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<jats:title>Abstract</jats:title> <jats:p>In this paper, we extend our previous study on the Lemaitre–Tolman (LT) model showing how the prediction of the model changes when the equation of state (EoS) parameter (<jats:italic>w</jats:italic>) of dark energy (DE) is modified. In the previous study, it was considered that DE was merely constituted by the cosmological constant. In this paper, as in the previous study, we also took into account the effect of angular momentum and dynamical friction (<jats:italic>J</jats:italic> <jats:italic>η</jats:italic>LT model) that modifies the evolution of a perturbation, initially moving with the Hubble flow. As a first step, solving the equations of motion, we calculated the relationship between mass, <jats:italic>M</jats:italic>, and the turn-around radius, <jats:italic>R</jats:italic> <jats:sub>0</jats:sub>. If one knows the value of the turn-around radius <jats:italic>R</jats:italic> <jats:sub>0</jats:sub>, it is possible to obtain the mass of the studied objects. As a second step, we build up, as in the previous paper, a relationship between the velocity, <jats:italic>v</jats:italic>, and radius, <jats:italic>R</jats:italic>. The relation was fitted to data of groups and clusters. Since the relationship <jats:italic>v</jats:italic>–<jats:italic>R</jats:italic> depends on the Hubble constant and the mass of the object, we obtained optimized values of the two parameters of the objects studied. The mass decreases of a factor of maximum 25% comparing the <jats:italic>J</jats:italic> <jats:italic>η</jats:italic>LT results (for which <jats:italic>w</jats:italic> = −1) and the case <jats:italic>w</jats:italic> = −1/3, while the Hubble constant increases going from <jats:italic>w</jats:italic> = −1 to <jats:italic>w</jats:italic> = −1/3. Finally, the obtained values of the mass, <jats:italic>M</jats:italic>, and <jats:italic>R</jats:italic> <jats:sub>0</jats:sub> of the studied objects can put constraints on the DE EoS parameter, <jats:italic>w</jats:italic>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Solid ammonia (NH<jats:sub>3</jats:sub>) is the only nitrogen-containing polyatomic molecule reported in both interstellar and solar system ices. However, an examination of the literature reveals significant omissions and difficulties in earlier work that can hinder quantitative measurements of solid NH<jats:sub>3</jats:sub> by infrared (IR) methods by both astronomical observers and laboratory spectroscopists. Here we reinvestigate the IR spectra of NH<jats:sub>3</jats:sub> ices in amorphous and crystalline forms to determine mid- and near-IR intensities. The IR absorption coefficients, band strengths, and optical constants are presented for both amorphous and crystalline NH<jats:sub>3</jats:sub>, along with new density and refractive index (<jats:italic>λ</jats:italic> = 670 nm) measurements needed to quantify our IR results. We find that two widely used approximate IR band strengths for amorphous NH<jats:sub>3</jats:sub> are nearly 30% higher than measured values after corrections for the compound’s density. We have also used our new results to rescale two NH<jats:sub>3</jats:sub> near-IR band strengths in the literature, finding that they increase by about 60%. Some applications of our new results are described along with suggestions for future studies. Optical constants are available in electronic form.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Optical secondary eclipse measurements made by Kepler reveal a diverse set of geometric albedos for hot Jupiters with equilibrium temperatures between 1550 and 1700 K. The presence or absence of high-altitude condensates, such as Mg<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub>, Fe, Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, and TiO<jats:sub>2</jats:sub>, can significantly alter optical albedos, but these clouds are expected to be confined to localized regions in the atmospheres of these tidally locked planets. Here, we present 3D general circulation models and corresponding cloud and albedo maps for six hot Jupiters with measured optical albedos in this temperature range. We find that the observed optical albedos of K2-31b and K2-107b are best matched by either cloud-free models or models with relatively compact cloud layers, while Kepler-8b’s and Kepler-17b’s optical albedos can be matched by moderately extended (<jats:italic>f</jats:italic> <jats:sub>sed</jats:sub> = 0.1) parametric cloud models. HATS-11b has a high optical albedo, corresponding to models with bright Mg<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub> clouds extending to very low pressures (<jats:italic>f</jats:italic> <jats:sub>sed</jats:sub> = 0.03). We are unable to reproduce Kepler-7b’s high albedo, as our models predict that the dayside will be dominated by dark Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> clouds at most longitudes. We compare our parametric cloud model with a microphysical cloud model. We find that even after accounting for the 3D thermal structure, no single cloud model can explain the full range of observed albedos within the sample. We conclude that a better knowledge of the vertical mixing profiles, cloud radiative feedback, cloud condensate properties, and atmospheric metallicities is needed in order to explain the unexpected diversity of albedos in this temperature range.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Morphological studies are crucial to investigate the connections between active galactic nucleus (AGN) activities and the evolution of galaxies. Substantial studies have found that radiative-mode AGNs primarily reside in disk galaxies, questioning the merger-driven mechanism of AGN activities. In this study, through Sérsic profile fitting and nonparametric morphological parameter measurements, we investigated the morphology of host galaxies of 485 optical variability-selected low-luminosity AGNs at <jats:italic>z</jats:italic> ≲ 4.26 in the COSMOS field. We analyzed high-resolution images of the Hubble Space Telescope to measure these morphological parameters. We only successfully measured the morphological parameters for 76 objects and most AGN hosts (∼70%) were visually compact point-like sources. We examined the obtained morphological information as a function of redshift and compared them with literature data. We found that these AGN host galaxies showed no clear morphological preference. However, the merger rate increased with higher host star formation rate and AGN luminosity. Interestingly, we found ongoing star formation consistent with the typical star-forming populations in both elliptical and spiral galaxies, while these two types of galaxies were more symmetric than normal star-forming galaxies. These results suggest that optical variability-selected AGNs have higher probabilities to reside in elliptical galaxies than infrared-selected AGNs, whose host galaxies have a strong disk dominance, and support recent findings that the AGN feedback can enhance star-forming activities in host galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The detections of gravitational waves (GWs) from binary neutron star systems and neutron star–black hole systems provide new insights into dense matter properties in extreme conditions and associated high-energy astrophysical processes. However, currently, information about the neutron star equation of state (EoS) is extracted with very limited precision. Meanwhile, the fruitful results from the serendipitous discovery of the <jats:italic>γ</jats:italic>-ray burst alongside GW170817 show the necessity of early warning alerts. Accurate measurements of the matter effects and sky location could be achieved by joint GW detection from space and ground. In our work, based on two example cases, GW170817 and GW200105, we use the Fisher information matrix analysis to investigate the multiband synergy between the space-borne decihertz GW detectors and the ground-based Einstein Telescope (ET). We especially focus on the parameters pertaining to the spin-induced quadrupole moment, tidal deformability, and sky localization. We demonstrate that (i) only with the help of multiband observations we can constrain the quadrupole parameter; and (ii) with the inclusion of decihertz GW detectors, the errors of tidal deformability would be a few times smaller, indicating that many more EoSs could be excluded; (iii) with the inclusion of ET, the sky localization improves by about 1 order of magnitude. Furthermore, we have systematically compared the different limits from four planned decihertz detectors and adopting two widely used waveform models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Following the latest work of Wu et al., we construct time-transformed explicit symplectic schemes for a Hamiltonian system on the description of charged particles moving around a deformed Schwarzschild black hole with an external magnetic field. Numerical tests show that such schemes have good performance in stabilizing energy errors without secular drift. Meantime, tangent vectors are solved from the variational equations of the system with the aid of an explicit symplectic integrator. The obtained tangent vectors are used to calculate several chaos indicators, including Lyapunov characteristic exponents, fast Lyapunov indicators, a smaller alignment index, and a generalized alignment index. It is found that the smaller alignment index and generalized alignment index are the fastest indicators for distinguishing between regular and chaotic cases. The smaller alignment index is applied to explore the effects of the parameters on the dynamical transition from order to chaos. When the positive deformation factor and angular momentum decrease, or when the energy, positive magnetic parameter, and the magnitude of the negative deformation parameter increase, chaos easily occurs for the appropriate choices of initial conditions and the other parameters.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of ALMA ∼2 mm, ≲1″-resolution observations of 10 (ultra)luminous infrared galaxies ([U]LIRGs; infrared luminosity ≳10<jats:sup>11.7</jats:sup> <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub>) at <jats:italic>z</jats:italic> &lt; 0.15, targeting dense (&gt;10<jats:sup>4</jats:sup> cm<jats:sup>−3</jats:sup>) molecular (HCN, HCO<jats:sup>+</jats:sup>, and HNC <jats:italic>J</jats:italic> = 2–1) and 183 GHz H<jats:sub>2</jats:sub>O 3<jats:sub>1,3</jats:sub>–2<jats:sub>2,0</jats:sub> emission lines. Active galactic nucleus (AGN)-important ULIRGs tend to show higher HCN/HCO<jats:sup>+</jats:sup> <jats:italic>J</jats:italic> = 2–1 flux ratios than starburst-classified sources. We detect 183 GHz H<jats:sub>2</jats:sub>O emission in almost all AGN-important ULIRGs, and elevated H<jats:sub>2</jats:sub>O emission is found in two sources with elevated HCN <jats:italic>J</jats:italic> = 2–1 emission, relative to HCO<jats:sup>+</jats:sup> <jats:italic>J</jats:italic> = 2–1. Except one ULIRG (the Superantennae), the H<jats:sub>2</jats:sub>O emission largely comes from the entire nuclear regions (∼1 kpc), rather than an AGN-origin megamaser at the very center (≪1 kpc). Nuclear (∼1 kpc) dense molecular gas mass derived from HCO<jats:sup>+</jats:sup> <jats:italic>J</jats:italic> = 2–1 luminosity is ≳ a few × 10<jats:sup>8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and its depletion time is estimated to be ≳10<jats:sup>6</jats:sup> yr in all sources. Vibrationally excited <jats:italic>J</jats:italic> = 2–1 emission lines of HCN and HNC are detected in a few (U)LIRGs, but those of HCO<jats:sup>+</jats:sup> are not. It is suggested that in mid-infrared-radiation-exposed innermost regions around energy sources, HCO<jats:sup>+</jats:sup> and HNC are substantially less abundant than HCN. In our ALMA ∼2 mm data of 10 (U)LIRGs, two continuum sources are serendipitously detected within ∼10″, which are likely to be an infrared-luminous dusty galaxy at <jats:italic>z</jats:italic> &gt; 1 and a blazar.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Extended main-sequence turnoffs (eMSTOs) apparent in most young and intermediate-age clusters (younger than ∼2 Gyr) are known features caused by fast rotating early-type (earlier than F-type) stars. Late-type stars are not fast rotators because their initial angular momenta have been quickly dispersed due to magnetic braking. However, the mass limit below which stars have been magnetically braked has not been well constrained by observation. In this paper, we present an analysis of the eMSTO of NGC 6819, an open cluster of an intermediate-age (∼2.5 Gyr), believed to be comparable to the lifetime of stars near the mass limit for magnetic braking. By comparing the observation with synthetic color–magnitude diagrams, we find that NGC 6819 does not harbor an obvious eMSTO. The morphology of its turnoff region can be readily explained by a simple stellar population considering the observational uncertainties as well as the differential reddening. In addition, the MSTO stars in NGC 6819 have very small values of average rotational velocity and dispersion, indicating that they have undergone significant magnetic braking. Combining with results in the literature for clusters of younger ages, our current work suggests that the critical age for the disappearance of eMSTO in star clusters must be shorter but very close to the age of NGC 6819, and this in turn implies a critical stellar mass for magnetic braking at solar metallicity above but close to 1.54 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> based on the PARSEC model. We emphasize that the phenomenon of eMSTO could provide an unique way to constrain the onset mass of magnetic braking.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Current sheets (CSs) are widespread objects in space plasma capable of storing and, then, explosively releasing the accumulated magnetic energy. In planetary magnetotails the cross-tail CS plays an important role in the global dynamics of the tail and in the transformation of the magnetic energy into the kinetic and thermal energies of the ambient plasma. We have analyzed 114 crossings of the cross-tail CS by the MAVEN spacecraft at <jats:italic>X</jats:italic> <jats:sub>MSO</jats:sub> ∼ [−1.0, −2.8]<jats:italic>R</jats:italic> <jats:sub>M</jats:sub>. Magnetic field observations with high time resolution allowed the observation of the inner superthin CS (STCS) with a half-thickness <jats:italic>L</jats:italic> <jats:sub>STCS</jats:sub> ∼ (1–100)<jats:italic>ρ</jats:italic> <jats:sub>e</jats:sub> (<jats:italic>ρ</jats:italic> <jats:sub>e</jats:sub> is the gyroradius of thermal electrons) in 75 intervals of the CS crossings from our database. The STCS was embedded into a thicker ion-scale CS and provides 10%–50% of the total current density in the cross-tail CS. Our analysis has shown that the observed <jats:italic>L</jats:italic> <jats:sub>STCS</jats:sub> and the embedding parameter, <jats:italic>σ</jats:italic> <jats:sub>emb</jats:sub>, characterizing the contribution of the STCS to the total current density in the CS are well described by the novel analytical kinetic model of a multilayered CS with an inner embedded electron-scale layer: <jats:italic>L</jats:italic> <jats:sub>STCS</jats:sub>∼ (0.9–1.2)<jats:italic>λ</jats:italic> and <jats:italic>σ</jats:italic> <jats:sub>emb</jats:sub> ∼ (0.9–1.2) <jats:italic>σ</jats:italic> <jats:sub>model</jats:sub>, where the universal spatial scaling <jats:italic>λ</jats:italic> ∼ <jats:italic>δ</jats:italic> <jats:sub> <jats:italic>i</jats:italic> </jats:sub> <jats:sup>2</jats:sup>/<jats:italic>ρ</jats:italic> <jats:sub> <jats:italic>P</jats:italic> </jats:sub> and the embedding parameter<jats:italic> σ</jats:italic> <jats:sub>model</jats:sub> ∼ <jats:italic>δ</jats:italic> <jats:sub> <jats:italic>i</jats:italic> </jats:sub>/<jats:italic>ρ</jats:italic> <jats:sub> <jats:italic>P</jats:italic> </jats:sub> are determined by the local ion inertial length (<jats:italic>δ</jats:italic> <jats:sub> <jats:italic>i</jats:italic> </jats:sub>) and gyroradius of thermal protons (<jats:italic>ρ</jats:italic> <jats:sub> <jats:italic>P</jats:italic> </jats:sub>) in the STCS.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work we explore the possibility of variations in the primordial scalar power spectrum around the power-law shape, as predicted by single-field slow-roll inflationary scenarios. We search for a trace of these fluctuations in a semiblind, model-independent way in observations of the cosmic microwave background (CMB) sky. In particular, we use two sets of perturbation patterns, specific patterns with typical features such as oscillations, bumps, and transitions, as well as perturbation modes, constructed from eigenanalysis of the forecasted or measured covariance of perturbation parameters. These modes, in principle, span the parameter space of all possible perturbations to the primordial spectrum and, when rank ordered, the ones with the highest detectability would suffice to explore the constrainable features around the power-law spectrum in a data-driven (and not theoretically biased) manner. With Planck measurements of CMB anisotropies, the amplitudes of all perturbation patterns considered in this work are found to be consistent with zero. This finding confirms, in the absence of theoretical biases, the consistency of the Planck data with the assumption of a power-law inflationary pattern for the primordial spectrum.</jats:p>