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<jats:title>Abstract</jats:title> <jats:p>In this manuscript, the composite galaxy SDSS J103911-000057 (=SDSS J1039) is reported as a true Type-2 AGN candidate without hidden BLRs. Only narrow emission lines, not broad, detected in SDSS J1039 can be confirmed both by the F-test technique and by the expected broad emission lines with an EW smaller than 13.5 Å with a 99% confidence level. Meanwhile, a reliable AGN power-law component is preferred with a confidence level higher than 7<jats:italic>σ</jats:italic> in SDSS J1039. Furthermore, the long-term variability of SDSS J1039 from Catalina Sky Survey can be described by the DRW process with an intrinsic variability timescale <jats:italic>τ</jats:italic> ∼ 100 days, similar to normal quasars. And, based on BH mass in SDSS J1039 through the <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>–<jats:italic>σ</jats:italic> relation and on the correlation between AGN continuum luminosity and total H<jats:italic>α</jats:italic> luminosity, the expected broad H<jats:italic>α</jats:italic>, if there was one, could be reconstructed with a line width of about 300–1000 km s<jats:sup>−1</jats:sup> and with a line flux of about 666 × 10<jats:sup>−17</jats:sup> erg s<jats:sup>−1</jats:sup> cm<jats:sup>−2</jats:sup> under the virialization assumption to BLRs, providing robust evidence to reject the probability that the intrinsic probable broad H<jats:italic>α</jats:italic> was overwhelmed by noises of the SDSS spectrum in SDSS J1039. Moreover, SDSS J1039 follows the same correlation between continuum luminosity and [O <jats:sc>iii</jats:sc>] line luminosity as the one for normal broad-line AGN, indicating SDSS J1039 classified as a changing-look AGN in the dim state can be ruled out. Therefore, under the current knowledge, SDSS J1039 is a better candidate for a true Type-2 AGN.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In accepted models, magnetic tension drives reconnected magnetic flux away from the reconnection site at the local Alfvén speed. Numerous observational signatures of these outflows have been identified in solar flares, notable among them being supra-arcade downflows (SADs), almost none move at the Alfvén speed as predicted by models. Well-studied examples of SADs or SAD loops found in the flare of 2017 September 10 (SOL2017-09-10T15:35:00) move at a quarter or less of the expected Alfvén speed. Among those reasons posited to explain such discrepancies is the possibility that reconnected flux experiences a drag force during its outflow. Drag has not been included in previous reconnection models. Here, we develop the first such model in order to test the possibility that drag can explain sub-alfveńic reconnection outflows. Our model uses thin flux tube dynamics, previously shown to match features of flare observations other than outflow speed, including for the 2017 September 10 flare. We supplement the dynamics with a drag force representing the tube’s interaction with surrounding plasma through the formation of a wake. The wake’s width appears as a parameter in the force. We perform simulations, varying the drag parameter and synthesizing EUV observations, to test whether a drag force can produce a reasonable fit to observed features of the September 10 flare. We find that that slower retraction increases the brightness of emission and lowers the temperature of the synthetic plasma sheet. With proper choice of parameters the drag enables the simulation to agree reasonably with the observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study how stellar rotation curves (RCs) of galaxies are correlated on average with morphology and stellar mass (<jats:italic>M</jats:italic> <jats:sub>star</jats:sub>) using the final release of Sloan Digital Sky Survey IV MaNGA data. We use the visually assigned <jats:italic>T</jats:italic>-types for the morphology indicator, and adopt a functional form for the RC that can model non-flat RCs at large radii. We discover that within the radial coverage of the MaNGA data, the popularly known flat rotation curve at large radii applies only to the particular classes of galaxies, i.e., massive late types (<jats:italic>T</jats:italic>-type ≥ 1, <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> ≳ 10<jats:sup>10.8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) and S0 types (<jats:italic>T</jats:italic>-type = −1 or 0, <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> ≳ 10<jats:sup>10.0</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). The RC of late-type galaxies at large radii rises more steeply as <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> decreases, and its slope increases to about +9 km s<jats:sup>−1</jats:sup> kpc<jats:sup>−1</jats:sup> at <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> ≈ 10<jats:sup>9.7</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. By contrast, elliptical galaxies (<jats:italic>T</jats:italic>-type ≤ −2) have descending RCs at large radii. Their slope becomes more negative as <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> decreases, and reaches as negative as −15 km s<jats:sup>−1</jats:sup> kpc<jats:sup>−1</jats:sup> at <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> ≈ 10<jats:sup>10.2</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. We also find that the inner slope of the RC is highest for elliptical galaxies with <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> ≈ 10<jats:sup>10.5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and decreases as <jats:italic>T</jats:italic>-type increases or <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> changes away from 10<jats:sup>10.5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The velocity at the turnover radius <jats:italic>R</jats:italic> <jats:sub> <jats:italic>t</jats:italic> </jats:sub> is higher for higher <jats:italic>M</jats:italic> <jats:sub>star</jats:sub>, and <jats:italic>R</jats:italic> <jats:sub> <jats:italic>t</jats:italic> </jats:sub> is larger for higher <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> and later <jats:italic>T</jats:italic>-types. We show that the inner slope of the RC is coupled with the central surface stellar mass density, which implies that the gravitational potential of central regions of galaxies is dominated by baryonic matter. With the aid of simple models for matter distribution, we discuss what determines the shapes of RCs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on a Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the young, energetic pulsar PSR J1617–5055. Parkes Observatory 3 GHz radio observations of the pulsar (taken about 7 yr before the NuSTAR observations) are also reported here. NuSTAR detected pulsations at a frequency of <jats:italic>f</jats:italic> ≈ 14.4 Hz (<jats:italic>P</jats:italic> ≈ 69.44 ms) and, in addition, the observation was long enough to measure the source’s frequency derivative, <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{f}\approx -2.8\times {10}^{-11}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> <mml:mo>≈</mml:mo> <mml:mo>−</mml:mo> <mml:mn>2.8</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>11</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac30e2ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> Hz s<jats:sup>−1</jats:sup>. We find that the pulsar shows one peak per period at both hard X-ray and radio wavelengths, but that the hard X-ray pulse is broader (having a duty cycle of ∼0.7), than the radio pulse (having a duty cycle of ∼0.08). Additionally, the radio pulse is strongly linearly polarized. J1617's phase-integrated hard X-ray spectrum is well fit by an absorbed power-law model, with a photon index Γ = 1.59 ± 0.02. The hard X-ray pulsations are well described by three Fourier harmonics, and have a pulsed fraction that increases with energy. We also fit the phase-resolved NuSTAR spectra with an absorbed power-law model in five phase bins and find that the photon index varies with phase from Γ = 1.52 ± 0.03 at phases around the flux maximum to Γ = 1.79 ± 0.06 around the flux minimum. Last, we compare our results with other pulsars whose magnetospheric emission is detected at hard X-ray energies and find that, similar to previous studies, J1617's hard X-ray properties are more similar to the MeV pulsars than the GeV pulsars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In late 2016, the Interstellar Boundary Explorer (IBEX) observed an enhancement of hydrogen energetic neutral atom (ENA) flux in ∼20° south from the nose direction. This enhancement was a consequence of an abrupt increase of the solar wind (SW) dynamic pressure observed at 1 au in late 2014. In subsequent years, the increased flux of 4.3 keV ENAs was observed at higher latitudes filling in the heliosheath, in ENAs at lower energies, and the Ribbon flux. We observe that the rapid increase of SW pressure occurs every solar cycle (SC) from the beginning of the regular in situ SW measurements in the ecliptic plane. The SW pressure pulse happens about 4.7 yr from the beginning of each SC, it is during the maximum phase of solar activity, and repeats with a period of ∼10.2 yr. These repeating pulses of the SW pressure can cause periodic SC variations of the ENA production in the heliosheath. We follow McComas et al. results for the relation between SW pressure increase and ENA flux enhancement to investigate the periodic SW pressure increases and their consequences for the heliosphere. Our study of time delay between the cause (pressure pulse at 1 au) and the consequence (ENA enhancement) show that IBEX observed in 2009–2011 remnants of the SW pressure pulse that happened during the maximum of SC 23.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The structured hadron-quark mixed phase, known as the pasta phase, is expected to appear in the core of massive neutron stars. Motivated by the recent advances in astrophysical observations, we explore the possibility of the appearance of quarks inside neutron stars and check its compatibility with current constraints. We investigate the properties of the hadron-quark pasta phases and their influences on the equation of state (EOS) for neutron stars. In this work, we extend the energy minimization (EM) method to describe the hadron-quark pasta phase, where the surface and Coulomb contributions are included in the minimization procedure. By allowing different electron densities in the hadronic and quark matter phases, the total electron chemical potential with the electric potential remains constant, and local <jats:italic>β</jats:italic> equilibrium is achieved inside the Wigner–Seitz cell. The mixed phase described in the EM method shows the features lying between the Gibbs and Maxwell constructions, which is helpful for understanding the transition from the Gibbs construction to the Maxwell construction with increasing surface tension. We employ the relativistic mean-field model to describe the hadronic matter, while the quark matter is described by the MIT bag model with vector interactions. It is found that the vector interactions among quarks can significantly stiffen the EOS at high densities and help enhance the maximum mass of neutron stars. Other parameters like the bag constant can also affect the deconfinement phase transition in neutron stars. Our results show that hadron-quark pasta phases may appear in the core of massive neutron stars that can be compatible with current observational constraints.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>PSR J0218+4232 is one of the most energetic millisecond pulsars known and has long been considered as one of the best candidates for very high-energy (VHE; &gt;100 GeV) <jats:italic>γ</jats:italic>-ray emission. Using 11.5 yr of Fermi Large Area Telescope (LAT) data between 100 MeV and 870 GeV, and ∼90 hr of Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in the 20 GeV to 20 TeV range, we searched for the highest energy <jats:italic>γ</jats:italic>-ray emission from PSR J0218+4232. Based on the analysis of the LAT data, we find evidence for pulsed emission above 25 GeV, but see no evidence for emission above 100 GeV (VHE) with MAGIC. We present the results of searches for <jats:italic>γ</jats:italic>-ray emission, along with theoretical modeling, to interpret the lack of VHE emission. We conclude that, based on the experimental observations and theoretical modeling, it will remain extremely challenging to detect VHE emission from PSR J0218+4232 with the current generation of Imaging Atmospheric Cherenkov Telescopes, and maybe even with future ones, such as the Cherenkov Telescope Array.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of second-epoch ALMA observations of 321 GHz H<jats:sub>2</jats:sub>O emission toward two nearby active galactic nuclei, NGC 4945 and the Circinus galaxy, together with Tidbinbilla 70 m monitoring of their 22 GHz H<jats:sub>2</jats:sub>O masers. The two-epoch ALMA observations show that the strengths of the 321 GHz emission are variable by a factor of at least a few, confirming a maser origin. In the second epoch, 321 GHz maser emission from NGC 4945 was not detected, while for the Circinus galaxy the flux density significantly increased and the velocity gradient and dispersion have been measured. With the velocity gradient spanning ∼110 km s<jats:sup>−1</jats:sup>, we calculate the disk radius to be ∼28 pc, assuming disk rotation around the nucleus. We also estimate the dynamical mass within the central 28 pc to be 4.3 × 10<jats:sup>8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub>, which is significantly larger than the larger-scale dynamical mass, suggesting the velocity gradient does not trace circular motions on that scale. The overall direction of the velocity gradient and velocity range of the blueshifted features are largely consistent with those of the 22 GHz maser emission in a thin disk with smaller radii of 0.1–0.4 pc and molecular outflows within ∼1 pc from the central engine of the galaxy, implying that the 321 GHz masers could trace part of the circumnuclear disk or the nuclear outflows.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the analysis of simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton data of eight Compton-thick active galactic nuclei (CT-AGN) candidates selected in the Swift-BAT 100 month catalog. This work is part of an ongoing effort to find and characterize all CT-AGN in the Local (<jats:italic>z</jats:italic> ≤ 0.05) Universe. We used two physically motivated models, <jats:monospace>MYTorus</jats:monospace> and <jats:monospace>borus02</jats:monospace>, to characterize the sources in the sample, finding five of them to be confirmed CT-AGN. These results represent an increase of ∼19% over the previous NuSTAR-confirmed, BAT-selected CT-AGN at <jats:italic>z</jats:italic> ≤ 0.05, bringing the total number to 32. This corresponds to an observed fraction of ∼8% of all AGN within this volume-limited sample, although it increases to 20% ± 5% when limiting the sample to <jats:italic>z</jats:italic> ≤ 0.01. Out of a sample of 48 CT-AGN candidates, selected using BAT and soft (0.3−10 keV) X-ray data, only 24 are confirmed as CT-AGN with the addition of the NuSTAR data. This highlights the importance of NuSTAR when classifying local obscured AGN. We also note that most of the sources in our full sample of 48 Seyfert 2 galaxies with NuSTAR data have significantly different lines of sight and average torus column densities, favoring a patchy torus scenario.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent wide-field integral-field spectroscopy has revealed the detailed properties of high-redshift Ly<jats:italic>α</jats:italic> nebulae, most often targeted due to the presence of an active galactic nucleus (AGN). Here, we use VLT/MUSE to resolve the morphology and kinematics of a nebula initially identified due to strong Ly<jats:italic>α</jats:italic> emission at <jats:italic>z</jats:italic> ∼ 3.2 (LABn06). Our observations reveal a two-lobed Ly<jats:italic>α</jats:italic> nebula, at least ∼173 pkpc in diameter, with a light-weighted centroid near a mid-infrared source (within ≈17.2 pkpc) that appears to host an obscured AGN. The Ly<jats:italic>α</jats:italic> emission near the AGN is also coincident in velocity with the kinematic center of the nebula, suggesting that the nebula is both morphologically and kinematically centered on the AGN. Compared to AGN-selected Ly<jats:italic>α</jats:italic> nebulae, the surface-brightness profile of this nebula follows a typical exponential profile at large radii (&gt;25 pkpc), although at small radii, the profile shows an unusual dip at the location of the AGN. The kinematics and asymmetry are similar to, and the C <jats:sc>iv</jats:sc> and He <jats:sc>ii</jats:sc> upper limits are consistent with, other AGN-powered Ly<jats:italic>α</jats:italic> nebulae. Double-peaked and asymmetric line profiles suggest that Ly<jats:italic>α</jats:italic> resonant scattering may be important in this nebula. These results support the picture of the AGN being responsible for powering a Ly<jats:italic>α</jats:italic> nebula that is oriented roughly in the plane of the sky. Further observations will explore whether the central surface-brightness depression is indicative of either an unusual gas or dust distribution or variation in the ionizing output of the AGN over time.</jats:p>