0/1">Simon Dicker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dvorkin_C/0/1/0/all/0/1">Cora Dvorkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferraro_S/0/1/0/all/0/1">Simone Ferraro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuller_G/0/1/0/all/0/1">George M. Fuller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gluscevic_V/0/1/0/all/0/1">Vera Gluscevic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Han_D/0/1/0/all/0/1">Dongwon Han</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jain_B/0/1/0/all/0/1">Bhuvnesh Jain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnson_B/0/1/0/all/0/1">Bradley Johnson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Klaassen_P/0/1/0/all/0/1">Pamela Klaassen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meerburg_D/0/1/0/all/0/1">Daan Meerburg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Motloch_P/0/1/0/all/0/1">Pavel Motloch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spergel_D/0/1/0/all/0/1">David N. Spergel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Engelen_A/0/1/0/all/0/1">Alexander van Engelen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Adshead_P/0/1/0/all/0/1">Peter Adshead</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Armstrong_R/0/1/0/all/0/1">Robert Armstrong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baccigalupi_C/0/1/0/all/0/1">Carlo Baccigalupi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barron_D/0/1/0/all/0/1">Darcy Barron</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Basu_K/0/1/0/all/0/1">Kaustuv Basu</a>, <aRead More →

Constraining dark matter-neutrino interactions with IceCube-170922A. (arXiv:1903.03302v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Choi_K/0/1/0/all/0/1">Ki-Young Choi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_J/0/1/0/all/0/1">Jongkuk Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rott_C/0/1/0/all/0/1">Carsten Rott</a> Astrophysical neutrinos travel long distances from their sources to the Earth traversing dark matter halos of clusters of galaxies and that of our own Milky Way. The interaction of neutrinos with dark matter may affect the flux of neutrinos. The recent multi-messenger observation of a high energy neutrino, IceCube-170922A, can give a robust upper bound $sigma /M_{dm} lesssim 5.1times 10^{-23} {rm cm}^2 /$GeV on the interaction between neutrino and dark matter at a neutrino energy of 290 TeV allowing 90% suppression. Combining the constraints from CMB and LSSRead More →

Dynamics to the universal structure of one-dimensional self-gravitating systems in the quasi-equilibrium state. (arXiv:1903.03307v1 [cond-mat.stat-mech]) <a href="http://arxiv.org/find/cond-mat/1/au:+Tashiro_T/0/1/0/all/0/1">Tohru Tashiro</a> We investigate the quasi-equilibrium state of one-dimensional self-gravitating systems. If the null virial condition is satisfied at initial time, it is found that the number density around the center of the system at the quasi-equilibrium state has the universality similar to two- and three-dimensional self-gravitating systems reported in cite{Tashiro16,Tashiro10}. The reason why the null virial condition is sufficient for the universality is unveiled by the envelope equation. We present a phenomenological model to describe the universal structure by using a special Langevin equation with a distinctive randomRead More →

Colorado Ultraviolet Transit Experiment Data Simulator. (arXiv:1903.03314v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sreejith_A/0/1/0/all/0/1">Aickara Gopinathan Sreejith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fossati_L/0/1/0/all/0/1">Luca Fossati</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fleming_B/0/1/0/all/0/1">Brian T. Fleming</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+France_K/0/1/0/all/0/1">Kevin France</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koskinen_T/0/1/0/all/0/1">Tommi Koskinen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Egan_A/0/1/0/all/0/1">Arika Egan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rudisser_H/0/1/0/all/0/1">Hannah T. R&#xfc;disser</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Steller_M/0/1/0/all/0/1">Manfred Steller</a> The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on-board a low-resolution (R~2000–3000), near-ultraviolet (2500–3300 {AA}) spectrograph. It has a rectangular primary Cassegrain telescope to maximize the collecting area. CUTE, which is planned for launch in Spring 2020, is designed to monitor transiting extra-solar planets orbiting bright, nearby stars aiming at improving our understanding of planet atmospheric escape and star-planet interaction processes. We present here the CUTERead More →

Reverse Shocks in the Relativistic Outflows of Gravitational Wave Detected Neutron Star Binary Mergers. (arXiv:1903.03320v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Lamb_G/0/1/0/all/0/1">Gavin P Lamb</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kobayashi_S/0/1/0/all/0/1">Shiho Kobayashi</a> The afterglows to gamma-ray bursts (GRBs) are due to synchrotron emission from shocks generated as an ultra-relativistic outflow decelerates. A forward and a reverse shock will form, however, where emission from the forward shock is well studied as a potential counterpart to gravitational wave detected neutron star mergers the reverse shock has been neglected. Here, we show how the reverse shock contributes to the afterglow from an off-axis and structured outflow. The reverse shock will be observable as a brightening feature inRead More →

Efficient Selection of Quasar Candidates Based on Optical and Infrared Photometric Data Using Machine Learning. (arXiv:1903.03335v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Jin_X/0/1/0/all/0/1">Xin Jin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Y/0/1/0/all/0/1">Yanxia Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_J/0/1/0/all/0/1">Jingyi Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhao_Y/0/1/0/all/0/1">Yongheng Zhao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_X/0/1/0/all/0/1">Xue-bing Wu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fan_D/0/1/0/all/0/1">Dongwei Fan</a> We aim to select quasar candidates based on the two large survey databases, Pan-STARRS and AllWISE. Exploring the distribution of quasars and stars in the color spaces, we find that the combination of infrared and optical photometry is more conducive to select quasar candidates. Two new color criterions (yW1W2 and izW1W2) are constructed to distinguish quasars from stars efficiently. With izW1W2, 98.30% of star contamination is eliminated, while 99.50% ofRead More →

Application of Google Cloud Platform in Astrophysics. (arXiv:1903.03337v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Landoni_M/0/1/0/all/0/1">M. Landoni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taffoni_G/0/1/0/all/0/1">G. Taffoni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bignamini_A/0/1/0/all/0/1">A. Bignamini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smareglia_R/0/1/0/all/0/1">R. Smareglia</a> The availability of new Cloud Platform offered by Google motivated us to propose nine Proof of Concepts (PoC) aiming to demonstrated and test the capabilities of the platform in the context of scientifically-driven tasks and requirements. We review the status of our initiative by illustrating 3 out of 9 successfully closed PoC that we implemented on Google Cloud Platform. In particular, we illustrate a cloud architecture for deployment of scientific software as microservice coupling Google Compute Engine with Docker and Pub/Sub to dispatch heavilyRead More →

The activation method for cross section measurements in nuclear astrophysics. (arXiv:1903.03339v1 [nucl-ex]) <a href="http://arxiv.org/find/nucl-ex/1/au:+Gyurky_G/0/1/0/all/0/1">Gy. Gy&#xfc;rky</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Fulop_Z/0/1/0/all/0/1">Zs. F&#xfc;l&#xf6;p</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Kappeler_F/0/1/0/all/0/1">F. K&#xe4;ppeler</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Kiss_G/0/1/0/all/0/1">G.G. Kiss</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Wallner_A/0/1/0/all/0/1">A. Wallner</a> The primary aim of experimental nuclear astrophysics is to determine the rates of nuclear reactions taking place in stars in various astrophysical conditions. These reaction rates are important ingredient for understanding the elemental abundance distribution in our solar system and the galaxy. The reaction rates are determined from the cross sections which need to be measured at energies as close to the astrophysically relevant ones as possible. In many cases the final nucleus of an astrophysically important reactionRead More →

An extremely low-mass He white dwarf orbiting the millisecond pulsar J1342+2822B in the globular cluster M3. (arXiv:1903.03345v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Cadelano_M/0/1/0/all/0/1">M. Cadelano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferraro_F/0/1/0/all/0/1">F. R. Ferraro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Istrate_A/0/1/0/all/0/1">A. G. Istrate</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pallanca_C/0/1/0/all/0/1">C. Pallanca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lanzoni_B/0/1/0/all/0/1">B. Lanzoni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Freire_P/0/1/0/all/0/1">P. C. C. Freire</a> We report on the discovery of the companion star to the millisecond pulsar J1342+2822B in the globular cluster M3. We exploited a combination of near-ultraviolet and optical observations acquired with the Hubble Space Telescope in order to search for the optical counterparts to the known millisecond pulsars in this cluster. At a position in excellent agreement with that of the radio pulsar J1342+2822B (M3B), weRead More →

The ALMA-PILS survey: First detection of nitrous acid (HONO) in the interstellar medium. (arXiv:1903.03378v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Coutens_A/0/1/0/all/0/1">A. Coutens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ligterink_N/0/1/0/all/0/1">N. F. W. Ligterink</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Loison_J/0/1/0/all/0/1">J.-C. Loison</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wakelam_V/0/1/0/all/0/1">V. Wakelam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Calcutt_H/0/1/0/all/0/1">H. Calcutt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Drozdovskaya_M/0/1/0/all/0/1">M. N. Drozdovskaya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jorgensen_J/0/1/0/all/0/1">J. K. J&#xf8;rgensen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muller_H/0/1/0/all/0/1">H. S. P. M&#xfc;ller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dishoeck_E/0/1/0/all/0/1">E. F. van Dishoeck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wampfler_S/0/1/0/all/0/1">S. F. Wampfler</a> Nitrogen oxides are thought to play a significant role as a nitrogen reservoir and to potentially participate in the formation of more complex species. Until now, only NO, N$_2$O and HNO have been detected in the interstellar medium. We report the first interstellar detection of nitrous acid (HONO). Twelve lines wereRead More →

Matter Growth in Imperfect Fluid Cosmology. (arXiv:1903.03383v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Zimdahl_W/0/1/0/all/0/1">Winfried Zimdahl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Velten_H/0/1/0/all/0/1">Hermano Velten</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Algoner_W/0/1/0/all/0/1">William C. Algoner</a> Extensions of Einstein’s General Relativity (GR) can formally be given a GR structure in which additional geometric degrees of freedom are mapped on an effective energy-momentum tensor. The corresponding effective cosmic medium can then be modeled as an imperfect fluid within GR. The imperfect fluid structure allows us to include, on a phenomenological basis, anisotropic stresses and energy fluxes which are considered as potential signatures for deviations from the cosmological standard $Lambda$-cold-dark-matter ($Lambda$CDM) model. As an example, we consider the dynamics of a scalar-tensor extension of theRead More →

The Analogous Structure of Accretion Flows in Supermassive and Stellar Mass Black Holes. (arXiv:1903.02553v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ruan_J/0/1/0/all/0/1">John J. Ruan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anderson_S/0/1/0/all/0/1">Scott F. Anderson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eracleous_M/0/1/0/all/0/1">Michael Eracleous</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Green_P/0/1/0/all/0/1">Paul J. Green</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haggard_D/0/1/0/all/0/1">Daryl Haggard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+MacLeod_C/0/1/0/all/0/1">Chelsea L. MacLeod</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Runnoe_J/0/1/0/all/0/1">Jessie C. Runnoe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sobolewska_M/0/1/0/all/0/1">Malgosia Sobolewska</a> Black holes grow rapidly through the accretion of gas. As the accretion rate onto a black hole decreases, the structure of its surrounding accretion flow is believed to dramatically transition from a luminous thin disc to become quasi-spherical and radiatively inefficient. These accretion state transitions are commonly observed for stellar mass black holes in Galactic X-ray binary systems, but it isRead More →

Ionization age of iron ejecta in the Galactic Type Ia supernova remnant G306.3-0.9. (arXiv:1903.02554v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sawada_M/0/1/0/all/0/1">Makoto Sawada</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tachibana_K/0/1/0/all/0/1">Katsuhiro Tachibana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uchida_H/0/1/0/all/0/1">Hiroyuki Uchida</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ito_Y/0/1/0/all/0/1">Yuta Ito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matsumura_H/0/1/0/all/0/1">Hideaki Matsumura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bamba_A/0/1/0/all/0/1">Aya Bamba</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsuru_T/0/1/0/all/0/1">Takeshi Go Tsuru</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tanaka_T/0/1/0/all/0/1">Takaaki Tanaka</a> We present a 190 ks observation of the Galactic supernova remnant (SNR) G306.3-0.9 with Suzaku. To study ejecta properties of this possible Type Ia SNR, the absolute energy scale at the Fe-K band was calibrated to a level of uncertainty less than 10 eV by a cross-calibration with the Hitomi microcalorimeter using the Perseus cluster spectra. This enabled us for the first time to accuratelyRead More →

Evidence of two spectral breaks in the prompt emission of Gamma Ray Bursts. (arXiv:1903.02555v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ravasio_M/0/1/0/all/0/1">M. E. Ravasio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ghirlanda_G/0/1/0/all/0/1">G. Ghirlanda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nava_L/0/1/0/all/0/1">L. Nava</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ghisellini_G/0/1/0/all/0/1">G. Ghisellini</a> The long-lasting tension between the observed spectra of Gamma Ray Bursts (GRBs) and the predicted synchrotron emission spectrum might be solved if electrons do not completely cool. Evidence for incomplete cooling was recently found in Swift GRBs with prompt observations down to 0.1 keV and in one bright Fermi burst, GRB 160625B. Here we systematically search for evidence of incomplete cooling in the spectra of the ten brightest short and long GRBs observed by Fermi. We findRead More →

DASH: Deep Learning for the Automated Spectral Classification of Supernovae and their Hosts. (arXiv:1903.02557v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Muthukrishna_D/0/1/0/all/0/1">Daniel Muthukrishna</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parkinson_D/0/1/0/all/0/1">David Parkinson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tucker_B/0/1/0/all/0/1">Brad Tucker</a> We present {tt DASH} (Deep Automated Supernova and Host classifier), a novel software package that automates the classification of the type, age, redshift, and host galaxy of supernova spectra. {tt DASH} makes use of a new approach which does not rely on iterative template matching techniques like all previous software, but instead classifies based on the learned features of each supernova type and age bin. It has achieved this by employing a deep convolutional neural network to train a matching algorithm.Read More →