bluuebunny/crossref_metadata_2025_split huggingface dataset:
RAMSES II: RAMan Search for Extragalactic Symbiotic Stars Project Concept, Commissioning, and Early Results from the Science Verification Phase
Authors: Angeloni Rodolfo , Gonçalves Denise R. , Akras Stavros , Gimeno German , Diaz Ruben , Scharwächter Julia , Nuñez Natalia E. , Luna Gerardo Juan M. , Lee Hee-Won , Heo Jeong-Eun , Lucy Adrian B. , Arancibia Marcelo Jaque , Moreno Cristian , Chirre Emmanuel , Goodsell Stephen J. , King Piera Soto , Sokoloski Jennifer L. , Choi Bo-Eun , Ribeiro Mateus Dias 
Published: March 2019

Abstract
Symbiotic stars (SySts) are long-period interacting binaries composed of a hot compact star, an evolved giant star, and a tangled network of gas and dust nebulae. They represent unique laboratories for studying a variety of important astrophysical problems, and have also been proposed as possible progenitors of SNIa. Presently, we know of 257 SySts in the Milky Way and 69 in external galaxies. However, these numbers are still in striking contrast with the predicted population of SySts in our Galaxy. Because of other astrophysical sources that mimic SySt colors, no photometric diagnostic tool has so far demonstrated the power to unambiguously identify a SySt, thus making the recourse to costly spectroscopic follow-up still inescapable. In this paper we present the concept, commissioning, and science verification phases, as well as the first scientific results, of RAMSES II—a Gemini Observatory Instrument Upgrade Project that has provided each GMOS instrument at both Gemini telescopes with a set of narrow-band filters centered on the Raman O vi 6830 Å band. Continuum-subtracted images using these new filters clearly revealed known SySts with a range of Raman O vi line strengths, even in crowed fields. RAMSES II observations also produced the first detection of Raman O vi emission from the SySt LMC 1 and confirmed Hen 3-1768 as a new SySt—the first photometric confirmation of a SySt. Via Raman O vi narrow-band imaging, RAMSES II provides the astronomical community with the first purely photometric tool for hunting SySts in the local universe.
The Chemical Evolution of Carbon, Nitrogen, and Oxygen in Metal-poor Dwarf Galaxies*
Authors: Berg Danielle A. , Erb Dawn K. , Henry Richard B. C. , Skillman Evan D. , McQuinn Kristen B. W. 
Published: March 2019

Abstract
Ultraviolet nebular emission lines are important for understanding the time evolution and nucleosynthetic origins of their associated elements, but the underlying trends of their relative abundances are unclear. We present UV spectroscopy of 20 nearby low-metallicity, high-ionization dwarf galaxies obtained using the Hubble Space Telescope. Building upon previous studies, we analyze the C/O relationship for a combined sample of 40 galaxies with significant detections of the UV O+2/C+2 collisionally excited lines and direct-method oxygen abundance measurements. Using new analytic carbon ionization correction factor relationships, we confirm the flat trend in C/O versus O/H observed for local metal-poor galaxies. We find an average log(C/O) = −0.71 with an intrinsic dispersion of σ = 0.17 dex. The C/N ratio also appears to be constant at log(C/N) = 0.75, plus significant scatter (σ = 0.20 dex), with the result that carbon and nitrogen show similar evolutionary trends. This large and real scatter in C/O over a large range in O/H implies that measuring the UV C and O emission lines alone does not provide a reliable indicator of the O/H abundance. By modeling the chemical evolution of C, N, and O of individual targets, we find that the C/O ratio is very sensitive to both the detailed star formation history and to supernova feedback. Longer burst durations and lower star formation efficiencies correspond to low C/O ratios, while the escape of oxygen atoms in supernovae winds produces decreased effective oxygen yields and larger C/O ratios. Further, a declining C/O relationship is seen with increasing baryonic mass due to increasing effective oxygen yields.
The Central 1000 au of a Pre-stellar Core Revealed with ALMA. I. 1.3 mm Continuum Observations
Authors: Caselli Paola , Pineda Jaime E. , Zhao Bo , Walmsley Malcolm C. , Keto Eric , Tafalla Mario , Chacón-Tanarro Ana , Bourke Tyler L. , Friesen Rachel , Galli Daniele , Padovani Marco 
Published: March 2019

Abstract
Stars like our Sun form in self-gravitating dense and cold structures within interstellar clouds that are referred to as pre-stellar cores. Although much is known about the physical structure of dense clouds just before and soon after the switch-on of a protostar, the central few thousand astronomical units (au) of pre-stellar cores are unexplored. It is within these central regions that stellar systems assemble and fragmentation may take place, with the consequent formation of binaries and multiple systems. We present Atacama Large Millimetre and submillimetre Array (ALMA) Band 6 observations (Atacama Compact Array and 12 m array) of the dust continuum emission of the 8 M
⊙ pre-stellar core L1544, with an angular resolution of 2″ × 1.″6 (linear resolution 270 au × 216 au). Within the primary beam, a compact region of 0.1 M
⊙, which we call a “kernel,” has been unveiled. The kernel is elongated, with a central flat zone with radius R
ker ≃ 10″ (≃1400 au). The average number density within R
ker is ≃1 × 106 cm−3, with possible local density enhancements. The region within R
ker appears to have fragmented, but detailed analysis shows that similar substructure can be reproduced by synthetic interferometric observations of a smooth centrally concentrated dense core with a similar central flat zone. The presence of a smooth kernel within a dense core is in agreement with non-ideal magnetohydro-dynamical simulations of a contracting cloud core with a peak number density of 1 × 107 cm−3. Dense cores with lower central densities are completely filtered out when simulated 12 m array observations are carried out. These observations demonstrate that the kernel of dynamically evolved dense cores can be investigated at high angular resolution with ALMA.
LSST Target-of-opportunity Observations of Gravitational-wave Events: Essential and Efficient
Authors: Cowperthwaite P. S. , Villar V. A. , Scolnic D. M. , Berger E. 
Published: March 2019

Abstract
We present simulated observations to assess the ability of the Large Synoptic Survey Telescope (LSST) and the wide-fast-deep (WFD) survey to detect and characterize kilonovae—the optical emission associated with binary neutron star (and possibly black hole–neutron star) mergers. We expand on previous studies in several critical ways by exploring a range of kilonova models and several choices of cadence, as well as by evaluating the information content of the resulting light curves. We find that, depending on the precise choice of cadence, the WFD survey will achieve an average kilonova detection efficiency of ≈1.6%–2.5% and detect only ≈3–6 kilonovae per year. The detected kilonovae will be within the detection volume of the Advanced LIGO/Virgo (ALV). By refitting the best resulting LSST light curves with the same model used to generate them, we find that the model parameters are generally weakly constrained, and are accurate to at best a factor of 2–3. Motivated by the finding that the WFD will yield a small number of kilonova detections, with poor light curves and marginal information content, and that the detections are in any case inside the ALV volume, we argue that target-of-opportunity follow-up of gravitational-wave triggers is a much more effective approach for kilonova studies. We outline the qualitative foundation for such a program with the goal of minimizing the impact on LSST operations. We argue that observations in the gz-bands with a total time investment per event of ≈1.5 hr per 10 deg2 of a search area is sufficient to rapidly detect and identify kilonovae with ≳90% efficiency. For an estimated event rate of ∼20 per year visible to LSST, this accounts for ∼1.5% of the total survey time. In this regime, LSST has the potential to be a powerful tool for kilonovae discovery, with detected events handed off to other narrow-field facilities for further monitoring.
The Effect of Dark Matter–Dark Radiation Interactions on Halo Abundance: A Press–Schechter Approach
Authors: Sameie Omid , Benson Andrew J. , Sales Laura V. , Yu Hai-bo , Moustakas Leonidas A. , Creasey Peter 
Published: March 2019

Abstract
We study halo mass functions with the Press–Schechter formalism for interacting dark matter models, where matter power spectra are damped due to dark acoustic oscillations in the early universe. After adopting a smooth window function, we calibrate the analytical model with numerical simulations from the “effective theory of structure formation” (ETHOS) project and fix the model parameters in the high-mass regime, M
h ≳ 3 × 1010
M
⊙. We also perform high-resolution cosmological simulations with halo masses down to M
h ∼ 108
M
⊙ to cover a wide mass range for comparison. Although the model is calibrated with ETHOS1 and cold dark matter simulations for high halo masses at redshift z = 0, it successfully reproduces simulations for two other ETHOS models in the low-mass regime at low and high redshifts. As an application, we compare the cumulative number density of halos to that of observed galaxies at z = 6, and find that the interacting dark matter models with a kinetic decoupling temperature below 0.5 keV is disfavored. We also perform the abundance-matching analysis and derive the stellar–halo mass relation for these models at z = 4. Suppression in halo abundance leads to less massive halos that host observed galaxies in the stellar mass range

M

*

≃

10

5

–

10

7

M

⊙

.
The Halo Mass of Optically Luminous Quasars at z ≈ 1–2 Measured via Gravitational Deflection of the Cosmic Microwave Background
Authors: Geach J. E. , Peacock J. A. , Myers A. D. , Hickox R. C. , Burchard M. C. , Jones M. L. 
Published: March 2019

Abstract
We measure the average deflection of cosmic microwave background photons by quasars at

. Our sample is selected from the Sloan Digital Sky Survey to cover the redshift range 0.9 ≤ z ≤ 2.2 with absolute i-band magnitudes of M

i
≤ −24 (K-corrected to z = 2). A stack of nearly 200,000 targets reveals an 8σ detection of Planck's estimate of the lensing convergence toward the quasars. We fit the signal with a model comprising a Navarro–Frenk–White density profile and a two-halo term accounting for correlated large-scale structure, which dominates the observed signal. The best-fitting model is described by an average halo mass

and linear bias b = 2.7 ± 0.3 at

, in excellent agreement with clustering studies. We also report a hint, at a 90% confidence level, of a correlation between the convergence amplitude and luminosity, indicating that quasars brighter than M

i
≲ −26 reside in halos of typical mass

, scaling roughly as

at

mag, in good agreement with physically motivated quasar demography models. Although we acknowledge that this luminosity dependence is a marginal result, the observed M
h–L
opt relationship could be interpreted as a reflection of the cutoff in the distribution of black hole accretion rates toward high Eddington ratios: the weak trend of M
h with L
opt observed at low luminosity becomes stronger for the most powerful quasars, which tend to be accreting close to the Eddington limit.
The Mass–Metallicity Relation of Local Active Galaxies
Authors: Thomas Adam D. , Kewley Lisa J. , Dopita Michael A. , Groves Brent A. , Hopkins Andrew M. , Sutherland Ralph S. 
Published: March 2019

Abstract
We systematically measure the gas-phase metallicities and the mass–metallicity relation of a large sample of local active galaxies for the first time. Observed emission-line fluxes from the Sloan Digital Sky Survey are compared to a four-dimensional grid of photoionization models using the Bayesian parameter estimation code NebulaBayes. For the first time we take into account arbitrary mixing between H ii region and narrow-line region (NLR) emission, and the models are also varied with metallicity, ionization parameter in the NLR, and gas pressure. The active galactic nucleus oxygen abundance is found to increase by

Δ
O

/

H
∼
0.1

dex as a function of host galaxy stellar mass over the range

10.1
<
log

M

*

/

M

⊙

<
11.3

. We also measure the metallicity and ionization parameter of 231,000 star-forming galaxies for comparison with the sample of 7670 Seyfert 2 galaxies. A systematic offset in oxygen abundance of 0.09 dex is observed between the mass–metallicity relations of the star-forming and active galaxies. We investigate potential causes of the offset, including sample selection and the treatment in the models of diffuse ionized gas, pressure, and ionization parameter. We cannot identify the major cause(s), but suspect contributions due to deficiencies in modeling the ionizing spectra and the treatment of dust physics. Optical diagnostic diagrams are presented with the star-forming and Seyfert data colored by the inferred oxygen abundance, ionization parameter, and gas pressure, clearly illustrating the trends in these quantities.
Unraveling the Complex Structure of AGN-driven Outflows. IV. Comparing AGNs with and without Strong Outflows
Authors: Luo Rongxin , Woo Jong-Hak , Shin Jaejin , Kang Daeun , Bae Hyun-Jin , Karouzos Marios 
Published: March 2019

Abstract
Active galactic nucleus (AGN)-driven outflows are considered as one of the processes driving the coevolution of supermassive black holes with their host galaxies. We present integral field spectroscopy of six Type 2 AGNs at z < 0.1, which are selected as AGNs without strong outflows based on the kinematics of [O iii] gas. Using spatially resolved data, we investigate the ionized gas kinematics and photoionization properties in comparison with AGNs with strong outflows. We find significant difference between the kinematics of ionized gas and stars for two AGNs, which indicates the presence of AGN-driven outflows. Nevertheless, the low velocity and velocity dispersion of ionized gas indicate relatively weak outflows in these AGNs. Our results highlight the importance of spatially resolved observation in investigating gas kinematics and identifying the signatures of AGN-driven outflows. While it is unclear what determines the occurrence of outflows, we discuss the conditions and detectability of AGN-driven outflows based on a larger sample of AGNs with and without outflows, suggesting the importance of gas content in the host galaxies.
Is Supernova Remnant Cassiopeia A a PeVatron?
Authors: Zhang Xiao , Liu Siming 
Published: March 2019

Abstract
Cassiopeia A, a well-observed young core-collapse supernova remnant (SNR), is considered to be one of the best candidates for studying very high-energy particle acceleration up to PeV via the diffusive shock mechanism. Recently, MAGIC observations revealed a γ-ray spectral cutoff at

∼
3.5

TeV

, suggesting that if the TeV γ-rays have a hadronic origin, SNR Cas A can only accelerate particles to tens of TeV. Here, we propose a two-zone emission model for regions associated with the forward (zone 1) and inward/reverse shocks (zone 2). Given the low density in zone 1, it dominates the high-frequency radio emission, soft X-ray rim via the synchrotron process, and TeV γ-ray via the inverse Comptonization. With a relatively softer particle distribution and a higher cutoff energy for electrons, emissions from zone 2 dominate the low-frequency radio, hard X-ray via the synchrotron process and GeV γ-ray via hadronic processes. There is no evidence for high-energy cutoffs in the proton distributions implying that Cas A can still be a PeVatron. Hadronic processes from zone 1 dominate very high-energy gamma-ray emission. Future observations in the hundreds of TeV range can test this model.
Brightest Cluster Galaxy Alignments in Merging Clusters
Authors: Wittman David , Foote Drake , Golovich Nathan 
Published: March 2019

Abstract
The orientations of brightest cluster galaxies (BCGs) and their host clusters tend to be aligned, but the mechanism driving this is not clear. To probe the role of cluster mergers in this process, we quantify alignments of 38 BCGs in 22 clusters undergoing major mergers (up to ∼1 Gyr after first pericenter). We find alignments entirely consistent with those of clusters in general. This suggests that alignments are robust against major cluster mergers. If, conversely, major cluster mergers actually help orient the BCG, such a process is acting quickly because the orientation is in place within ∼1 Gyr after first pericenter.
A Model of Rotating Convection in Stellar and Planetary Interiors. I. Convective Penetration
Authors: Augustson K. C. , Mathis S. 
Published: March 2019

Abstract
A monomodal model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale as a function of rotation rate as well as with thermal and viscous diffusivities. The convection model is used as a boundary condition for a linearization of the equations of motion in the transition region between convectively unstable and stably stratified regions, yielding the depth to which convection penetrates into the stable region and establishing a relationship between that depth and the local convective Rossby number, diffusivity, and pressure scale height of those flows. Upward and downward penetrative convection have a similar scaling with rotation rate and diffusivities, but they depend differently upon the pressure scale height, due to the differing energetic processes occurring in convective cores of early-type stars versus convective envelopes of late-type stars.
Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. II. Atomic Diffusion in M67 Stars
Authors: Souto Diogo , Prieto C. Allende , Cunha Katia , Pinsonneault Marc , Smith Verne V. , Garcia-Dias R. , Bovy Jo , García-Hernández D. A. , Holtzman Jon , Johnson J. A. , Jönsson Henrik , Majewski Steve R. , Shetrone Matthew , Sobeck Jennifer , Zamora Olga , Pan Kaike , Nitschelm Christian 
Published: March 2019

AbstractChemical abundances for 15 elements (C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Ni) are presented for 83 stellar members of the 4 Gyr old solar-metallicity open cluster M67. The sample contains stars spanning a wide range of evolutionary phases, from G dwarfs to red clump stars. The abundances were derived from near-IR (λ1.5–1.7μm) high-resolution spectra (R = 22,500) from the SDSS-IV/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. A 1D local thermodynamic equilibrium abundance analysis was carried out using the APOGEE synthetic spectral libraries, via χ2minimization of the synthetic and observed spectra with the qASPCAP code. We found significant abundance differences (∼0.05–0.30 dex) between the M67 member stars as a function of the stellar mass (or position on the Hertzsprung–Russell diagram), where the abundance patterns exhibit a general depletion (in [X/H]) in stars at the main-sequence turnoff. The amount of the depletion is different for different elements. We find that atomic diffusion models provide, in general, good agreement with the abundance trends for most chemical species, supporting recent studies indicating that measurable atomic diffusion operates in M67 stars.
CHIANTI—An Atomic Database for Emission Lines. XV. Version 9, Improvements for the X-Ray Satellite Lines
Authors: Dere K. P. , Zanna G. Del , Young P. R. , Landi E. , Sutherland R. S. 
Published: March 2019

Abstract
CHIANTI contains a large quantity of atomic data for the analysis of astrophysical spectra. Programs are available in IDL and Python to perform calculation of the expected emergent spectrum from these sources. The database includes atomic energy levels, wavelengths, radiative transition probabilities, rate coefficients for collisional excitation, ionization, and recombination, as well as data to calculate free–free, free–bound, and two-photon continuum emission. In Version 9, we improve the modeling of the satellite lines at X-ray wavelengths by explicitly including autoionization and dielectronic recombination processes in the calculation of level populations for select members of the lithium isoelectronic sequence and Fe xviii–xxiii. In addition, existing data sets are updated, new ions are added, and new total recombination rates for several Fe ions are included. All data and IDL programs are freely available at http://www.chiantidatabase.org or through SolarSoft, and the Python code ChiantiPy is also freely available at https://github.com/chianti-atomic/ChiantiPy.
Benzofurocaine: effects on experimental periodontitis, anti-diabetic activity and molecular mechanisms of action
Authors: Galenko-Yaroshevsky Pavel A. , Popkov Victor L. , Bedrosova Karine A. , Faustov Leonid A. , Sukoyan Galina V. , Zadorozhny Andrey V. , Gulevskaya Ol’ga N. , Uvarov Aleksandr V. , Dobrodomova Valeriya S. 
Published: March 2019

Introduction: A promising compound for the treatment of inflammatory periodontal diseases is benzofuracaine (BFC) .BFC has pronounced anti-inflammatory, analgesic, reparative, hypoglycemic and other effects. Objective: To assess the influence of benzofuracaine on experimental periodontitis and to study its antidiabetic activity and molecular mech-anisms of action
Materials and methods: The work was performed on 232 white nonlinear rats of both sexes and 55 male mice. To assess the effect of BFС on experimental periodontitis, the amount of gingival fluid (AGF) was determined, an in-depth morphofunctional study of periodontal tissues was conducted, as well as the study of the biochemical composition of the gingiva and blood. Antidiabetic properties were studied using the glucose tolerance test (GTT), as well as the as-sessment of endothelium-dependent vasodilation and transmembrane K+-currents on an isolated aortic segment of ratswith streptozotocin-induced diabetes mellitus (DM).
Results and discussion: In experimental periodontitis, BFC improves the morphological picture and decreases AGF, in-creases the level of blood microcirculation in the attached gingiva, has a normalizing effect on the prekallikrein-kallikrein system, reduces the synthesis of bradykinin, proinflammatory cytokines and PGE2, increases the level of VEGF, reduces the level of endothelin-1, increases the ATP content and NADH-ubiquinone-reductase activity, exhibits antioxidant properties,reduces the content of nitrosothiols and NO metabolites (NO2/NO3), increases the level of transferrin; when conducting a
glucose tolerance test in mice, it reduces the level of glucose in the blood, but in this respect is inferior to glibenclamide, has a hypoglycemic effect in the early stages of diabetes (30 days), tends to restore endothelium-dependent dilatation of smooth muscle cells (SMC) of the aorta and does not affect the functioning of the K+-channels of the aortic SMC.
Conclusion: BFС is an effective drug for the treatment of periodontitis and can be recommended for further preclinical and clinical studies.