bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metasurfaces: a new look at Maxwell’s equations and new ways to control light
Authors: Remnev M A , Klimov V V 
Published: August 2017

Abstract
The basic principles of light controling by means of metasurfaces are reviewed. Metasurfaces are able to control the phase, amplitude, polarization, and frequency of radiation propagating through them. The formulation of the generalized Snell’s law is presented. Ways to realize metasurfaces using resonances and the methods of phase shift within 2 π are discussed. An overview of experiments and recent achievements in the field of the light controling by means of the metasurfaces is also presented. Possible applications of metasurfaces and further development of this paradigm are considered, too.
Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets
Authors: Christiansen Jessie L. , Vanderburg Andrew , Burt Jennifer , Fulton B. J. , Batygin Konstantin , Benneke Björn , Brewer John M. , Charbonneau David , Ciardi David R. , Cameron Andrew Collier , Coughlin Jeffrey L. , Crossfield Ian J. M. , Dressing Courtney , Greene Thomas P. , Howard Andrew W. , Latham David W. , Molinari Emilio , Mortier Annelies , Mullally Fergal , Pepe Francesco , Rice Ken , Sinukoff Evan , Sozzetti Alessandro , Thompson Susan E. , Udry Stéphane , Vogt Steven S. , Barman Travis S. , Batalha Natasha E. , Bouchy François , Buchhave Lars A. , Butler R. Paul , Cosentino Rosario , Dupuy Trent J. , Ehrenreich David , Fiorenzano Aldo , Hansen Brad M. S. , Henning Thomas , Hirsch Lea , Holden Bradford P. , Isaacson Howard T. , Johnson John A. , Knutson Heather A. , Kosiarek Molly , López-Morales Mercedes , Lovis Christophe , Malavolta Luca , Mayor Michel , Micela Giuseppina , Motalebi Fatemeh , Petigura Erik , Phillips David F. , Piotto Giampaolo , Rogers Leslie A. , Sasselov Dimitar , Schlieder Joshua E. , Ségransan Damien , Watson Christopher A. , Weiss Lauren M. 
Published: August 2017

Abstract
HD 3167 is a bright (V = 8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 ± 0.38

for HD 3167 b, a hot super-Earth with a likely rocky composition (

=

g cm−3), and

for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement (

=

g cm−3). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 ± 0.045 d (between planets b and c) and a minimum mass of 6.90 ± 0.71

. We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.°3 because we do not observe transits of planet d. From 1.°3 to 40°, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time. From 40° to 60°, Kozai–Lidov oscillations increase the system’s instability, but it can remain stable for up to 100 Myr. Above 60°, the system is unstable. HD 3167 promises to be a fruitful system for further study and a preview of the many exciting systems expected from the upcoming NASA TESS mission.
Properties of the Irregular Satellite System around Uranus Inferred from K2, Herschel, and Spitzer Observations
Authors: Farkas-Takács A. , Kiss Cs. , Pál A. , Molnár L. , Szabó Gy. M. , Hanyecz O. , Sárneczky K. , Szabó R. , Marton G. , Mommert M. , Szakáts R. , Müller T. , Kiss L. L. 
Published: August 2017

Abstract
In this paper, we present visible-range light curves of the irregular Uranian satellites Sycorax, Caliban, Prospero, Ferdinand, and Setebos taken with the Kepler Space Telescope over the course of the K2 mission. Thermal emission measurements obtained with the Herschel/PACS and Spitzer/MIPS instruments of Sycorax and Caliban were also analyzed and used to determine size, albedo, and surface characteristics of these bodies. We compare these properties with the rotational and surface characteristics of irregular satellites in other giant planet systems and also with those of main belt and Trojan asteroids and trans-Neptunian objects. Our results indicate that the Uranian irregular satellite system likely went through a more intense collisional evolution than the irregular satellites of Jupiter and Saturn. Surface characteristics of Uranian irregular satellites seem to resemble the Centaurs and trans-Neptunian objects more than irregular satellites around other giant planets, suggesting the existence of a compositional discontinuity in the young solar system inside the orbit of Uranus.
Observations of the Ultraviolet-bright Star Y453 in the Globular Cluster M4 (NGC 6121)
Authors: Dixon William V. , Chayer Pierre , Latour Marilyn , Bertolami Marcelo Miguel Miller , Benjamin Robert A. 
Published: August 2017

Abstract
We present a spectral analysis of the UV-bright star Y453 in M4. Model fits to the star’s optical spectrum yield

∼ 56,000 K. Fits to the star’s FUV spectrum, obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope, reveal it to be considerably hotter, with

∼ 72,000 K. We adopt

= 72,000 ± 2000 K and

= 5.7 ± 0.2 as our best-fit parameters. Scaling the model spectrum to match the star’s optical and near-infrared magnitudes, we derive a mass

and luminosity

, consistent with the values expected of an evolved star in a globular cluster. Comparing the star with post-horizontal-branch evolutionary tracks, we conclude that it most likely evolved from the blue horizontal branch, departing the asymptotic giant branch before third dredge-up. It should thus exhibit the abundance pattern (O-poor and Na-rich) characteristic of the second-generation (SG) stars in M4. We derive the star’s photospheric abundances of He, C, N, O, Si, S, Ti, Cr, Fe, and Ni. CNO abundances are roughly 0.25 dex greater than those of the cluster’s SG stars, while the Si and S abundances match the cluster values. Abundances of the iron-peak elements (except for iron itself) are enhanced by 1–3 dex. Rather than revealing the star’s origin and evolution, this pattern reflects the combined effects of diffusive and mechanical processes in the stellar atmosphere.
Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae
Authors: Godon Patrick , Sion Edward M. , Balman Şölen , Blair William P. 
Published: August 2017

Abstract
The standard disk is often inadequate to model disk-dominated cataclysmic variables (CVs) and generates a spectrum that is bluer than the observed UV spectra. X-ray observations of these systems reveal an optically thin boundary layer (BL) expected to appear as an inner hole in the disk. Consequently, we truncate the inner disk. However, instead of removing the inner disk, we impose the no-shear boundary condition at the truncation radius, thereby lowering the disk temperature and generating a spectrum that better fits the UV data. With our modified disk, we analyze the archival UV spectra of three novalikes that cannot be fitted with standard disks. For the VY Scl systems MV Lyr and BZ Cam, we fit a hot inflated white dwarf (WD) with a cold modified disk (

a few 10−9
M
⊙ yr−1). For V592 Cas, the slightly modified disk (

) completely dominates the UV. These results are consistent with Swift X-ray observations of these systems, revealing BLs merged with ADAF-like flows and/or hot coronae, where the advection of energy is likely launching an outflow and heating the WD, thereby explaining the high WD temperature in VY Scl systems. This is further supported by the fact that the X-ray hardness ratio increases with the shallowness of the UV slope in a small CV sample we examine. Furthermore, for 105 disk-dominated systems, the International Ultraviolet Explorer spectra UV slope decreases in the same order as the ratio of the X-ray flux to optical/UV flux: from SU UMa’s, to U Gem’s, Z Cam’s, UX UMa’s, and VY Scl’s.
Dynamical Properties of Internal Shocks Revisited
Authors: Pe’er Asaf , Long Killian , Casella Piergiorgio 
Published: August 2017

Abstract
Internal shocks between propagating plasma shells, originally ejected at different times with different velocities, are believed to play a major role in dissipating the kinetic energy, thereby explaining the observed light curves and spectra in a large range of transient objects. Even if initially the colliding plasmas are cold, following the first collision, the plasma shells are substantially heated, implying that in a scenario of multiple collisions, most collisions take place between plasmas of non-zero temperatures. Here, we calculate the dynamical properties of plasmas resulting from a collision between arbitrarily hot plasma shells, moving at arbitrary speeds. We provide simple analytical expressions valid for both ultrarelativistic and Newtonian velocities for both hot and cold plasmas. We derive the minimum criteria required for the formation of the two-shock wave system, and show that in the relativistic limit, the minimum Lorentz factor is proportional to the square root of the ratio of the initial plasmas enthalpies. We provide basic scaling laws of synchrotron emission from both the forward and reverse-shock waves, and show how these can be used to deduce the properties of the colliding shells. Finally, we discuss the implications of these results in the study of several astronomical transients, such as X-ray binaries, radio-loud quasars, and gamma-ray bursts.
Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
Authors: Davis Allen B. , Cisewski Jessi , Dumusque Xavier , Fischer Debra A. , Ford Eric B. 
Published: August 2017

Abstract
Photospheric velocities and stellar activity features such as spots and faculae produce measurable radial velocity signals that currently obscure the detection of sub-meter-per-second planetary signals. However, photospheric velocities are imprinted differently in a high-resolution spectrum than are Keplerian Doppler shifts. Photospheric activity produces subtle differences in the shapes of absorption lines due to differences in how temperature or pressure affects the atomic transitions. In contrast, Keplerian Doppler shifts affect every spectral line in the same way. With a high enough signal-to-noise (S/N) and resolution, statistical techniques can exploit differences in spectra to disentangle the photospheric velocities and detect lower-amplitude exoplanet signals. We use simulated disk-integrated time-series spectra and principal component analysis (PCA) to show that photospheric signals introduce spectral line variability that is distinct from that of Doppler shifts. We quantify the impact of instrumental resolution and S/N for this work.
An Optically Faint Quasar Survey at z ∼ 5 in the CFHTLS Wide Field: Estimates of the Black Hole Masses and Eddington Ratios
Authors: Ikeda H. , Nagao T. , Matsuoka K. , Kawakatu N. , Kajisawa M. , Akiyama M. , Miyaji T. , Morokuma T. 
Published: August 2017

Abstract
We present the result of our spectroscopic follow-up observation for faint quasar candidates at z ∼ 5 in part of the Canada–France–Hawaii Telescope Legacy Survey wide field. We select nine photometric candidates and identify three z ∼ 5 faint quasars, one z ∼ 4 faint quasar, and a late-type star. Since two faint quasar spectra show the C iv emission line without suffering from a heavy atmospheric absorption, we estimate their black hole masses (

) and Eddington ratios (

). The inferred

are 9.04 ± 0.14 and 8.53 ± 0.20, respectively. In addition, the inferred

are −1.00 ± 0.15 and −0.42 ± 0.22, respectively. If we adopt that

, the seed black hole masses (

) of our z ∼ 5 faint quasars are expected to be

in most cases. We also compare the observational results with a mass accretion model, where angular momentum is lost due to supernova explosions. Accordingly,

of the z ∼ 5 faint quasars in our sample can be explained even if

is

. Since z ∼ 6 luminous qusars and our z ∼ 5 faint quasars are not on the same evolutionary track, z ∼ 6 luminous quasars and our z ∼ 5 quasars are not the same populations but different populations, due to the difference of a period of the mass supply from host galaxies. Furthermore, we confirm that one can explain

of z ∼ 6 luminous quasars and our z ∼ 5 faint quasars even if their seed black holes are formed at z ∼ 7.
High-energy Gamma Rays from the Milky Way: Three-dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities in the Interstellar Medium
Authors: Porter T. A. , Jóhannesson G. , Moskalenko I. V. 
Published: August 2017

Abstract
High-energy γ-rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well understood and are reproduced by existing CR propagation models employing 2D galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the Fermi Large Area Telescope reveal significant deviations from the model predictions on few to tens of degrees scales, indicating the need to include the details of the Galactic spiral structure and thus requiring 3D spatial modeling. In this paper, the high-energy interstellar emissions from the Galaxy are calculated using the new release of the GALPROP code employing 3D spatial models for the CR source and interstellar radiation field (ISRF) densities. Three models for the spatial distribution of CR sources are used that are differentiated by their relative proportion of input luminosity attributed to the smooth disk or spiral arms. Two ISRF models are developed based on stellar and dust spatial density distributions taken from the literature that reproduce local near- to far-infrared observations. The interstellar emission models that include arms and bulges for the CR source and ISRF densities provide plausible physical interpretations for features found in the residual maps from high-energy γ-ray data analysis. The 3D models for CR and ISRF densities provide a more realistic basis that can be used for the interpretation of the nonthermal interstellar emissions from the Galaxy.
The Importance of Preventive Feedback: Inference from Observations of the Stellar Masses and Metallicities of Milky Way Dwarf Galaxies
Authors: Lu Yu , Benson Andrew , Wetzel Andrew , Mao Yao-Yuan , Tonnesen Stephanie , Peter Annika H. G. , Boylan-Kolchin Michael , Wechsler Risa H. 
Published: August 2017

Abstract
Dwarf galaxies are known to have remarkably low star formation efficiency due to strong feedback. Adopting the dwarf galaxies of the Milky Way (MW) as a laboratory, we explore a flexible semi-analytic galaxy formation model to understand how the feedback processes shape the satellite galaxies of the MW. Using Markov Chain Monte Carlo, we exhaustively search a large parameter space of the model and rigorously show that the general wisdom of strong outflows as the primary feedback mechanism cannot simultaneously explain the stellar mass function and the mass–metallicity relation of the MW satellites. An extended model that assumes that a fraction of baryons is prevented from collapsing into low-mass halos in the first place can be accurately constrained to simultaneously reproduce those observations. The inference suggests that two different physical mechanisms are needed to explain the two different data sets. In particular, moderate outflows with weak halo mass dependence are needed to explain the mass–metallicity relation, and prevention of baryons falling into shallow gravitational potentials of low-mass halos (e.g., “pre-heating”) is needed to explain the low stellar mass fraction for a given subhalo mass.
Where and When: Optimal Scheduling of the Electromagnetic Follow-up of Gravitational-wave Events Based on Counterpart Light-curve Models
Authors: Salafia Om Sharan , Colpi Monica , Branchesi Marica , Chassande-Mottin Eric , Ghirlanda Giancarlo , Ghisellini Gabriele , D. Vergani Susanna 
Published: August 2017

Abstract
The electromagnetic (EM) follow-up of a gravitational-wave (GW) event requires scanning a wide sky region, defined by the so-called “skymap,” to detect and identify a transient counterpart. We propose a novel method that exploits the information encoded in the GW signal to construct a “detectability map,” which represents the time-dependent (“when”) probability of detecting the transient at each position of the skymap (“where”). Focusing on the case of a neutron star binary inspiral, we model the associated short gamma-ray burst afterglow and macronova emission using the probability distributions of binary parameters (sky position, distance, orbit inclination, mass ratio) extracted from the GW signal as inputs. The resulting family of possible light curves is the basis for constructing the detectability map. As a practical example, we apply the method to a simulated GW signal produced by a neutron star merger at 75 Mpc whose localization uncertainty is very large (∼1500 deg2). We construct observing strategies for optical, infrared, and radio facilities based on the detectability maps, taking VST, VISTA, and MeerKAT as prototypes. Assuming limiting fluxes of

,

(AB magnitudes), and

(

) for ∼1000 s of exposure each, the afterglow and macronova emissions are successfully detected with a minimum observing time of 7, 15, and 5 hr respectively.
X-Ray Morphological Analysis of the Planck ESZ Clusters
Authors: Lovisari Lorenzo , Forman William R. , Jones Christine , Ettori Stefano , Andrade-Santos Felipe , Arnaud Monique , Démoclès Jessica , Pratt Gabriel W. , Randall Scott , Kraft Ralph 
Published: August 2017

Abstract
X-ray observations show that galaxy clusters have a very large range of morphologies. The most disturbed systems, which are good to study how clusters form and grow and to test physical models, may potentially complicate cosmological studies because the cluster mass determination becomes more challenging. Thus, we need to understand the cluster properties of our samples to reduce possible biases. This is complicated by the fact that different experiments may detect different cluster populations. For example, Sunyaev–Zeldovich (SZ) selected cluster samples have been found to include a greater fraction of disturbed systems than X-ray selected samples. In this paper we determine eight morphological parameters for the Planck Early Sunyaev–Zeldovich (ESZ) objects observed with XMM-Newton. We found that two parameters, concentration and centroid shift, are the best to distinguish between relaxed and disturbed systems. For each parameter we provide the values that allow selecting the most relaxed or most disturbed objects from a sample. We found that there is no mass dependence on the cluster dynamical state. By comparing our results with what was obtained with REXCESS clusters, we also confirm that the ESZ clusters indeed tend to be more disturbed, as found by previous studies.
On Estimation of Contamination from Hydrogen Cyanide in Carbon Monoxide Line-intensity Mapping
Authors: Chung Dongwoo T. , Li Tony Y. , Viero Marco P. , Church Sarah E. , Wechsler Risa H. 
Published: August 2017

Abstract
Line-intensity mapping surveys probe large-scale structure through spatial variations in molecular line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide line emission, specifically the CO(1-0) line, face potential contamination from a disjointed population of sources emitting in a hydrogen cyanide emission line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN–halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model, which is based on current understanding of the galaxy–halo connection. Given the fiducial model, we expect the bias in overall CO detection significance due to HCN to be less than 1%.
IL-1β and IL-23 Promote Extrathymic Commitment of CD27+CD122− γδ T Cells to γδT17 Cells
Authors: Muschaweckh Andreas , Petermann Franziska , Korn Thomas 
Published: August 2017

Abstract
γδT17 cells are a subset of γδ T cells committed to IL-17 production and are characterized by the expression of IL-23R and CCR6 and lack of CD27 expression. γδT17 cells are believed to arise within a narrow time window during prenatal thymic development. In agreement with this concept, we show in this study that adult Rag1−/− recipient mice of Il23rgfp/+ (IL-23R reporter) bone marrow selectively lack IL-23R+ γδT17 cells. Despite their absence in secondary lymphoid tissues during homeostasis, γδT17 cells emerge in bone marrow chimeric mice upon induction of skin inflammation by topical treatment with imiquimod cream (Aldara). We demonstrate that IL-1β and IL-23 together are able to promote the development of bona fide γδT17 cells from peripheral CD122−IL-23R− γδ T cells, whereas CD122+ γδ T cells fail to convert into γδT17 cells and remain stable IFN-γ producers (γδT1 cells). IL-23 is instrumental in expanding extrathymically generated γδT17 cells. In particular, TCR-Vγ4+ chain–expressing CD122−IL-23R− γδ T cells are induced to express IL-23R and IL-17 outside the thymus during skin inflammation. In contrast, TCR-Vγ1+ γδ T cells largely resist this process because prior TCR engagement in the thymus has initiated their commitment to the γδT1 lineage. In summary, our data reveal that the peripheral pool of γδ T cells retains a considerable degree of plasticity because it harbors “naive” precursors, which can be induced to produce IL-17 and replenish peripheral niches that are usually occupied by thymus-derived γδT17 cells.
Chemokine Receptor–Dependent Control of Skin Tissue–Resident Memory T Cell Formation
Authors: Zaid Ali , Hor Jyh Liang , Christo Susan N. , Groom Joanna R. , Heath William R. , Mackay Laura K. , Mueller Scott N. 
Published: August 2017

Abstract
Infection or inflammation of the skin recruits effector CD8+ T cells that enter the epidermis and form populations of long-lived tissue-resident memory T (TRM) cells. These skin TRM cells migrate within the constrained epidermal environment by extending multiple dynamic dendritic projections and squeezing between keratinocytes to survey the tissue for pathogens. In this study, we examined the signals required for this distinctive mode of T cell migration by inhibiting key cytoskeletal components and performing intravital two-photon microscopy to visualize TRM cell behavior. We found that TRM cell motility and dendrite formation required an intact actomyosin cytoskeleton and the Rho-associated coiled-coil containing kinases. We also identified an essential role for microtubules for maintaining skin TRM cell shape and cellular integrity. We reveal a role for pertussis toxin–sensitive signaling for TRM cell dendritic morphology and migration that is independent of CXCR3 or CXCR6, or the skin-selective chemokine receptors CCR10 and CCR8. However, we found that CXCR6 and CCR10 expression by CD8+ T cells was required for the optimal formation of memory T cell populations, in particular TRM cell populations in the skin.