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<jats:title>Abstract</jats:title> <jats:p>We present the results of surveying [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub>, <jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3, and 630 <jats:italic>μ</jats:italic>m dust continuum emission for 36 nearby ultra/luminous infrared galaxies (U/LIRGs) using the Band 8 receiver mounted on the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array. We describe the survey, observations, data reduction, and results; the main results are as follows. (i) We confirmed that [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub> has a linear relationship with both the <jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3 and 630 <jats:italic>μ</jats:italic>m continuum. (ii) In NGC 6052 and NGC 7679, <jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3 was detected but [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub> was not detected with a [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub>/<jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3 ratio of ≲0.08. Two possible scenarios of weak [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub> emission are C<jats:sup>0</jats:sup>-poor/CO-rich environments and an environment with an extremely large [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub> missing flux. (iii) There is no clear evidence showing that galaxy mergers, AGNs, and dust temperatures control the ratios of [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub>/<jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3 and <jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{[{\rm{C}}\,{\rm\small{I}}](1-0)}^{{\prime} }/{L}_{630\mu {\rm{m}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">[</mml:mo> <mml:mi mathvariant="normal">C</mml:mi> <mml:mspace width="0.25em" /> <mml:mi mathsize="small" mathvariant="normal">I</mml:mi> <mml:mo stretchy="false">]</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msubsup> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>630</mml:mn> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac16dfieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. (iv) We compare our nearby U/LIRGs with high-<jats:italic>z</jats:italic> galaxies, such as galaxies on the star formation main sequence (MS) at <jats:italic>z </jats:italic>∼ 1 and submillimeter galaxies (SMGs) at <jats:italic>z</jats:italic> = 2–4. We found that the mean value for the [C <jats:sc>i</jats:sc>] <jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>1</jats:sub>–<jats:sup>3</jats:sup> <jats:italic>P</jats:italic> <jats:sub>0</jats:sub>/<jats:sup>12</jats:sup>CO <jats:italic>J</jats:italic> = 4 − 3 ratio of U/LIRGs is similar to that of SMGs but smaller than that of galaxies on the MS.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work, we continue large-scale ab initio computations for single ionized lanthanides. Extended atomic calculations for the set of ions from Pr <jats:sc>ii</jats:sc> (<jats:italic>Z</jats:italic> = 59) to Gd <jats:sc>ii</jats:sc> (<jats:italic>Z</jats:italic> = 64) have been performed in our previous work. In this study, ions from Tb <jats:sc>ii</jats:sc> (<jats:italic>Z</jats:italic> = 65) to Yb <jats:sc>ii</jats:sc> (<jats:italic>Z</jats:italic> = 70) are analyzed. By employing the same multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods that are implemented in the general-purpose relativistic atomic structure package GRASP2018, the energy levels and transition data of electric dipole (E1) transitions are computed. These computations are based on the strategies (with small variations) of Paper I. Accuracy of data is evaluated by comparing the computed energy levels with the data provided by the National Institute of Standards and Technology (NIST) database and with data from various methods. We obtain the average accuracy in the energy level compared with the NIST database: 6%, 5%, 4%, 5%, 3%, and 3% for Tb <jats:sc>ii</jats:sc>, Dy <jats:sc>ii</jats:sc>, Ho <jats:sc>ii</jats:sc>, Er <jats:sc>ii</jats:sc>, Tm <jats:sc>ii</jats:sc>, and Yb <jats:sc>ii</jats:sc>, respectively. We also provide extensive comparison of transition probabilities and wavelengths. Our results reach the average accuracy of transition wavelengths: 9%, 9%, 9%, 3%, 4%, and 11% for Tb <jats:sc>ii</jats:sc>, Dy <jats:sc>ii</jats:sc>, Ho <jats:sc>ii</jats:sc>, Er <jats:sc>ii</jats:sc>, Tm <jats:sc>ii</jats:sc>, and Yb <jats:sc>ii</jats:sc>, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a morphological and spectral study of a sample of 99 BL Lac objects using the LOFAR Two-Metre Sky Survey Second Data Release (LDR2). Extended emission has been identified at gigahertz frequencies around BL Lac objects, but with LDR2 it is now possible to systematically study their morphologies at 144 MHz, where more diffuse emission is expected. LDR2 reveals the presence of extended radio structures around 66/99 of the BL Lac nuclei, with angular extents ranging up to 115″, corresponding to spatial extents of 410 kpc. The extended emission is likely to be both unbeamed diffuse emission and beamed emission associated with relativistic bulk motion in jets. The spatial extents and luminosities of the extended emission are consistent with the unification scheme for active galactic nuclei, where BL Lac objects correspond to low-excitation radio galaxies with the jet axis aligned along the line of sight. While extended emission is detected around the majority of BL Lac objects, the median 144–1400 MHz spectral index and core dominance at 144 MHz indicate that the core component contributes ∼42% on average to the total low-frequency flux density. A stronger correlation was found between the 144 MHz core flux density and the <jats:italic>γ</jats:italic>-ray photon flux (<jats:italic>r</jats:italic> = 0.69) than between the 144 MHz extended flux density and the <jats:italic>γ</jats:italic>-ray photon flux (<jats:italic>r</jats:italic> = 0.42). This suggests that the radio-to-<jats:italic>γ</jats:italic>-ray connection weakens at low radio frequencies because the population of particles that give rise to the <jats:italic>γ</jats:italic>-ray flux are distinct from the electrons producing the diffuse synchrotron emission associated with spatially extended features.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Understanding the origins of small-scale flats of CCDs and their wavelength-dependent variations plays an important role in high-precision photometric, astrometric, and shape measurements of astronomical objects. Based on the unique flat data of 47 narrowband filters provided by JPAS-Pathfinder, we analyze the variations of small-scale flats as a function of wavelength. We find moderate variations (from about 1.0% at 390 nm to 0.3% at 890 nm) of small-scale flats among different filters, increasing toward shorter wavelengths. Small-scale flats of two filters close in central wavelengths are strongly correlated. We then use a simple physical model to reproduce the observed variations to a precision of about ±0.14% by considering the variations of charge collection efficiencies, effective areas, and thicknesses between CCD pixels. We find that the wavelength-dependent variations of the small-scale flats of the JPAS-Pathfinder camera originate from inhomogeneities of the quantum efficiency (particularly charge collection efficiency), as well as the effective area and thickness of CCD pixels. The former dominates the variations in short wavelengths, while the latter two dominate at longer wavelengths. The effects on proper flat-fielding, as well as on photometric/flux calibrations for photometric/slitless spectroscopic surveys, are discussed, particularly in blue filters/wavelengths. We also find that different model parameters are sensitive to flats of different wavelengths, depending on the relations between the electron absorption depth, photon absorption length, and CCD thickness. In order to model the wavelength-dependent variations of small-scale flats, a small number (around 10) of small-scale flats with well-selected wavelengths are sufficient to reconstruct small-scale flats in other wavelengths.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, we present a provably positive, divergence-free constrained transport (CT) scheme to simulate the steady-state solar wind ambient with the three-dimensional magnetohydrodynamics numerical model. The positivity can be lost in two ways: one way is in the reconstruction process, and the other is in the updating process when the variables are advanced to the next time step. We adopt a self-adjusting strategy to bring the density and pressure into the permitted range in the reconstruction process, and use modified wave speeds in the Harten–Lax–van Leer flux to ensure the positivity in the updating process. The CT method can keep the magnetic fields divergence-free if the magnetic fields are divergence-free initially. Thus, we combine the least-squares reconstruction of the magnetic fields with the divergence-free constraints to make the magnetic fields globally solenoidal initially. Furthermore, we adopt a radial basis function method to interpolate variables at boundaries that can keep the magnetic field locally divergence-free. To verify the capability of the model in producing structured solar wind, the modeled results are compared with Parker Solar Probe (PSP) in situ observations during its first two encounters, as well as Wind observations at 1 au. Additionally, a solar maximum solar wind background is simulated to show the property of the model’s ability to preserve the positivity. The results show that the model can provide a relatively satisfactory comparison with PSP or Wind observations, and the divergence error is about 10<jats:sup>−10</jats:sup> for all of the tests in this paper.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>There have been a few previous studies claiming that the effects of geomagnetic storms strongly depend on the orientation of the magnetic cloud portion of coronal mass ejections (CMEs). Aparna &amp; Martens, using halo-CME data from 2007 to 2017, showed that the magnetic field orientation of filaments at the location where CMEs originate on the Sun can be used to credibly predict the geoeffectiveness of the CMEs being studied. The purpose of this study is to extend their survey by analyzing the halo-CME data for 1996–2006. The correlation of filament axial direction on the solar surface and the corresponding Bz signatures at L1 are used to form a more extensive analysis for the results previously presented by Aparna &amp; Martens. This study utilizes Solar and Heliospheric Observatory Extreme-ultraviolet Imaging Telescope 195 Å, Michelson Doppler Imager magnetogram images, and Kanzelhöhe Solar Observatory and Big Bear Solar Observatory H<jats:italic>α</jats:italic> images for each particular time period, along with ACE data for interplanetary magnetic field signatures. Utilizing all these, we have found that the trend in Aparna &amp; Martens’ study of a high likelihood of correlation between the axial field direction on the solar surface and Bz orientation persists for the data between 1996 and 2006, for which we find a match percentage of 65%.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, we design an effective and robust model to solve the 3D single-fluid solar wind plasma magnetohydrodynamics (MHD) problem of low plasma <jats:italic>β</jats:italic>. This MHD model is formulated on a six-component composite grid system free of polar singularities. The computational domain ranges from the solar surface to the super-Alfvénic region. As common to all MHD codes, this code must handle the physical positivity-preserving property, time-step enlargement, and magnetic field divergence-free maintenance. To maintain physical positivity, we employ a positivity-preserving Harten–Lax–van Leer Riemann solver and take a self-adjusting and positivity-preserving method for variable reconstruction. To loosen the time-step limitation, we resort to the implicit lower–upper symmetric Gauss–Seidel method and keep the sparse Jacobian matrix diagonally dominant to improve the convergence rate. To deal with the constant theme of a magnetic field that is divergence-free, we adopt a globally solenoidality-preserving approach. After establishing the solar wind model, we use its explicit and implicit versions to numerically investigate the steady-state solar wind in Carrington rotations (CRs) 2172 and 2210. Both simulations achieve almost the same results for the two CRs and are basically consistent with solar coronal observations and mapped in situ interplanetary measurements. Furthermore, we use the implicit method to conduct an ad hoc simulation by multiplying the initial magnetic field of CR 2172 with a factor of 6. The simulation shows that the model can robustly and efficiently deal with the problem of a plasma <jats:italic>β</jats:italic> as low as about 5 × 10<jats:sup>−7</jats:sup>. Therefore, the established implicit solar wind MHD model is very promising for simulating complex and strong magnetic environments.</jats:p>