RAS_WEB (Page 2,439)

Coupled Multi-Proca Vector Dark Energy. (arXiv:2004.06466v3 [gr-qc] UPDATED) <a href="http://arxiv.org/find/gr-qc/1/au:+Gomez_L/0/1/0/all/0/1">L. Gabriel Gomez</a> (1), <a href="http://arxiv.org/find/gr-qc/1/au:+Rodriguez_Y/0/1/0/all/0/1">Yeinzon Rodriguez</a> (1,2,3) ((1) Universidad Industrial de Santander, (2) Universidad Antonio Narino, (3) The Abdus Salam International Centre for Theoretical Physics) We study a new class of vector dark energy models where multi-Proca fields $A_mu^a$ are coupled to cold dark matter by the term $f(X)tilde{mathcal{L}}_{m}$ where $f(X)$ is a general function of $Xequiv -frac{1}{2}A^mu_ a A^a_mu$ and $tilde{mathcal{L}}_{m}$ is the cold dark matter Lagrangian. From here, we derive the general covariant form of the novel interaction term sourcing the field equations. This result is quite general in the sense that encompassesRead More →

Proper motion measurements for stars up to $100$ kpc with Subaru HSC and SDSS Stripe 82. (arXiv:2004.12899v2 [astro-ph.GA] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Qiu_T/0/1/0/all/0/1">Tian Qiu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_W/0/1/0/all/0/1">Wenting Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takada_M/0/1/0/all/0/1">Masahiro Takada</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yasuda_N/0/1/0/all/0/1">Naoki Yasuda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ivezic_Z/0/1/0/all/0/1">&#x17d;eljko Ivezi&#x107;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lupton_R/0/1/0/all/0/1">Robert H. Lupton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chiba_M/0/1/0/all/0/1">Masashi Chiba</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ishigaki_M/0/1/0/all/0/1">Miho Ishigaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Komiyama_Y/0/1/0/all/0/1">Yutaka Komiyama</a> We present proper motion measurements for more than $0.55$ million main-sequence stars, by comparing astrometric positions of matched stars between the multi-band imaging datasets from the Hyper Suprime-Cam (HSC) Survey and the SDSS Stripe 82. In doing this we use $3$ million galaxies to recalibrate the astrometry and set up a common reference frame between the two catalogues.Read More →

Satisfying the compressibility sum rule in neutron matter. (arXiv:2007.06589v2 [nucl-th] UPDATED) <a href="http://arxiv.org/find/nucl-th/1/au:+Buraczynski_M/0/1/0/all/0/1">Mateusz Buraczynski</a>, <a href="http://arxiv.org/find/nucl-th/1/au:+Martinello_S/0/1/0/all/0/1">Samuel Martinello</a>, <a href="http://arxiv.org/find/nucl-th/1/au:+Gezerlis_A/0/1/0/all/0/1">Alexandros Gezerlis</a> The static-response function of strongly interacting neutron matter contains crucial information on this interacting many-particle system, going beyond ground-state properties. In this work, we employ quantum Monte Carlo (QMC) approaches for two large classes of nuclear forces (phenomenological and chiral) at several different densities. We handle finite-size effects via self-consistent energy-density functional (EDF) calculations for 4224 particles in a periodic volume. We combine these QMC and EDF computations in an attempt to produce a model-independent extraction of the static response function. Our results are consistentRead More →

Strong bound on canonical ultra-light axion dark matter from the Lyman-alpha forest. (arXiv:2007.12705v3 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Rogers_K/0/1/0/all/0/1">Keir K. Rogers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peiris_H/0/1/0/all/0/1">Hiranya V. Peiris</a> We present a new bound on the ultra-light axion (ULA) dark matter mass $m_text{a}$, using the Lyman-alpha forest to look for suppressed cosmic structure growth: a 95% lower limit $m_text{a} > 2 times 10^{-20},text{eV}$. This strongly disfavors ($> 99.7%$ credibility) the canonical ULA with $10^{-22},text{eV} < m_text{a} < 10^{-21},text{eV}$, motivated by the string axiverse and solutions to possible tensions in the cold dark matter model. We strengthen previous equivalent bounds by about an order of magnitude. We demonstrate the robustness of ourRead More →

Constraints on variation of fine structure constant from joint SPT-SZ and XMM-Newton observations. (arXiv:2008.10541v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Bora_K/0/1/0/all/0/1">Kamal Bora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Desai_S/0/1/0/all/0/1">Shantanu Desai</a> We search for a variation of the electromagnetic fine structure constant ($alpha equiv e^2/hbar c$) using a sample of 58 SZ selected clusters in the redshift range ($0.2<z<1.5$) detected by the South Pole Telescope, along with X-ray measurements using the XMM-Newton observatory. We use the ratio of the integrated SZ Compto-ionization to its X-ray counterpart as our observable for this search. We first obtain a model-independent constraint on $alpha$ of about 0.7%, using the fact that the aforementioned ratio is constant as aRead More →

SolO campfires in SDO images. (arXiv:2009.00376v3 [astro-ph.SR] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Rutten_R/0/1/0/all/0/1">Robert J. Rutten</a> I present the appearance of “Solar Orbiter campfires” in simultaneous images from the Solar Dynamics Observatory where most are visible although less sharp. I also show such features elsewhere in the SDO database. I show some in detail and discuss their nature. I present the appearance of “Solar Orbiter campfires” in simultaneous images from the Solar Dynamics Observatory where most are visible although less sharp. I also show such features elsewhere in the SDO database. I show some in detail and discuss their nature. http://arxiv.org/icons/sfx.gifRead More →

Resolved spectral variations of the centimetre-wavelength continuum from the rho Oph W photo-dissociation-region. (arXiv:2010.00185v2 [astro-ph.GA] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Casassus_S/0/1/0/all/0/1">Simon Casassus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vidal_M/0/1/0/all/0/1">Matias Vidal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arce_Tord_C/0/1/0/all/0/1">Carla Arce-Tord</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dickinson_C/0/1/0/all/0/1">Clive Dickinson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+White_G/0/1/0/all/0/1">Glenn J. White</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burton_M/0/1/0/all/0/1">Michael Burton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Indermuehle_B/0/1/0/all/0/1">Balthasar Indermuehle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hensley_B/0/1/0/all/0/1">Brandon Hensley</a> Cm-wavelength radio continuum emission in excess of free-free, synchrotron and Rayleigh-Jeans dust emission (excess microwave emission, EME), and often called `anomalous microwave emission’, is bright in molecular cloud regions exposed to UV radiation, i.e. in photo-dissociation regions (PDRs). The EME correlates with IR dust emission on degree angular scales. Resolved observations of well-studied PDRs are needed to compare the spectral variations of the cm-continuumRead More →

Mimetic Inflation. (arXiv:2010.13495v3 [gr-qc] UPDATED) <a href="http://arxiv.org/find/gr-qc/1/au:+Mansoori_S/0/1/0/all/0/1">Seyed Ali Hosseini Mansoori</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Talebian_A/0/1/0/all/0/1">Alireza Talebian</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Firouzjahi_H/0/1/0/all/0/1">Hassan Firouzjahi</a> We study inflationary solution in an extension of mimetic gravity with the higher derivative interactions coupled to gravity. Because of the higher derivative interactions, the setup is free from the ghost and gradient instabilities while it hosts a number of novel properties. The dispersion relation of scalar perturbations develops quartic momentum correction similar to the setup of ghost inflation. Furthermore, the tilt of tensor perturbations can take either signs with a modified consistency relation between the tilt and the amplitude of tensor perturbations. Despite the presence of higher derivativeRead More →

Improved deep learning techniques in gravitational-wave data analysis. (arXiv:2011.04418v2 [astro-ph.HE] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Xia_H/0/1/0/all/0/1">Heming Xia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shao_L/0/1/0/all/0/1">Lijing Shao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhao_J/0/1/0/all/0/1">Junjie Zhao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cao_Z/0/1/0/all/0/1">Zhoujian Cao</a> In recent years, convolutional neural network (CNN) and other deep learning models have been gradually introduced into the area of gravitational-wave (GW) data processing. Compared with the traditional matched-filtering techniques, CNN has significant advantages in efficiency in GW signal detection tasks. In addition, matched-filtering techniques are based on the template bank of the existing theoretical waveform, which makes it difficult to find GW signals beyond theoretical expectation. In this paper, based on the task of GW detection of binary black holes, weRead More →

Particle acceleration driven by null electromagnetic fields near a Kerr black hole. (arXiv:2011.06799v2 [gr-qc] UPDATED) <a href="http://arxiv.org/find/gr-qc/1/au:+Kojima_Y/0/1/0/all/0/1">Yasufumi Kojima</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Kimura_Y/0/1/0/all/0/1">Yuto Kimura</a> Short timescale variability is often associated with a black hole system. The consequence of an electromagnetic outflow suddenly generated near a Kerr black hole is considered assuming that it is described by a solution of a force-free field with a null electric current. We compute charged particle acceleration induced by the burst field. The interaction between the particle and the field is characterized by a large dimensionless number. We show that the particle is instantaneously accelerated to the relativistic regime by the field withRead More →

Primordial black holes and secondary gravitational waves from inflationary model with a non-canonical kinetic term. (arXiv:2011.10606v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Yi_Z/0/1/0/all/0/1">Zhu Yi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_Q/0/1/0/all/0/1">Qing Gao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gong_Y/0/1/0/all/0/1">Yungui Gong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_Z/0/1/0/all/0/1">Zong-hong Zhu</a> With the enhancement mechanism provided by a non-canonical kinetic term with a peak, the amplitude of primordial curvature perturbations can be enhanced by seven-orders of magnitude at small scales while keeping to be consistent with observations at large scales. The peak function and inflationary potential are not restricted in this mechanism. We use the Higgs model and T-model as examples to show how abundant primordial black hole dark matter with different mass and induced secondaryRead More →

Phase Modeling of the TRAPPIST-1 Planetary Atmospheres. (arXiv:2012.00080v2 [astro-ph.EP] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Kane_S/0/1/0/all/0/1">Stephen R. Kane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jansen_T/0/1/0/all/0/1">Tiffany Jansen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fauchez_T/0/1/0/all/0/1">Thomas Fauchez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Selsis_F/0/1/0/all/0/1">Franck Selsis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ceja_A/0/1/0/all/0/1">Alma Y. Ceja</a> Transiting compact multi-planet systems provide many unique opportunities to characterize the planets, including studies of size distributions, mean densities, orbital dynamics, and atmospheric compositions. The relatively short orbital periods in these systems ensure that events requiring specific orbital locations of the planets (such as primary transit and secondary eclipse points) occur with high frequency. The orbital motion and associated phase variations of the planets provide a means to constrain the atmospheric compositions through measurement of their albedos. HereRead More →

MusE GAs FLOw and Wind (MEGAFLOW) VII. A NOEMA pilot program to probe molecular gas in galaxies with measured circumgalactic gas flows. (arXiv:2012.04667v2 [astro-ph.GA] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Freundlich_J/0/1/0/all/0/1">Jonathan Freundlich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bouche_N/0/1/0/all/0/1">Nicolas F. Bouch&#xe9;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Contini_T/0/1/0/all/0/1">Thierry Contini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Daddi_E/0/1/0/all/0/1">Emanuele Daddi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zabl_J/0/1/0/all/0/1">Johannes Zabl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schroetter_I/0/1/0/all/0/1">Ilane Schroetter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boogaard_L/0/1/0/all/0/1">Leindert Boogaard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Richard_J/0/1/0/all/0/1">Johan Richard</a> We present a pilot program using IRAM’s NOrthern Extended Millimeter Array (NOEMA) to probe the molecular gas reservoirs of six $z=0.6-1.1$ star-forming galaxies whose circumgalactic medium has been observed in absorption along quasar lines-of-sight as part of the MusE GAs FLOw and Wind (MEGAFLOW) survey and for which we have estimates of either the accretionRead More →

Backflow in simulated MHD accretion disks. (arXiv:2012.13194v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mishra_R/0/1/0/all/0/1">Ruchi Mishra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cemeljic_M/0/1/0/all/0/1">Miljenko &#x10c;emelji&#x107;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kluzniak_W/0/1/0/all/0/1">Wlodek Klu&#x17a;niak</a> We perform resistive MHD simulations of accretion disk with alpha-viscosity, accreting onto a rotating star endowed with a magnetic dipole. We find backflow in the presence of strong magnetic field and large resistivity, and probe for the dependence on Prandtl number. We find that in the magnetic case the distance from the star at which backflow begins, the stagnation radius, is different than in the hydrodynamic case, and the backflow shows non-stationary behavior. We compare the results with hydrodynamics simulations. We perform resistive MHD simulations of accretion diskRead More →

Free-space optical links for space communication networks. (arXiv:2012.13166v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Carrasco_Casado_A/0/1/0/all/0/1">Alberto Carrasco-Casado</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mata_Calvo_R/0/1/0/all/0/1">Ramon Mata-Calvo</a> Future spacecraft will require a paradigm shift in the way the information is transmitted due to the continuous increase in the amount of data requiring space links. Current radiofrequency-based communication systems impose a bottleneck in the volume of data that can be transmitted back to Earth due to technological as well as regulatory reasons. Free-space optical communication has finally emerged as a key technology for solving the increasing bandwidth limitations for space communication while reducing the size, weight and power of satellite communication systems, and taking advantage of a license-freeRead More →

BlackHawk: A tool for computing Black Hole evaporation. (arXiv:2012.12902v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Auffinger_J/0/1/0/all/0/1">J&#xe9;r&#xe9;my Auffinger</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Arbey_A/0/1/0/all/0/1">Alexandre Arbey</a> We present the public code texttt{BlackHawk}, a powerful tool to compute the evaporation of any distribution of Schwarzschild and Kerr Black Holes and the emission spectra of Hawking radiation. We present the public code texttt{BlackHawk}, a powerful tool to compute the evaporation of any distribution of Schwarzschild and Kerr Black Holes and the emission spectra of Hawking radiation. http://arxiv.org/icons/sfx.gifRead More →

Physics and astrophysics of ultra-high energy cosmic rays: recent results from the Pierre Auger Observatory. (arXiv:2012.12943v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Neto_J/0/1/0/all/0/1">Joao de Mello Neto</a> (for the Pierre Auger Collaboration) Ultra-high-energy cosmic rays (UHECRs) are the highest energy messengers in the universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. The primary particles interact in the atmosphere (or in the Earth) and generate extensive air showers. Analysis of those showers enables one not only to estimate the energy, direction and most probable mass of the primary cosmicRead More →

Decoherence from General Relativity. (arXiv:2012.12903v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Allali_I/0/1/0/all/0/1">Itamar J. Allali</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Hertzberg_M/0/1/0/all/0/1">Mark P. Hertzberg</a> It is of great interest to explore matter in nontrivial quantum arrangements, including Schrodinger cat-like states. Such states are sensitive to decoherence from their environment. Recently, in Ref. [1] we computed the rate of decoherence of a piece of superposed matter that primarily only interacts gravitationally, a dark-matter-Schrodinger-cat-state (DMSCS), within the nonrelativistic approximation. In this work we improve this to a general relativistic analysis. We firstly derive a single particle relativistic Schrodinger equation for a probe particle that passes through the DMSCS; the interaction is provided by the weak field metricRead More →

Driving galactic winds with magnetic fields at low and high redshift. (arXiv:2012.12905v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Steinwandel_U/0/1/0/all/0/1">Ulrich P. Steinwandel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dolag_K/0/1/0/all/0/1">Klaus Dolag</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lesch_H/0/1/0/all/0/1">Harald Lesch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burkert_A/0/1/0/all/0/1">Andreas Burkert</a> Although playing a key role for our understanding of the evolution of galaxies, the exact way how observed galactic outflows are driven is still far from being understood and therefore our understanding of associated feedback mechanisms that control the evolution of galaxies is still plagued by many enigmas. In this work we present a simple toy model that can provide insight on how non-axis-symmetric instabilities in galaxies (bars, spiral-arms, warps) can lead to local exponential magnetic field growth byRead More →

Improving Damped Random Walk parameters for SDSS Stripe 82 Quasars with Pan-STARRS1. (arXiv:2012.12907v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Suberlak_K/0/1/0/all/0/1">Krzysztof Suberlak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ivezic_Z/0/1/0/all/0/1">&#x17d;eljko Ivezi&#x107;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+MacLeod_C/0/1/0/all/0/1">Chelsea MacLeod</a> We use the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1, PS1) data to extend the Sloan Digital Sky Survey (SDSS) Stripe 82 quasar light curves. Combining PS1 and SDSS light curves provides a 15 yr baseline for 9248 quasars – 5 yr longer than prior studies that used only SDSS. We fit the light curves with the damped random walk (DRW) model model – a statistical description of their variability. We correlate the resulting DRW model parameters: asymptotic variabilityRead More →