bluuebunny/crossref_metadata_2025_split huggingface dataset:
Offshore financial activity and tax policy: evidence from a leaked data set
Authors: Caruana-Galizia Paul , Caruana-Galizia Matthew 
Published: March 2016

AbstractWe assess the European Union’s (EU) most significant international tax policy. The 2005 Tax and Savings Directive obliges cooperating jurisdictions to withhold tax or report on interest income earned by entities whose beneficial owner is an EU resident. As the Directive applies only to beneficial ownership in cooperative jurisdictions, it can be circumvented by transferring ownership to a non-EU resident or company or by transferring the entity to a non-cooperative jurisdiction. Using a database on individual offshore entities leaked from two firms in 2013, we compare the response of EU-owned entities with a control group of non-EU-owned entities. We show that the growth of EU-owned entities declined immediately after the Directive’s implementation, whereas that of non-EU-owned entities remained stable. We observe the substitution of EU ownership for non-EU ownership, as well as the substitution of cooperative for non-cooperative offshore jurisdictions. This calls for anti-evasion policies that are broader in scope and scale.
Comparing the epidemiology of hospital-acquired methicillin-resistant Staphylococcus aureus clone groups in Alberta, Canada
Authors: BRUZZESE S. , BUSH K. , LEAL J. , KIM J. , VICKERS D. M. , RUSK A. , FATHIMA S. , LI V. , CHUI L. , LOUIE M. , HENDERSON E. 
Published: March 2016

SUMMARYPatients with methicillin-resistant Staphylococcus aureus (MRSA) clones, which were traditionally seen in the community setting (USA400/CMRSA7 and USA300/CMRSA10), are often identified as hospital-acquired (HA) infections using Infection Prevention and Control (IPC) surveillance definitions. This study examined the demographics and healthcare risk factors of patients with HA-MRSA to help understand if community MRSA clones are from a source internal or external to the hospital setting. Despite USA300/CMRSA10 being the predominant clone in Alberta, hospital clones (USA100/CMRSA2) still dominated in the acute care setting. In the Alberta hospitalized population, patients with USA400/CMRSA7 and USA300/CMRSA10 clones were significantly younger, had fewer comorbidities, and a greater proportion had none or ambulatory care-only healthcare exposure. These findings suggest that there are two distinct populations of HA-MRSA patients, and the patients with USA400/CMRSA7 and USA300/CMRSA10 clones identified in hospital more greatly resemble patients affected by those clones in the community. It is possible that epidemiological assessment overidentifies HA acquisition of MRSA in patients unscreened for MRSA on admission to acute care.
Disentangling AGN and starburst activities in NGC 6240 from an X-ray perspective
Authors: Wang Junfeng 
Published: March 2016

AbstractThe circum-nuclear region in an active galaxy is often complex with presence of high excitation gas, collimated radio outflow, and star formation activities, besides the actively accreting supermassive black hole. The unique spatial resolving power of Chandra X-ray imaging spectroscopy enables more investigations to disentangle the active galactic nuclei and starburst activities. For galaxies in the throes of a violent merging event such as NGC6240, we were able to resolve the high temperature gas surrounding its binary active black holes and discovered a large scale soft X-ray halo.
Multi-wavelength observations of the narrow-line Seyfert 1 galaxy RX J2314.9+2243
Authors: Komossa S. , Myserlis I. , Fuhrmann L. , Xu D. , Grupe D. , Fan Z. , Yao S. , Angelakis E. , Karamanavis V. , Zensus J. A. , Yuan W. 
Published: March 2016

AbstractNarrow-line Seyfert 1 (NLS1) galaxies are a sub-class of active galactic nuclei (AGN) with relatively low-mass black holes, accreting near the Eddington rate. A small fraction of them is radio-loud and harbors relativistic jets. As a class, these provide us with new insights into the cause(s) of radio-loudness, the blazar phenomenon at low black hole masses, and the operation of radio-mode feedback. The NLS1 galaxy RXJ2314.9+2243 is remarkable for its multi-wavelength properties. We present new radio observations taken at Effelsberg, and a summary of the recent results from our multi-wavelength study. RXJ2314.9+2243 is radio-loud, luminous in the infrared, has a flat X-ray spectrum and peculiar UV spectrum, and hosts an exceptionally broad and blueshifted [OIII]λ5007 emission line, indicating the presence of a strong outflow. RXJ2314.9+2243 likely represents an extreme case of AGN induced feedback in the local universe.
Radio-loud narrow-line Seyfert 1 galaxies with high-velocity outflows
Authors: Komossa S. , Xu D. , Zensus J. A. 
Published: March 2016

AbstractWe have studied four radio-loud Narrow-line Seyfert 1 (NLS1) galaxies with extreme optical emission-line shifts, indicating radial outflow velocities of up 2450 km s−1. The shifts are accompanied by strong line broadening, up to 2270 km s−1 in [NeV]. A significant ionization stratification (higher line shift at higher ionization potential) of most ions implies that we see a large-scale wind rather than single, localized jet-cloud interactions. The observations are consistent with a scenario, where the signatures of outflows are maximized because of a pole-on view into the central engine of these radio-loud NLS1 galaxies.
Detecting tidal disruption events of massive black holes in normal galaxies with the Einstein Probe
Authors: Yuan W. , Komossa S. , Zhang C. , Feng H. , Ling Z.-X. , Zhao D.H. , Zhang S.-N. , Osborne J.P. , O'Brien P. , Willingale R. , Lapington J. ,   the Einstein Probe team
Published: March 2016

AbstractStars are tidally disrupted and accreted when they approach massive black holes (MBHs) closely, producing a flare of electromagnetic radiation. The majority of the (approximately two dozen) tidal disruption events (TDEs) identified so far have been discovered by their luminous, transient X-ray emission. Once TDEs are detected in much larger numbers, in future dedicated transient surveys, a wealth of new applications will become possible. Here, we present the proposed Einstein Probe mission, which is a dedicated time-domain soft X-ray all-sky monitor aiming at detecting X-ray transients including TDEs in large numbers. The mission consists of a wide-field micro-pore Lobster-eye imager (60° × 60°), and is designed to carry out an all-sky transient survey at energies of 0.5-4 keV. It will also carry a more sensitive telescope for X-ray follow-ups, and will be capable of issuing public transient alerts rapidly. Einstein Probe is expected to revolutionise the field of TDE research by detecting several tens to hundreds of events per year from the early phase of flares, many with long-term, well sampled lightcurves.
On the relationship between black hole mass and X-ray variability amplitude in the low-mass regime of active galactic nuclei
Authors: Pan H. , Yuan W. , Zhou X.-L. , Dong X. , Liu B. 
Published: March 2016

AbstractRecent studies of active galactic nuclei (AGN) found a statistical inverse scaling between the X-ray normalized excess variance σrms2 (variability amplitude) and the black hole mass spanning over MBH = 106 − 109M⊙. We present a study of this relation by including AGN with MBH = 105 − 106M⊙. It is found that the relation is no longer a simple extrapolation of the known inverse proportion, but starts to flatten around 106M⊙. This behavior can be understood by the shape of the power spectrum density of AGN and its dependence on the black hole mass.
Merging of unequal mass binary black holes in non-axisymmetric galactic nuclei
Authors: Berczik Peter , Wang Long , Nitadori Keigo , Spurzem Rainer 
Published: March 2016

AbstractIn this work we study the stellar-dynamical hardening of unequal mass massive black hole (MBH) binaries in the central regions of galactic nuclei. We present a comprehensive set of direct N-body simulations of the problem, varying both the total mass and the mass ratio of the MBH binary. Our initial model starts as an axisymmetric, rotating galactic nucleus, to describe the situation right after the galaxies have merged, but the black holes are still unbound to each other. We confirm that results presented in earlier works (Berczik et al. 2006; Khan et al. 2013; Wang et al. 2014) about the solution of the “last parsec problem” (sufficiently fast black hole coalescence for black hole growth in cosmological context) are robust for both for the case of unequal black hole masses and large particle numbers. The MBH binary hardening rate depends on the reduced mass ratio through a single parameter function, which quantitatively quite well agrees with standard 3 body scattering theory (see e.g., Hills 1983). Based on our results we conclude that MBH binaries at high redshifts are expected to merge with a factor of ~ 2 more efficiently, which is important to determine the possible overall gravitational wave signals. However, we have not yet fully covered all the possible parameter space, in particular with respect to the preceding of the galaxy mergers, which may lead to a wider variety of initial models, such as initially more oblate and / or even significantly triaxial galactic nuclei. Our N-body simulations were carried out on a new special supercomputers using the hardware acceleration with graphic processing units (GPUs).
The effect of binary stars on photometric redshift for galaxies at z ~ 2.0
Authors: Zhang Yu , Liu Jinzhong 
Published: March 2016

AbstractEvolutionary population synthesis (EPS) models play an important role in many studies on the formation and evolution of galaxy. The poorly calibration for some stellar evolution stages in EPS models can lead to uncertainty of the parameter determinations for galaxies. By means of the HyperZ code and a set of theoretical galaxy template, which are built on the EPS models with and without binary interactions, we present photometric redshift (photo-z) estimates for passive galaxy sample at redshift z ~ 2.0. The passive galaxy sample is selected from Fang et al., and they also provide the redshift for these passive galaxies. By comparing the photo-z determined from EPS models with and without binary interactions, we find that the binary interactions have little effect in the photo-z determinations.
Evolution of binary supermassive black holes and the final-parsec problem
Authors: Vasiliev Eugene 
Published: March 2016

AbstractI review the evolution of binary supermassive black holes and focus on the stellar-dynamical mechanisms that may help to overcome the final-parsec problem – the possible stalling of the binary at a separation much larger than is required for an efficient gravitational wave emission. RecentN-body simulations have suggested that a departure from spherical symmetry in the nucleus of the galaxy may keep the rate of interaction of stars with the binary at a high enough level so that the binary continues to shrink rather rapidly. However, a major problem of all these simulations is that they do not probe the regime where collisionless effects are dominant – in other words, the number of particles in the simulation is still not sufficient to reach the asymptotic behavior of the system. I present a novel Monte Carlo method for simulating both collisional and collisionless evolution of non-spherical stellar systems, and apply it for the problem of binary supermassive black hole evolution. I show that in triaxial galaxies the final-parsec problem is largely non-existent, while in the axisymmetric case it seems to still exist in the limit of purely collisionless regime relevant for real galaxies, but disappears in theN-body simulations where the feasible values ofNare still too low to get rid of collisional effects.
The interaction between supermassive black holes and globular clusters
Authors: Spera Mario , Arca-Sedda Manuel , Capuzzo-Dolcetta Roberto 
Published: March 2016

AbstractAlmost all galaxies along the Hubble sequence host a compact massive object (CMO) in their center. The CMO can be either a supermassive black hole (SMBH) or a very dense stellar cluster, also known as nuclear star cluster (NSC). Generally, heavier galaxies (mass ≳ 1011 M⊙) host a central SMBH while lighter show a central NSC. Intermediate mass hosts, instead, contain both a NSC and a SMBH. One possible formation mechanisms of a NSC relies on the dry-merger (migratory) scenario, in which globular clusters (GCs) decay toward the center of the host galaxy and merge. In this framework, the absence of NSCs in high-mass galaxies can be imputed to destruction of the infalling GCs by the intense tidal field of the central SMBH. In this work, we report preliminary results of N-body simulations performed using our high-resolution, direct, code HiGPUs, to investigate the effects of a central SMBH on a single GC orbiting around it. By varying either the mass of the SMBH and the mass of the host galaxy, we derived an upper limit to the mass of the central SMBH, and thus to the mass of the host, above which the formation of a NSC is suppressed.
Sculpting the central parsec of our Galaxy
Authors: Chen Xian 
Published: March 2016

AbstractRecent observations have revealed various structures within the gravitational influence of Sgr A* – the massive black hole in the Galactic center. These structures apparently defy the fundamental principles of star formation and stellar dynamics. On one hand, the red giants display a flat density profile, contrary to the cuspy one predicted by conventional stellar relaxation. On the other, Wolf-Rayet and OB stars are observed where in-situ star formation should have been prohibited by the strong tidal force from Sgr A*, and their spatial and phase-space distributions also contradict our understanding of stellar dynamics. To explain each of these inconsistencies, many scenarios have been proposed, which render the model increasingly complicated. Here, we suggest that the sub-parsec stellar disk surrounding Sgr A*, which was recently discovered, can reconcile all the above inconsistencies. We show that during the fragmenting past of this disk, the star-forming clumps could efficiently deplete red giants by repeatedly colliding with them. We also show that because of the torque exerted by the disk, stars within the central arcsec from Sgr A* would quickly mix in the angular-momentum space, which naturally explains the observed distributions of Wolf-Rayet and OB stars. Our results imply that Sgr A* was fueled by gas and stars several millions years ago and could have been an energetic AGN. We discuss future observations that can further testify our model.
Orientation of galactic bulge planetary nebulae toward the Galactic center
Authors: Danehkar Ashkbiz , Parker Quentin A. 
Published: March 2016

AbstractWe have used the Wide Field Spectrograph on the Australian National University 2.3-m telescope to perform the integral field spectroscopy for a sample of the Galactic planetary nebulae. The spatially resolved velocity distributions of the Hα emission line were used to determine the kinematic features and nebular orientations. Our findings show that some bulge planetary nebulae toward the Galactic center have a particular orientation.
Radiative efficiency of hot accretion flow and the radio/X-ray correlation in X-ray binaries
Authors: Xie Fu-Guo 
Published: March 2016

AbstractSignificant progresses have been made since the discovery of hot accretion flow, a theory successfully applied to the low-luminosity active galactic nuclei (LLAGNs) and black hole (BH) X-ray binaries (BHBs) in their hard states. Motivated by these updates, we re-investigate the radiative efficiency of hot accretion flow. We find that, the brightest regime of hot accretion flow shows a distinctive property, i.e. it has a constant efficiency independent of accretion rates, similar to the standard thin disk. For less bright regime, the efficiency has a steep positive correlation with the accretion rate, while for faint regime typical of advection-dominated accretion flow, the correlation is shadower. This result can naturally explain the observed two distinctive correlations between radio and X-ray luminosities in black hole X-ray binaries. The key difference in systems with distinctive correlations could be the viscous parameter, which determines the critical luminosity of different accretion modes.
Exotic populations in globular clusters: blue stragglers as tracers of the internal dynamical evolution of stellar systems
Authors: Ferraro Francesco R. 
Published: March 2016

AbstractIn this paper I present an overview of the main observational properties of a special class of exotic objects (the so-called Blue Straggler Stars, BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency and their radial distribution are discussed in the framework of using this stellar population as probe of GC internal dynamics. In particular, the shape of the BSS radial distribution has been found to be a powerful tracer of the dynamical evolution of stellar systems, thus allowing the definition of an empirical “clock”able to measure the dynamical age of stellar aggregates from pure observational properties.
Searching for IMBHs in Galactic globular clusters through radial velocities of individual stars
Authors: Lanzoni Barbara 
Published: March 2016

AbstractI present an overview of our ongoing project aimed at building a new generation of velocity dispersion profiles ad rotation curves for a representative sample of Galactic globular clusters, from the the radial velocity of hundreds of individual stars distributed at different distances from the cluster center. The innermost portion of the profiles will be used to constrain the possible presence of intermediate-mass black holes. The adopted methodology consists of combining spectroscopic observations acquired with three different instruments at the ESO-VLT: the adaptive-optics assisted, integral field unit (IFU) spectrograph SINFONI for the innermost and highly crowded cluster cores, the multi-IFU spectrograph KMOS for the intermediate regions, and the multi-fiber instrument FLAMES/GIRAFFE-MEDUSA for the outskirts. The case of NGC 6388, representing the pilot project that motivated the entire program, is described in some details.
Monte Carlo modeling of globular star clusters: many primordial binaries and IMBH formation
Authors: Giersz Mirek , Leigh Nathan , Marks Michael , Hypki Arkadiusz , Askar Abbas 
Published: March 2016

AbstractWe will discuss the evolution of star clusters with a large initial binary fraction, up to 95%. The initial binary population is chosen to follow the invariant orbital-parameter distributions suggested by Kroupa (1995). The Monte Carlo MOCCA simulations of star cluster evolution are compared to the observations of Milone et al. (2012) for photometric binaries. It is demonstrated that the observed dependence on cluster mass of both the binary fraction and the ratio of the binary fractions inside and outside of the half mass radius are well recovered by the MOCCA simulations. This is due to a rapid decrease in the initial binary fraction due to the strong density-dependent destruction of wide binaries described by Marks, Kroupa & Oh (2011). We also discuss a new scenario for the formation of intermediate mass black holes in dense star clusters. In this scenario, intermediate mass black holes are formed as a result of dynamical interactions of hard binaries containing a stellar mass black hole, with other stars and binaries. We will discuss the necessary conditions to initiate the process of intermediate mass black hole formation and the dependence of its mass accretion rate on the global cluster properties.
Expansion techniques for collisionless stellar dynamical simulations
Authors: Meiron Yohai 
Published: March 2016

AbstractWe present ETICS, a collisionless N-body code based on two kinds of series expansions of the Poisson equation, implemented for graphics processing units (GPUs). The code is publicly available and can be used as a standalone program or as a library (an AMUSE plugin is included). One of the two expansion methods available is the self-consistent field (SCF) method, which is a Fourier-like expansion of the density field in some basis set; the other is the multipole expansion (MEX) method, which is a Taylor-like expansion of the Green's function. MEX, which has been advocated in the past, has not gained as much popularity as SCF. Both are particle-field methods and optimized for collisionless galactic dynamics, but while SCF is a “pure” expansion, MEX is an expansion in just the angular part; thus, MEX is capable of capturing radial structure easily, while SCF needs a large number of radial terms.
The role of three-body stability in tidally interacting globular clusters
Authors: Kennedy Gareth F. 
Published: March 2016

AbstractThe role of stability in the general three-body problem is investigated with regard to the tidal radius of a globular cluster (GC) in a galactic potential. This proceedings is a summary of two papers which outline the stability method (Kennedy 2014a) and compare the predicted stability boundary radius to observations of velocity dispersion profiles in Milky Way GCs (Kennedy 2014b).
Evolution of a globular cluster with a two-component BH mass spectrum
Authors: Park Dawoo , Kim Chunglee , Lee Hyung Mok , Bae Yeong-Bok 
Published: March 2016

AbstractGlobular clusters (GCs) is dominated by behaviors of high-mass components such as neutron stars (NSs) and black holes (BHs). In this work, we perform direct N-body simulations of a GC assuming two BH masses. We used the BH masses of 10 and 20 M⊙ with total math ratio between those two populations is assumed to be 2:1 and 5:1. Our results show that the heavier BHs (20 M⊙) are depleted in the early stage of cluster evolution. The existence of heavier BH components increase the retention rate of lighter BHs during the cluster evolution. About 30% of ejected BHs are in binaries.
The X-ray spectral evolution and radio–X-ray correlation in radiatively efficient black-hole sources
Authors: Dong Ai-Jun , Wu Qingwen , Cao Xiao-Feng 
Published: March 2016

AbstractWe explore X-ray spectral evolution and radio–X-ray correlation simultaneously for four X-ray binaries (XRBs). We find that hard X-ray photon indices, Γ, are anti- and positively correlated to X-ray fluxes when the X-ray flux, F3–9keV, is below and above a critical flux, FX,crit, which may be regulated by ADAF and disk-corona respectively. We find that the data points with anti-correlation of Γ-F3–9keV follow the universal radio–X-ray correlation of FR ∝ FXb (b ~ 0.5-0.7), while the data points with positive X-ray spectral evolution follow a steeper radio–X-ray correlation (b ~ 1.4, the so-called ‘outliers track’). The bright active galactic nuclei (AGNs) share similar X-ray spectral evolution and radio–X-ray correlation as XRBs in ‘outliers’ track, and we present a new fundamental plane of log LR=1.59+0.28−0.22 log LX−0.22+0.19−0.20 log MBH−28.97+0.45−0.45 for these radiatively efficient BH sources.
GraviDy: a modular, GPU-based, direct-summation N-body code
Authors: Maureira-Fredes Cristián , Amaro-Seoane Pau 
Published: March 2016

AbstractThe direct-summation of N gravitational forces is a complex problem for which there is no analytical solution. Dense stellar systems such as galactic nuclei and stellar clusters are the loci of different interesting problems. In this work we present a new GPU, direct-summation N-body integrator written from scratch and based on the Hermite scheme. The first release of the code consists of the Hermite integrator for a system of N bodies with softening. We find an acceleration factor of about ≈ 90 of the GPU version in a single node as compared to the Serial-Single-CPU one. We additionally investigate the impact of using softening in the dynamics of a dense cluster. We study how it affects the two body relaxation, as compared with another code, NBODY6, which uses KS regularization, so as to understand the role of softening in the evolution of the system. This initial release is the first step towards more and more realistic scenarios, starting for a proper treatment for binary evolution, close encounters and the role of a massive black hole.