Miracle-dz/UniFAR-FTUs huggingface dataset:
Cosmic evolution of the C iv in high-resolution hydrodynamic simulations

We investigate the properties of triply ionized carbon (C iv) in the intergalactic medium (IGM) using a set of high resolution and large box size cosmological hydrodynamic simulations of a Lambda cold dark matter (ΛCDM) model. We rely on a modification of the publicly available TreeSPH code gadget-2 that self-consistently follows the metal enrichment mechanism by means of a detailed chemical evolution model. We focus on several numerical implementations of galactic feedback: galactic winds in the energy-driven and momentum-driven prescriptions, galactic winds hydrodynamically coupled to the surrounding gas and active galactic nuclei (AGNs) powered by gas accretion on to massive black holes. Furthermore, our results are compared to a run in which galactic feedback is not present and we also explore different initial stellar mass function. After having addressed some global properties of the simulated volume like the impact on the star formation rate and the content in carbon and C iv, we extract mock IGM transmission spectra in neutral hydrogen (H i) and C iv and perform Voigt profile fitting. The results are then compared with high-resolution quasar (QSO) spectra obtained with the Ultraviolet Echelle Spectrograph (UVES) at the Very Large Telescope (VLT) and the High Resolution Echelle Spectrograph (HIRES) at Keck. We find that feedback has little impact on statistics related to the neutral hydrogen, while C iv is more affected by galactic winds and/or AGN feedback. The feedback schemes investigated have a different strength and redshift evolution with a general tendency for AGN feedback to be more effective at lower redshift than galactic winds. When the same analysis is performed over observed and simulated C iv lines, we find a reasonably good agreement between data and simulations over the column density range NC IV= 1012.5-15 cm−2. Also the C iv linewidth distribution appears to be in agreement with the observed values, while the H i Doppler parameters, bH I, are in general too large, showing that the diffuse cosmic web is heated more than what is inferred by observations. The simulation without feedback fails in reproducing the C iv systems at high column densities at all redshift, while the AGN feedback case agrees with observations only at z < 3, when this form of feedback is particularly effective. We also present scatter plots in the b–N and in the NC IV–NH I planes, showing that there is rough agreement between observations and simulations only when feedback is taken into account. Although it seems difficult to constrain the nature and the strength of galactic feedback using the present framework and find a unique model that fits all the observations, these simulations offer the perspective of understanding the galaxy–IGM interplay and how metals produced by stars can reach the low-density IGM.
How well does CO emission measure the H2 mass of MCs

We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain $^{12}$CO and $^{13}$CO emission maps for the $J=1\rightarrow0$ rotational transition. The emission maps are analysed with commonly used observational methods, i.e. the $^{13}$CO column density measurement, the virial mass estimate and the so-called $X_{\textrm{CO}}$ (also CO-to-H$_2$) conversion factor, and then the inferred quantities (i.e. mass and column density) are compared to the physical values. We generally find that most methods examined here recover the CO-emitting H$_{2}$ gas mass of MCs within a factor of two uncertainty if the metallicity is not too low. The exception is the $^{13}$CO column density method. It is affected by chemical and optical depth issues, and it measures both the true H$_{2}$ column density distribution and the molecular mass poorly. The virial mass estimate seems to work the best in the considered metallicity and radiation field strength range, even when the overall virial parameter of the cloud is above the equilibrium value. This is explained by a systematically lower virial parameter (i.e. closer to equilibrium) in the CO-emitting regions; in CO emission, clouds might seem (sub-)virial, even when, in fact, they are expanding or being dispersed. A single CO-to-H$_{2}$ conversion factor appears to be a robust choice over relatively wide ranges of cloud conditions, unless the metallicity is low. The methods which try to take the metallicity dependence of the conversion factor into account tend to systematically overestimate the true cloud masses.
γ-rays as a diagnostic of the origin of core radiation in low-luminosity active galactic nuclei

The respective contribution of disc and jet components to the total emission in low-luminosity active galactic nuclei (LLAGNs) is an open question. This paper suggests that γ-rays emitted from electrons accelerated in jets could be a direct diagnostic tool for a jet component to the total emission. We demonstrate γ-ray flux from jets based on a synchrotron self-Compton model on the assumption that radio and X-rays are dominantly produced from jets in the case of a high state of a nearby LLAGN, NGC 4278. We also survey parameter space in the model. Observational properties of LLAGNs in radio and X-ray bands allow to constrain physical parameters in an emission region. The size of the emission region R is limited to 10 16 ≤ R≤ 10 17.5 cm if the observed tight correlation between radio and X-ray emission originates from the same jet component. If the beaming factor of the emission region is close to the observed parsec scale jet of NGC 4278 and R~ 10 16 cm, the γ-rays may be detected by the Cherenkov Telescope Array and the jet domination can be tested in the near future.
Influential Factors of Online Shopping Decision

With the technology advances, online shopping has experienced a phenomenal growth. In line with such phenomenon and its relevancy, a considerable number of studies have shown an interest within this area. Although recent researches have particularly addressed the online consumer’s behavior, findings were inconsistent. Thereby, further researches have been called for. The present study aims to investigate the effect of few variables derived from existing literature which are price, trust, promotion, easiness, service quality, and product on online consumers’ buying decision. A survey method was employed to gather data from 84 university’s students. They were recruited using purposive sampling technique in which previous online shopping experiences was required. Data were then analyzed using multiple regression. The results of data analysis showed that the six factors significantly affect consumer’s buying decision. Moreover, this study revealed that the largest contributor of these influences was price. Further discussion and managerial implications are presented.
DETERMINANTS OF SUCCESSFUL IMPLEMENTATION OF E-GOVERNMENT SYSTEM

To determine the effect of the determinants of the success of the implementation of the Local Government Information System using the DeLone and McLean model is the purpose of this study. Questionnaires were distributed to obtain data. Purposive sampling method with a total sample of 80 sample. Path analysis using Partial Least Square is a data analysis technique used. It is proven in the research, namely that the belief system of information quality affects the system use, while service quality, social factors and system quality, has no effect on system use. The results also show that system trust, information quality, social factors affect system user satisfaction, while service quality and system quality have no effect on user satisfaction. Then, it also proves that user satisfaction and system use affect individual performance. The success of this system is measured based on user satisfaction with and as a result of the application of the system and individual efforts, so that the implementation of the Local Government Information System in all regions of the Regional Apparatus Organization in Kupang Regency is quite successful.
OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge

We use the extended and updated Optical Gravitational Lensing Experiment (OGLE) Collection of Variable Stars to thoroughly analyze the distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive the absolute Wesenheit magnitude and individual distance of each RR Lyrae star. We confirm results from our earlier study showing that RR Lyrae stars are present in between the Magellanic Clouds, though their three-dimensional distribution more resembles two extended overlapping structures than a strict bridge-like connection. The contours do connect in the southern parts of the Bridge, albeit on a level too low to state that an evident connection exists. To test the sample numerically, we use multi-Gaussian fitting and conclude that there is no additional population or overdensity located in the Bridge. We also try to reproduce results on the putative RR Lyrae Magellanic Bridge stream by selecting RR Lyrae candidates from Gaia Data Release 1. We show that we are not able to obtain the evident connection of the Clouds without many spurious sources in the sample, as the cuts are not able to remove artifacts without eliminating the evident connection at the same time. Moreover, for the first time, we present the Gaia Data Release 2 RR Lyrae stars in the Magellanic Bridge area and show that their distribution matches our results.
HUNTING A WANDERING SUPERMASSIVE BLACK HOLE IN THE M31 HALO HERMITAGE

In the hierarchical structure formation scenario, galaxies enlarge through multiple merging events with less massive galaxies. In addition, the Magorrian relation indicates that almost all galaxies are occupied by a central supermassive black hole (SMBH) of mass 10−3 times the mass of its spheroidal component. Consequently, SMBHs are expected to wander in the halos of their host galaxies following a galaxy collision, although evidence of this activity is currently lacking. We investigate a current plausible location of an SMBH wandering in the halo of the Andromeda galaxy (M31). According to theoretical studies of N-body simulations, some of the many substructures in the M31 halo are remnants of a minor merger occurring about 1 Gyr ago. First, to evaluate the possible parameter space of the infalling orbit of the progenitor, we perform numerous parameter studies using a graphics processing unit cluster. To reduce uncertainties in the predicted position of the expected SMBH, we then calculate the time evolution of the SMBH in the progenitor dwarf galaxy from N-body simulations using the plausible parameter sets. Our results show that the SMBH lies within the halo (∼20–50 kpc from the M31 center), closer to the Milky Way than the M31 disk. Furthermore, the predicted current positions of the SMBH were restricted to an observational field of 0. °6 × 0. °7 in the northeast region of the M31 halo. We also discuss the origin of the infalling orbit of the satellite galaxy and its relationships with the recently discovered vast thin disk plane of satellite galaxies around M31.
The angular momentum of disc galaxies: implications for gas accretion, outflows, and dynamical friction

We combine constraints on the galaxy–dark matter connection with structural and dynamical scaling relations to investigate the angular momentum content of disc galaxies. For haloes with masses in the interval 1011.3 M⊙≲Mvir≲ 1012.7 M⊙ we find that the galaxy spin parameters are basically independent of halo mass with . This is significantly lower than for relaxed Λcold dark matter (ΛCDM) haloes, which have an average spin parameter . The average ratio between the specific angular momentum of disc galaxies and their host dark matter haloes is therefore . This calls into question a standard assumption made in the majority of all (semi-analytical) models for (disc) galaxy formation, namely that . Using simple disc formation models we show that it is particularly challenging to understand why is independent of halo mass, while the galaxy formation efficiency (eGF; proportional to the ratio of galaxy mass to halo mass) reveals a strong halo mass dependence. We argue that the empirical scaling relations between eGF, and halo mass require both feedback (i.e. galactic outflows) and angular momentum transfer from the baryons to the dark matter (i.e. dynamical friction). Most importantly, the efficiency of angular momentum loss needs to decrease with increasing halo mass. Such a mass dependence may reflect a bias against forming stable discs in high-mass, low-spin haloes or a transition from cold-mode accretion in low-mass haloes to hot-mode accretion at the massive end. However, current hydrodynamical simulations of galaxy formation, which should include these processes, seem unable to reproduce the empirical relation between eGF and . We conclude that the angular momentum build-up of galactic discs remains poorly understood.
Comment on “Fermionic entanglement ambiguity in noninertial frames”

In this comment we show that the ambiguity of entropic quantities calculated in Physical Review A 83, 062323 (2011) for fermionic fields in the context of Unruh effect is not related to the properties of anticommuting fields, as claimed in Physical Review A 83, 062323 (2011), but rather to wrong mathematical manipulations with them and not taking into account a fundamental superselection rule of quantum field theory.
Origin of reduced polaron recombination in organic semiconductor devices

We propose a model to explain the reduced bimolecular recombination rate found in state-of-the-art bulk heterojunction solar cells. When compared to the Langevin recombination, the experimentally observed rate is one to four orders of magnitude lower, but gets closer to the Langevin case for low temperatures. Our model considers the organic solar cell as device with carrier concentration gradients, which form due to the electrode/blend/electrode device configuration. The resulting electron concentration under working conditions of a solar cell is higher at the cathode than at the anode, and vice versa for holes. Therefore, the spatially dependent bimolecular recombination rate, proportional to the local product of electron and hole concentration, is much lower as compared to the calculation of the recombination rate based on the extracted and thus averaged charge carrier concentrations. We consider also the temperature dependence of the recombination rate, which can for the first time be described with our model.
The SAMI Galaxy Survey: the link between angular momentum and optical morphology

We investigate the relationship between stellar and gas specific angular momentum j, stellar mass M-* and optical morphology for a sample of 488 galaxies extracted from the Sydney-AAO Multi-object Integral field Galaxy Survey. We find that j, measured within one effective radius, monotonically increases with M-* and that, for M-* > 10(9.5) M-aS (TM), the scatter in this relation strongly correlates with optical morphology (i.e. visual classification and S,rsic index). These findings confirm that massive galaxies of all types lie on a plane relating mass, angular momentum and stellar-light distribution, and suggest that the large-scale morphology of a galaxy is regulated by its mass and dynamical state. We show that the significant scatter in the M-*-j relation is accounted for by the fact that, at fixed stellar mass, the contribution of ordered motions to the dynamical support of galaxies varies by at least a factor of 3. Indeed, the stellar spin parameter (quantified via lambda(R)) correlates strongly with S,rsic and concentration indices. This correlation is particularly strong once slow rotators are removed from the sample, showing that late-type galaxies and early-type fast rotators form a continuous class of objects in terms of their kinematic properties.
Homogeneous Photometry VI: Variable Stars in the Leo I Dwarf Spheroidal Galaxy

From archival ground-based images of the Leo I dwarf spheroidal galaxy, we have identified and characterized the pulsation properties of 164 candidate RR Lyrae variables and 55 candidate anomalous and/or short-period Cepheids. We have also identified 19 candidate long-period variable stars and 13 other candidate variables whose physical nature is unclear, but due to the limitations of our observational material we are unable to estimate reliable periods for them. On the basis of its RR Lyrae star population, Leo I is confirmed to be an Oosterhoff-intermediate type galaxy, like several other dwarf spheroidals. From the RR Lyrae stars we have derived a range of possible distance moduli for Leo I : 22.06 ± 0.08 ≲ μ0 ≲ 22.25 ± 0.07 mag depending on the metallicity assumed for the old population ([Fe/H] from -1.43 to -2.15). This is in agreement with previous independent estimates. We show that in their pulsation properties, the RR Lyrae stars—representing the oldest stellar population in the galaxy—are not significantly different from those of five other nearby, isolated dwarf spheroidal galaxies. A similar result is obtained when comparing them to RR Lyrae stars in recently discovered ultra-faint dwarf galaxies. We are able to compare the period distributions and period-amplitude relations for a statistically significant sample of ab-type RR Lyrae stars in dwarf galaxies (∼1300 stars) with those in the Galactic halo field (∼14,000 stars) and globular clusters (∼1000 stars). Field RRLs show a significant change in their period distribution when moving from the inner (dG ≲ 14 kpc) to the outer (dG ≳ 14 kpc) halo regions. This suggests that the halo formed from (at least) two dissimilar progenitors or types of progenitor. Considered together, the RR Lyrae stars in classical dwarf spheroidal and ultra-faint dwarf galaxies—as observed today—do not appear to follow the well defined pulsation properties shown by those in either the inner or the outer Galactic halo, nor do they have the same properties as RR Lyraes in globular clusters. In particular, the samples of fundamental-mode RR Lyrae stars in dwarf galaxies seem to lack High Amplitudes and Short Periods (“HASP”: AV≥1.0 mag and P ≲ 0.48 d) when compared with those observed in the Galactic halo field and globular clusters. The observed properties of RR Lyrae stars do not support the idea that currently existing classical dwarf spheroidal and ultra-faint dwarf galaxies are surviving representative examples of the original building blocks of the Galactic halo.
Homogeneous vacua of (generalized) new massive gravity

We obtain all homogeneous solutions of new massive gravity models on S3 and AdS3 by extending previously known results for the cosmological topologically massive theory of gravity in three dimensions. In all cases, apart from the maximally symmetric vacua, there are axially symmetric (i.e. bi-axially squashed) as well as totally anisotropic (i.e. tri-axially squashed) metrics of a special algebraic type. Transitions among the vacua are modeled by instanton solutions of (3 + 1) Hořava–Lifshitz gravity with an anisotropic scaling parameter z = 4.
FIRST RESULTS FROM THE SWARMS SURVEY. SDSS 1257+5428: A NEARBY, MASSIVE WHITE DWARF BINARY WITH A LIKELY NEUTRON STAR OR BLACK HOLE COMPANION

We present the first results from the SWARMS survey, an ongoing project to identify compact white dwarf (WD) binaries in the spectroscopic catalog of the Sloan Digital Sky Survey (SDSS). The first object identified by SWARMS, SDSS 1257+5428, is a single-lined spectroscopic binary in a circular orbit with a period of 4.56 hr and a semiamplitude of 322.7 ± 6.3 km s-1. From the spectrum and photometry, we estimate a WD mass of 0.92+0.28−0.32 M☉. Together with the orbital parameters of the binary, this implies that the unseen companion must be more massive than 1.62+0.20−0.25 M☉, and is in all likelihood either a neutron star or a black hole. At an estimated distance of 48+10−19 pc, this would be the closest known stellar remnant of a supernova explosion.
A comprehensive design and performance analysis of low Earth orbit satellite quantum communication

Optical quantum communication utilizing satellite platforms has the potential to extend the reach of quantum key distribution (QKD) from terrestrial limits of ∼200 km to global scales. We have developed a thorough numerical simulation using realistic simulated orbits and incorporating the effects of pointing error, diffraction, atmosphere and telescope design, to obtain estimates of the loss and background noise which a satellite-based system would experience. Combining with quantum optics simulations of sources and detection, we determine the length of secure key for QKD, as well as entanglement visibility and achievable distances for fundamental experiments. We analyse the performance of a low Earth orbit satellite for downlink and uplink scenarios of the quantum optical signals. We argue that the advantages of locating the quantum source on the ground justify a greater scientific interest in an uplink as compared to a downlink. An uplink with a ground transmitter of at least 25 cm diameter and a 30 cm receiver telescope on the satellite could be used to successfully perform QKD multiple times per week with either an entangled photon source or with a weak coherent pulse source, as well as perform long-distance Bell tests and quantum teleportation. Our model helps to resolve important design considerations such as operating wavelength, type and specifications of sources and detectors, telescope designs, specific orbits and ground station locations, in view of anticipated overall system performance.
The binary companion mass ratio distribution: an imprint of the star formation process?

We explore the effects of dynamical evolution in dense clusters on the companion mass ratio distribution (CMRD) of binary stars. Binary systems are destroyed by interactions with other stars in the cluster, lowering the total binary fraction and significantly altering the initial semi-major axis distribution. However, the shape of the CMRD is unaffected by dynamics; an equal number of systems with high mass ratios are destroyed compared to systems with low mass ratios. We might expect a weak dependence of the survivability of a binary on its mass ratio because its binding energy is proportional to both the primary and secondary mass components of the system. However, binaries are broken up by interactions in which the perturbing star has a significantly higher energy (by a factor of >10, depending on the particular binary properties) than the binding energy of the binary, or through multiple interactions in the cluster. We therefore suggest that the shape of the observed binary CMRD is an outcome of the star formation process, and should be measured in preference to the distributions of orbital parameters, such as the semi-major axis distribution.