{ "articles": [ { "in_graph": false, "uuid": 6027156110966784, "title": "Self-acceleration in scalar-bimetric theories. (arXiv:1712.04520v1 [gr-qc] CROSS LISTED)", "url": "http://arxiv.org/abs/1712.04520", "abstract": "We describe scalar-bimetric theories where the dynamics of the Universe aregoverned by two separate metrics, each with an Einstein-Hilbert term. In thissetting, the baryonic and dark matter components of the Universe couple tometrics which are constructed as functions of these two gravitational metrics.The scalar field, contrary to dark energy models, does not have a potentialwhose role is to mimic a late-time cosmological constant. The late-timeacceleration of the expansion of the Universe can be easily obtained at thebackground level in these models by appropriately choosing the couplingfunctions appearing in the decomposition of the vierbeins for the baryonic anddark matter metrics. We explicitly show how the concordance model can beretrieved with negligible scalar kinetic energy. This requires the scalarcoupling functions to show variations of order unity during the acceleratedexpansion era. This leads in turn to deviations of order unity for theeffective Newton constants and a fifth force that is of the same order asNewtonian gravity, with peculiar features. The baryonic and dark matterself-gravities are amplified although the gravitational force between baryonsand dark matter is reduced and even becomes repulsive at low redshift. Thisslows down the growth of baryonic density perturbations on cosmological scales,while dark matter perturbations are enhanced. In our local environment, theupper bound on the time evolution of Newton's constant requires an efficientscreening mechanism that both damps the fifth force on small scales anddecouples the local value of Newton constant from its cosmological value. Thiscannot be achieved by a quasi-static chameleon mechanism, and requires goingbeyond the quasi-static regime and probably using derivative screenings, suchas Kmouflage or Vainshtein screening, on small scales.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.04520", "stored": "2017-12-17T19:43:22", "published": "2017-12-17T19:43:22", "type_of": "feed" }, { "in_graph": false, "uuid": 4820738989096960, "title": "Two distinct components of the delayed single electron background signals in liquid xenon emission detectors. (arXiv:1711.07025v2 [physics.ins-det] UPDATED)", "url": "http://arxiv.org/abs/1711.07025", "abstract": "Single electron background signals with millisecond timescales are known tofollow ionizing events in liquid/gas xenon emission detectors. Due to the longtimescale, these signals can present a limiting background to the low-energythreshold of dark matter searches, and prevent discovery-class searches for MeVscale hidden sector dark matter. A systematic study reveals a fast (tau_1) andslow (tau_2) component to the background. The fast component is compatible withelectrons which were trapped at the liquid surface, and can be reduced byincreasing the electric field. However, the slow component increases linearlywith electric field. Hypotheses for the origin of the effect are discussed, andtechniques for mitigation are suggested.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1711.07025", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 4925753355403264, "title": "Observational signatures from horizonless black shells imitating rotating black holes. (arXiv:1712.00511v2 [hep-th] UPDATED)", "url": "http://arxiv.org/abs/1712.00511", "abstract": "In arXiv:1705.10172 it was proposed that string theory replaces Schwarzschildblack holes with horizonless thin shells with an AdS interior. In this paper weextend the analysis to slowly rotating black holes, solving theIsrael-Lanczos-Sen junction conditions for a rotating shell composed of stringymatter to determine the metric. Outside of the shell we find a vacuum solutionthat differs from Kerr with a 32% larger quadrupole moment. We discuss theobservational consequences and explore the possibility to distinguish between ablack shell and a black hole. Promising methods include imaging of the blackhole at the center of the Milky Way using the Event Horizon Telescope,precision measurements of stars in close orbits around the central black hole,and future observations of colliding super massive black holes using the spacebased gravitational wave observatory LISA.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.00511", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 5193641471508480, "title": "Hidden Markov model tracking of continuous gravitational waves from young supernova remnants. (arXiv:1710.00460v2 [astro-ph.IM] UPDATED)", "url": "http://arxiv.org/abs/1710.00460", "abstract": "Searches for persistent gravitational radiation from nonpulsating neutronstars in young supernova remnants (SNRs) are computationally challengingbecause of rapid stellar braking. We describe a practical, efficient,semi-coherent search based on a hidden Markov model (HMM) tracking scheme,solved by the Viterbi algorithm, combined with a maximum likelihood matchedfilter, the $\\mathcal{F}$-statistic. The scheme is well suited to analyzingdata from advanced detectors like the Advanced Laser InterferometerGravitational Wave Observatory (Advanced LIGO). It can track rapid phaseevolution from secular stellar braking and stochastic timing noise torquessimultaneously without searching second- and higher-order derivatives of thesignal frequency, providing an economical alternative to stack-slide-basedsemi-coherent algorithms. One implementation tracks the signal frequency alone.A second implementation tracks the signal frequency and its first timederivative. It improves the sensitivity by a factor of a few upon the firstimplementation, but the cost increases by two to three orders of magnitude.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1710.00460", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 6194546555748352, "title": "Model-Independent Predictions for Smooth Cosmic Acceleration Scenarios. (arXiv:1712.04289v2 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1712.04289", "abstract": "Through likelihood analyses of both current and future data that constrainboth the expansion history of the universe and the clustering of matterfluctuations, we provide falsifiable predictions for three broad classes ofmodels that explain the accelerated expansions of the universe: $\\Lambda$CDM,the quintessence scenario and a more general class of smooth dark energy modelsthat can cross the phantom barrier $w(z)=-1$. Our predictions are modelindependent in the sense that we do not rely on a specific parametrization, butwe instead use a principal component (PC) basis function constructed a priorifrom a noise model of supernovae and Cosmic Microwave Background observations.For the supernovae measurements, we consider two type of surveys: the currentJLA and the upcoming WFIRST surveys. We show that WFIRST will be able toimprove growth predictions in curved models significantly. The remainingdegeneracy between spatial curvature and $w(z)$ could be overcome with improvedmeasurements of $\\sigma_8 \\Omega_m^{1/2}$, a combination that controls theamplitude of the growth of structure. We also point out that a PC-based Figureof Merit reveals that the usual two-parameter description of $w(z)$ does notexhaust the information that can be extracted from current data (JLA) or futuredata (WFIRST).", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.04289", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 6225824118210560, "title": "Complete super-sample lensing covariance in the response approach. (arXiv:1711.07467v2 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1711.07467", "abstract": "We derive the complete super-sample covariance (SSC) of the matter and weaklensing convergence power spectra using the power spectrum response formalismto accurately describe the coupling of super-to-intra survey modes. The SSCterm is completely characterized by the survey window function, the nonlinearmatter power spectrum and the full first-order nonlinear power spectrumresponse function, which describes the response to super-survey density andtidal field perturbations. Separate universe simulations can efficientlymeasure these responses in the nonlinear regime of structure formation, whichis necessary for lensing applications. Under the Limber and flat-skyapproximations, we show that the tidal contributions, which have not beenincluded in cosmological analyses so far, represent a significant fraction($\\approx 20-25\\%$) of the total SSC, even for an isotropic survey footprint onthe sky. The SSC is the dominant off-diagonal contribution to the total lensingcovariance for survey sky fractions $f_{\\rm sky} \\lesssim 0.3$, making itimportant to include these tidal terms in cosmic shear analyses.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1711.07467", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 6304632909332480, "title": "Enhancing the H2O Megamaser Detection Rate Using Optical and Mid-infrared Photometry. (arXiv:1712.04204v2 [astro-ph.GA] UPDATED)", "url": "http://arxiv.org/abs/1712.04204", "abstract": "Water megamasers from circumnuclear disks in galaxy centers provide the mostaccurate measurements of supermassive black hole masses and uniquely probe thesub-parsec accretion processes. At the same time, these systems offerindependent crucial constraints of the Hubble Constant in the nearby universe,and thus, the arguably best single constraint on the nature of dark energy. Thechances of finding these golden standards are however abysmally low, at anoverall ~<3% for any level of water maser emission detected at 22 GHz, and ~<1%for those exhibiting the disk-like configuration. We provide here a thoroughsummary of the current state of the detection of water megamaser disks, alongwith a novel investigation of the chances of increasing their detection ratesbased on a multivariate parameter analysis of optical and mid-infraredphotometric properties of the largest database of galaxies surveyed for the 22GHz emission. We find that galaxies with water megamaser emission tend toassociate with strong emission in all WISE mid-infrared wavelengths, with thestrongest enhancement in the W4 band, at 22 micron, as well as with previouslyproposed and newly found indicators of AGN strength in the mid-infrared, suchas red W1-W2 and W1-W4 colors, and the integrated mid-infrared luminosity ofthe host galaxy. While these trends offer a potential boost of the megamaserdetection rates to 6 - 15%, or a factor of 2-8 relative to the current rates,depending on the chosen sample selection criteria, the completeness rateremains generally low (40 -- 60% of megamasers would not be targeted). Bycombining criteria of mid-IR brightness, optical colors, and the opticalbrightness, the detection rate of disk masers can be effectively boosted to ~>6%, with ~> 60% completeness rates.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.04204", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 6315322378289152, "title": "Time Assignment System and Its Performance aboard the Hitomi Satellite. (arXiv:1712.01484v2 [astro-ph.IM] UPDATED)", "url": "http://arxiv.org/abs/1712.01484", "abstract": "Fast timing capability in X-ray observation of astrophysical objects is oneof the key properties for the ASTRO-H (Hitomi) mission. Absolute timingaccuracies of 350 micro second or 35 micro second are required to achievenominal scientific goals or to study fast variabilities of specific sources.The satellite carries a GPS receiver to obtain accurate time information, whichis distributed from the central onboard computer through the large and complexSpaceWire network. The details on the time system on the hardware and softwaredesign are described. In the distribution of the time information, thepropagation delays and jitters affect the timing accuracy. Six other itemsidentified within the timing system will also contribute to absolute timeerror. These error items have been measured and checked on ground to ensure thetime error budgets meet the mission requirements. The overall timingperformance in combination with hardware performance, software algorithm, andthe orbital determination accuracies, etc, under nominal conditions satisfiesthe mission requirements of 35 micro second. This work demonstrates key pointsfor space-use instruments in hardware and software designs and calibrationmeasurements for fine timing accuracy on the order of microseconds formid-sized satellites using the SpaceWire (IEEE1355) network.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.01484", "stored": "2017-12-17T19:43:21", "published": "2017-12-17T19:43:21", "type_of": "feed" }, { "in_graph": false, "uuid": 4634371130654720, "title": "Amateur astronomers and the new golden age of cataclysmic variable star astronomy. (arXiv:1712.05393v1 [astro-ph.SR])", "url": "http://arxiv.org/abs/1712.05393", "abstract": "The study of cataclysmic variable stars has long been a fruitful area ofco-operation between amateur and professional astronomers. In this PresidentialAddress, I shall take stock of our current understanding of these fascinatingbinary systems, highlighting where amateurs can still contribute to pushingback the frontiers of knowledge. I shall also consider the sky surveys that arealready coming on stream, which will provide near continuous and exquisitelyprecise photometry of these systems. I show that whilst these surveys might beperceived as a threat to amateur observations, they will actually provide newopportunities, although the amateur community shall need to adapt and focus itsefforts. I will identify areas where amateurs equipped for either visualobserving or CCD photometry can make scientifically useful observations.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05393", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 4901256204124160, "title": "Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II. (arXiv:1705.01820v2 [astro-ph.GA] UPDATED)", "url": "http://arxiv.org/abs/1705.01820", "abstract": "We present a new technique to probe the central dark matter (DM) densityprofile of galaxies that harnesses both the survival and observed properties ofstar clusters. As a first application, we apply our method to the ultra-faint'dwarf Eridanus II (Eri II) that has a lone star cluster ~45 pc from its centre.Using a grid of collisional $N$-body simulations, incorporating the effects ofstellar evolution, external tides and dynamical friction, we show that a DMcore for Eri II naturally reproduces the size and the projected position of itsstar cluster. By contrast, a dense cusped galaxy requires the cluster to lieimplausibly far from the centre of Eri II (>1 kpc), with a high inclinationorbit that must be observed at a particular orbital phase. Our results implythat either a cold DM cusp was heated up' at the centre of Eri II by burstystar formation, or we are seeing an evidence for physics beyond cold DM.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1705.01820", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 5072683649728512, "title": "A comparison of Einstein-Boltzmann solvers for testing General Relativity. (arXiv:1709.09135v2 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1709.09135", "abstract": "We compare Einstein-Boltzmann solvers that include modifications to GeneralRelativity and find that, for a wide range of models and parameters, they agreeto a high level of precision. We look at three general purpose codes thatprimarily model general scalar-tensor theories, three codes that modelJordan-Brans-Dicke (JBD) gravity, a code that models f(R) gravity, a code thatmodels covariant Galileons, a code that models Ho\\v{r}ava-Lifschitz gravity andtwo codes that model non-local models of gravity. Comparing predictions of theangular power spectrum of the cosmic microwave background and the powerspectrum of dark matter for a suite of different models, we find agreement atthe sub-percent level. This means that this suite of Einstein-Boltzmann solversis now sufficiently accurate for precision constraints on cosmological andgravitational parameters.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1709.09135", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 5163126701948928, "title": "A lepto-hadronic model of gamma rays from the Eta Carinae and prospects for neutrino telescopes. (arXiv:1706.10051v2 [astro-ph.HE] UPDATED)", "url": "http://arxiv.org/abs/1706.10051", "abstract": "The stellar binary $\\eta$ Carinae has been observed during its full orbitalperiod in gamma rays by the Fermi-Large Area Telescope (LAT). Theshock-accelerated electrons in the colliding winds of the two stars radiatesynchrotron photons in the magnetic field of the shocked region and inverseCompton photons, where the target photons are from the thermal emissions by themore massive and luminous of the two stars. The inverse Compton emissiondominates the gamma-ray flux data from the $\\eta$ Carinae, however the spectralenergy distribution shows signature of a hadronic component in the $\\sim10$-300 GeV range during the periastron passage. Current and future airCherenkov telescopes will be able to constrain this component at TeV energies.Acceleration of cosmic-ray protons to $\\gg 1$ TeV energies in the collidingwinds, required to explain the hadronic emission component through photopioninteractions, can lead to detectable signal of $\\gtrsim 10$ TeV neutrino eventsin large kilometer scale neutrino telescopes.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1706.10051", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 5640510806949888, "title": "The Einstein@Home Gamma-Ray Pulsar Survey II. Source Selection, Spectral Analysis and Multi-wavelength Follow-up. (arXiv:1712.05395v1 [astro-ph.HE])", "url": "http://arxiv.org/abs/1712.05395", "abstract": "We report on the analysis of 13 gamma-ray pulsars discovered in theEinstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8data. The 13 new gamma-ray pulsars were discovered by searching 118unassociated LAT sources from the third LAT source catalog (3FGL), selectedusing the Gaussian Mixture Model (GMM) machine learning algorithm on the basisof their gamma-ray emission properties being suggestive of pulsarmagnetospheric emission. The new gamma-ray pulsars have pulse profiles andspectral properties similar to those of previously-detected young gamma-raypulsars. Follow-up radio observations have revealed faint radio pulsations fromtwo of the newly-discovered pulsars, and enabled us to derive upper limits onthe radio emission from the others, demonstrating that they are likelyradio-quiet gamma-ray pulsars. We also present results from modeling thegamma-ray pulse profiles and radio profiles, if available, using differentgeometric emission models of pulsars. The high discovery rate of this survey,despite the increasing difficulty of blind pulsar searches in gamma rays,suggests that new systematic surveys such as presented in this article shouldbe continued when new LAT source catalogs become available.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05395", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 5698892834275328, "title": "Staying ahead of the curve: progress in British variable star astronomy. (arXiv:1712.05399v1 [astro-ph.SR])", "url": "http://arxiv.org/abs/1712.05399", "abstract": "The BAA Variable Star Section is the world's longest established organisationfor the systematic observation of variable stars, having been formed in 1890.Its database contains nearly 3 million measurements going back to 1840 and isan important resource for researchers. The aim of this Presidential Address isto reveal some of the lesser known tales that lie deep within the database.This includes bringing to life stories about some of the people that wereinvolved, especially in the early years, including Joseph Baxendell, Mary AdelaBlagg and Arthur Stanley Williams, as well as shedding light on some of thestars that have been observed. Finally we look to the future as the VariableStar Section builds on the legacy of its forebears, ensuring that it shallalways stay ahead of the curve.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05399", "stored": "2017-12-17T19:43:20", "published": "2017-12-17T19:43:20", "type_of": "feed" }, { "in_graph": false, "uuid": 4861403638792192, "title": "The Star Formation Reference Survey. II. Activity demographics and host-galaxy properties for Infrared-selected galaxies. (arXiv:1712.05371v1 [astro-ph.GA])", "url": "http://arxiv.org/abs/1712.05371", "abstract": "We present activity demographics and host-galaxy properties ofinfrared-selected galaxies in the local Universe, using the representative StarFormation Reference Survey (SFRS). Our classification scheme is based on acombination of optical emission-line diagrams (BPT) and IR-color diagnostics.Using the weights assigned to the SFRS galaxies based on its parent sample, afar-infrared-selected sample comprises 71\\% H\\,\\textsc{ii} galaxies, 13\\%Seyferts, 3\\% Transition Objects (TOs), and 13\\% Low-Ionization NuclearEmission-Line Regions (LINERs). For the SFRS H\\,\\textsc{ii} galaxies we derivenuclear star-formation rates and gas-phase metallicities. We measurehost-galaxy metallicities for all galaxies with available long-slitspectroscopy and abundance gradients for a subset of 12 face-on galaxies. Themajority of H\\,\\textsc{ii} galaxies show a narrow range of metallicities, closeto solar, and flat metallicity profiles. Based on their host-galaxy and nuclearproperties, the dominant ionizing source in the far-infrared selected TOs isstar-forming activity. LINERs are found mostly in massive hosts (median of$10^{10.5}$ M$_{\\odot}$), median $L(60\\mu m) = 10^{9}$ L$_{\\odot}$, mediandust temperatures of $F60/F100 = 0.36$, and median $L_{\\textrm{H}\\alpha}$surface density of $10^{40.2}$ erg s$^{-1}$kpc$^{-2}$, indicating olderstellar populations as their main ionizing source rather than AGN activity.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05371", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 5085130095853568, "title": "Scalar dark matter explanation of the DAMPE data in the minimal Left-Right symmetric model. (arXiv:1712.05351v1 [hep-ph])", "url": "http://arxiv.org/abs/1712.05351", "abstract": "Left-Right symmetric model (LRSM) has been an attractive extension of theStandard Model (SM) which can address the parity violation in the SMelectroweak (EW) interaction, generate tiny neutrino masses, accommodate darkmatter (DM) candidates and generate baryogenesis through leptogenesis. In thiswork we utilize the minimal LRSM to study the recently reported DAMPE resultsof cosmic $e^+e^-$ measurement which exhibits a tentative peak around 1.4 TeV,while satisfying the current neutrino data. The minimal LRSM predicts 10physical Higgs bosons: four CP-even $H_{1,2,3,4}$, two CP-odd $A_{1,2}$, twosingly charged $H^\\pm_{1,2}$ and two doubly charged $H^{\\pm\\pm}_{1,2}$, allwith increasing masses in the ascending order. We propose to explain the DAMPEpeak with scalar DM $m_\\chi\\sim$ 3 TeV in two scenarios: 1) $\\chi\\chi \\toH_1^{++}H_1^{--} \\to \\ell_i^+\\ell_i^+\\ell_j^-\\ell_j^-$; 2) $\\chi\\chi \\toH_{\\{k,l\\}}^{++}H_{\\{k,l\\}}^{--} \\to \\ell_i^+\\ell_i^+\\ell_j^-\\ell_j^-$accompanied by $\\chi\\chi \\to H_1^+ H_1^- \\to \\ell_i^+ \\nu_{\\ell_i} \\ell_j^-\\nu_{\\ell_j}$ with $\\ell_{i,j}=e,\\mu,\\tau,\\,H_{\\{k,l\\}}^{\\pm\\pm}=H_{\\{1,2\\}}^{\\pm\\pm}$. We impose various experimentalconstraints such as accommodation of a SM-like Higgs, the observed DM relicabundance, DM direct detection bounds, lepton flavor violation measurements andEW precision observables. We found that there are ample parameter space whichcan interpret the DAMPE data while passing the above constraints. We alsodiscuss the collider signals for benchmark model points.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05351", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 5099924211367936, "title": "Measuring the duration of inflation with the curvaton. (arXiv:1712.05364v1 [astro-ph.CO])", "url": "http://arxiv.org/abs/1712.05364", "abstract": "Simple models of single-field inflation in the very early universe cangenerate the observed amplitude and scale dependence of the primordial densityperturbation, but models with multiple fields can provide an equally good fitto current data. We show how future observations will be able to distinguishbetween currently favoured models. If a curvaton field generates the primordialperturbations after inflation, we show how the total duration of inflation canbe measured.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05364", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 5557239981015040, "title": "The paper \"How proper are Bayesian models in the astronomical literature?\" [arXiv:1712.03549] by Tak, Ghosh and Ellis is improper. (arXiv:1712.05335v1 [astro-ph.IM])", "url": "http://arxiv.org/abs/1712.05335", "abstract": "In their \"How proper are Bayesian models in the astronomical literature?\"[arXiv:1712.03549], Hyungsuk Tak, Sujit K. Ghosh and Justin A. Ellis criticisedmy work with false statements. This is an infamous case of straw man fallacy.They give the impression of refuting an opponent's argument, while they refutean argument that was not presented.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05335", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 6228113872650240, "title": "The continuous rise of bulges out of galactic disks. (arXiv:1712.05354v1 [astro-ph.GA])", "url": "http://arxiv.org/abs/1712.05354", "abstract": "(abridged) This study revolves around dmB, a new distance- andextinction-independent measure of the contribution by stellar populations olderthan 9 Gyr to the mean r-band surface brightness of the bulge component in 135late-type galaxies (LTGs) from the CALIFA survey, spanning a range of 2.6 dexand 3 dex in total and bulge stellar mass (M*T~10^(8.9-11.5) M_solar andM*B~10^(8.3-11.3) M_solar, respectively). The main insight from this study isthat LTG bulges form a continuous sequence of increasing dmB with increasingM*T, M*B, stellar mass surface density S* and mass-weighted age andmetallicity: high-dmB bulges are the oldest, densest and most massive ones, andvice versa. Furthermore, we find that the bulge-to-disk age and metallicitycontrast, as well as the bulge-to-disk mass ratio increase with M*T, raisingfrom, respectively, ~0 Gyr, 0 dex and 0.25 to ~3 Gyr, ~0.3 dex and 0.67 acrossthe mass range covered by our sample. Whereas gas excitation in lower-massbulges is invariably dominated by star formation (SF), LINER- andSeyfert-specific emission-line ratios were exclusively documented in high-mass,high-S* bulges. The continuity both in the properties of LTG bulges themselvesand in their age and metallicity contrast to their parent disks suggests thatthese components evolve alongside in a concurrent process that leads to acontinuum of physical and evolutionary characteristics. Our results areconsistent with a picture where bulge growth in LTGs is driven by asuperposition of quick-early and slow-secular processes, the relativeimportance of which increases with M*T. These processes, which presumablycombine in situ SF in the bulge and inward migration of material from the disk,are expected to lead to a non-homologous radial growth of S* and a trend for anincreasing Sersic index with increasing galaxy mass.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05354", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 6276420712005632, "title": "Coincident detection significance in multimessenger astronomy. (arXiv:1712.05392v1 [astro-ph.HE])", "url": "http://arxiv.org/abs/1712.05392", "abstract": "We derive a Bayesian criterion for assessing whether signals observed in twoseparate data sets originate from a common source. The Bayes factor for acommon vs. unrelated origin of signals includes an overlap integral of theposterior distributions over the common source parameters. Focusing onmultimessenger gravitational-wave astronomy, we apply the method to the spatialand temporal association of independent gravitational-wave and electromagnetic(or neutrino) observations. As an example, we consider the coincidence betweenthe recently discovered gravitational-wave signal GW170817 from a binaryneutron star merger and the gamma-ray burst GRB 170817A: we find that thecommon source model is enormously favored over a model describing them asunrelated signals.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05392", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 6657039908470784, "title": "Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us. (arXiv:1712.05331v1 [astro-ph.HE])", "url": "http://arxiv.org/abs/1712.05331", "abstract": "Supernova remnants (SNRs) arise from the interaction between the ejecta of asupernova (SN) explosion and the surrounding circumstellar and interstellarmedium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However,to understand SNRs as a whole, large samples of SNRs must be assembled andstudied. Here, we describe the radio, optical, and X-ray techniques which havebeen used to identify and characterize almost 300 Galactic SNRs and more than1200 extragalactic SNRs. We then discuss which types of SNRs are being foundand which are not. We examine the degree to which the luminosity functions,surface-brightness distributions and multi-wavelength comparisons of thesamples can be interpreted to determine the class properties of SNRs anddescribe efforts to establish the type of SN explosion associated with a SNR.We conclude that in order to better understand the class properties of SNRs, itis more important to study (and obtain additional data on) the SNRs in galaxieswith extant samples at multiple wavelength bands than it is to obtain samplesof SNRs in other galaxies", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05331", "stored": "2017-12-17T19:43:19", "published": "2017-12-17T19:43:19", "type_of": "feed" }, { "in_graph": false, "uuid": 4543107471245312, "title": "Growth and evolution of satellites in a Jovian massive disc. (arXiv:1712.05327v1 [astro-ph.EP])", "url": "http://arxiv.org/abs/1712.05327", "abstract": "The formation of satellite systems in circum-planetary discs is considered tobe similar to the formation of rocky planets in a proto-planetary disc,especially Super-Earths. Thus, it is possible to use systems with largesatellites to test formation theories that are also applicable to extrasolarplanets. Furthermore, a better understanding of the origin of satellites mightyield important information about the environment near the growing planetduring the last stages of planet formation. In this work we investigate theformation and migration of the Jovian satellites through N-body simulations. Wesimulated a massive, static, low viscosity, circum-planetary disc in agreementwith the minimum mass sub-nebula model prescriptions for its total mass. Inhydrodynamic simulations we found no signs of gaps, therefore type II migrationis not expected. Hence, we used analytic prescriptions for type I migration,eccentricity and inclination damping, and performed N-body simulations withdamping forces added. Detailed parameter studies showed that the number offinal satellites is strong influenced by the initial distribution of embryos,the disc temperature, and the initial gas density profile. For steeper initialdensity profiles it is possible to form systems with multiple satellites inresonance while a flatter profile favours the formation of satellites close tothe region of the Galilean satellites. We show that the formation of massivesatellites such as Ganymede and Callisto can be achieved for hotter discs withan aspect ratio of H/r ~ 0.15 for which the ice line was located around 30 R_J.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05327", "stored": "2017-12-17T19:43:18", "published": "2017-12-17T19:43:18", "type_of": "feed" }, { "in_graph": false, "uuid": 5305950034460672, "title": "Peculiarities of super-Eddington flares from the X-ray pulsar LMC X-4 with NuSTAR. (arXiv:1712.05322v1 [astro-ph.HE])", "url": "http://arxiv.org/abs/1712.05322", "abstract": "We present results of the analysis of super-Eddington flares registered fromthe X-ray pulsar LMC X-4 by the NuSTAR observatory in the broad energy range3-79 keV. The pulsar spectrum is well described by the thermal comptonizationmodel both in a quiescent state and during flares, when the peak luminosityreaches values $L_{\\rm x} \\sim (2-4)\\times10^{39}$ erg s$^{-1}$. An importantfeature, found for the first time, is that the order of magnitude increase inthe luminosity during flares is observed primarily at energies below 25-30 keV,whereas at higher energies (30-70 keV) the shape of the spectrum and the sourceflux remain practically unchanged. The luminosity increase is accompanied bychanges in the source pulse profile -- in the energy range of 3-40 keV itbecomes approximately triangular, and the pulsed fraction increases withincreasing energy, reaching 60-70% in the energy range of 25-40 keV. The paperdiscusses possible changes in the geometry of the accretion column, which canexplain variations in spectra and pulse profiles.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05322", "stored": "2017-12-17T19:43:18", "published": "2017-12-17T19:43:18", "type_of": "feed" }, { "in_graph": false, "uuid": 5659257533890560, "title": "Group quenching and galactic conformity at low redshift. (arXiv:1712.05318v1 [astro-ph.GA])", "url": "http://arxiv.org/abs/1712.05318", "abstract": "We quantify the quenching impact of the group environment using thespectroscopic survey GAMA to z=0.2. The fraction of quiescent galaxies (redfraction), whether in groups or isolated, increases with both stellar mass andlarge-scale (5 Mpc) density. At fixed stellar mass and density, the redfraction of satellites and group centrals is higher than that of isolatedgalaxies, supporting the idea of \"group quenching\" rather than satellitequenching. The quenching efficiency with respect to isolated galaxies (aformalism that flattens out the effect of both stellar mass and density) is anincreasing function of central color, group stellar mass, and density forsatellites of red centrals only, inducing \"galactic conformity\" : the quenchingefficiency is on average higher for satellites of red centrals than of bluecentrals. However most of the conformity signal originates from the mostmassive groups, which reside in the densest environments around the reddestcentrals. The star-formation of blue satellites around red centrals inrich/massive groups is also slightly suppressed compared to blue field galaxiesof the same mass. In the range of group stellar mass that red and blue centralshave in common, some amount of conformity persists at fixed group stellar mass,independent of density. However, assuming a color-dependenthalo-to-stellar-mass ratio, whereby red central galaxies inhabit significantlymore massive halos than blue ones of the same stellar mass, we find thatconformity disappears entirely at fixed halo mass.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05318", "stored": "2017-12-17T19:43:18", "published": "2017-12-17T19:43:18", "type_of": "feed" }, { "in_graph": false, "uuid": 5701466861862912, "title": "Measuring patchy reionisation with kSZ$^2$-21 cm correlations. (arXiv:1712.05305v1 [astro-ph.CO])", "url": "http://arxiv.org/abs/1712.05305", "abstract": "We study cross-correlations of the kinetic Sunyaev-Zel'dovich effect (kSZ)and 21 cm signals during the epoch of reionisation (EoR) to measure the effectsof patchy reionisation. Since the kSZ effect is proportional to theline-of-sight velocity, the kSZ-21 cm cross correlation suffers fromcancellation at small angular scales. We thus focus on the correlation betweenthe kSZ-squared field (kSZ$^2$) and 21 cm signals. When the global ionisationfraction is low ($x_e\\lesssim 0.7$), the kSZ$^2$ fluctuation is dominated byrare ionised bubbles which leads to an anti-correlation with the 21 cm signal.When $0.8\\lesssim x_e<1$, the correlation is dominated by small pockets ofneutral regions, leading to a positive correlation. However, at very highredshifts when $x_e<0.15$, the spin temperature fluctuations change the sign ofthe correlation from negative to positive, as weakly ionised regions can havestrong 21 cm signals in this case. To extract this correlation, we find thatWiener filtering is effective in removing large signals from the primary CMBanisotropy. The expected signal-to-noise ratios for a $\\sim$10-hour integrationof upcoming Square Kilometer Array data cross-correlated with maps from thecurrent generation of CMB observatories with 3.4~$\\mu$K arcmin noise and1.7~arcmin beam over 100~deg$^2$ are 51, 60, and 37 for $x_e=0.2$, 0.5, and0.9, respectively.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1712.05305", "stored": "2017-12-17T19:43:18", "published": "2017-12-17T19:43:18", "type_of": "feed" } ], "next": "http://semantics.projectchronos.eu/?bookmark=CkoKFgoJcHVibGlzaGVkEgkIgMONkOeR2AISLGoQZX5jaHJvbm9zdHJpcGxlc3IYCxILV2ViUmVzb3VyY2UYgICAmMOukAoMGAAgAQ==" }