{ "articles": [ { "in_graph": false, "uuid": 6036717203095552, "title": "Astronaut and moonwalker Alan Bean dies at 86", "url": "https://phys.org/news/2018-05-astronaut-moonwalker-alan-bean-dies.html", "abstract": "Former Apollo 12 astronaut and painter Alan Bean, who was the fourth person to walk on the moon and later turned his passion for space into art, has died. He was 86.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=https://phys.org/news/2018-05-astronaut-moonwalker-alan-bean-dies.html", "stored": "2018-05-27T01:38:02", "published": "2018-05-26T21:20:37", "type_of": "feed" }, { "in_graph": false, "uuid": 6480271629090816, "title": "Alan Bean", "url": "http://feedproxy.google.com/~r/nasawatch/Aekt/~3/PBa5XJFYicA/alan-bean.html", "abstract": "Remembering Alan Bean, Apollo Moon Walker and Artist, Astronaut Scholarship Foundation \"Apollo and Skylab astronaut Alan Bean, the fourth human to walk on the moon and an accomplished artist, has died. Bean, 86, died on Saturday, May 26, at Houston...", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://feedproxy.google.com/~r/nasawatch/Aekt/~3/PBa5XJFYicA/alan-bean.html", "stored": "2018-05-26T20:48:01", "published": "2018-05-26T17:39:45", "type_of": "feed" }, { "in_graph": false, "uuid": 6606275769008128, "title": "New Head Of Roscosmos Is Under Formal U.S. Sanction", "url": "http://feedproxy.google.com/~r/nasawatch/Aekt/~3/VQ_ywc2ZjH8/new-head-of-ros.html", "abstract": "Putin appoints head of Roscosmos, TASS \"Russian President Vladimir Putin has nominated former Deputy PM Dmitry Rogozin to head the State Space Corporation Roscosmos. The meeting between Putin and Rogozin took place on the sidelines of the St. Petersburg International...", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://feedproxy.google.com/~r/nasawatch/Aekt/~3/VQ_ywc2ZjH8/new-head-of-ros.html", "stored": "2018-05-26T20:48:01", "published": "2018-05-26T12:54:57", "type_of": "feed" }, { "in_graph": false, "uuid": 6586852584718336, "title": "BepiColombo", "url": "http://nineplanets.org/news/bepicolombo/", "abstract": "Getting to Mercury is a series of short vital steps prior to launch. Another one is complete.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://nineplanets.org/news/bepicolombo/", "stored": "2018-05-26T13:38:01", "published": "2018-05-26T11:11:16", "type_of": "feed" }, { "in_graph": false, "uuid": 5154776002068480, "title": "Overview of the SAPHIRA Detector for AO Applications. (arXiv:1805.08419v2 [astro-ph.IM] UPDATED)", "url": "http://arxiv.org/abs/1805.08419", "abstract": "We discuss some of the unique details of the operation and behavior ofLeonardo SAPHIRA detectors, particularly in relation to their usage foradaptive optics wavefront sensing. SAPHIRA detectors are 320$\\times$256@24$\\mu$m pixel HgCdTe linear avalanche photodiode arrays and are sensitive to0.8-2.5 $\\mu m$ light. SAPHIRA arrays permit global or line-by-line resets, ofthe entire detector or just subarrays of it, and the order in which pixels arereset and read enable several readout schemes. We discuss three readout modes,the benefits, drawbacks, and noise sources of each, and the observational modesfor which each is optimal. We describe the ability of the detector to readsubarrays for increased frame rates, and finally clarify the differencesbetween the avalanche gain (which is user-adjustable) and the charge gain(which is not).", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.08419", "stored": "2018-05-26T01:38:13", "published": "2018-05-26T01:38:13", "type_of": "feed" }, { "in_graph": false, "uuid": 5383527033995264, "title": "$\\alpha$ Centauri A as a potential stellar model calibrator: establishing the nature of its core. (arXiv:1805.09103v2 [astro-ph.SR] UPDATED)", "url": "http://arxiv.org/abs/1805.09103", "abstract": "Understanding the physical process responsible for the transport of energy inthe core of $\\alpha$ Centauri A is of the utmost importance if this star is tobe used in the calibration of stellar model physics. Adoption of differentparallax measurements available in the literature results in differences in theinterferometric radius constraints used in stellar modelling. Further, this isat the origin of the different dynamical mass measurements reported for thisstar. With the goal of reproducing the revised dynamical mass derived byPourbaix & Boffin, we modelled the star using two stellar grids varying in theadopted nuclear reaction rates. Asteroseismic and spectroscopic observableswere complemented with different interferometric radius constraints during theoptimisation procedure. Our findings show that best-fit models reproducing therevised dynamical mass favour the existence of a convective core ($\\gtrsim$ 70%of best-fit models), a result that is robust against changes to the modelphysics. If this mass is accurate, then $\\alpha$ Centauri A may be used tocalibrate stellar model parameters in the presence of a convective core.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.09103", "stored": "2018-05-26T01:38:13", "published": "2018-05-26T01:38:13", "type_of": "feed" }, { "in_graph": false, "uuid": 4921430672146432, "title": "Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey II: Report of a Community Workshop on the Scientific Synergies Between the SPHEREx Survey and Other Astronomy Observatories. (arXiv:1805.05489v2 [astro-ph.IM] UPDATED)", "url": "http://arxiv.org/abs/1805.05489", "abstract": "SPHEREx is a proposed NASA MIDEX mission selected for Phase A study. SPHERExwould carry out the first all-sky spectral survey in the near infrared. At theend of its two-year mission, SPHEREx would obtain 0.75-to-5$\\mu$m spectra ofevery 6.2 arcsec pixel on the sky, with spectral resolution R>35 and a5-$\\sigma$ sensitivity AB$>$19 per spectral/spatial resolution element. Moredetails concerning SPHEREx are available at this http URL TheSPHEREx team has proposed three specific science investigations to be carriedout with this unique data set: cosmic inflation, interstellar and circumstellarices, and the extra-galactic background light. Though these three themes areundoubtedly compelling, they are far from exhausting the scientific output ofSPHEREx. Indeed, SPHEREx would create a unique all-sky spectral databaseincluding spectra of very large numbers of astronomical and solar systemtargets, including both extended and diffuse sources. These spectra wouldenable a wide variety of investigations, and the SPHEREx team is dedicated tomaking the data available to the community to enable these investigations,which we refer to as Legacy Science. To that end, we have sponsored twoworkshops for the general scientific community to identify the most interestingLegacy Science themes and to ensure that the SPHEREx data products areresponsive to their needs. In February of 2016, some 50 scientists from allfields met in Pasadena to develop these themes and to understand theirimplications for the SPHEREx mission. The 2016 workshop highlighted manysynergies between SPHEREx and other contemporaneous astronomical missions,facilities, and databases. Consequently, in January 2018 we convened a secondworkshop at the Center for Astrophysics in Cambridge to focus specifically onthese synergies. This white paper reports on the results of the 2018 SPHERExworkshop.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.05489", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 5125552507715584, "title": "Collimation, Acceleration and Recollimation Shock in the Jet of Gamma-Ray-emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy 1H 0323+342. (arXiv:1805.08299v2 [astro-ph.HE] UPDATED)", "url": "http://arxiv.org/abs/1805.08299", "abstract": "We investigated the detailed radio structure of the jet of 1H 0323+342 usinghigh-resolution multi-frequency Very Long Baseline Array observations. Thissource is known as the nearest $\\gamma$-ray emitting radio-loud narrow-lineSeyfert 1 (NLS1) galaxy. We discovered that the morphology of the inner jet iswell characterized by a parabolic shape, indicating the jet being continuouslycollimated near the jet base. On the other hand, we found that the jet expandsmore rapidly at larger scales, resulting in a conical-like shape. The locationof the \"collimation break\" is coincident with a bright quasi-stationary featureat 7 mas from core (corresponding to a deprojected distance of the order of$\\sim$100pc), where the jet width locally contracts together with highlypolarized signals, suggesting a recollimation shock. We found that thecollimation region is coincident with the region where the jet speed graduallyaccelerates, suggesting the coexistence of the jet acceleration and collimationzone, ending up with the recollimation shock, which could be a potential siteof high-energy $\\gamma$-ray flares detected by the Fermi-LAT. Remarkably, theseobservational features of the 1H 0323+342 jet are overall very similar to thoseof the nearby radio galaxy M87 and HST-1 as well as some blazars, suggestingthat a common jet formation mechanism might be at work. Based on the similarityof the jet profile between the two sources, we also briefly discuss the mass ofthe central black hole of 1H 0323+342, which is also still highly controversialon this source and NLS1s in general.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.08299", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 5373770747346944, "title": "Scanamorphos for the APEX-ArT\\'eMiS 350-450 $\\mu$m camera : description and user guide. (arXiv:1803.04264v2 [astro-ph.IM] UPDATED)", "url": "http://arxiv.org/abs/1803.04264", "abstract": "Scanamorphos is public software initially developed to post-process scanobservations performed with the Herschel photometer arrays. Thispost-processing mainly consists in subtracting the total low-frequency noise(both its thermal and non-thermal components), masking cosmic ray hits, andprojecting the data onto a map. Building upon the results obtained forP-ArT\\'eMiS (the prototype of ArT\\'eMiS), Herschel and then NIKA2 (a residentcamera of the IRAM 30-m telescope operating at 1.25 and 2 mm), it has now beentailored to the ArT\\'eMiS camera, an ESO and OSO P.I. instrument installed atthe APEX 12-m telescope, demonstrating our initial claim that the softwareprinciples were directly transposable to scan observations made with otherinstruments, including from the ground, provided they entail sufficientredundancy. This document explains how the algorithm was modified to cope withthe specificities of ArT\\'eMiS observations and with the atmospheric emissionat 350 and 450 $\\mu$m, far dominating the instrumental drifts that were theonly low-frequency noise component in Herschel data. Like in the originalsoftware, this was accomplished without assuming any noise model and withoutapplying any Fourier-space filtering, by exploiting the redundancy built in theobservations - taking advantage of the fact that each portion of the sky issampled at multiple times by multiple bolometers. It remains an interactivesoftware in the sense that the user is allowed to optionally visualize andcontrol results at each intermediate step, but the processing is fullyautomated. It has been grafted onto the ArT\\'eMiS pipeline, in charge of theformatting, calibration and projection of the data, that is describedelsewhere.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1803.04264", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 5911766135472128, "title": "Internal dynamics of the Large Magellanic Cloud from Gaia DR2. (arXiv:1805.08157v2 [astro-ph.GA] UPDATED)", "url": "http://arxiv.org/abs/1805.08157", "abstract": "We use the proper motions (PM) of half a million red giant stars in LargeMagellanic Cloud measured by Gaia to construct a 2d kinematic map of mean PMand its dispersion across the galaxy, out to 7 Kpc from its centre. We thenexplore a range of dynamical models and measure the rotation curve, meanazimuthal velocity, velocity dispersion profiles, and the orientation of thegalaxy. We find that the circular velocity reaches 100 km/s at 5 Kpc, and thatthe velocity dispersion ranges from 40-50 km/s in the galaxy centre to 20 km/sat 7 Kpc.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.08157", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 6009996869369856, "title": "Relativistic magnetised perturbations: magnetic pressure vs magnetic tension. (arXiv:1803.02747v3 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1803.02747", "abstract": "We study the linear evolution of magnetised cosmological perturbations in thepost-recombination epoch. Using full general relativity and adopting the idealmagnetohydrodynamic approximation, we refine and extend the previoustreatments. More specifically, this is the first relativistic study thataccounts for the effects of the magnetic tension, in addition to those of thefield's pressure. Our solutions show that on sufficiently large scales, largerthan the (purely magnetic) Jeans length, the perturbations evolve essentiallyunaffected by the magnetic presence. The magnetic pressure dominates on smallscales, where it forces the perturbations to oscillate and decay. Close to theJeans length, however, the field's tension takes over and leads to a weakgrowth of the inhomogeneities. These solutions clearly demonstrate the opposingaction of the aforementioned two magnetic agents, namely of the field'spressure and tension, on the linear evolution of cosmological densityperturbations.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1803.02747", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 6179492653432832, "title": "On the Formation and Properties of Fluid Shocks and Collisionless Shock Waves in Astrophysical Plasmas. (arXiv:1803.09744v2 [physics.plasm-ph] UPDATED)", "url": "http://arxiv.org/abs/1803.09744", "abstract": "When two plasmas collide, their interaction can be mediated by collisionlessplasma instabilities or binary collisions between particles of each shell. Bycomparing the maximum growth rate of the collisionless instabilities with thecollision frequency between particles of the shells, we determine the criticaldensity separating the collisionless formation from the collisional formationof the resulting shock waves. This critical density is also the density beyondwhich the shock downstream is field free, as plasma instabilities do not havetime to develop electromagnetic patterns. We further determine the conditionson the shells initial density and velocity for the downstream to becollisional. If these quantities fulfill the determined conditions, thecollisionality of the downstream also prevents the shock from acceleratingparticles or generating strong magnetic fields. We compare the speed of soundwith the relative speed of collision between the two shells, thus determiningthe portion of the parameters space where strong shock formation is possiblefor both classical and degenerate plasmas. Finally, we discuss theobservational consequences in several astrophysical settings.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1803.09744", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 6206729188540416, "title": "Old, Metal-Poor Extreme Velocity Stars in the Solar Neighborhood. (arXiv:1805.03194v2 [astro-ph.GA] UPDATED)", "url": "http://arxiv.org/abs/1805.03194", "abstract": "We report the discovery of 30 stars with extreme space velocities (> 480km/s) in the Gaia-DR2 archive. These stars are a subset of 1743 stars withhigh-precision parallax, large tangential velocity (v_{tan}>300 km/s), andmeasured line-of-sight velocity in DR2. By tracing the orbits of the stars backin time, we find at least one of them is consistent with having been ejected bythe supermassive black hole at the Galactic center. Another star has an orbitthat passes near the Large Magellanic Cloud (LMC) about 200 Myr ago. Unlikepreviously discovered blue hypervelocity stars, our sample is metal-poor (-1.5< [Fe/H] < -1.0) and quite old (>1 Gyr). We discuss possible mechanisms foraccelerating old stars to such extreme velocities. The high observed spacedensity of this population, relative to potential acceleration mechanisms,implies that these stars are probably bound to the Milky Way. If they arebound, the discovery of this population would require a local escape speed ofaround 600 km/s and consequently imply a virial mass of M_{200} = 1.4 x 10^{12}Msun for the Milky Way.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.03194", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 6285826916876288, "title": "The mid-2016 flaring activity of the flat spectrum radio quasar PKS 2023-07. (arXiv:1805.05640v2 [astro-ph.HE] UPDATED)", "url": "http://arxiv.org/abs/1805.05640", "abstract": "Flat spectrum radio quasars (FSRQs) can suffer strong absorption above E =25/(1+z) GeV, due to gamma-gamma interaction if the emitting region is atsub-parsec scale from the super-massive black hole (SMBH). Gamma-ray flaresfrom these astrophysical sources can investigate the location of thehigh-energy emission region and the physics of the radiating processes. Wepresent a remarkable gamma-ray flaring activity from FSRQ PKS 2023-07 duringApril 2016, as detected by both AGILE and Fermi satellites. An intensivemulti-wavelength campaign, triggered by Swift, covered the entire duration ofthe flaring activity, including the peak gamma-ray activity. We report theresults of multiwavelength observations of the blazar. We found that, duringthe peak emission, the most energetic photon had an energy of 44 GeV, puttingstrong constraints on the opacity of the gamma-ray dissipation region. Theoverall Spectral Energy Distribution (SED) is interpreted in terms of leptonicmodels for blazar jet, with the emission site located beyond the Broad LineRegion (BLR).", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.05640", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 6589511974780928, "title": "Modeling evolution of dark matter substructure and annihilation boost. (arXiv:1803.07691v2 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1803.07691", "abstract": "We study evolution of dark matter substructures, especially how they lose themass and change density profile after they fall in gravitational potential oflarger host halos. We develop an analytical prescription that models thesubhalo mass evolution and calibrate it to results of N-body numericalsimulations of various scales from very small (Earth size) to large (galaxiesto clusters) halos. We then combine the results with halo accretion histories,and calculate the subhalo mass function that is physically motivated down toEarth-mass scales. Our results --- valid for arbitrary host masses andredshifts --- show reasonable agreement with those of numerical simulations atresolved scales. Our analytical model also enables self-consistent calculationsof the boost factor of dark matter annhilation, which we find to increase fromtens of percent at the smallest (Earth) and intermediate (dwarfs) masses to afactor of several at galaxy size, and to become as large as a factor of$\\sim$10 for the largest halos (clusters) at small redshifts. Our analyticalapproach can accommodate substructures in the subhalos (sub-subhalos) in aconsistent framework, which we find to give up to a factor of a few enhancementto the annihilation boost. Presence of the subhalos enhances the intensity ofthe isotropic gamma-ray background by a factor of a few, and as the result, themeasurement by Fermi Large Area Telescope excludes the annihilation crosssection greater than $\\sim$$4\\times 10^{-26}$ cm$^3$ s$^{-1}$ for dark mattermasses up to $\\sim$200 GeV.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1803.07691", "stored": "2018-05-26T01:38:12", "published": "2018-05-26T01:38:12", "type_of": "feed" }, { "in_graph": false, "uuid": 5082314266640384, "title": "LSST: from Science Drivers to Reference Design and Anticipated Data Products. (arXiv:0805.2366v5 [astro-ph] UPDATED)", "url": "http://arxiv.org/abs/0805.2366", "abstract": "(Abridged) We describe here the most ambitious survey currently planned inthe optical, the Large Synoptic Survey Telescope (LSST). A vast array ofscience will be enabled by a single wide-deep-fast sky survey, and LSST willhave unique survey capability in the faint time domain. The LSST design isdriven by four main science themes: probing dark energy and dark matter, takingan inventory of the Solar System, exploring the transient optical sky, andmapping the Milky Way. LSST will be a wide-field ground-based system sited atCerro Pach\\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 meffective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixelcamera. The standard observing sequence will consist of pairs of 15-secondexposures in a given field, with two such visits in each pointing in a givennight. With these repeats, the LSST system is capable of imaging about 10,000square degrees of sky in a single filter in three nights. The typical 5$\\sigma$point-source depth in a single visit in $r$ will be $\\sim 24.5$ (AB). Theproject is in the construction phase and will begin regular survey operationsby 2022. The survey area will be contained within 30,000 deg$^2$ with$\\delta<+34.5^\\circ$, and will be imaged multiple times in six bands, $ugrizy$,covering the wavelength range 320--1050 nm. About 90\\% of the observing timewill be devoted to a deep-wide-fast survey mode which will uniformly observe a18,000 deg$^2$ region about 800 times (summed over all six bands) during theanticipated 10 years of operations, and yield a coadded map to $r\\sim27.5$. Theremaining 10\\% of the observing time will be allocated to projects such as aVery Deep and Fast time domain survey. The goal is to make LSST data products,including a relational database of about 32 trillion observations of 40 billionobjects, available to the public and scientists around the world.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/0805.2366", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 5196661596880896, "title": "Expected Precision of Europa Clipper Gravity Measurements. (arXiv:1801.08946v2 [astro-ph.EP] UPDATED)", "url": "http://arxiv.org/abs/1801.08946", "abstract": "The primary gravity science objective of NASA's Clipper mission to Europa isto confirm the presence or absence of a global subsurface ocean beneathEuropa's Icy crust. Gravity field measurements obtained with a radio scienceinvestigation can reveal much about Europa's interior structure. Here, weconduct extensive simulations of the radio science measurements with theanticipated spacecraft trajectory and attitude (17F12v2) and assets on thespacecraft and the ground, including antenna orientations and beam patterns,transmitter characteristics, and receiver noise figures. In addition to two-wayDoppler measurements, we also include radar altimeter crossover rangemeasurements. We concentrate on +/-2 hour intervals centered on the closestapproach of each of the 46 flybys. Our covariance analyses reveal the precisionwith which the tidal Love number k2, second-degree gravity coefficients C20 andC22, and higher-order gravity coefficients can be determined. The resultsdepend on the Deep Space Network (DSN) assets that are deployed to track thespacecraft. We find that some DSN allocations are sufficient to conclusivelyconfirm the presence or absence of a global ocean. Given adequate crossoverrange performance, it is also possible to evaluate whether the ice shell ishydrostatic.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1801.08946", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 5451850543267840, "title": "Identify binary extreme-mass-ratio inspirals with multi-band gravitational-wave observations. (arXiv:1801.07060v3 [gr-qc] UPDATED)", "url": "http://arxiv.org/abs/1801.07060", "abstract": "A small compact object spiraling into a supermassive black hole (SMBH) formsan extreme-mass-ratio inspiral (EMRI). It is one of the most important sourcesof gravitational waves (GWs) because the waveform is several months long andcontains rich information about the space-time geometry of the SMBH. Recently,we have shown that the small bodies in EMRIs could be binary black holes(BBHs). In this Letter we demonstrate that these binary-EMRIs (b-EMRIs) emitboth $10^2$ Hz and $10^{-3}$ Hz GWs at the same time, and hence are idealtargets for future joint observations using both ground- and space-based GWdetectors, because the BBHs would coalesce into single black holes (BHs) at asmall distance from the SMBHs. Since the coalescence induces a large recoilvelocity to the post-merger remnants, we propose a novel method of detectingb-EMRIs by looking for glitches in the waveforms of EMRIs and cross-correlatingthem with LIGO/Virgo events. The detection, in turn, can be used to measure themagnitude and direction of the recoil velocity to a precision as high as$(0.3-0.4)\\%$, as well as constrain the mass loss due to the GW radiation to aprecision of $0.1\\%$.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1801.07060", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 5480375862165504, "title": "Baryon Content in a Sample of 91 Galaxy Clusters Selected by the South Pole Telescope at 0.2 < z < 1.25. (arXiv:1711.00917v3 [astro-ph.CO] UPDATED)", "url": "http://arxiv.org/abs/1711.00917", "abstract": "We estimate total mass ($M_{500}$), intracluster medium (ICM) mass($M_{\\mathrm{ICM}}$) and stellar mass ($M_{\\star}$) in a Sunyaev-Zel'dovicheffect (SZE) selected sample of 91 galaxy clusters with masses$M_{500}\\gtrsim2.5\\times10^{14}M_{\\odot}$ and redshift $0.2 < z < 1.25$ fromthe 2500 deg$^2$ South Pole Telescope SPT-SZ survey. The total masses $M_{500}$are estimated from the SZE observable, the ICM masses $M_{\\mathrm{ICM}}$ areobtained from the analysis of $Chandra$ X-ray observations, and the stellarmasses $M_{\\star}$ are derived by fitting spectral energy distributiontemplates to Dark Energy Survey (DES) $griz$ optical photometry and $WISE$ or$Spitzer$ near-infrared photometry. We study trends in the stellar mass, theICM mass, the total baryonic mass and the cold baryonic fraction with clustermass and redshift. We find significant departures from self-similarity in themass scaling for all quantities, while the redshift trends are allstatistically consistent with zero, indicating that the baryon content ofclusters at fixed mass has changed remarkably little over the past $\\approx9$Gyr. We compare our results to the mean baryon fraction (and the stellar massfraction) in the field, finding that these values lie above (below) those incluster virial regions in all but the most massive clusters at low redshift.Using a simple model of the matter assembly of clusters from infalling groupswith lower masses and from infalling material from the low density environmentor field surrounding the parent halos, we show that the measured mass trendswithout strong redshift trends in the stellar mass scaling relation could beexplained by a mass and redshift dependent fractional contribution from fieldmaterial. Similar analyses of the ICM and baryon mass scaling relations provideevidence for the so-called \"missing baryons\" outside cluster virial regions.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1711.00917", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 6194435381526528, "title": "A possible explanation of the parallel tracks in kilohertz quasi-periodic oscillations from low-mass-X-ray binaries. (arXiv:1801.02000v2 [astro-ph.HE] UPDATED)", "url": "http://arxiv.org/abs/1801.02000", "abstract": "We recalculate the modes of the magnetohydrodynamics (MHD) waves in the MHDmodel (Shi, Zhang & Li 2014) of the kilohertz quasi-periodic oscillations (kHzQPOs) in neutron star low mass X-ray binaries (NS-LMXBs), in which thecompressed magnetosphere is considered. A method on pointby- point scanning forevery parameter of a normal LMXBs is proposed to determine the wave number in aNS-LMXB. The dependence of the twin kHz QPO frequencies on accretion rates (DOt(M) ) is obtained with the wave number and magnetic field (B?) determined byour method. Based on the MHD model, a new explanation of the parallel tracks,i.e. the slowly varying effective magnetic field leads to the shift of paralleltracks in a source, is presented. In this study, we obtain a simple power-lawrelation between the kHz QPO frequencies and Dot(M) /B^2 ? in those sources.Finally, we study the dependence of kHz quasi-periodic oscillation frequencieson the spin, mass and radius of a neutron star. We find that the effectivemagnetic field, the spin, mass and radius of a neutron star lead to theparallel tracks in different sources.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1801.02000", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 6259173692014592, "title": "Do SN 2002cx-like and SN Ia-CSM objects share the same origin?. (arXiv:1801.00228v2 [astro-ph.HE] UPDATED)", "url": "http://arxiv.org/abs/1801.00228", "abstract": "SN 2002cx-like and SN Ia-CSM objects show similar early spectra and bothbelong to a young stellar population, suggesting that they could share the sameprogenitor origin. Adopting the framework of the common-envelope-wind (CEW)model developed in \\citet{MENGXC17}, we here propose that both subclasses ofSNe Ia are caused by the explosion of hybrid carbon-oxygen-neon white dwarfs(CONe WDs) in single-degenerate systems, where SNe Ia-CSM explode in systemswith a massive common envelope (CE) of $\\sim1~M_{\\odot}$, while SN 2002cx-likeevents correspond to those events where most of the CE has been lost in a wind.Using binary-population-synthesis (BPS) calculations, we estimate a numberratio of SNe Ia-CSM to SN 2002cx-like objects between $\\frac{1}{3}$ and$\\frac{2}{3}$, consistent with observational constraints, and an overallcontribution from hybrid CONe WDs to the total SN Ia population that alsomatches the observed number from these peculiar objects. Our model predicts astatistical sequence of CSM density from SN Ia-CSM to SN 2002cx-like events andnormal SNe Ia, consistent with existing radio constraints. We also find a newsubclass of hybrid SNe which share the properties of Type II and Type Ia SNe,consistent with some observed SNe, which do not have a surviving companion. Insome cases these could even produce SNe Ia from apparently single WDs.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1801.00228", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 6449079965974528, "title": "Scale-invariant scalar field dark matter through the Higgs portal. (arXiv:1802.09434v2 [hep-ph] UPDATED)", "url": "http://arxiv.org/abs/1802.09434", "abstract": "We discuss the dynamics and phenomenology of an oscillating scalar fieldcoupled to the Higgs boson that accounts for the dark matter in the Universe.The model assumes an underlying scale invariance such that the scalar fieldonly acquires mass after the electroweak phase transition, behaving as darkradiation before the latter takes place. While for a positive coupling to theHiggs field the dark scalar is stable, for a negative coupling it acquires avacuum expectation value after the electroweak phase transition and may decayinto photon pairs, albeit with a mean lifetime much larger than the age of theUniverse. We explore possible astrophysical and laboratory signatures of such adark matter candidate in both cases, including annihilation and decay intophotons, Higgs decay, photon-dark scalar oscillations and induced oscillationsof fundamental constants. We find that dark matter within this scenario will begenerically difficult to detect in the near future, except for the promisingcase of a 7 keV dark scalar decaying into photons, which naturally explains theobserved galactic and extra-galactic 3.5 keV X-ray line.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1802.09434", "stored": "2018-05-26T01:38:11", "published": "2018-05-26T01:38:11", "type_of": "feed" }, { "in_graph": false, "uuid": 4835134335352832, "title": "Magnetar Signature - The U Curve. (arXiv:1805.09770v1 [astro-ph.HE])", "url": "http://arxiv.org/abs/1805.09770", "abstract": "This work looks at some definitive signatures of magnetars, in particular ofperiod closures accompanied by a decline of X-ray radiation in two models. Wereview some of the previous works which are based on the well known dynamomodel in which the star is born with a period of a few milliseconds at hightemperatures. In such a convection regime the dynamo mechanism can amplify thethe magnetic fields to the magnetar value. This is in contrast to a screenedcore model which posits that a high density phase transition occurs in theinner core of magnetars that dynamically aligns all the neutron magneticmoments producing a large magnetic field in the core. The accompanying changeof flux gives rise to shielding or screening currents in the surrounding highconductivity plasma that do not permit the field to exit to the surface.Ambipolar diffusion then transports the field to the crust dissipating energyin neutrinos and X-rays. The up-welling field cleaves the crust resulting inflares and X-ray radiation from ohmic dissipation in the crust till thescreening currents are spent and the surface polar field attains its finalvalue. In the dynamo model the polar magnetic field decreases with time whereasin our screened model it increases to its final value. One consequence of thisis that in the latter model, as a function of time and period, the ratio of thedipole radiation loss, $\\dot E$ to the X-ray luminosity, $L_X$, is a 'U'curve, indicating that it is the exponential decline in $L_X$, that bringsclosure to the periods that are observed for magnetars.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.09770", "stored": "2018-05-26T01:38:10", "published": "2018-05-26T01:38:10", "type_of": "feed" }, { "in_graph": false, "uuid": 5080829281697792, "title": "Uncertainties in WIMP Dark Matter Scattering Revisited. (arXiv:1805.09795v1 [hep-ph])", "url": "http://arxiv.org/abs/1805.09795", "abstract": "We revisit the uncertainties in the calculation of spin-independentscattering matrix elements for the scattering of WIMP dark matter particles onnuclear matter. In addition to discussing the uncertainties due to limitationsin our knowledge of the nucleonic matrix elements of the light quark scalardensities < N |{\\bar u} u, {\\bar d} d, {\\bar s} s| N>, we also discuss theimportances of heavy quark scalar densities < N |{\\bar c} c, {\\bar b} b, {\\bart} t| N >, and comment on uncertainties in quark mass ratios. We analyzeestimates of the light-quark densities made over the past decade using latticecalculations and/or phenomenological inputs. We find an uncertainty in thecombination < N |{\\bar u} u + {\\bar d} d | N > that is larger than has beenassumed in some phenomenological analyses, and a range of < N |{\\bar s} s| N >that is smaller but compatible with earlier estimates. We also analyze theimportance of the {\\cal O}(\\alpha_s^3) calculations of the heavy-quark matrixelements that are now available, which provide an important refinement of thecalculation of the spin-independent scattering cross section. We use forillustration a benchmark CMSSM point in the focus-point region that iscompatible with the limits from LHC and other searches.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.09795", "stored": "2018-05-26T01:38:10", "published": "2018-05-26T01:38:10", "type_of": "feed" }, { "in_graph": false, "uuid": 5109111909777408, "title": "The relation between stellar magnetic field geometry and chromospheric activity cycles II: The rapid 120 day magnetic cycle of Tau Bootis. (arXiv:1805.09769v1 [astro-ph.SR])", "url": "http://arxiv.org/abs/1805.09769", "abstract": "One of the aims of the BCool programme is to search for cycles in other starsand to understand how similar they are to the Sun. In this paper we aim tomonitor the evolution of $\\tau$ Boo's large-scale magnetic field usinghigh-cadence observations covering its chromospheric activity maximum. For thefirst time, we detect a polarity switch that is in phase with $\\tau$ Boo's 120day chromospheric activity maximum and its inferred X-ray activity cyclemaximum. This means that $\\tau$ Boo has a very fast magnetic cycle of only 240days. At activity maximum $\\tau$ Boo's large-scale field geometry is verysimilar to the Sun at activity maximum: it is complex and there is a weakdipolar component. In contrast, we also see the emergence of a strong toroidalcomponent which has not been observed on the Sun, and a potentially overlappingbutterfly pattern where the next cycle begins before the previous one hasfinished.", "keywords_url": "http://semantics.projectchronos.eu/keywords/filterby?url=http://arxiv.org/abs/1805.09769", "stored": "2018-05-26T01:38:10", "published": "2018-05-26T01:38:10", "type_of": "feed" } ], "next": "http://semantics.projectchronos.eu/?bookmark=CkoKFgoJcHVibGlzaGVkEgkIgMmI_56i2wISLGoQZX5jaHJvbm9zdHJpcGxlc3IYCxILV2ViUmVzb3VyY2UYgICAhN3WiQkMGAAgAQ==" }