RAS_WEB (Page 4,635)

DASH: a library of dynamical subhalo evolution. (arXiv:1901.08601v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ogiya_G/0/1/0/all/0/1">Go Ogiya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bosch_F/0/1/0/all/0/1">Frank C. van den Bosch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hahn_O/0/1/0/all/0/1">Oliver Hahn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Green_S/0/1/0/all/0/1">Sheridan B. Green</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miller_T/0/1/0/all/0/1">Tim B. Miller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burkert_A/0/1/0/all/0/1">Andreas Burkert</a> The abundance and demographics of dark matter substructure is important for many areas in astrophysics and cosmological $N$-body simulations have been the primary tool used to investigate them. However, it has recently become clear that the simulations are subject to numerical artefacts, which hampers a proper treatment of the tidal evolution of subhaloes. Unfortunately, no analytical models that accurately describe subhalo evolution exist either. We therefore present a library of idealized, high resolutionRead More →

Hyperinflation generalised: from its attractor mechanism to its tension with the `swampland conjectures’. (arXiv:1901.08603v1 [hep-th]) <a href="http://arxiv.org/find/hep-th/1/au:+Bjorkmo_T/0/1/0/all/0/1">Theodor Bjorkmo</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Marsh_M/0/1/0/all/0/1">M. C. David Marsh</a> In negatively curved field spaces, inflation can be realised even in steep potentials. Hyperinflation invokes the `centrifugal force’ of a field orbiting the hyperbolic plane to sustain inflation. We generalise hyperinflation by showing that it can be realised in models with any number of fields ($N_fgeq2$), and in broad classes of potentials that, in particular, don’t need to be rotationally symmetric. For example, hyperinflation can follow a period of radial slow-roll inflation that undergoes geometric destabilisation, yet this inflationary phase is notRead More →

Implications on Spatial Models of Interstellar Gamma-Ray Inverse-Compton Emission from Synchrotron Emission Studies in Radio and Microwaves. (arXiv:1901.08604v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Orlando_E/0/1/0/all/0/1">E. Orlando</a> Cosmic rays interacting with gas and photon fields in the Galaxy produce interstellar gamma-ray emission (IGE), which accounts for almost 50% of the photons detected at gamma-ray energies. Models of this IGE have to be very accurate for interpreting the high-quality observations by present gamma-ray telescopes, such as Fermi Large Area Telescope (LAT). Standard models of IGE, used as reference models for analyses of the Fermi LAT data, show spatial discrepancies with respect to the data, underlining the necessity of more realistic models.Read More →

Investing for Discovery and Sustainability in Astronomy in the 2020s. (arXiv:1901.08605v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Najita_J/0/1/0/all/0/1">Joan R. Najita</a> As the next decade approaches, it is once again time for the US astronomical community to assess its investment priorities for the coming decade on the ground and in space. This report, created to aid NOAO in its planning for the 2020 Decadal Survey on Astronomy and Astrophysics, reviews the outcome of the previous Decadal Survey (Astro2010); describes the themes that emerged from the 2018 NOAO community planning workshop “NOAO Community Needs for Science in the 2020s”; and based on the above, offers thoughts for the coming review. WeRead More →

Triple-Lens Gravitational Microlensing: Critical Curves for Arbitrary Spatial Configuration. (arXiv:1901.08610v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Danek_K/0/1/0/all/0/1">Kamil Danek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heyrovsky_D/0/1/0/all/0/1">David Heyrovsky</a> Since the first observation of triple-lens gravitational microlensing in 2006, analyses of six more events have been published by the end of 2018. In three events the lens was a star with two planets; four involved a binary star with a planet. Other possible triple lenses such as triple stars or stars with a planet with a moon are yet to be detected. The analysis of triple-lens events is hindered by the lack of understanding of the diversity of their caustics and critical curves. We present a methodRead More →

Protostellar Outflows at the EarliesT Stages (POETS). II. A possible radio synchrotron jet associated with the EGO G035.02+0.35. (arXiv:1901.08611v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sanna_A/0/1/0/all/0/1">A. Sanna</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moscadelli_L/0/1/0/all/0/1">L. Moscadelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goddi_C/0/1/0/all/0/1">C. Goddi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beltran_M/0/1/0/all/0/1">M. Beltran</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brogan_C/0/1/0/all/0/1">C.L. Brogan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garatti_A/0/1/0/all/0/1">A. Caratti o Garatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carrasco_Gonzalez_C/0/1/0/all/0/1">C. Carrasco-Gonzalez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hunter_T/0/1/0/all/0/1">T.R. Hunter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Massi_F/0/1/0/all/0/1">F. Massi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Padovani_M/0/1/0/all/0/1">M. Padovani</a> Centimeter continuum observations of protostellar jets have revealed the presence of knots of shocked gas where the flux density decreases with frequency. This spectrum is characteristic of nonthermal synchrotron radiation and implies the presence of both magnetic fields and relativistic electrons in protostellar jets. Here, we report on one of the few detectionsRead More →

RADYNVERSION: Learning to Invert a Solar Flare Atmosphere with Invertible Neural Networks. (arXiv:1901.08626v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Osborne_C/0/1/0/all/0/1">Christopher M. J. Osborne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Armstrong_J/0/1/0/all/0/1">John A. Armstrong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fletcher_L/0/1/0/all/0/1">Lyndsay Fletcher</a> During a solar flare, it is believed that reconnection takes place in the corona followed by fast energy transport to the chromosphere. The resulting intense heating strongly disturbs the chromospheric structure, and induces complex radiation hydrodynamic effects. Interpreting the physics of the flaring solar atmosphere is one of the most challenging tasks in solar physics. Here we present a novel deep learning approach, an invertible neural network, to understanding the chromospheric physics of a flaring solar atmosphere via theRead More →

Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere. (arXiv:1901.08640v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Helling_C/0/1/0/all/0/1">Ch. Helling</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gourbin_P/0/1/0/all/0/1">P. Gourbin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Woitke_P/0/1/0/all/0/1">P. Woitke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parmentier_V/0/1/0/all/0/1">V. Parmentier</a> WASP-18b is an utra-hot Jupiter with a temperature difference of upto 2500K between day and night. Such giant planets begin to emerge as planetary laboratory for understanding cloud formation and gas chemistry in well-tested parameter regimes in order to better understand planetary mass loss and for linking observed element ratios to planet formation and evolution. We aim to understand where clouds form, their interaction with the gas phase chemistry through depletion and enrichment,Read More →

A Hot Ultraviolet Flare on the M Dwarf Star GJ 674. (arXiv:1901.08647v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Froning_C/0/1/0/all/0/1">C.S. Froning</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kowalski_A/0/1/0/all/0/1">A. Kowalski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+France_K/0/1/0/all/0/1">K. France</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Loyd_R/0/1/0/all/0/1">R.O. Parke Loyd</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schneider_P/0/1/0/all/0/1">P. Christian Schneider</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Youngblood_A/0/1/0/all/0/1">A. Youngblood</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilson_D/0/1/0/all/0/1">D. Wilson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_A/0/1/0/all/0/1">A. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berta_Thompson_Z/0/1/0/all/0/1">Z. Berta-Thompson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pineda_J/0/1/0/all/0/1">J. Sebastian Pineda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Linsky_J/0/1/0/all/0/1">J. Linsky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rugheimer_S/0/1/0/all/0/1">S. Rugheimer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miguel_Y/0/1/0/all/0/1">Y. Miguel</a> As part of the Mega MUSCLES Hubble Space Telescope (HST) Treasury program, we obtained time-series ultraviolet spectroscopy of the M2.5V star, GJ~674. During the FUV monitoring observations, the target exhibited several small flares and one large flare (E_FUV = 10^{30.75} ergs) that persisted over the entirety of a HST orbitRead More →

ALMA Autocorrelation Spectroscopy of Comets: The HCN/H^13CN ratio in C/2012 S1 (ISON). (arXiv:1901.08676v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Cordiner_M/0/1/0/all/0/1">M. A. Cordiner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Palmer_M/0/1/0/all/0/1">M. Y. Palmer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Val_Borro_M/0/1/0/all/0/1">M. de Val-Borro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Charnley_S/0/1/0/all/0/1">S. B. Charnley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paganini_L/0/1/0/all/0/1">L. Paganini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Villanueva_G/0/1/0/all/0/1">G. Villanueva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bockelee_Morvan_D/0/1/0/all/0/1">D. Bockel&#xe9;e-Morvan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Biver_N/0/1/0/all/0/1">N. Biver</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Remijan_A/0/1/0/all/0/1">A. J. Remijan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuan_Y/0/1/0/all/0/1">Y.-J. Kuan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Milam_S/0/1/0/all/0/1">S. N. Milam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crovisier_J/0/1/0/all/0/1">J. Crovisier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lis_D/0/1/0/all/0/1">D. C. Lis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mumma_M/0/1/0/all/0/1">M. J. Mumma</a> The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful tool for high-resolution mapping of comets, but the main interferometer (comprised of 50×12-m antennas) is insensitive to the largest coma scales due to a lack of very short baselines. In this work,Read More →

Investigation of the Mode-Switching Phenomenon in Pulsar B0329+54 Through Polarimetric Analysis. (arXiv:1901.08677v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Brinkman_C/0/1/0/all/0/1">Casey Brinkman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mitra_D/0/1/0/all/0/1">Dipanjan Mitra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rankin_J/0/1/0/all/0/1">Joanna Rankin</a> The phenomenon of profile mode switching in pulsars, where the stable average pulse profile changes to another stable state on the timescale of a pulsar’s period, remains poorly understood. We sought to understand how pulsars undergo profile mode switching through a comparative analysis of the polarization and geometry of the two different profile modes of PSR B0329+54. The polarization behavior and fitted parameters of the rotation-vector model remain constant between modes, and the emission height remains constant as well. These similarities lend supportRead More →

Fourier series expansion of the dark energy equation of state. (arXiv:1901.08679v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Tamayo_D/0/1/0/all/0/1">David Tamayo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vazquez_J/0/1/0/all/0/1">J. Alberto Vazquez</a> The dark energy component of the universe still remains as a mystery, however, several papers based on observational data have shown that its equation of state may have an oscillatory behaviour. In this paper, we provide a general description for the dark-energy equation-of-state $w(z)$ in the form of Fourier series. This description generalises some previous dynamical dark energy models and is in agreement with the $w(z)$ reconstructions. We make use of a modified version of a simple and fast Markov Chain Monte Carlo code to constraintRead More →

The Local Perspective on the Hubble Tension: Local Structure Does Not Impact Measurement of the Hubble Constant. (arXiv:1901.08681v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kenworthy_W/0/1/0/all/0/1">W. D&#x27;Arcy Kenworthy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Scolnic_D/0/1/0/all/0/1">Dan Scolnic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riess_A/0/1/0/all/0/1">Adam Riess</a> We use the largest sample to date of spectroscopic SN Ia distances and redshifts to look for evidence in the Hubble diagram of large scale outflows caused by local voids suggested to exist at zRead More →

The Galactic Center: An Improved Astrometric Reference Frame for Stellar Orbits around the Supermassive Black Hole. (arXiv:1901.08685v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sakai_S/0/1/0/all/0/1">Shoko Sakai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lu_J/0/1/0/all/0/1">Jessica R. Lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ghez_A/0/1/0/all/0/1">Andrea Ghez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jia_S/0/1/0/all/0/1">Siyao Jia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Do_T/0/1/0/all/0/1">Tuan Do</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Witzel_G/0/1/0/all/0/1">Gunther Witzel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gautam_A/0/1/0/all/0/1">Abhimat K. Gautam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hees_A/0/1/0/all/0/1">Aurelien Hees</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Becklin_E/0/1/0/all/0/1">E. Becklin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matthews_K/0/1/0/all/0/1">K. Matthews</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hosek_M/0/1/0/all/0/1">M.W.Hosek Jr</a> Precision measurements of the stars in short-period orbits around the supermassive black hole at the Galactic Center are now being used to constrain general relativistic effects, such as the gravitational redshift and periapse precession. One of the largest systematic uncertainties in the measured orbits has been errors in the astrometric reference frame,Read More →

Selected topics in scalar-tensor theories and beyond. (arXiv:1901.08690v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Quiros_I/0/1/0/all/0/1">Israel Quiros</a> Scalar fields have played an important role in the development of the fundamental theories of physics as well as in other branches of physics such as gravitation and cosmology. For a long time these escaped detection until 2012 year when the Higgs boson was observed for the first time. Since then alternatives to the general theory of relativity like the Brans-Dicke theory, scalar-tensor theories of gravity and their higher derivative generalizations — collectively known as Horndeski theories — have acquired renewed interest. In the present review we discuss on several selected topics regardingRead More →

Astrophysics with core-collapse supernova gravitational wave signals in the next generation of gravitational wave detectors. (arXiv:1901.08692v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Roma_V/0/1/0/all/0/1">Vincent Roma</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Powell_J/0/1/0/all/0/1">Jade Powell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heng_I/0/1/0/all/0/1">Ik Siong Heng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Frey_R/0/1/0/all/0/1">Ray Frey</a> The next generation of gravitational wave detectors will improve the detection prospects for gravitational waves from core-collapse supernovae. The complex astrophysics involved in core-collapse supernovae pose a significant challenge to modeling such phenomena. The Supernova Model Evidence Extractor (SMEE) attempts to capture the main features of gravitational wave signals from core-collapse supernovae by using numerical relativity waveforms to create approximate models. These models can then be used to perform Bayesian model selection to determine ifRead More →

1I/`Oumuamua As Debris of Dwarf Interstellar Comet That Disintegrated Before Perihelion. (arXiv:1901.08704v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sekanina_Z/0/1/0/all/0/1">Zdenek Sekanina</a> Intrinsically faint comets in nearly-parabolic orbits with perihelion distances much smaller than 1 AU exhibit strong propensity for suddenly disintegrating at a time not long before perihelion, as shown by Bortle (1991). Evidence from available observations of such comets suggests that the disintegration event usually begins with an outburst and that the debris is typically a massive cloud of dust grains that survives over a limited period of time. Recent CCD observations revealed, however, that also surviving could be a sizable fragment, resembling a devolatilized aggregate of loosely-bound dustRead More →