bluuebunny/crossref_metadata_2025_split huggingface dataset:
A DISK-BASED DYNAMICAL CONSTRAINT ON THE MASS OF THE YOUNG BINARY DQ TAU
Authors: Czekala I. , Andrews S. M. , Torres G. , Jensen E. L. N. , Stassun K. G. , Wilner D. J. , Latham D. W. 
Published: February 2016

ABSTRACT
We present new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of CO J = 2−1 line emission from the DQ Tau circumbinary disk. These data are used to tomographically reconstruct the Keplerian disk velocity field in a forward-modeling inference framework, and thereby provide a dynamical constraint on the mass of the DQ Tau binary of

. Those results are compared with an updated and improved orbital solution for this double-lined system based on long-term monitoring of its stellar radial velocities. Both of these independent dynamical constraints on the binary mass are in excellent agreement: taken together, they demonstrate that the DQ Tau system mass is 1.21 ± 0.26 M
⊙ and that the disk and binary orbital planes are aligned within 3° (at 3σ confidence). The predictions of various theoretical models for pre-main-sequence stellar evolution are also consistent with these masses, though more detailed comparisons are difficult due to lingering uncertainties regarding the photospheric properties of the individual components. DQ Tau is the third, nearly equal-mass, double-lined spectroscopic binary with a circumbinary disk that has been dynamically “weighed” with these two independent techniques: all show consistent results, validating the overall accuracy of the disk-based approach and demonstrating that it can be robustly applied to large samples of young, single stars as ALMA ramps up to operations at full capacity.
STABILITY OF RIGIDLY ROTATING SUPERMASSIVE STARS AGAINST GRAVITATIONAL COLLAPSE
Authors: Shibata Masaru , Uchida Haruki , Sekiguchi Yu-ichiro 
Published: February 2016

ABSTRACT
We revisit secular stability against quasi-radial collapse for rigidly rotating supermassive stars (SMSs) in general relativity. We suppose that the SMSs are in a nuclear-burning phase and can be modeled by polytropic equations of state with the polytropic index n
p slightly smaller than 3. The stability is determined in terms of the turning point method. We find a fitting formula of the stability condition for the plausible range of n
p (

) for SMSs. This condition reconfirms that while non-rotating SMSs with a mass of

–

may undergo a general relativistically induced quasi-radial collapse, rigidly rotating SMSs with a ratio of rotational to gravitational potential energy (β) of

are likely to be stable against collapse unless they are able to accrete ∼5 times more mass during the (relatively brief) hydrogen-burning phase of their evolution. We discuss the implications of our results.
A NUMERICAL SCHEME FOR SPECIAL RELATIVISTIC RADIATION MAGNETOHYDRODYNAMICS BASED ON SOLVING THE TIME-DEPENDENT RADIATIVE TRANSFER EQUATION
Authors: Ohsuga Ken , Takahashi Hiroyuki R. 
Published: February 2016

ABSTRACT
We develop a numerical scheme for solving the equations of fully special relativistic, radiation magnetohydrodynamics (MHDs), in which the frequency-integrated, time-dependent radiation transfer equation is solved to calculate the specific intensity. The radiation energy density, the radiation flux, and the radiation stress tensor are obtained by the angular quadrature of the intensity. In the present method, conservation of total mass, momentum, and energy of the radiation magnetofluids is guaranteed. We treat not only the isotropic scattering but also the Thomson scattering. The numerical method of MHDs is the same as that of our previous work. The advection terms are explicitly solved, and the source terms, which describe the gas–radiation interaction, are implicitly integrated. Our code is suitable for massive parallel computing. We present that our code shows reasonable results in some numerical tests for propagating radiation and radiation hydrodynamics. Particularly, the correct solution is given even in the optically very thin or moderately thin regimes, and the special relativistic effects are nicely reproduced.
APODIZED PUPIL LYOT CORONAGRAPHS FOR ARBITRARY APERTURES. V. HYBRID SHAPED PUPIL DESIGNS FOR IMAGING EARTH-LIKE PLANETS WITH FUTURE SPACE OBSERVATORIES
Authors: N’Diaye Mamadou , Soummer Rémi , Pueyo Laurent , Carlotti Alexis , Stark Christopher C. , Perrin Marshall D. 
Published: February 2016

ABSTRACT
We introduce a new class of solutions for Apodized Pupil Lyot Coronagraphs (APLC) with segmented aperture telescopes to remove broadband diffracted light from a star with a contrast level of 1010. These new coronagraphs provide a key advance to enabling direct imaging and spectroscopy of Earth twins with future large space missions. Building on shaped pupil (SP) apodization optimizations, our approach enables two-dimensional optimizations of the system to address any aperture features such as central obstruction, support structures, or segment gaps. We illustrate the technique with a design that could reach a 1010 contrast level at 34 mas for a 12 m segmented telescope over a 10% bandpass centered at a wavelength of

500 nm. These designs can be optimized specifically for the presence of a resolved star and, in our example, for stellar angular size up to 1.1 mas. This would allow one to probe the vicinity of Sun-like stars located beyond 4.4 pc, therefore, fully retiring this concern. If the fraction of stars with Earth-like planets is

, with 18% throughput, assuming a perfect, stable wavefront and considering photon noise only, 12.5 exo-Earth candidates could be detected around nearby stars with this design and a 12 m space telescope during a five-year mission with two years dedicated to exo-Earth detection (one total year of exposure time and another year of overheads). Our new hybrid APLC/SP solutions represent the first numerical solution of a coronagraph based on existing mask technologies and compatible with segmented apertures, and that can provide contrast compatible with detecting and studying Earth-like planets around nearby stars. They represent an important step forward toward enabling these science goals with future large space missions.
AN X-RAY SPECTRAL MODEL OF REPROCESSING BY SMOOTH AND CLUMPY MOLECULAR TORI IN ACTIVE GALACTIC NUCLEI WITH THE MONACO FRAMEWORK
Authors: Furui Shun’ya , Fukazawa Yasushi , Odaka Hirokazu , Kawaguchi Toshihiro , Ohno Masanori , Hayashi Kazuma 
Published: February 2016

ABSTRACT
We construct an X-ray spectral model of reprocessing by a torus in an active galactic nucleus (AGN) with the Monte Carlo simulation framework MONACO. Two torus geometries of smooth and clumpy cases are considered and compared. In order to reproduce a Compton shoulder accurately, MONACO includes not only free electron scattering but also bound electron scattering. Raman and Rayleigh scattering are also treated, and scattering cross sections dependent on chemical states of hydrogen and helium are included. Doppler broadening by turbulence velocity can be implemented. Our model gives results consistent with other available models, such as MYTorus, except for differences due to different physical parameters and assumptions. We studied the dependence on torus parameters for a Compton shoulder, and found that a intensity ratio of a Compton shoulder to the line core mainly depends on column density, inclination angle, and metal abundance. For instance, an increase of metal abundance makes a Compton shoulder relatively weak. Also, the shape of a Compton shoulder depends on the column density. Furthermore, these dependences become different between smooth and clumpy cases. Then, we discuss the possibility of ASTRO-H/SXS spectroscopy of Compton shoulders in AGN reflection spectra.
SYSTEMATIC STUDIES OF SHOCK REVIVAL AND THE SUBSEQUENT EVOLUTIONS IN CORE-COLLAPSE SUPERNOVAE WITH PARAMETRIC PROGENITOR MODELS
Authors: Yamamoto Yu , Yamada Shoichi 
Published: February 2016

ABSTRACT
We conducted one-dimensional and two-dimensional hydrodynamic simulations of post-shock revival evolutions in core-collapse supernovae, employing the simple neutrino light bulb approximation to produce explosions rather easily. In order to estimate the explosion energy, we took into proper account nuclear recombinations and fusions consistently with the equation of state for matter not in statistical equilibrium in general. The methodology is similar to our previous work, but is somehow improved. In this paper, we studied the influence of the progenitor structure on the dynamics systematically. In order to expedite our understanding of the systematics, we constructed six parametric progenitor models, which are different in masses of Fe iron core and Si+S layer, instead of employing realistic models provided by stellar evolution calculations, which are sometimes of stochastic nature as a function of stellar mass on the main sequence. We found that the explosion energy is tightly correlated with the mass accretion rate at shock revival irrespective of dimension and the progenitors with light iron cores but with rather high entropies, which have yet to be produced by realistic stellar evolution calculations, may reproduce the canonical values of explosion energy and nickel mass. The mass of the Si+S layer is also important in the mass accretion history after bounce, on the other hand; the higher mass accretion rates and resultant heavier cores tend to hamper strong explosions.
BAROCLINIC INSTABILITY IN THE SOLAR TACHOCLINE. II. THE EADY PROBLEM
Authors: Gilman Peter A. 
Published: February 2016

ABSTRACT
We solve the nongeostrophic baroclinic instability problem for the tachocline for a continuous model with a constant vertical rotation gradient (the Eady problem), using power series generated by the Frobenius method. The results confirm and greatly extend those from a previous two-layer model. For effective gravity G independent of height, growth rates and ranges of unstable longitudinal wavenumbers m and latitudes increase with decreasing G. As with the two-layer model, the overshoot tachocline is much more unstable than the radiative tachocline. The e-folding growth times range from as short as 10 days to as long as several years, depending on latitude, G, and wavenumber. For a more realistic effective gravity that decreases linearly from the radiative interior to near zero at the top of the tachocline, we find that only m = 1, 2 modes are unstable, with growth rates somewhat larger than for constant G, with the same value as at the bottom of the tachocline. All results are the same whether we assume that the vertical velocity or the perturbation pressure is zero at the top of the layer; this is a direct consquence of not employing the geostrophic assumption for perturbations. We explain most of the properties of the instability in terms of the Rossby deformation radius. We discuss further improvements in the realism of the model, particularly adding toroidal fields that vary in height, and including latitudinal gradients of both rotation and toroidal fields.
DOES THE INTERMEDIATE-MASS BLACK HOLE IN LEDA 87300 (RGG 118) FOLLOW THE NEAR-QUADRATIC Mbh–Mspheroid RELATION?
Authors: Graham Alister W. , Ciambur Bogdan C. , Soria Roberto 
Published: February 2016

ABSTRACT
The mass scaling relation between supermassive black holes and their host spheroids has previously been described by a quadratic or steeper relation at low masses (105 < M
bh/M
⊙ ≲ 107). How this extends into the realm of intermediate-mass black holes (102 < M
bh/M
⊙ < 105) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of M
bh = 5 × 104 M
⊙ residing in a “spheroid” of stellar mass equal to 6.3 × 108 M
⊙. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic M
bh–M
sph,* relation. However, Baldassare et al. modeled the bulge and bar as the single spheroidal component of this galaxy. Here we perform a 3-component bulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times fainter than the published “bulge” luminosity. After correcting for dust, we find that M
bulge = 0.9 × 108 M
⊙ and M
bulge/M
disk = 0.04—which is now in accord with ratios typically found in Scd–Sm galaxies. We go on to discuss slight revisions to the stellar velocity dispersion (40 ± 11 km s−1) and black hole mass (

) and show that LEDA 87300 remains consistent with the M
bh–σ relation, and also the near-quadratic M
bh–M
sph,* relation when using the reduced bulge mass. LEDA 87300 therefore offers the first support for the rapid but regulated (near-quadratic) growth of black holes, relative to their host bulge/spheroid, extending into the domain of intermediate-mass black holes.
EVIDENCE FOR THE RAPID FORMATION OF LOW-MASS EARLY-TYPE GALAXIES IN DENSE ENVIRONMENTS
Authors: Liu Yiqing , Peng Eric W. , Blakeslee John , Côté Patrick , Ferrarese Laura , Jordán Andrés , Puzia Thomas H. , Toloba Elisa , Zhang Hong-Xin 
Published: February 2016

ABSTRACT
We explore the environmental dependence of star formation timescales in low-mass galaxies using the [α/Fe] abundance ratio as an evolutionary clock. We present integrated [α/Fe] measurements for 11 low-mass (

) early-type galaxies (ETGs) with a large range of cluster-centric distance in the Virgo Cluster. We find a gradient in [α/Fe], where the galaxies closest to the cluster center (the cD galaxy, M87) have the highest values. This trend is driven by galaxies within a projected radius of 0.4 Mpc (0.26 times the virial radius of Virgo A), all of which have super-solar [α/Fe]. Galaxies in this mass range exhibit a large scatter in the [α/Fe]–σ diagram, and do not obviously lie on an extension of the relation defined by massive ETGs. In addition, we find a correlation between [α/Fe] and globular cluster specific frequency (S

N
), suggesting that low-mass ETGs that formed their stars over a short period of time were also efficient at forming massive star clusters. The innermost low-mass ETGs in our sample have [α/Fe] values comparable to that of M87, implying that environment is the controlling factor for star formation timescales in dense regions. These low-mass galaxies could be the surviving counterparts of the objects that have already been accreted into the halo of M87, and may be the link between present-day low-mass galaxies and the old, metal-poor, high-[α/Fe], high-S

N
stellar populations seen in the outer halos of massive ETGs.
INTERPLAY AMONG COOLING, AGN FEEDBACK, AND ANISOTROPIC CONDUCTION IN THE COOL CORES OF GALAXY CLUSTERS
Authors: Karen Yang H.-Y. , Reynolds Christopher S. 
Published: February 2016

ABSTRACT
Feedback from the active galactic nuclei (AGNs) is one of the most promising heating mechanisms to circumvent the cooling-flow problem in galaxy clusters. However, the role of thermal conduction remains unclear. Previous studies have shown that anisotropic thermal conduction in cluster cool cores (CCs) could drive the heat-flux-driven buoyancy instabilities (HBIs) that reorient the field lines in the azimuthal directions and isolate the cores from conductive heating from the outskirts. However, how the AGN interacts with the HBI is still unknown. To understand these interwined processes, we perform the first 3D magnetohydrodynamic simulations of isolated CC clusters that include anisotropic conduction, radiative cooling, and AGN feedback. We find the following: (1) For realistic magnetic field strengths in clusters, magnetic tension can suppress a significant portion of HBI-unstable modes, and thus the HBI is either completely inhibited or significantly impaired, depending on the unknown magnetic field coherence length. (2) Turbulence driven by AGN jets can effectively randomize magnetic field lines and sustain conductivity at ∼1/3 of the Spitzer value; however, the AGN-driven turbulence is not volume filling. (3) Conductive heating within the cores could contribute to ∼10% of the radiative losses in Perseus-like clusters and up to ∼50% for clusters twice the mass of Perseus. (4) Thermal conduction has various impacts on the AGN activity and intracluster medium properties for the hottest clusters, which may be searched by future observations to constrain the level of conductivity in clusters. The distribution of cold gas and the implications are also discussed.
CONSTRAINTS ON FEEDBACK IN THE LOCAL UNIVERSE: THE RELATION BETWEEN STAR FORMATION AND AGN ACTIVITY IN EARLY-TYPE GALAXIES
Authors: Vaddi Sravani , O’Dea Christopher P. , Baum Stefi A. , Whitmore Samantha , Ahmed Rabeea , Pierce Katherine , Leary Sara 
Published: February 2016

ABSTRACT
We address the relation between star formation and active galactic nucleus (AGN) activity in a sample of 231 nearby (0.0002 < z < 0.0358) early-type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR, and radio. Our results indicate that early-type galaxies in the current epoch are rarely powerful AGNs, with

for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The star formation rate (SFR) of these galaxies is less than 0.1 M
⊙ yr−1. They also tend to be radio faint (

). There is a nearly equal fraction of star-forming galaxies in radio faint (

) and radio bright galaxies (

) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.
THE RADIO/X-RAY CORRELATION AND BLACK HOLE FUNDAMENTAL PLANE FOR YOUNG RADIO SOURCES: IMPLICATIONS FOR X-RAY ORIGIN AND ACCRETION MODE
Authors: Fan Xu-Liang , Bai Jin-Ming 
Published: February 2016

ABSTRACT
We find that the young radio sources (gigahertz-peaked spectrum and compact steep spectrum radio sources) follow in the radio/X-ray correlation with

(

), and the fundamental plane of black hole activity with the form

and the intrinsic scatter

. The flatter coefficient between radio and X-ray bands denies the jet origin of the X-ray emission in these types of sources. Meanwhile, the higher ratio of X-ray luminosity to Eddington luminosity (

) suggests that the X-ray emission is produced by the hot corona coupling with the standard thin disk. The deviation with the radiative efficient fundamental plane proposed by Dong et al. is mainly due to the extended radio emission in young radio sources. This fundamental plane manifests that even the kiloparsec-scaled radio emission has a tight connection with the accretion process, and could be suitable for the radio-loud active galactic nuclei whose radio and X-ray emission are dominated by the extended jets and the radiative efficient accretion flow, respectively. Otherwise, the high-excitation galaxies and low-excitation galaxies do not have obvious distinctions in the radio/X-ray correlation and the fundamental plane.
THEORETICAL LIMITS ON MAGNETIC FIELD STRENGTHS IN LOW-MASS STARS
Authors: Browning Matthew K. , Weber Maria A. , Chabrier Gilles , Massey Angela P. 
Published: February 2016

ABSTRACT
Observations have suggested that some low-mass stars have larger radii than predicted by 1D structure models. Some theoretical models have invoked very strong interior magnetic fields (of order 1 MG or more) as a possible cause of such large radii. Whether fields of that strength could in principle be generated by dynamo action in these objects is unclear, and we do not address the matter directly. Instead, we examine whether such fields could remain in the interior of a low-mass object for a significant amount of time, and whether they would have any other obvious signatures. First, we estimate the timescales for the loss of strong fields by magnetic buoyancy instabilities. We consider a range of field strengths and simple morphologies, including both idealized flux tubes and smooth layers of field. We confirm some of our analytical estimates using thin flux tube magnetohydrodynamic simulations of the rise of buoyant fields in a fully convective M-dwarf. Separately, we consider the Ohmic dissipation of such fields. We find that dissipation provides a complementary constraint to buoyancy: while small-scale, fibril fields might be regenerated faster than they rise, the dissipative heating associated with such fields would in some cases greatly exceed the luminosity of the star. We show how these constraints combine to yield limits on the internal field strength and morphology in low-mass stars. In particular, we find that for stars of 0.3 solar masses, no fields in flux tubes stronger than about 800 kG are simultaneously consistent with both constraints.
COMET 252P/LINEAR: BORN (ALMOST) DEAD?
Authors: Ye (叶泉志) Quan-Zhi , Brown Peter G. , Wiegert Paul A. 
Published: February 2016

ABSTRACT
Previous studies have revealed Jupiter-family comet 252P/LINEAR as a comet that was recently transported into the near-Earth object (NEO) region in ∼1800 AD yet only being weakly active. In this Letter, we examine the “formed (almost) dead” hypothesis for 252P/LINEAR using both dynamical and observational approaches. By statistically examining the dynamical evolution of 252P/LINEAR over a period of 107 years, we find the median elapsed residency in the NEO region to be 4 × 102 years, which highlights the likelihood of 252P/LINEAR as an (almost) first-time NEO. With available cometary and meteor observations, we find the dust production rate of 252P/LINEAR to be on the order of 106 kg per orbit since its entry to the NEO region. These two lines of evidence support the hypothesis that the comet was likely to have formed in a volatile-poor environment. Cometary and meteor observations during the comet's unprecedented close approach to the Earth around 2016 March 21 would be useful for understanding of the surface and evolutionary properties of this unique comet.
Anisotropic spaces in Romania: a case study of the Timiş-Cerna Corridor
Authors: Creţan Remus , Jucu Sebastian , Antoni Maria 
Published: February 2016

This paper presents a critical discussion of Romania’s south-west, analyzing the proposal that the Timiş-Cerna Corridor should be systemically considered anisotropic. The aim of our paper is to test the possible anisotropic matrix system by using a methods approach based on interpreting human and material mobilities in the area. We use the theoretical framework of regional geography in a systemic context and specifically the concept of anisotropy defined as a territorial anomaly in homogenous and polarized regions, in order to reveal the social and physical relations in which anisotropy is embedded. Our results show that the Timiş-Cerna Corridor is an anisotropic area fitting the structural system of this specific type of space as the dynamics of flows inside the axis are asymmetrical, generating disparities, while transit flows are predominant.
Être réfugié à Delhi
Authors: Baujard Julie 
Published: February 2016

<p class="resume">Bien que l’Inde ne reconnaisse pas légalement le statut international de réfugié, elle accueille de nombreuses personnes qui, parties sous la contrainte de leur pays d’origine, sollicitent un refuge légal auprès d’un autre État c’est-à-dire des réfugiés. Depuis son indépendance, en 1947, plusieurs grandes crises se sont produites dans la région sud-asiatique, générant un nombre important d’entrée sur son territoire : réfugiés de la partition du sous-continent en 1947, Tibétains depuis 1959, Chakma du Pakistan oriental au début des années 1960, Bengalis en 1971, Afghans à partir de 1979, Tamouls sri lankais depuis 1983, Birmans à partir de 1988, Bhoutanais dans les années 1990. Certains de ces réfugiés ont été ou sont accueillis dans des camps plus ou moins ouverts, tandis que d’autres vivent dans les campagnes et les villes indiennes, au sein de la population locale. </p>